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Diagnosis, Therapy and Evidence

When Dr. Novella recently wrote about plausibility in science-based medicine, one of our most assiduous commenters, Daedalus2u, added a very important point. The data are always right, but the explanations may be wrong. The idea of treating ulcers with antibiotics was not incompatible with any of the data about ulcers; it was only incompatible with the idea that ulcers were caused by too much acid. Even scientists tend to think on the level of the explanations rather than on the level of the data that led to those explanations.

A valuable new book elaborates on this concept: Diagnosis, Therapy and Evidence: Conundrums in Modern American Medicine, by medical historian Gerald N. Grob and sociologist Allan V. Horwitz. They point out that 

many claims about the causes of disease, therapeutic practices, and even diagnoses are shaped by beliefs that are unscientific, unproven, or completely wrong.

While we try to be science-based, we are not always as scientific or as logical as we would like to think. We form hypotheses that are compatible with existing data, and then our assumptions guide our thinking and future research and sometimes interfere with our reception of new data. We must recognize those assumptions and constantly re-evaluate them. It’s important that we look the imperfections of science-based medicine squarely in the face if we are going to have any hope of overcoming them.

Of the therapies recommended in a 1927 textbook only 23 were later validated as effective or preventive. The other 211 were subsequently found to be either harmful, useless, of questionable value, or simply symptomatic.

Medical treatment has had a big impact on human health, but there’s more to the story. We developed effective treatments for ulcers, but the incidence of ulcers was already declining before those treatments had any impact. The decline of rheumatic heart disease is probably not due to antibiotics but may be due to decreased virulence of the causal bacteria. We have no idea why the incidence of stomach cancer has decreased in the US, or why it is so high in Japan.

A popular concept today is that cancer is largely a preventable illness linked to diet, environmental carcinogens and behavior. This is rooted largely in belief and hope rather than fact. Smoking is the one notable exception. Genetic factors and the many physiologic changes of aging may contribute more than we would like to think. To some extent, disease is an unavoidable consequence of life: the idea that science can eventually provide perfect health may be a chimera.

In our efforts to prevent heart attacks we are essentially treating risk factors, without a clear understanding of how they relate to pathophysiology. We are treating hypertension, hyperlipidemia and other risk factors rather than directly treating the cause(s) of cardiovascular disease. We offer behavioral prescriptions based on assumptions derived from inadequate epidemiologic evidence, and this kind of thinking can lead us astray. Recommending a low fat diet helped fuel an epidemic of obesity as people replaced the fat in their diet with extra carbohydrates.

Once we have formed a belief we are slow to respond to new evidence that refutes it. The book covers the history of tonsillectomy. Tonsillectomies remained fashionable long after the evidence showed most of them were useless.

The most interesting question they ask is

How do diagnoses come into existence and why do many disappear with the passage of time?

What ever happened to chlorosis and neurasthenia? The same patient presenting with the same symptoms in 1890 and 2010 would get entirely different diagnoses. The ailments that afflict humans don’t change much; our diagnostic categories do.

Autism, CFS and fibromyalgia are all relatively new diagnoses for conditions that undoubtedly existed long before the diagnostic name was coined. “Their pathobiology remains unknown, and there is little agreement on their diagnostic boundaries. Once given a name, however, the numbers given to each diagnosis have expanded exponentially.”

Psychiatric diagnoses are particularly slippery. Where exactly do you draw the line between normal sadness and depression? Disease occurs on a continuum and we try to fit it into discrete boxes. We organize the data differently at different times as influenced by historical circumstances. The Diagnostic and Statistical Manual of Mental Disorders (in its many iterations, now up to DSM-5) changes as it reflects not only new data but cultural, social, and political forces. There is no evidence that the new DSM categories of anxiety have improved the diagnosis, treatment, or understanding of anxiety disorders. The popularity of the diagnosis of post traumatic stress disorder (PTSD) raises issues about the connection between external causes, individual responses, and resulting symptoms. Broadened criteria for PTSD have made it possible for almost everyone to be diagnosed or considered at risk.

We differentiate between science-based medicine and belief-based medicine, but we mustn’t forget that scientists form beliefs too. Our interpretation of the evidence is influenced by our working hypotheses. We must remember to constantly guard against overinterpretation and to concentrate only on what the evidence actually shows. When we use a diagnosis, we must remember that it is not definitive, but only an artificial category we have imposed on nature to help us understand our patients’ symptoms and provide a framework for treatment decisions. When we have an explanation, we must keep re-evaluating the data to make sure another explanation doesn’t fit the data just as well.

Ionannidis showed that most published studies are wrong. Grob and Horwitz show that many of our current diagnoses, treatments, and ideas about disease may be wrong too.

I suggest that we all repeat the mantra: “I could be wrong” and keep asking “Could any other explanation fit the data?”

Posted in: Book & movie reviews, Science and Medicine

Leave a Comment (258) ↓

258 thoughts on “Diagnosis, Therapy and Evidence

  1. Anarres says:

    “…CFS and fibromyalgia are all relatively new diagnoses for conditions that undoubtedly existed long before the diagnostic name was coined.”

    CFS, FM -and MCS- are really valid diagnoses?

  2. Draal says:

    I never heard of Ionannidis but here’s the reference if others are interested too: http://www.sciencebasedmedicine.org/?p=4204

    “I’m a man.
    But I can change.
    If I have too.
    I guess.” -Red Green

  3. BillyJoe says:

    “The Diagnostic and Statistical Manual of Mental Disorders (in its many iterations, now up to DSM-5)”

    DSM-5 is not yet a reality.
    Due out in 2013 I think.

  4. art malernee dvm says:

    The idea of treating ulcers with antibiotics was not incompatible with any of the data about ulcers; it was only incompatible with the idea that ulcers were caused by too much acid. >>>>

    I suggest that we all repeat the mantra: “I could be wrong” and keep asking “Could any other explanation fit the data?”>>>>

    What were we measuring when doctors had the explanation ulcers were caused by too much acid? The quacks on TV selling all natural cures for ulcers now tell people to treat their ulcers with acid to cure them.

  5. anoopbal says:

    There is really good saying among researchers which goes along with this post:” The greatest sin a scientist can commit is to believe in his hypothesis”

  6. TimonT says:

    This post is a perfect example of why I have beome a fan of SBM. Thanks.

  7. Versus says:

    I think part of the problem is that patients put a great deal of pressure on physicians to give them a diagnosis. They want a label for their symptoms and want to hand the problem over to the physician to “fix.” I don’t have good evidence for this hypothesis, just anecdotal evidence from many conversations with physicians.

    If a real physician can’t figure out the problem, there are many faux physicians who will step into the breach. Alt med practitioners seem never at a loss for a diagnosis and treatment — thus making the real physican look like a dummy in the patient’s eyes.

  8. Galadriel says:

    Anarres, I’m told I have fibromyalgia. It’s intriguing. After being rear-ended yet again last summer, I started having bizarre unexplained pain, and even light contact on parts of my body is painful. The pain management doctor who started me on meds for “neuralgic pain” told me that he’s often seen this happen when someone has had a lot of different chronic pain over a period of time, especially with repeated physical trauma.

    I’m not in the medical field; I don’t have access to studies, so I don’t know how to find the references that were mentioned to me. But the doc at Mayo who diagnosed me tells me that there are studies showing something that they think is fibromyalgia in animals too. If I understand correctly, there are a number of correlations with FM in both people and animals: things like lack of proper sleep, which might be associated with the cause of the pain, or might be an effect, or it might just happen a lot in similar circumstances. Another seems to be over-sensitivity to medication and medication side effects. This is all filtered through my non-doctor understanding (so I may have it wrong), and again I don’t know how to find sources; I’m simply repeating what the doctor told me.

    FM is not a major problem for me most of the time; it’s just inexplicably THERE. I’m not hiding behind it, not using it as some kind of excuse, not trying to wave it around and go, “Oh, man, I’m so abuuuused, look at me!” which it seems is what most people think of in people who say they have. I tend not discuss it, because a lot of people do seem to think that it’s an invention. All it means to me is yet another kind of pain, tolerable most of the time, an annoyance a lot of the time, and something else to consider when putting together treatment programs.

    Perhaps this annoyance in my life can be explained by something else. Perhaps “fibromyalgia” will eventually be replaced by something else as a diagnosis, if they understand it better or find better treatments. In the meantime, I’m just trying to follow the advice of the doc who thinks that he can help me get yet another aggravating variety of pain under control.

  9. Robin says:

    “Autism, CFS and fibromyalgia are all relatively new diagnoses for conditions that undoubtedly existed long before the diagnostic name was coined. Their pathobiology remains unknown, and there is little agreement on their diagnostic boundaries. Once given a name, however, the numbers given to each diagnosis have expanded exponentially.”

    AND

    “When we use a diagnosis, we must remember that it is not definitive, but only an artificial category we have imposed on nature to help us understand our patients’ symptoms and provide a framework for treatment decisions. ”

    I’m a CFS patient. Defining it has been a huge issue.

    There are a few diagnostics that appear over and over in a subset of patients: natural killer cell dysfunction, increased inflammatory cytokines, upregulation of RNASEL pathway, evidence of chronic herpes infections (EBV, CMV, HHV-6) dysautonomia/POTS. The fatigue is better described as post-exertional morbidity, or poor, slow and painful recovery after exertion.

    Fatigue is a diffuse symptom that can have many many causes. Unless the most strict criteria are used in research, it’s difficult to ensure that clinically “same” CFS patients are included. This has been very controversial as researchers in the UK, and formerly at the CDC have expanded their research definitions to include almost 1% of the population, or anyone feeling chronically “unwell”. It makes a lot of their research essentially meaningless.

    Until there is more of a careful consensus about what CFS is, or a categorizing of patients into subsets based on diagnostics, the pathology will surely remain unknown.

  10. cervantes says:

    Ioannidis’s point, in a nutshell — which is perhaps slightly distorting — is essentially a profound application of Bayes Theorem; it is heavily influenced by his experience with genome wide association studies. Essentially, if you test hypotheses at random, with no initial theory to raise the prior probability, you can imagine almost anything; and all but an infinitesimal proportion of what you imagine will be false. Under those conditions, a p value of < .05 is like a screening test with a prior probability close to zero. Even specificity of .95 means that a positive test is probably false — assuming of course that you are selecting the positive tests from a large number of tested hypotheses.

    This is why in order to conduct any sort of quantitative investigation, we have to start with a plausible theory, and our chances of a correct finding depend almost entirely on establishing a substantial prior probability. It doesn't have to be very large, but the point is, the prior probability of a random hypothesis is so low that we're going to get lots of statistically significant findings which are just noise. So the "stickiness" of paradigms is actually essential to scientific progress, even though it also slows us down quite often.

