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Mammography and overdiagnosis, revisited

Reading mammograms
[Editor Note: This is a greatly expanded version of my initial thoughts on a study about mammography published in the New England Journal of Medicine last week on my not-so-super-secret other blog. It’s such an important topic that I thought SBM should see my discussion too, and I couldn’t just cut and paste it. You deserve original material.]

I knew it. I just knew it. I knew I couldn’t get through October, a.k.a. Breast Cancer Awareness Month, without a controversial mammography study to sink my teeth into. And I didn’t. I suppose I should just be used to this now. I’m referring to the latest opus from H. Gilbert Welch and colleagues that appeared in the New England Journal of Medicine last week, “Breast-Cancer Tumor Size, Overdiagnosis, and Mammography Screening Effectiveness.” Yes, it’s about overdiagnosis, something I’ve blogged about more times than I can remember now, but it’s actually a rather interesting take on the issue.

Before 2008 or so, I never gave that much thought to the utility of mammographic screening as a means of early detection of breast cancer and—more or less—accepted the paradigm that early detection was always a good thing. Don’t get me wrong. I knew that the story was more complicated than that, but not so much more complicated that I had any significant doubts about the overall paradigm. Then, in 2009, the United States Preventative Services Task Force (USPSTF) dropped a bombshell with its recommendation that mammographic screening beginning at age 50 rather than age 40 for women at average risk of breast cancer. Ever since then, there have been a number of studies that have led to a major rethinking of screening, in particular screening mammography and PSA testing for prostate cancer. It’s a rethinking that affects discussions even up to today, with advocates of screening arguing that critics of screening are killing patients and skeptics of screening terming it useless. Depending on the disease being screened for, the answer usually lies somewhere in between. Basically, screening is not the panacea that we had once hoped for, and the main reason is the phenomenon of overdiagnosis. Before I go on, though, remember that we are talking about screening asymptomatic populations. If a woman has symptoms or a palpable lump, none of this discussion applies. That woman should undergo mammography.
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Posted in: Cancer, Public Health

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When science- and evidence-based guidelines conflict with patient wishes: What’s a doc to do?

Evidence-based medicine triad

There’s a misconception that I frequently hear about evidence-based medicine (EBM), which can equally apply to science-based medicine (SBM). Actually, there are several, but they are related. These misconceptions include the idea that EBM/SBM guidelines are a straightjacket, that they are “cookbook medicine,” and that EBM/SBM should be the be-all and end-all of how to practice clinical medicine. New readers might not be familiar with the difference between EBM and SBM, and here is not the place to explain the difference in detail because this post isn’t primarily about that difference. However, for interested readers, a fuller explanation can be found here, here, here, and here. The CliffsNote version is that EBM fetishizes the randomized clinical trial above all other forms of medical investigation, a system that makes sense if the treatments being tested in RCTs have a reasonably high prior probability of translating to human therapies based on basic science mechanisms, experimental evidence in cell culture, and animal experiments. Using Bayesian considerations, when the prior probability is very low (as is the case for, for example, homeopathy), there will be a lot of false positive trials. Such is how EBM was blindsided by the pseudoscience of “complementary and alternative medicine” (CAM) or, as it is called now, “integrative medicine.”

However, for purposes of this post, SBM and EBM can be considered more or less equivalent, because we are not going to be discussing CAM, but rather widely accepted treatment guidelines based on science, both basic and clinical trial science. I merely mention this difference for completeness and for new readers who might not be familiar with the topics routinely discussed here. For purposes of this post, I’m talking evidence-based guidelines from major medical societies. More specifically, I want to address the disconnect between what patients often want and what our current guidelines state. It’s not just patients either, but doctors; however, for purposes of this post I’m going to focus more on patients. It’s a topic I’ve addressed before, in particular when it comes to breast cancer, where I’ve discussed changes in the mammography screening guidelines and Choosing Wisely guidelines for breast cancer. There are many other examples that I haven’t discussed. (more…)

Posted in: Cancer, Diagnostic tests & procedures

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Confusing overdiagnosis for an “epidemic” of thyroid cancer in Japan after Fukushima

A Japanese girl being screen for thyroid cancer.

A Japanese girl being screen for thyroid cancer.

One of my favorite topics to blog about for SBM is the topic of overdiagnosis and overtreatment. These are two interrelated phenomena that most people are blissfully unaware of. Unfortunately, I’d also say that the majority of physicians are only marginally more aware than the public about these confounders of screening programs, if even that.