    It's a difficult balance to strike.

  11. Harriet Hall says:

    From the book:

    Fibromyalgia was given its name by a committee of the American College of Rheumatology in 1990. The lead author of the paper, Fredrick Wolfe, has all but recanted the diagnosis and considers the condition to be a response to stress, depression, and anxiety. “Some of us in those days thought that we had actually identified a disease, which this is clearly not. To make people ill, to give them an illness, was the wrong thing.”

  12. Harriet Hall says:

    “patients put a great deal of pressure on physicians to give them a diagnosis. They want a label for their symptoms”

    Three thoughts about this:

    (1) There’s an old story about a patient who was delighted with her doctor because he had diagnosed her with cephalalgia after all the other doctors had told her she only had headaches. :-)

    (2) I have inflammatory polyarthritis. This is a description of the signs and symptoms, not a diagnosis. One rheumatologist thought I probably had early rheumatoid arthritis that wasn’t showing up on the tests yet, then he decided I had Still’s disease. My current rheumatologist just says I have some kind of inflammatory arthritis that doesn’t happen to fit into any of the neat diagnostic categories, but who cares? since my symptoms have completely resolved with treatment. She and I are perfectly happy with not having a label.

    (3) My favorite diagnosis is IBTHOOM. It Beats The Hell Out Of Me. I’ve seen a lot of cases of that.

  13. Galadriel says:

    I’m perplexed by Harriet Hall’s quote, above. “The condition”–whatever the cause–is apparently still a condition, no? It may not be a *disease* (I certainly don’t know) but neither are a lot of conditions that are given names and have treatment programs. I mean, allergies aren’t a disease, but there are treatments for them.

    (And if fibromyalgia is a response to stress, depression, and anxiety, I’d like to know what’s going on with me, please. Stress I have, mainly due to chronic pain of various kinds, but surprisingly I don’t have much in the way of depression or anxiety. Perhaps this is something else?)

  14. Harriet Hall says:

    I think by “condition” Wolfe meant a constellation of symptoms. When different constellations of symptoms overlap, attaching a diagnostic label to one of them may not be meaningful. Before we can look for the “causes” of fibromyalgia we have to make sure we are dealing with a discrete diagnosable entity rather than an artificially limited segment of a continuum. I think he meant that there is a continuum of patients who respond to stress, depression and anxiety with a variety of symptoms and that the committee was not justified in cutting the pie the way they did.

  15. clgood says:

    What a fabulous post. This is the meat and potatoes of what I love about SBM!

  16. cervantes says:

    I had a stiff big toe so I got referred to a podiatrist. He told me I had hallux rigidus. I asked what’s that? He said it means a “stiff big toe.” So this guy is getting paid $150/hour to translate it into Latin.

    I mention this to a colleague who is an MD. He said oh yeah, when he was a resident this guy came in with an itchy bump and the attending diagnosed pruritis nodularis. I’m sure you can guess what that means.

  17. Sir Eccles says:

    As much as I agree with Versus and Harriet about patients being happier when given a diagnosis almost to the point of demanding their diagnosis come with a catchy TLA. It is also worth pointing out that insurance companies are more likely to pay out for a condition which can be categorized on the DSM. For example, I have heard anecdotes of parents getting various speech/behavioral therapies payed for by insurance companies only when an official “autism” diagnosis was made. The diagnosis was only made in order to enable the needed therapy.

  18. micheleinmichigan says:

    # Versus

    “I think part of the problem is that patients put a great deal of pressure on physicians to give them a diagnosis.”

    And Dr. H’s response.

    As a patient I prefer a diagnoses (when possible). Why? First it makes it easier when I talk to another doctor or if my doctor leaves or I have to switch. I have Hashimoto’s Thyroiditis is so much easier to communicate than…well you can imagine. Computerized records have helped with this. As long as the diagnosing doctor keeps good records and other doctors can easily assess those, having a label to give another doctor is not as important.

    The second reason I like the diagnoses is that it makes it easier to understand my health. For instance, I have a variety of silly little allergy and inflammation things. Knowing that I have the auto-immune thyroid disease and that people who have it are a bit more prone to allergies or inflammation puts things in perspective and I don’t get too bent out of shape about it.

    Other the other hand I do understand that a diagnoses is not always accurate or desirable. My sister has a rather severe skin disorder that has never been diagnoses beyond maybe being an atypical presentation of one of the auto-immune skin diseases.

    The doctors work with her to find her triggers and find what works for her. It doesn’t appear that a diagnoses would be helpful and if inaccurate it could be unhelpful.

    Just my two cents.

    Great Article Dr. H. really enjoyed it!

  19. ebohlman says:

    In the very unlikely event that I ever get to host Saturday Night Live, the sketch I want to do is an infomercial for Miracle KiddieGrow. I’d have a mother saying how short her kid was (visuals of a toddler, well, toddling) and then what happened after she started feeding him the supplement (visuals of same kid taking a jump ball in an eighth-grade basketball game). She says “I saw it work with my own eyes!”

    The question, of course, is what that “it” was. The whole point of the joke is that the only thing she actually saw with her own eyes was that her son is taller at fourteen than he was at two. That’s not a very remarkable observation: the only parents who don’t see that are ones whose kids die tragically young or are forced to separate from their kids. Everything else isn’t an observation, it’s an attribution. But from her point of view, questioning her attribution is the same thing as questioning her observation.

    There was an elderly couple who had a dog and a cat and spoiled them both rotten. One day someone with the ability to talk to animals asked them about their lives. They both talked about how wonderful they were, with the dog concluding “they must be really powerful and important if they treat me like that” and the cat concluding “I must be really powerful and important if they treat me like that.” Same observation, different attributions.

    The problem is that a lot of people don’t seem to understand the difference between “I think you’ve jumped to an incorrect conclusion” and “you’re lying.”

  20. Harriet Hall says:

    One of the dangers of diagnosis is that once we fix on a diagnosis we tend to stop thinking. Groopman talks about this in his book “How Doctors Think.” We try to fit everything into the framework of that diagnosis rather than remembering old findings that didn’t quite fit or looking seriously at new findings that might point to a different diagnosis. A good diagnostician will not even want to hear what other doctors have said, but will start from scratch and listen to the patient’s story in her own words and try to form a truly independent opinion.

  21. Davdoodles says:

    “A popular concept today is that cancer is largely a preventable illness linked to diet, environmental carcinogens and behavior. This is rooted largely in belief and hope rather than fact. Smoking is the one notable exception.”

    Not disagreeing but, at least here in Australia, a couple more environmental carcinogens are fairly notable: the role of asbestos particles in mesothelioma and the sun, re skin cancer.

    Excellent article, btw.
    .

  22. micheleinmichigan says:

    “I have heard anecdotes of parents getting various speech/behavioral therapies payed for by insurance companies only when an official “autism” diagnosis was made.”

    This can go both ways. I have heard of insurance companies refusing to pay for SP or other therapies with a diagnoses of autism. Their rational is they don’t pay for developmental delays. That it is an educational need (not medical.)

    Otherwise, do you need a diagnoses for insurance payment or is it just the all powerful “code”? (U.S. reference.)

  23. Harriet Hall says:

    “a couple more environmental carcinogens are fairly notable: the role of asbestos particles in mesothelioma and the sun, re skin cancer.”

    Yes, and benzene, and others. But I suppose you could still argue that lung cancer was more “notable.” It certainly overwhelms the others in numbers.

    One other important factor: the normal process of DNA replication involves a certain number of copying errors and some of these lead to cancers. Probably no way to avoid that, although we can hope for treatments to improve error correction and/or elimination of faulty cells.

    Bottom line: the idea that most cancers can be avoided by diet and lifestyle changes and avoidance of environmental carcinogens is most likely a false hope.

  24. Tsuken says:

    Excellent article. I’ve been looking at the DSM5 draft recently, and wondering exactly how long it is before my profession goes the way of the dodo.

    In psychiatry we appear to have forgotten that these categories are artificial constructs created in an attempt to bring some order and reliability, to lump patients into sets to possibly aid in our understanding of what is really going wrong. Rather we have reified the constructs – and the Book in which they are held – and have largely stopped questioning them (well, many of us might as individuals, but the profession doesn’t seem to do so in any meaningful way).

    You make a really good distinction between data and explanations, and I think we would all do well to remember it

    @Sir Eccles, re: insurance paying only for diagnoses – that’s one of the factors cited by the DSM5 working group when discussing the proposal of childhood “temper dysregulation with dysphoria”; the suggestion is that many kids have been diagnosed with bipolar disorder in order to gain them access to a higher level of input than they would otherwise be offered. >_<

  25. Zoe237 says:

    “A popular concept today is that cancer is largely a preventable illness linked to diet, environmental carcinogens and behavior. This is rooted largely in belief and hope rather than fact. Smoking is the one notable exception.”

    Any evidence for this? That one, it’s true, and two, there are people out there (besides alt medders) who believe the “largely preventable” part? Might your impression be because those are the only things we can control, at least somewhat? It seems every week there are more possible carcinogens added to the list, at least according to the EPA. I was under the impression that scientists weren’t quite sure what causes cancer, or DNA mutations. Not that I live my life in fear, but I’m genuinely curious about this issue.

    I’ll just post through C, out of hundreds listed:

    http://www.cancer.org/docroot/PED/content/PED_1_3x_Known_and_Probable_Carcinogens.asp

    4-Aminobiphenyl
    Arsenic and arsenic compounds (Note: This evaluation applies to the group of compounds as a whole and not necessarily to all individual compounds within the group)
    Asbestos
    Azathioprine
    Benzene
    Benzidine
    Benzo[a]pyrene
    Beryllium and beryllium compounds
    N,N-Bis(2-chloroethyl)-2-naphthylamine (Chlornaphazine)
    Bis(chloromethyl)ether and chloromethyl methyl ether (technical-grade)
    1,3-Butadiene
    1,4-Butanediol dimethanesulfonate (Busulphan; Myleran)
    Cadmium and cadmium compounds
    Chlorambucil
    1-(2-Chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea (Methyl-CCNU; Semustine)
    Chromium[VI]
    Ciclosporin
    Cyclophosphamide

    “Cancer is caused by changes (mutations) in a cell’s DNA — its genetic “blueprint”. Some of these changes may be inherited from our parents, while others may be caused by outside exposures, which are often referred to as environmental factors. Environmental factors can include a wide range of exposures, such as lifestyle factors (nutrition, tobacco use, physical activity, etc.), naturally occurring exposures (ultraviolet light, radon, infectious agents, etc.), medical treatments (chemotherapy, radiation, and immune system-suppressing drugs used after organ transplants, etc.), workplace and household exposures, and pollution. “

  26. Zoe237 says:

    “A popular concept today is that cancer is largely a preventable illness linked to diet, environmental carcinogens and behavior. This is rooted largely in belief and hope rather than fact. Smoking is the one notable exception.”

    Any evidence for this? That one, it’s true, and two, there are people out there (besides alt medders) who believe the “largely preventable” part? Might your impression be because those are the only things we can control, at least somewhat? It seems every week there are more possible carcinogens added to the list, at least according to the EPA. I was under the impression that scientists weren’t quite sure what causes cancer, or DNA mutations. Not that I live my life in fear, but I’m genuinely curious about this issue.

    I’ll just post through C, out of hundreds listed:

    http://www.cancer.org/docroot/PED/content/PED_1_3x_Known_and_Probable_Carcinogens.asp

    4-Aminobiphenyl
    Arsenic and arsenic compounds (Note: This evaluation applies to the group of compounds as a whole and not necessarily to all individual compounds within the group)
    Asbestos
    Azathioprine
    Benzene
    Benzidine
    Benzo[a]pyrene
    Beryllium and beryllium compounds
    N,N-Bis(2-chloroethyl)-2-naphthylamine (Chlornaphazine)
    Bis(chloromethyl)ether and chloromethyl methyl ether (technical-grade)
    1,3-Butadiene
    1,4-Butanediol dimethanesulfonate (Busulphan; Myleran)
    Cadmium and cadmium compounds
    Chlorambucil
    1-(2-Chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea (Methyl-CCNU; Semustine)
    Chromium[VI]
    Ciclosporin
    Cyclophosphamide

    “Cancer is caused by changes (mutations) in a cell’s DNA — its genetic “blueprint”. Some of these changes may be inherited from our parents, while others may be caused by outside exposures, which are often referred to as environmental factors. Environmental factors can include a wide range of exposures, such as lifestyle factors (nutrition, tobacco use, physical activity, etc.), naturally occurring exposures (ultraviolet light, radon, infectious agents, etc.), medical treatments (chemotherapy, radiation, and immune system-suppressing drugs used after organ transplants, etc.), workplace and household exposures, and pollution. “

  27. Harriet Hall says:

    Zoe237,

    Yes, there’s plenty of evidence that it is commonly believed that cancer is largely preventable (while there’s no convincing evidence to support that belief). And no, it’s not just alt-medders who believe that. The book cites numerous references. For instance:

    Scientists at the Harvard School of Public Health estimate that up to 75% of American cancer deaths can be prevented. They list these risk factors:

    Smoking and tobacco use 30%
    Obesity and diet (red meat vs. fruits and vegetables) 30%
    Lack of exercise 5%
    Carcinogens in the workplace 5%
    Viruses (hepatitis, human papillomavirus) 5%
    Family history of cancer 5%
    Body size (taller, bigger people get more cancer) 5%
    Women’s reproductive factors (late or no childbearing, late menopause, early periods) 3%
    Excessive alcohol consumption 3%
    Poverty (aside from bad diet) 3%
    Environmental pollution 2%
    Excessive exposure to sun 2%
    Medical procedures, drugs 1%
    Salt, food additives, contaminants 1%

    http://www.health.harvard.edu/newsletters/Harvard_Mens_Health_Watch/2009/April/The-10-commandments-of-cancer-prevention

    Estimates like these have been criticized in the literature by other scientists who are not convinced that most cancers are preventable.

    There are lots of known carcinogens such as the ones you listed, but all added together they explain only a very small percentage of all cancer cases.

  28. JMB says:

    I think there are certain concepts shared by doctors that may not always be evident in discussions. I think those things left unsaid may be the source of some differences in opinion.

    To doctors, cancer is a broad category of diseases. Just like infectious disease, there are many different etiologies, but a few shared features. If you wish to discuss factors in the development of cancer, you must specify not only the category of cancer, but even the cell type (there are different forms of lung cancer, breast cancer, bone marrow cancer, etc.). Blanket statements about cancer usually refer to an average of the most common lethal cancers.

    Toxins are another subject that I think there is a conceptual difference. To a doctor, the main concern is the concentration of the toxin in the body, and the toxicity of the substance. The oxygen and water you are dependent on, can become toxic at certain concentrations, or in certain scenarios (and I don’t mean drowning). There are a few substances that are toxic in trace quantities. Those lists of carcinogenic substances don’t usually specify the concentrations at which they become carcinogenic. Although there may be test tube tests to compare the likelyhood of damage to DNA, there is a big lack of information in most cases about what concentrations may be carcinogenic.

    I think a shift is currently occurring in medicine as advances in genetics become fully understood. The rate of mutation of our DNA is probably much greater than we ever understood, and the bodies compensation for damage to DNA is also much greater than we have previously understood. Changes in the bodies capacity to compensate for DNA damage may be a bigger factor in the development of cancer than we have given it credit for. The timing of exposure to carcinogens based on the number of stem cells present may also be a factor (when women become pregnant, deliver, and breast feed, the stem cells of the breast may be stimulated to differentiate, reducing the sensitivity of the breast to carcinogenic factors because of the reduction of stem cell populations). Again, when I refer to cancer, I’m talking about the average of the more common lethal forms of cancer.

    That may be some of the background that may lead to some disagreements.

    @cervantes “I had a stiff big toe so I got referred to a podiatrist. He told me I had hallux rigidus. I asked what’s that? He said it means a “stiff big toe.” So this guy is getting paid $150/hour to translate it into Latin.

    I mention this to a colleague who is an MD. He said oh yeah, when he was a resident this guy came in with an itchy bump and the attending diagnosed pruritis nodularis. I’m sure you can guess what that means.”

    You might just be joking about it, but I’ll address it for those who would take it seriously.

    There are different types of diagnosis. Pruritis nodularis is more of a classification of physical findings and symptoms, what the government used to call a provisional diagnosis. The Latin terminology implies that some observer with experience in classifying skin physical exam features has observed it. Pruritis nodularis doesn’t mean much more because there are so many different etiologies that have to be considered.

    Hallux rigidus is a more involved diagnosis that usually involves both the history and physical, and the xray findings (although the physical exam may suffice in many instances). It has implications about what caused it (a mechanical degenerative process), the prognosis (unlikely to improve by physical therapy, pain may be controlled by medication, but such treatment will have to be continued indefinitely), and the treatment (usually requires surgery for permanent relief when the symptoms become debilitating). Orthopedists and podiatrists may come down pretty hard on me for my oversimplification of hallux rigidus.

    The use of Latin was a tradition in medicine, but did allow more specific information to be communicated between doctors. Compare, “stiff big toe that hurts” to hallux rigidus. A “stiff big toe” could be due to many things, such as gout.

    Diagnosis is really an abbreviated summary of medical findings, the findings may consist of history, physical exam, laboratory or imaging findings, or pathology findings from microscopic or macroscopic examination of tissues. The diagnosis may also include the patient’s response to the disease process, or simply the pattern of behavioral responses. You can describe a diagnosis as being a provisional diagnosis, a final diagnosis, a laboratory or imaging diagnosis, a medical diagnosis, a surgical diagnosis, a psychological diagnosis, and on and on.

    You’re paying for more than just the Latin, you’re paying for the educational background and the determination of what may need to be done to relieve the patient’s complaints, or what further tests may be needed to determine the cause.

  29. BillyJoe says:

    cervantes,

    “I had a stiff big toe so I got referred to a podiatrist. He told me I had hallux rigidus. I asked what’s that? He said it means a “stiff big toe.” So this guy is getting paid $150/hour to translate it into Latin.

    I mention this to a colleague who is an MD. He said oh yeah, when he was a resident this guy came in with an itchy bump and the attending diagnosed pruritis nodularis. I’m sure you can guess what that means.”

    Here’s another one:

    A doctor friend of mine (I’m making this up, I don’t have a doctor friend) complained bitterly about a patient who came in every week with a list of minor, self-limiting, innocuous symptoms demanding his diagnosis. Imagine his delight when one day he was able to write in her history: diagnosis “Proctalgia”!

  30. micheleinmichigan says:

    Women’s reproductive factors (late or no childbearing, late menopause, early periods) 3%

    I don’t want to address the other factors, but this one jumped out. How is this preventable?

  31. Zoe237 says:

    I don’t think Dr. Hall’s list was about preventable factors solely, since family history was on there too. But 75% is definitely a big number.

    Okay, so the Harvard School of Public Health link answers my second question, so how about some evidence that cancer is NOT largely preventable? Sounds like there is some legitimate scientific debate on boths sides and that categorical statements about the root causes of cancer, whether genetics or environmental, are not yet justified by the evidence. But that’s merely my general impression as a layperson.

  32. Harriet Halls list of the Harvard School of Public Health’s risk factors adds up to 100%. Presumably these are the “preventable” ones, and the “unpreventable” causes are on another list.

    It’s not clear why age (not on the list) is presumably considered “unpreventable” while “family history” is considered “preventable.” Perhaps because family history can be prevented by not having biological children?

    Or is this a list of all causes, and age is not an independent risk factor after all?

  33. weing says:

    A lot of my patients are getting over asteatotic eczema now that it’s warming up. It sounds much better than winter itch.

  34. micheleinmichigan says:

    Actually, I get it now. Dr. H is a list of risk factors. Some of those risk factors may be preventable, others not so much…like tallness, family history, etc.

    I guess I was bottom up reading again. Bad habit.

  35. “Women’s reproductive factors (late or no childbearing, late menopause, early periods) 3%

    I don’t want to address the other factors, but this one jumped out. How is this preventable?”

    When women get pregnant, the breast tissue begins changing to get ready for nursing. “Lobules” that will eventually produce milk develop from “type 1″ to “type 4″ across the pregnancy. If the pregnancy ends somehow before delivery, you have tissue that has been provoked into a growth mode, then interrupted before the natural course of this growth. In the “type 2″ or “type 3″ phase.

    While miscarriage is a reason for interrpupted pregnancies, the vast majority of such ended pregancies, while the breast tissue has these “lobules” in the “type 2″ and “type 3″ phase, are by choice. So, if a woman chooses to not voluntarily end any pregnancy she has up to the age of 40, then she is at lower risk of breast cancer.

    There is an impressive body of evidence regarding this phenomenon. For political reasons, it is generally discounted.

    There are a lot of web sites with this info, like this site:
    http://www.abortionbreastcancer.com/

    Additionally, it is more politically correct to acknowledge that the length of time a woman’s body is exposed to estrogen increases the likelihood of breast cancer. So, these are risk factors for breast cancer: earlier onset of menses; later onset of menopause, having fewer children or no children (pregnancy interrupts the otherwise normal estrogen exposure cycle).

    There are well over a million voluntary abortions per year. So, obviously, there is some missed opportunity to prevent some breast cancer cases in women. To realize this, you have to be willing to dispassionately review evidence outside of the echo chamber.