Overdiagnosis has long been appreciated to be a major impediment to translating programs to screen for disease into better outcomes in a number of diseases but has only recently really seeped into the public consciousness, beginning in particular in 2009 when the United States Preventative Services Task Force (USPSTF) issued mammography recommendations that pushed back the recommended age to start screening to 50. Certainly, the concept of overdiagnosis is counterintuitive. After all, why do we screen for disease in asymptomatic people? The reason is simple—and maddeningly intuitive. We screen for disease based on the belief that catching potentially deadly diseases like cancer early, before they produce clinical symptoms, will allow earlier intervention and save lives. It seems blindingly obvious that this should be the case, doesn’t it? Unfortunately, real life biology and pathophysiology aren’t quite so neat and tidy, and the relationship between early detection and improved survival is muddied by phenomena such as lead time bias and the Will Rogers effect, in addition to overdiagnosis.

What is overdiagnosis? In brief, it is the detection of pathology or disease that, if left untreated, would never endanger the life of a patient or even harm him. Note that overdiagnosis is not the same thing as a false positive. A false positive occurs when a test detects disease that isn’t really there; in contrast with overdiagnosis there is definite pathology. The disease being screened for is there, at least in an early form. It’s just that, at the very early stage detected, it’s either not progressive or so indolent that the patient will grow old and die of something else before it would ever cause a problem. Indeed, it’s been estimated that as many as one in three breast cancers detected by mammography in asymptomatic women might be overdiagnosed and that one in five might spontaneously regress. However, because we don’t know which ones are unlikely to cause harm and haven’t worked out a safe method of observing them and intervening if they look as though they are progressing, we are obligated to treat them all when discovered. The problem of overdiagnosis has led to multiple alterations in what once were considered definitive recommendations for screening mammography, first by the USPSTF and most recently by the American Cancer Society.
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Posted in: Cancer, Epidemiology

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On “integrative medicine” and walking and chewing gum at the same time

Walk and chew gum at the same time

I didn’t think I’d be discussing Dr. David Katz again so soon. In fact, when Mark Crislip (who clearly hates me, given how often he sends me links to articles like this) sent me a link to Dr. Katz’s latest article, “Cleaning the House of Medicine“, published—where else?—in The Huffington Post, that home for “reputable” quack-friendly bloviation since 2005, when I first read the article, my first reaction was that Katz must surely be trolling us here at SBM. At first, I wasn’t going to respond to him again. However, Katz’s article represents a very common misconception about science-based medicine that is worth refuting. It is not my intention to be arguing back and forth with Dr. Katz every couple of weeks, but I did think it worth one more round. I think you’ll understand why by the end of this post.

First, however, a brief recap is in order for readers who might not have been following the discussion over the last month or so. It all started a couple of weeks ago, when Jann Bellamy, in response to a special issue of the American Journal of Preventative Medicine edited by Katz and dedicated to making the case for integrative medicine in preventive medicine training, quite correctly discussed how “integrative medicine” is always all about the “potential.” Indeed, after having spent considerable sums of federal grant money studying the “integration” of pseudoscience into medicine with respect to preventive care, the journal couldn’t come up with any concrete examples how integrative medicine adds anything (other than quackery) to medicine. Dr. Katz, who is well-known in the world of quackademic medicine for his infamous 2008 speech in which he asserted that physicians need to use a “more fluid concept of evidence” in evaluating treatments, particularly “complementary and alternative medicine” (CAM), responded with another HuffPo article entitled “Science and Medicine, Fools and Fanatics: The ‘Fluidity’ of Woo“. In lieu of reasonable, science-based arguments, Dr. Katz’ article was little more than a rant that consisted mainly of outrage that mere mortals lacking his awesome academic credentials had had the temerity to question his awesomeness and dedication to science coupled with an accusation that we are just too rigid and simplistic in our thinking to understand the subtle complexities of how different standards of evidence must be applied to complex patients. Steve Novella and I both responded that we understand just fine, explained how doctors do this all the time without using quackery like naturopathy and homeopathy (both of which Katz has advocated), and pointed out his argumentum ad ignorantiam with respect to energy medicine.