  36. daedalus2u says:

    Uterine cancer is virtually 100% preventable by hysterectomy.

  37. apteryx says:

    Unfortunately it is well documented that rates of certain common cancers vary dramatically among cultures; for example, Americans have much higher age-adjusted rates of breast and colon cancer than people in many other countries. Please, everyone, note that those are age-adjusted rates and do not suggest that it’s because foreigners don’t live long enough to get cancer. There is no evidence to support a hypothesis that this is due to a uniquely high rate of genetic flaws in Americans, and considerable epidemiological evidence that environmental factors are involved: when people from the low-incidence cultures move here and adopt our diet and lifestyle, their risk rises.

  38. apteryx says:

    MedsVsTherapy – That is simply not true. Though women who do bear children are at less risk of breast cancer than those who do not, the best, largest epidemiological studies show zero increased risk in women who have had either voluntary or involuntary pregnancy terminations. Falsely threatening women with cancer to try to keep them from aborting has the negative side effect of creating needless cancerphobia in women who have miscarried through no fault of their own. If you respect the claim of this website to be about SCIENCE-based medicine, you had better back up your allegation by citing an epidemiological study in a peer-reviewed mainstream journal.

  39. micheleinmichigan says:

    # MedsVsTherapy – I think Dr. Gorski discussed that topic of Breast Cancer and Abortion in the article “Abortion and breast cancer: The manufactroversy that won’t die” once already. http://www.sciencebasedmedicine.org/?p=2749

    I was actually more focused on the early periods, late menopause aspect of the comment. I do not see a way to change those without Lupron or hormone treatment that would have it’s own risks.

  40. micheleinmichigan says:

    Oh well, malnutrition can delay puberty also. I guess you could try that instead of lupron.

  41. micheleinmichigan says:

    MedsVsTherapyon

    “Additionally, it is more politically correct to acknowledge that the length of time a woman’s body is exposed to estrogen increases the likelihood of breast cancer. So, these are risk factors for breast cancer: earlier onset of menses; later onset of menopause, having fewer children or no children (pregnancy interrupts the otherwise normal estrogen exposure cycle).”

    Hmm, so you’re addressing me (the commentor who just told the story about her infertility in another thread) tell me that breast cancer is “preventable” by bearing children. Shouldn’t “preventable” be, oh I don’t know, something that people have control over?

    See, that only confirms in my mind “Politically Correct” to some people = NOT being a jerk in my book.

  42. MedsVsTherapy on abortion as a cause of breast cancer:

    “So, if a woman chooses to not voluntarily end any pregnancy she has up to the age of 40, then she is at lower risk of breast cancer.

    “There is an impressive body of evidence regarding this phenomenon. For political reasons, it is generally discounted.”

    Amy Tuteur is “eagerly awaiting the new ‘right to life’ campaign aimed at high school girls, tentative slogan: ‘Sleep with your boyfriend, get pregnant, stop breast cancer!’”

    http://skepticalob.blogspot.com/2010/01/sleep-with-your-boyfriend-get-pregnant.html

    Actually, I think that rather than blaming abortion for breast cancer we should acknowledge that the real problem is that we aren’t having babies early enough. At 45 I’ve never been pregnant, so my risk of breast cancer is significantly higher than it would have been if I’d had a child at 15. (Of course, in that case my risk of obtaining higher education would have dropped significantly, but that’s not that important. I’m only a woman, after all.) As a public health measure we could encourage all fifteen year old girls to give birth and give their babies up for adoption to older parents. That way we kill two birds with one stone, because the older mothers will have the health benefits of not having to go through the stresses of childbearing and/or fertility interventions in middle age.

    Clearly the only reason we aren’t promoting teen pregnancy as a good thing is fear of being thought politically incorrect by foofy liberals. Since only unscientific sissies are afraid of foofy liberals, I expect to hear more from MedsVsTherapy on how sex education should fully inform teenagers of the benefits of having chilren early for the prevention of breast cancer.

  43. Argh! Post above unreadable due to html error. Trying again.

    MedsVsTherapy on abortion as a cause of breast cancer:

    “So, if a woman chooses to not voluntarily end any pregnancy she has up to the age of 40, then she is at lower risk of breast cancer.

    “There is an impressive body of evidence regarding this phenomenon. For political reasons, it is generally discounted.”

    Amy Tuteur is “eagerly awaiting the new ‘right to life’ campaign aimed at high school girls, tentative slogan: ‘Sleep with your boyfriend, get pregnant, stop breast cancer!’”

    http://skepticalob.blogspot.com/2010/01/sleep-with-your-boyfriend-get-pregnant.html

    Actually, I think that rather than blaming abortion for breast cancer we should acknowledge that the real problem is that we aren’t having babies early enough. At 45 I’ve never been pregnant, so my risk of breast cancer is significantly higher than it would have been if I’d had a child at 15. (Of course, in that case my risk of obtaining higher education would have dropped significantly, but that’s not that important. I’m only a woman, after all.) As a public health measure we could encourage all fifteen year old girls to give birth and give their babies up for adoption to older parents. That way we kill two birds with one stone, because the older mothers will have the health benefits of not having to go through the stresses of childbearing and/or fertility interventions in middle age.

    Clearly the only reason we aren’t promoting teen pregnancy as a good thing is fear of being thought politically incorrect by foofy liberals. Since only unscientific sissies are afraid of foofy liberals, I expect to hear more from MedsVsTherapy on how sex education should fully inform teenagers of the benefits of having chilren early for the prevention of breast cancer.

  44. Fifi says:

    Dr Hall – “A popular concept today is that cancer is largely a preventable illness linked to diet, environmental carcinogens and behavior. This is rooted largely in belief and hope rather than fact. Smoking is the one notable exception. Genetic factors and the many physiologic changes of aging may contribute more than we would like to think. To some extent, disease is an unavoidable consequence of life: the idea that science can eventually provide perfect health may be a chimera.”

    The very idea of “perfect health” is a chimera really. Could you provide some evidence for your assertion that diet, environmental carcinogens and behavior (or exercise) don’t play into the development (or non-development) of some cancers? After all, it’s popular amongst certain factions to deny the importance of diet, exercise and behavior on health for personal or ideological reasons. This doesn’t make one non-evidence based conclusion (aka an opinion) any more scientific or unbiased by political/economic/ideological beliefs than the other side.

    I’d love to read an actual SBM oncologist’s perspective on cancer prevention since Dr Hall’s assertions seem to be personal opinion about cancer prevention rather than being evidence-based or saying “we don’t know”. After all, a whole, rather expensive, vaccination campaign has been based on the idea that a certain kind of cancer can be prevented by vaccinating against HPV.

  45. Fifi says:

    Medical science is there to provide informed choice – not to force people to eat healthily, exercise or have lots of babies. We all have the freedom to choose to engage in dangerous or unhealthy behaviors – and most of us do on a daily basis and many of us get great pleasure from doing so (and some behaviors we just like to pretend aren’t dangerous because they’re so mundane). Everyone’s personal cost/benefit analysis is going to be informed by their own values and desires, and their personal situation.

    It’s good to know if not having children or having an abortion or miscarriage contributes to the possibility of developing breast cancer. Science is about uncovering these kinds of correlations and then chasing down the facts and/or causation. Reality is reality, it’s not a moral judgment (as much as the god-botherers like to believe it is). Knowing one has an increased risk of developing any disease or condition – through genetic heritability, behavior or exposure – simply means that one can be a bit more aware and get properly tested so, if anything can be done, it can be an early intervention. Or, if there are preventative measures that can be taken, the person can choose to do so.

  46. Harriet Hall says:

    Fifi asks,

    “Could you provide some evidence for your assertion that diet, environmental carcinogens and behavior (or exercise) don’t play into the development (or non-development) of some cancers?”

    No, of course I can’t, since I never asserted any such thing!

    Your comments made me very angry. If you can’t read carefully, please don’t comment on what you imagined you read!!

  47. weing says:

    “While miscarriage is a reason for interrpupted pregnancies, the vast majority of such ended pregancies, while the breast tissue has these “lobules” in the “type 2″ and “type 3″ phase, are by choice.”

    Do you have any data to back up this claim? Do you know how many miscarriages occur without the woman even knowing she was pregnant?

  48. Harriet Hall says:

    Fifi said, “Dr Hall’s assertions seem to be personal opinion about cancer prevention”

    I wasn’t asserting anything and I didn’t express a personal opinion. I was explaining what Grob and Horwitz said in their book and I was reporting some of the evidence they cited. My personal opinion is that many cancers are caused by environmental and preventable factors but that many are not, and that we don’t yet have reliable numbers and that the idea that cancer is mostly a preventable illness is not supported by convincing evidence.

    And where is your evidence for your statement that “it’s popular amongst certain factions to deny the importance of diet, exercise and behavior on health”? What factions are those? Certainly no one on SBM has ever denied that! In fact, I don’t remember ever hearing anyone anywhere say that those factors were not important to health.

  49. micheleinmichigan says:

    Okay, for those who haven’t read all the Dr Bios. Here is part of Dr. H.

    “She received her BA and MD from the University of Washington, did her internship in the Air Force (the second female ever to do so), and was the first female graduate of the Air Force family practice residency at Eglin Air Force Base. During a long career as an Air Force physician, she held various positions from flight surgeon to DBMS (Director of Base Medical Services) and did everything from delivering babies to taking the controls of a B-52.”

    Now, I worked with the military (as a civilian contractor) for about 5 years. Although it was Army and Marines, I think I can slightly generalize that knowledge to reinterpret this bio to read.

    “She is not a woman who is going to take alot of guff.”

    Which is why I enjoy your comments Dr. H. (As long as your sternness is not directed at me, of course.)

  50. lillym says:

    Dr. Hal, if I remember correctly this issue — whether or not cancer and certain other disease are preventable by diet and execise — was one of the (many) things that Fifi disagreed with Dr. Amy about. (and I think maybe that’s who she is refering to when she says “factions”).

    Fifi made the same accusation of “ideological” reasons against Dr. Amy.

    I’m not sure why Fifi is reacting in such an irrational way and attacking you but maybe it’s touched off a sore point and so she attacked out of some automatic reflex as if you were Dr. Amy.

  51. weing says:

    Some factions think that certain diets and behaviors prevent cancer. I prefer to think that they lower the risk of getting the cancer except for prophylactic orchiectomies, hysterectomies, etc.

  52. apteryx says:

    weing – If you consistently use “prevention” to mean avoidance of all risk, that’s fair enough; if lifetime adoption of a particular diet and lifestyle would cut your risk of colon cancer in half, there’s still that other half that wasn’t prevented. Should we be equally careful to say that statins don’t “prevent” second heart attacks, but “lower the risk” of having one?

  53. weing says:

    apteryx

    That would definitely be more accurate.

  54. Fifi says:

    Dr Hall, there are many popular beliefs about cancer that aren’t evidence based and, to this reader at least, you seem to have dismissed what seem like valid and evidence-based concerns about environmental toxins and the contribution of lifestyle to some conditions and diseases. You do seem, to me at least, to promote the idea that cancer is merely a natural result of aging and/or genes and that behavior makes no difference. (But perhaps your alignment with Dr Tuteur and views on global warming have led me to read your posts and comments with a certain cynicism.)

    There certainly seems to be enough evidence – gathered via scientific research – to indicate that diet, exercise and behavior probably influence the development and progression of some kinds of cancer. (I’m not even sure why you’d make sweeping generalizations about cancer considering how many different kinds we know about.) The link between sun exposure/burning and skin cancer, and certain substances like asbestos and lung cancer seem quite well supported by research (though I, as always, remain open to the possibility that the science is wrong, particularly since we’re still really at the early stages of understanding cancer – despite how far along we’ve come). Interestingly, in the case of Dr Wigand who blew the whistle on Big Tobacco, it was a cancer causing additive – coumarin – and not tobacco in and of itself that caused him to speak up. While Dr Wigand is to be commended as a person of conscience, I’m not sure if we can claim this as a victory for medical science since science was being abused by industry to sell more cigarettes and the whistle blowing was a matter of conscience rather than a scientific discovery. It’s pretty clear that industry has a big stake in promoting the idea that their practices, products or by-products (pollution) don’t cause cancer or any other disease (or global warming) so, ultimately, I’ll trust the oncologists and cancer researchers’ take on it (which, at the moment, seems to be that diet, exercise, behavior and genetics can play a role in who gets cancer – depending on the cancer being discussed, of course, and acknowledging that there are a diversity of opinions amongst the expert scientists).

    I am curious as to where you stand regarding the HPV vaccine in light of your views on cancer, causation and prevention. Some people obviously believe that there’s good enough evidence for a viral cause for certain kinds of cancer to think it’s good preventative medicine to promote vaccination against HPV. Do you?

    I’m sorry if my bringing this up or commenting on your posts makes you angry – but please don’t try to make me responsible for your emotional reactions. I may well be reading more into what you’ve written here based of the entirety of your writing that I’ve read, however you seem to bring your own baggage to my comments so we seem to be pretty much doing the same thing in that regard.

  55. Fifi says:

    weing – “I prefer to think that they lower the risk of getting the cancer except for prophylactic orchiectomies, hysterectomies, etc.”

    More or less my own take on it – depending on the type of cancer of course. I haven’t met that many people who think that being active and eating well will actually eliminate the risk of cancer, most people seem to believe the general concept promoted by cancer organizations – that eating well and exercising lowers cancer risk. And most people I know consider themselves at increased risk if there’s cancer in their family (that there’s a genetic risk).

  56. micheleinmichigan says:

    apteryx – “Should we be equally careful to say that statins don’t “prevent” second heart attacks, but “lower the risk” of having one?”

    I know you comment was addressed to weing not me. But to mention a something your comment illuminated for me.

    To say that second heart attacks are preventable, because we have stantins available, is quite different than saying statins prevent second heart attacks. This is assuming that there are a group of people who can not take statins.

    So, to me this is more about being factual than as another poster (FiFi, I think) suggested, blame, guilt, etc.

  57. Harriet Hall says:

    Fifi,

    Arrgh!! you say “you seem to have dismissed what seem like valid and evidence-based concerns about environmental toxins and the contribution of lifestyle to some conditions and diseases.” when I just got through saying “My personal opinion is that many cancers are caused by environmental and preventable factors…” Your response is positively surreal!

    It is as if I said something was black and you asked me for evidence for why I thought it was white. And then I said again that it was black and you persisted in questioning why I thought it was white. How many times do I have to say I think cancer IS frequently caused by environmental and preventable causes before you will hear what I am saying? You are making yourself look ridiculous, and I don’t need to waste any more time trying to answer your straw man nonsense. Other readers of this blog have already read and understood what I wrote despite your attempts to misrepresent it as just the opposite.

    Once and for all: I believe that diet, exercise, and behavior not only “can” but DO play a role in who gets cancer. I just don’t believe that the existing evidence is sufficient to support the assertion that MOST cancer is preventable with diet and lifestyle changes. Is that straightforward and simple enough for you to get the message?

    I will answer your question about HPV. I think the virus causes cancer. I think the vaccine prevents cancer. I persuaded both of my 20-something daughters to get the vaccine, and I even paid for their shots.

    If you continue as before, your next step may be to ask me why I don’t accept the evidence that a virus can cause cancer and why I reject the HPV vaccine. :-)

  58. weing says:

    “To say that second heart attacks are preventable, because we have stantins available, is quite different than saying statins prevent second heart attacks. This is assuming that there are a group of people who can not take statins.”

    Statins have been shown to lower the risk of a second MI by 20-30%. In combination with Niacin that risk can be lowered by 70%.

  59. pmoran says:

    Fifi: “There certainly seems to be enough evidence – gathered via scientific research – to indicate that diet, exercise and behavior probably influence the development and progression of some kinds of cancer.”

    Yes, to “the development” of cancer, but I have never seen any good evidence that the course of cancer is significantly influenced by lifestyle once it has developed. That appplies to extreme multimodal regimes often advocated within alt.med.

  60. apteryx says:

    micheleinmichigan: “To say that second heart attacks are preventable, because we have stantins available, is quite different than saying statins prevent second heart attacks. This is assuming that there are a group of people who can not take statins.”

    I’m not sure what distinction you are making there. Of course there are people who cannot take statins – those who develop liver damage or rhabdomyolysis when they do take them.

    My question referred to the fact that prospective controlled trials suggest that statins are a causal factor for a reduced risk of heart attacks (and very possibly an increased risk of cancer). I, and probably most lay English speakers, would therefore say that “statins prevent heart attacks,” even though many people who take statins have heart attacks anyway. There’s a difference between “prevent heart attacks” and “prevent ALL heart attacks.” Weing prefers to avoid using the word “prevent” unless the latter is meant. Perhaps this is a more technical usage, which I am happy to accept once it’s explained to me. (Although I note that we don’t pussyfoot around saying that cigarettes “increase the risk of cancer” just because they don’t “cause” cancer in ALL smokers.)

  61. Fifi says:

    Dr Hall – My response may seem surreal to you but it seems surreal to me that you make broad generalizations – that aren’t evidence based – then get upset when they’re questioned! As I said, I may be attributing some of the things that Dr Tuteur promoted here to you since you aligned yourself with her so closely, and be somewhat cynical about your skepticism and beliefs in general because of your position regarding global warming. I get the impression that you’re still pissed that Dr Tuteur wasn’t ultimately seen as being fit to be an SBM blogger.

    Thanks for clarifying what you believe about diet/exercise/behavior and cancer, it wasn’t at all evident from you blog post (which made it seem as if you only considered smoking to be relevant and that anyone who believes in diet/exercise/behavior as a preventative measure is being silly). It still seems that you’re still dealing more in the realms of beliefs/opinions than evidence though since you’re still talking in generalities. It seems to me that cancer requires a more specific discussion that takes into consideration the type of cancer being discussed (and I still would be interested in an SBM oncologist’s take on prevention and specific cancers). My main point in posting is that you’re making generalizations and assertions that aren’t evidence based yourself while critiquing others for making non-evidence based assertions.

    You made a generalization about people believing that diet/exercise/behavior can prevent cancer but we clearly hang around in different circles since few people I know or run across believe this (most are quite aware of the genetic link and whether there’s cancer in their family history, they may hope diet and exercise prevents them getting cancer but they don’t believe it’s absolute). I’ve run across some exceptions, people into fringe diets and CAM who have extreme beliefs, but they’re the exception. Just as people who believe that industrial toxins and pollution, and diet and exercise, don’t play any role in the development of cancer are the exceptions.

    If you continue like before…oh, never mind, I’ll leave you to play that game by yourself :-)

  62. Harriet Hall says:

    Fifi says my blog post made it seem as if I only considered smoking to be relevant and that anyone who believes in diet/exercise/behavior as a preventative measure is being silly.

    I would like to hear the opinions of other commenters. Did anyone other than Fifi interpret my words that way?

  63. Fifi says:

    pmoran – “Yes, to “the development” of cancer, but I have never seen any good evidence that the course of cancer is significantly influenced by lifestyle once it has developed. That applies to extreme multimodal regimes often advocated within alt.med.”

    Agreed but the discussion wasn’t about “curing” or changing the course of cancer once it developed, it was about prevention and preventing the development of cancer. (Or at least that’s what I understood was being discussed.) I’ve never seen any good evidence that the course of cancer is influenced by lifestyle once it had developed – though there do seem to be some interesting studies around the role exercise plays in the prevention of recurrence of breast cancer, but that’s a different thing all together. I’m no fan of cancer quackery – and I fully believe that some people will develop some cancers entirely independent of lifestyle – it just seems that there’s some pretty good evidence for the contribution of dietary and exercise habits, and exposure to certain materials and chemicals (be it the many carcinogens in cigarettes or asbestos), in the development of cancer.

  64. Fifi says:

    Dr Hall – “A popular concept today is that cancer is largely a preventable illness linked to diet, environmental carcinogens and behavior. This is rooted largely in belief and hope rather than fact. Smoking is the one notable exception.”

  65. Harriet Hall says:

    Fifi says “people who believe that industrial toxins and pollution, and diet and exercise, don’t play any role in the development of cancer are the exceptions.”

    Who are those peole who are the exceptions? Are they real “meat” people or are they made of straw and your imagination? I’ve never even heard of anyone who said those factors don’t play any role. Name one. Show us the evidence.

  66. Fifi says:

    Dr Hall – You make generalizations about beliefs based upon no evidence but I’m not allowed to offer up anecdotal evidence about beliefs I’ve encountered myself? Really, you have a rather unreasonable double standard and expectations regarding evidence and making generalizations for yourself and others. Do you truly doubt that people who believe that cancer is entirely genetic and unavoidable exist? (I mean, you seem to believe that prevention makes no difference for most cancers! – Dr Hall “I just don’t believe that the existing evidence is sufficient to support the assertion that MOST cancer is preventable with diet and lifestyle changes.” – or at least that there’s no evidence so both your and other’s beliefs about prevention aren’t evidence based.) Do you doubt the existence of those who simply believe that cancer is an act of God? Some people in the alt med community think cancer is caused by “bad thoughts” or a disruption in the aura, do you doubt these people exist even though this blog discusses them with some regularity?

  67. nsib says:

    Dr. Hall- Not at all. I thought you were quite clear when you said: “A popular concept today is that cancer is largely a preventable illness linked to diet, environmental carcinogens and behavior. This is rooted largely in belief and hope rather than fact. Smoking is the one notable exception.”

    I, too, would like to know Fifi’s disagreement with that statement, but it seems she’s not one for citing examples, or even organizing an argument. Her latest post makes things even more muddled; she shoots down her own argument that cancer can be prevented through lifestyle changes.

    I wonder if she’s confusing “prevention” with “lowering risk”?

  68. nsib says:

    Hmm. I see I was a bit slow in posting. My previous comment was responding to Dr. Hall @17 Mar 2010 at 6:21 pm.

    Fifi, it’s nice to see that you’re so fired up about your strawmen, but let’s focus on the issue at hand. First off, how about naming a preventable cancer, and how that cancer is preventable?

  69. Fifi says:

    pmoran – I can see how you might get the impression that I believe that diet and exercise can influence, prevent or even cure cancer once it’s developed (because I said “progression of cancer”) – that was a miscommunication on my part and sloppy writing that meant I said something I didn’t actually mean. Sorry about that and thanks for making me aware of it (and my apologies for initially responding to you as if I hadn’t actually written it!).

  70. Harriet Hall on (mis)interpretation:
    “I would like to hear the opinions of other commenters. Did anyone other than Fifi interpret my words that way?”

    _______
    “A popular concept today is that cancer is largely a preventable illness linked to diet, environmental carcinogens and behavior. This is rooted largely in belief and hope rather than fact.”
    _______

    I admit, I found this statement confusing. There are two parts to it: one about how preventable cancer is through ordinary lifestyle modifications, and another about how popular the belief in preventability is.

    If the concept under discussion is that cancer is very easily preventable (this interpretation is supported by your comment that it is rooted in “belief and hope rather than fact”) then in my limited experience, no, not many people believe that. So it’s strange that you would say it is a “popular” belief. Maybe by “popular” you mean “not that uncommon,” which, sure, I can go with.

    If the concept under discussion is that many cancers could be at least partly preventable then yes, I think a lot of people believe that. But then it’s surprising to me that you state that it is rooted in “belief and hope rather than fact,” because I thought that there was some basis for thinking that.

    I read those two sentences and was puzzled. Then I moved on to:

    “Genetic factors and the many physiologic changes of aging may contribute more than we would like to think.”

    Then I remembered that this was a book review, and you were probably just telling us that there is a chapter in the book that would explain in more detail why cancer is less preventable than we would like to think.

    I also thought that when I think about the preventability of cancer, I’m thinking of not getting cancer before the age of, say, 80. I’m not thinking of not getting cancer ever, even by the age of 200. So the puzzling opening sentences of the paragraph had too many levels to parse easily.

    I moved on. Yes, the juxtaposition of “largely preventable” and “popular” was unclear to me. But precisely because it was unclear, I couldn’t take away any particular conclusion about your “ideology.” If I have more questions I can read the book you are recommending.

    Does that help?

  71. Harriet Hall says:

    OK, you have a point. I will admit that there is a tiny minority of people who have unsupportable ideas about cancer causation and who deny all the evidence. They fall in the same category as AIDS denialists and germ theory denialists. They were not on my radar.

    There is no double standard here. I did not offer beliefs based on no evidence. You questioned my description of what the book said and I offered some of the evidence cited in the book (there is more in the book). When I say that I don’t believe that the current evidence supports the idea that “most” cancers are preventable with lifestyle changes, that doesn’t mean that I believe prevention makes no difference for most cancers. It means just what it says: that I believe that the current evidence doesn’t support the idea that most cancers are preventable with lifestyle changes. I have explained that I hold no beliefs about what percentage of cancers are due to what causes or what percentage can be prevented by lifestyle changes. I don’t think the evidence is sufficient to support any such beliefs. My belief is about the state of the evidence. It is evidence-based: it’s based on the evidence that there’s no credible evidence to support the idea that most cancers are preventable with lifestyle changes.

    If you believe that most cancers are preventable with lifestyle changes, why don’t you just say so and explain why you believe it? Instead, you are quibbling about what you thought I said. And this whole discussion of cancer is distracting from the message of the book. The point of the cancer business was to illustrate that if we prematurely accept one explanation it can handicap us in an objective search for the truth. Do you have any problem with that idea?

  72. Harriet Hall says:

    Yes, I said “A popular concept today is that cancer is largely a preventable illness linked to diet, environmental carcinogens and behavior. This is rooted largely in belief and hope rather than fact. Smoking is the one notable exception.”

    Lung cancer is largely (around 90%) preventable by not smoking. That’s an established fact. It is not established that other cancers are largely preventable by diet, avoidance of environmental carcinogens, and behavior. That IS a popular concept. I did not say HOW popular it was or even suggest that the majority of the public believed it. And I cited one of several studies that prove that it is accepted in some scientific circles, and you can find a fuller exposition in the book I was reviewing. My statement is perfectly compatible with your statement that people you know “don’t believe it’s absolute.”

    You are not going to get away with twisting my words. I don’t understand why you are doing this and I find it reprehensible.

  73. micheleinmichigan says:

    Dr. H. said “Other readers of this blog have already read and understood what I wrote despite your attempts to misrepresent it as just the opposite.”

    My interpretation-

    To begin the phrase in question “A popular concept today is that cancer is largely a preventable illness linked to diet, environmental carcinogens and behavior. This is rooted largely in belief and hope rather than fact.”

    Although you are talking about the book, to me it sounds like this is one of your take aways from the book.

    It appears that you are saying we do not have evidence that cancer is LARGELY preventable. I always assume “largely” is somewhere in the 70 – 100% range, maybe 65% to stretch it. That might be just me.

    “Smoking is the one notable exception.

    This would be the one line that I questioned. I thought “What THE one?” It seemed a bit of a throw away line. Perhaps “Smoking is one OF THE notable exceptions” would be more accurate. (I don’t know, though.)

    “Genetic factors and the many physiologic changes of aging may contribute more than we would like to think.”

    This line suggests only that we don’t understand the roles of genetic and other factors, so we can not accurately determine the interplay of environment and genetics and other factors.

    ” To some extent, disease is an unavoidable consequence of life: the idea that science can eventually provide perfect health may be a chimera.”

    Probably we are all still going to die, no matter what we eat or don’t.

    “Fifi says my blog post made it seem as if I only considered smoking to be relevant and that anyone who believes in diet/exercise/behavior as a preventative measure is being silly.”

    No, I did not read it that way. I would say that I read, “we’re not really sure of the role of a lot of factors in cancer, although we do know smoking’s bad. But we are probably not ever going to be able to prevent 100% of cancers through environmental or lifestyle choices.”

    IMO that is.

  74. Fifi says:

    Dr Hall – “If you believe that most cancers are preventable with lifestyle changes, why don’t you just say so and explain why you believe it?”

    If I believed that I would have said it (it gets a bit tedious that you seem to assume that anyone who has a different perspective than you or that questions a generalization you’ve made must hold the beliefs you so clearly disdain). What I believe at the moment – and this could easily change as new evidence emerges – is that SOME cancers seem to be preventable via lifestyle measures, this is based on research I’ve read and what appears to be a consensus amongst cancer researchers. (If it’s not, I’d love to hear from an SBM oncologist about prevention.)

    That doesn’t mean that I believe MOST are – I have no opinion about “most” cancers – you’re the one hung up on “most” and so on. I’ve stated quite clearly that I believe that one can’t generalize about cancer and that some people seem to develop some cancers entirely independent of lifestyle and some cancers seem to have very clear links to certain behaviors (smoking, working in an asbestos mine, etc) while others seem to be almost entirely genetic. I don’t have any hard and fast beliefs about most cancer, though I do see eating a healthy diet and exercising as being a sensible way to generally stay healthy in the here and now (and likely to promote good health as I age). Do I think being obsessive about diet and exercise will hold death at bay? Not at all. One can get hit by a bus, contract a fatal virus or discover they have advanced pancreatic cancer at any time (and extreme diets and exercise can come with their own risks). Do I think diet or exercise can cure cancer? No. I just think constantly belittling diet and exercise – and the role it plays in health – is weird.

  75. micheleinmichigan says:

    # Harriet Hallon 17 Mar 2010 at 7:27 pm

    OK, you have a point. I will admit that there is a tiny minority of people who have unsupportable ideas about cancer causation and who deny all the evidence. They fall in the same category as AIDS denialists and germ theory denialists.

    Actually, I think they work for Phillip Morris or at least still smoke. It’s the river thing again.

  76. Fifi says:

    Oh, and it seems to me that there’s some evidence that viruses may end up playing quite an important role in some cancers (so it’s not aging or genetics in these cases). We contract viruses – particularly HPV – through behaviors (though obviously some of these behaviors are simply going about our daily activities, they don’t involve explicit behaviors such as sex, smoking or working in an asbestos mine). Of course, that doesn’t discount there being an interaction between various factors such as a viral infection, genetics and exercise or any other number of potential factors. I’m much more curious about cancer than I am married to any particular belief about causation, and it looks like there are possibly are variety of causes or cofactors for the development of different cancers.

  77. Harriet Hall says:

    Fifi,

    So you agree with me! No matter what you think I wrote in the post, can we now agree to agree that diet and exercise are important for health, that there are lots of different causes of cancer, and that there isn’t any hard evidence to support beliefs about how many cancers are caused by what?

    I also agree with you that constantly belittling diet and exercise is weird; that’s why I have never done so. If you think I have, you are reading something into my words that I never put there.

  78. squirrelelite says:

    Harriet,

    Since you said:

    “I would like to hear the opinions of other commenters. Did anyone other than Fifi interpret my words that way?”

    I’ll try for a short and quick answer here. As Alison quoted, you said:
    _______
    “A popular concept today is that cancer is largely a preventable illness linked to diet, environmental carcinogens and behavior. This is rooted largely in belief and hope rather than fact.”
    _______

    A lot of the confusion, misunderstanding or disagreement here hinges on the interpretation of general descriptive words like largely and popular.

    I don’t think anyone on this comment thread falls into that category, but it does remind me of some of the back-and-forth’s we have had with lizkat/pec.

    She seemed to go on and on quibbling about whether disease X or cause Y should best be described by some or a lot or many or most or mostly or almost all or all.

    Personally, when I read “popular”, I take it mean that a lot of people but not necessarily more than 50% support it or like it.

    Similarly with “largely”, although I am more inclined to place that in the category of more than 50%, depending on what else is said about it.

    However, in the absence of specific numbers to compare with I don’t think it helps the discussion much to argue which side of 50% is “correct”.

    If we ask if the concept that “cancer is a largely preventable disease” is popular, we only have to check a few of our “favorite” healthy living sites to get plenty of confirmation. We don’t exactly need a nationwide Gallup Poll.

    Placed in the context of the overall theme of your blog, this is only an example introduced to illustrate the interplay between the raw scientific data and our beliefs, understanding and interpretation of those data and how those affect the treatment and prevention choices we make as patients or doctors.

    That is an important issue and one which was touched on or hinted at in previous posts on plausibility and facts, but not really tackled head-on.

    I think your blog did a fairly good job of describing this issue and discussing how these factors interplay.

  79. Zoe237 says:

    Well, I asked the original question, and I’m still not sure there has been any actual evidence presented. For example, why is the Harvard School of Public Health wrong? I’m not trying to argue so much as understand… how much exactly is cancer preventable? Will the trend continue that we seem to find more and more environmental causes of cancer? Obviously even lung cancer must involve interplay with different factors, as not smoking doesn’t prevent cancer as much as reduce its likelihood (dramatically).

    I will say that the same kind of people who are AGW denialists also deny any environmental causes of cancer. They tend to be libertarians or industry apologists. I don’t think Dr. Hall falls into this category, however.

    “Ionannidis showed that most published studies are wrong. Grob and Horwitz show that many of our current diagnoses, treatments, and ideas about disease may be wrong too.”

    I also have to offer kudos for this entire post, btw. The book sounds very interesting. And the post does exactly what I’ve been begging for on this site: address the shortfalls of conventional medicine. I’m asking because I’m curious, not to derail the discussion.

  80. Harriet Hall says:

    Zoe237 asks,

    “For example, why is the Harvard School of Public Health wrong?” It has been critiqued by other scientists for various reasons; the book mentions some of their objections. You could look up those critiques to learn exactly what they thought Harvard did wrong.

    “how much exactly is cancer preventable?”
    As I’ve been saying, we don’t know. All we have so far are a few isolated facts: about 95% of lung cancer can be prevented by never smoking, HPV vaccines can prevent many but not all cervical cancers, etc. And we know lots of risk factors, but we don’t have good data on what happens in the real world if we try to eliminate those risk factors.

    “Will the trend continue that we seem to find more and more environmental causes of cancer?” Now you want me to get out my crystal ball and put on my turban? OK, my crystal ball predicts that more and more carcinogens will be identified but that the total number of cancers due to environmental causes will turn out to be small compared to the number due to all the other causes, and will be a smaller and smaller fraction as we learn how to avoid those carcinogens.

  81. Zoe237 says:

    “It has been critiqued by other scientists for various reasons; the book mentions some of their objections. You could look up those critiques to learn exactly what they thought Harvard did wrong.”

    I certainly will, and I have done some reading in the past. The problem is that each “side” is so wrapped up in their own ideology that it is hard to get at the truth. It seems like public health officials, epidemiologists, toxicologists, environmental health scientists are firmly on one side, with many doctors on another. And most doctors are not scientists… so I wonder. I do however agree that the mainstream media (not to mention human nature) love to overstate the amount of control we have over our lives.

    Fifi, Dr. T would have made 20 irrelevant comments and 3 personal attacks and declared her post explained. Not the same at all lol.

  82. JMB says:

    Reproducible observations by independent unbiased observers can force a paradigm shift. If reproducible observations by independent unbiased observers is your definition of data, then I would agree it is for practical purposes always right.

    What many will call data, the reported observations from a single experiment, still requires some skeptical assessment, just as the explanations require skeptical analysis.

    Some will apply a different label to independently reproducible observations, and call it verifiable data.

    If we use a more exact definition of data, we might avoid some of the confusion that may occur when we say, “I don’t accept their data” (after saying data is always right). Then the phrase “I don’t accept their data”, could be more clearly stated as, “There has not been sufficient verification of their data”.

  83. micheleinmichigan says:

    Zoe, It occures to me that it’s possible that neither Harvard Public Health or Dr. H. are wrong. The are just looking at the issue from a different perspective. (the blind guys and the elephant)

    It is the duty of Public Health to seek out possible health concerns, investigate and control them, sometimes even when there are no current illness associated, the risk is sufficient to block a substance.

    From a practicing doctor’s perspective, they are looking at known causes and/or risks and need to use evidence to help an individual patient makes the best lifestyle or treatments decisions for them.

    I’m pretty sure I’m saying this badly, I didn’t sleep well last night and there is not enough coffee in the world right now. But it’s possible someone will get the just of what I’m saying.

  84. apteryx says:

    Dr Hall: “Did anyone other than Fifi interpret my words that way?””

    Yes, to an extent. There may not be evidence to prove that cancer is “largely” preventable by lifestyle changes, if “largely” is defined as “over 50%.” However, when you seem to deride people who hold similar opinions as irrational or ill-informed (“rooted in belief and hope rather than fact”), without acknowledging that a substantial fraction of cancer really is preventable*, it sounds very much like you are implying: “Don’t alter your lifestyle to try to reduce your risk, it will do you little or no good.” That’s not a good message to send. It also could be argued that restricting the discussion only to whether cancer is “largely preventable” is a straw man, because most of your apparent targets might agree that cancer was less than 50% preventable, while arguing that, say, 40% prevention would still be a good thing.

    *For men, the most common [potentially] life-threatening cancers are prostate, lung, and colorectal; for women, breast cancer is by far the most common, followed by lung and colorectal cancer. It is pretty well determined that all of these are influenced by environmental factors. Other cultures have dramatically lower rates of breast, colorectal, and prostate cancer – so long as they don’t adopt the Western lifestyle – and there are a number of plausible, data-supported hypotheses as to why that might be.
    Many of the somewhat less frequent cancers in the U.S. also are linked to environment. For example, we know that getting sunburned increases melanoma risk. And when, as for bladder and oral cancer, you see enormous racial and sexual differences in incidence within the U.S., it suggests that behavior or exposure to environmental toxins might play a role (which indeed has been backed up by epidemiological studies, e.g., that show that tobacco use increases risk for both).

  85. squirrelelite says:

    michelleinmichigan,

    I think I get the gist of your message. The story of the seven blind men and the elephant is probably a good analogy.

    What question we choose to ask ourselves and how we define the terms that go into it can affect the answer(s) that we get.

    The Harvard School of Public Health report referenced earlier says that up to 75% of cancers may be prevented and cites a slightly less sanguine number from the ACS of 60% that might be prevented. But, those are top end, idealized estimates that might be achieved under perfect conditions.

    However, when the Harvard report lists causes of cancers, at least as I read it, they are now talking about all cancers, not just preventable ones. So, that 100% of causes are not all preventable.

    I found an interestng report by Miranda Hitti and Louise Chang on
    medicinenet:

    http://www.medicinenet.com/script/main/art.asp?articlekey=98100

    It says:

    “Feb. 26, 2009 — About a third of common adult cancers may be preventable in the U.S. — and that doesn’t even count cancers that could be prevented by not smoking.

    That’s according to a new report from the World Cancer Research Fund (WCRF) and its sister organization, the American Institute for Cancer Research (AICR).

    In the new report, the WCRF and AICR estimate that in the U.S., eating a nutritious diet, being physically active, and keeping body fat under control may prevent:

    * 38% of breast cancers
    * 45% of colorectal cancers
    * 36% of lung cancers
    * 39% of pancreatic cancers
    * 47% of stomach cancers
    * 69% of esophageal cancers
    * 63% of cancers of the mouth, pharynx, or larynx
    * 70% of endometrial cancers
    * 24% of kidney cancers
    * 21% of gallbladder cancers
    * 15% of liver cancers
    * 11% of prostate cancers

    Diet, physical activity, and limited body fat could prevent 34% of those 12 cancers overall in the U.S., and 24% of all cancers, according to the report.”

    If we somehow get no one in the U.S. to smoke at all :) we might avoid the 30% of cancers that are lung cancers and manage to prevent 54% of all cancers. Possible, maybe achievable, but still pretty idealistic. I notice that only 3 of the 12 common adult cancers listed have more than 50% noted as preventable.

    In conclusion, I liked this little tidbit from the medicinenet page on lung cancer prevention:

    “Prevention means avoiding the risk factors and increasing the protective factors that can be controlled so that the chance of developing cancer decreases.

    Although many risk factors can be avoided, it is important to keep in mind that avoiding risk factors does not guarantee that you will not get cancer.”

  86. Fifi says:

    Dr Hall – “So you agree with me! No matter what you think I wrote in the post, can we now agree to agree that diet and exercise are important for health, that there are lots of different causes of cancer, and that there isn’t any hard evidence to support beliefs about how many cancers are caused by what?”

    Hmmm, maybe you haven’t actually been reading what I wrote…. But I’m glad that you can agree that diet and exercise are important for supporting general health, even if you can’t agree that diet and exercise may be a factor in preventing the development of certain types of cancer (despite the fact that you’ve provided no evidence and there is quite a bit of evidence by cancer researchers in this area that you haven’t actually challenged in any meaningful or scientific way). So, no, I don’t agree with you for a couple of reasons. The main one being simply that I try to stay away from making sweeping generalizations about cancer and you’re doing this yet again. Clearly there IS some hard evidence to support various beliefs about the different causes of cancer. For instance, there seems to be good evidence that the HPV virus is linked to developing a certain cancer. And you’ve already agreed there’s good evidence that smoking is linked to developing lung cancer…and perhaps you also acknowledge the link between smoking and HPV and other cancers too? There seems to be good evidence for the link between sunburn and skin cancer, and asbestos and lung cancer as well.

    All in all, you seem to be making generalizations as a means to make an argument that doesn’t really seem to hold up when you consider that there are, on one side the cancers caused by unknown factors and on the other side the cancers which have known factors (ingesting/inhaling known carcinogens, a virus, genetic susceptibility). While I’m quite open to the idea that certain cancers can be purely genetic in origin, and there seems to be a well established genetic susceptibility to certain types of cancer, you haven’t proven that purely genes or aging are the main factors in most cancers developing. In fact, the more recent discovery that there may well be a viral component to some cancers – which you acknowledge when it was brought up but ignored in your original blog post – kind of blows your “it’s all just a matter of genes and aging” hypothesis out of the water.

    Dr Hall, you seem to want to make cancer more mysterious than it actually is because what we do know doesn’t support your hypothesis (which is not to dismiss the great deal we still don’t know about cancer). All in all, this is why I’d love to see the topic of prevention and cancer tackled by an SBM oncologist who can talk specifics rather than using generalizations to make the case for a non-evidence based speculation about what causes cancer. It may need to be a series since generalizing about different cancers doesn’t seem to make sense but I suspect I’m not the only person who’d find it interesting and informative. After all, if there’s really evidence that diet and exercise (and environment and behavior) aren’t relevant when it comes to most forms of cancer then surely that should be discussed by SBM since even cancer societies and oncologists seem to be recommending people pay attention to diet and exercise. Or are you (obliquely) making the claim that they’re just part of a cancer industry promoting their own agenda for personal reasons and profit and aren’t really science based in practice?

  87. Harriet Hall on cancer prevention:
    “HPV vaccines can prevent many but not all cervical cancers, etc. And we know lots of risk factors, but we don’t have good data on what happens in the real world if we try to eliminate those risk factors.”

    Fifi on Harriet Hall:
    “In fact, the more recent discovery that there may well be a viral component to some cancers … kind of blows your “it’s all just a matter of genes and aging” hypothesis out of the water.”

    Fifi,
    I’m not getting an “it’s all just a matter of genes and aging” vibe from Dr Hall. I’m getting an “it’s complicated” vibe.

  88. Fifi says:

    You know, from the current research it seems to me (with full acknowledgment that I’m not an expert on cancer) like there isn’t going to be “one true cause” for all cancers since we’ve so far uncovered a variety of causes for different cancers (and potential cofactors and interaction between genes and environment/behavior). It seems to me that epigenetics is showing us that the interaction between genes and environment/behavior is actually quite complex and intense. (And that we also still have a lot to learn about genes and how they function.)

  89. Fifi says:

    Alison – Yes, she’s certainly expressing that now but what I got from the initial paragraph in the blog wasn’t “it’s complicated”. What I got – and I admit I may be sensitized to this due to Dr Hall’s alliance with Dr Tuteur and her views on climate change – was yet another oblique (perhaps even unconscious) attempt to make out that people who pay attention to diet and exercise and think it may have some preventative effect against developing cancer are engaged in woo and unsubstantiated beliefs (despite the fact that most people are quite keenly aware of the genetic component to cancer in my experience) but that her speculation (a speculation I recognized because she’s made it before) that most cancers are caused by genes and aging is somehow different despite not being evidence based. (Certainly she used some qualifying and precautionary words when proposing her own position but so do cancer societies and oncologists generally.)

    Combine that with the fact that we now vaccinate against HPV specifically to prevent cervical cancer – I thought due to evidence that there’s a relationship between contracting HPV and cervical cancer if it’s to be promoted as SBM – and Dr Hall’s speculative assertion seems not to be particularly supported by the science. Pointing this out doesn’t mean I believe diet and exercise are magical, it merely means that there does seem to be evidence that behaviors (including diet, exercise, smoking cigarettes, and safe sexual activity or vaccines to prevent infection with HPV) play some role in preventing or causing some cancers. I guess the problem I run up against is that Dr Hall is saying it’s too complex to speculate and then speculates herself and offers her beliefs/opinion (while dismissing other’s beliefs). That’s what seemed uneven to me.

  90. In this whole discussion there’s also the element of “staying on message” when talking to patients.

    Doctors want to communicate that patients should quit smoking, lose weight, get more exercise and eat lots of fruits and vegetables. If they do this they will feel better and probably stay healthier. These are the really critical elements. They don’t want smokers obsessing about whether their carpets are outgassing. They want them to focus on the important stuff. Eating organic? Taking vitamin supplements? Installing an air purifier? Sure, if they feel like it, once the big things are in place.

    Still, doctors can’t promise patients that they won’t get cancer or ever have a stroke even if they do eat right and exercise. So they have to be careful.

    And then there’s all the “theoretically interesting” stuff. I remember listening to a science show once (twenty years ago?) and a researcher was talking about using some sort of magnetic resonance or something to distinguish between the fatty acid profiles of blood samples of people with and without a particular type of cancer. I was fascinated: at the time I thought of cancer tumors as just fast-growing lumps, and the idea that a lump in, say, the pancreas could have effects on another organ, say the blood, was novel to me. I mentioned it to a doctor I knew socially, who practically shrieked at me: “NO! There is no blood test for cancer!” Which I hadn’t thought there was. I hadn’t thought there was a current test (the researcher on the radio show was talking about strictly lab work). And I hadn’t thought the theoretical test was something that would be useful in the real world (it sounded awfully expensive and was only 85% accurate). I just thought it was cool as a concept.

    The doctor, however, was upset about irrelevant information distracting the patient base. Or something. The theoretical possibility of a blood test for cancer was not something he wanted his patients thinking about, and by extension he didn’t want anyone else’s patients thinking about it either. And until it had a practical application in his daily practice, he probably didn’t want to think about it — the stuff that really is applicable is plenty to keep a practitioner busy, thankyouverymuch.

    When docs talk about not having enough information to make recommendations for cancer prevention, they aren’t thinking about things that are probably true, or that are true in the lab. They are thinking about what do they really know will make a real difference to the real person in front of them — what should they spend effort convincing someone to do, and when should they try to redirect the focus of someone’s health behaviours.

    This is a blog about science-based medicine, so most of the emphasis is going to be on the take-home message — which will be more pared-down than the totality of the research.

    (Have I got this right?)

  91. Harriet Hall says:

    Even when I agree with her, Fifi still wants to fight!

    She says, “even if you can’t agree that diet and exercise may be a factor in preventing the development of certain types of cancer”

    I DO AGREE with that. I never said I didn’t. Although I didn’t specify in so many words, when I said they were important for health I meant that they were important for cancer prevention, heart disease and many other aspects of health.

    “There seems to be good evidence that the HPV virus is linked to developing a certain cancer”

    Yes, and I already said that. Why are you trying to convince me of something I already said I believe?

    “kind of blows your “it’s all just a matter of genes and aging” hypothesis out of the water.” “you haven’t proven that purely genes or aging are the main factors in most cancers developing”

    Of course I haven’t. I do not have a hypothesis that it’s all just a matter of genes and aging. I never suggested that genes and aging were the main factors in most cancers developing. I made it clear that there are many different causes of cancer, and now you are arguing with me that there are many different causes of cancer.

    I don’t think “straw man” quite covers what Fifi is doing.

  92. Fifi says:

    Dr Hall – I’m just knocking down the strawman that you set up in your initial blog post regarding diet and exercise, not erecting another one. I don’t see much evidence that people who modify their behaviors to try to lesson their risk of developing cancer believe there are no genetic factors (barring some fringe types who believe that diet and exercise is a panacea) – in fact most people I’ve encountered who do modify their behaviors to try to lessen their risk of developing cancer seem to do so because someone in their family has had cancer. If you truly believe that it’s too complicated to speculate about, why speculate yourself? And why talk in generalities when clearly cancer risk and prevention is something that requires speaking about the specific types of cancer?

  93. Harriet Hall says:

    Fifi,

    Any straw man you saw in my original post is a figment of your imagination.

  94. Fifi says:

    Dr Hall – I understand that you are (or were) angry and annoyed that I commented on one of your blogs. I’m not angry about your regarding your blog post – and we do agree on many things regarding cancer upon further discussion – I just noticed that you set up what appeared to be a strawman about popular beliefs regarding cancer in your initial post. I don’t even have an issue with you speculating, just with doing so based on almost meaningless generalities and in opposition to a strawman about what others believe.

  95. micheleinmichigan says:

    It seems to me that some folks are responding to Dr. H’s article as if it was a piece on how to stay health and prevent cancer. Perhaps if it were, some of the critiques would be quite apt.

    To me, this was an article talking about how medicine should step back and take a look at the many things that they don’t know. How should doctors account for the fact that sometime the theory they are working with is wrong? How do we prevent ourself from settling for the convenient but inaccurate diagnoses that will lead us down the garden path to a wrong conclusion?

    Within this context, I think it is appropriate to highlight what we DON’T know about cancer and it’s prevention. I didn’t get any hint that she thought we should all stop exercising and eat chocolate cake washed down with vodka for breakfast*. I only got the idea that perhaps some of the measures that are held out as reliable today may have unknown consequences tomorrow.

    Thus this quote, “We offer behavioral prescriptions based on assumptions derived from inadequate epidemiologic evidence, and this kind of thinking can lead us astray. Recommending a low fat diet helped fuel an epidemic of obesity as people replaced the fat in their diet with extra carbohydrates.”

    To me this is an article that extols doctors and patients to consider what they don’t know as well as what they do know when making health decisions. That is not an easy place to be, but I think it’s a valuable message.

    It reminds me of a quote by Ralph Waldo Emerson “A foolish consistency is the hobgoblin of little minds”

    *as much as we all would love to do so.

  96. micheleinmichigan says:

    # squirrelelite – thanks for posting those statistics. Quite interesting.

    I also have to point out my error of “just” which you smartly recognized as “gist”

    I might add that this mistake is not as bad as the time I went on vacation and emailed my friends that I was “on the lamb”…

    To be honest, I don’t get the prevention/not prevention debate. I think most people have gotten the exercise, loss weight, eat veggies message.

    It’s putting the advice into action that is problematic for some people. Whether because they are rationalizing and indulgent (like me) or because they work 50 hours a week at a desk or standing and get home and still have to do homework with the kids, get dinner, etc (like my sister).

    But like you said, maybe achievable, maybe idealistic.

  97. Harriet Hall says:

    Fifi says

    ” I understand that you are (or were) angry and annoyed that I commented on one of your blogs”

    No, Fifi, I was not annoyed that you commented. I was only annoyed that your comments attacked me for something I did not say and did not believe.

    “set up what appeared to be a strawman about popular beliefs regarding cancer”? What I actually said was “A popular concept today is that cancer is largely a preventable illness.” I still think that is a true statement that can be confirmed by various sources of evidence. You chose to interpret the words “popular concept” and “largely” in a different sense than I intended them. I don’t think I was “speculating based on almost meaningless generalities.” I think you were speculating about my beliefs based on your own preconceptions and your idiosyncratic interpretation of my words. You didn’t ask me what I meant; and when I explained my position, it turned out you agreed with me. Your assumption that I didn’t think exercise and diet had anything to do with cancer causation and that I thought it was all genes and aging was spectacularly unwarranted. Next time, instead of immediately attacking me, you might ask questions first and give me a chance to clarify.

  98. Fifi says:

    Dr Hall – Um, actually you were the one that was immediately angry and attacking – in your first post to me you said “your comments make me very angry” (when I’d only addressed one comment to you in this thread!). I wasn’t the only one that got the impression that you were being dismissive of everything but smoking as a behavior that increases the risk of developing cancer, nor was I even the first to bring it up. Thanks for clarifying what you really meant.

  99. weing says:

    “To be honest, I don’t get the prevention/not prevention debate.”

    I don’t like lying to patients. If I put them on a statin and tell them it will prevent a heart attack I am telling them a lie. What will happen if the patient takes the statin but still gets a heart attack? Can he get so upset that he sues me for breach of contract? I don’t know, and I don’t want to learn the hard way.

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