There’s where I thought it would end. Unfortunately, I was mistaken. On Friday, Katz launched another broadside at us, couched in the form of an argument that medicine must “clean its own house” before worrying about his quackademic medicine. It’s something I hear often enough that I thought it would be worth responding to, even if Dr. Katz was indeed trolling us.
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Posted in: Critical Thinking, Medical Academia, Quality Improvement, Surgical Procedures

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The American Cancer Society’s new mammography guidelines: Déjà vu all over again

The American Cancer Society’s new mammography guidelines: <em>Déjà vu</em> all over again

One of the things that feels the weirdest about having done the same job, having been in the same specialty, for a longer and longer time is that you frequently feel, as the late, great Yogi Berra would have put it, déjà vu all over again. This is particularly true in science and medicine, where the same issues come up again and again and again, often with the same arguments on either side. Sometimes the same players are even involved. So it is with mammography recommendations. Indeed, I’m feeling déjà vu all over again right now, as I read headlines like “Women advised to get mammograms later, less often“, “American Cancer Society, in a Shift, Recommends Fewer Mammograms“, and “ACS: Breast cancer screening should begin at age 45“. What provoked these headlines was a major revision in the American Cancer Society’s recommendation for mammographic screening for breast cancer in women at average risk of the disease. In a seeming replay from 2009, when the United States Preventative Services Taskforce (USPSTF) sent shockwaves through the breast cancer world by recommending that most women not start mammography until age 50 and then only to have it done every two years instead of every year, the American Cancer Society (ACS) has now just similarly ratcheted back its recommendations for screening mammography, just not as much as the USPSTF did. The new recommendations were communicated in a special communication published by JAMA on Tuesday.

What changed regarding mammography recommendations

Before we get to the issues, how, specifically, did the ACS change its mammography recommendations? Before this change, the ACS basically recommended the same thing that most other American professional societies dealing with breast cancer did: yearly mammography starting at age 40 for the rest of a woman’s life. The new guidelines now recommend that women with an average risk of breast cancer should undergo regular screening mammography starting at age 45 years and continuing annually until age 54. From age 55 and older, the ACS recommends that women transition to every two years. (More details below.) As I Tweeted when I saw these recommendations, basically it appears that the ACS has more or less split the difference between the old recommendations and the USPSTF recommendations.

So why is the ACS changing its recommendations? And what does this say about the science and our values regarding cancer screening? If you’ve been reading this blog, you know that over the last several years there has been a steady drip, drip, drip of studies that range from highlighting the downside of widespread mammographic screening to downright questioning the value of mammography. That’s why I’ve been discussing rethinking screening for breast cancer since at least 2008. Basically, you can go back and read my old posts and, if you have a lot of time and are enough of a glutton for punishment to read them all, watch the evolution of my thinking about breast cancer screening over the last seven years.

Back in the day, I used to fully support breast cancer screening beginning at age 40 and proceeding yearly throughout. As I examined more and more of the evidence, I became less enthusiastic about screening so intensely and started to believe that starting at 40 was too young for most women. Indeed, I was probably the only breast cancer doctor at my cancer center in 2009 who supported the USPSTF recommendations when they were announced, which led to some—shall we say?—interesting discussions about what should be said to the press and what a press release our cancer center wanted to release ASAP should actually say. I also got myself into a little…trouble…for criticizing colleagues in radiology—not from my institution, I hasten to add!—for some rather blatant turf protection. Let’s just say that a prominent radiologist, one who’s achieved far more renown in his field than I ever have in mine, was most displeased with some of my commentary and let me know about it. I found this displeasure odd, given that I am most definitely not a nihilist with respect to mammography screening (and, make no mistake, there are quite a few of those out there these days). I’m just a lot more balanced and aware of its limitations than I used to be. On the other hand, I did call him out for some of his more obnoxious comments that implied that those who question mammography are cackling gleefully at the thought of more women dying of breast cancer. Interestingly, I don’t seem to get asked to contribute to such press releases that much anymore, but in fairness neither do most of the other breast cancer clinicians I work with; so I probably can’t blame it on my previous outspokenness.

What brought me to this point is an increasing understanding of the concepts of overdiagnosis and lead time bias, coupled with a string of studies that show more modest benefits (and, in one case, no benefit) from screening mammography. To be honest, the attack dog reaction by some mammography supporters to some of these negative studies also set my skeptical antennae a’twitchin’ as well.
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Posted in: Cancer, Public Health

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“Liquid biopsies” for cancer screening: Life-saving tests, or overdiagnosis and overtreatment taken to a new level?

Could a blood draw be all you need to diagnose cancer and identify the best treatment for it? Not so fast...

Could a blood draw be all you need to diagnose cancer and identify the best treatment for it? Not so fast…

I’ve written many times about how the relationship between the early detection of cancer and decreased mortality from cancer is not nearly as straightforward as the average person—even the average doctor—thinks, the first time being in the very first year of this blog’s existence. Since then, the complexities and overpromising of various screening modalities designed to detect disease at an early, asymptomatic phase have become a relatively frequent topic on this blog. Before that, on my not-so-super-secret other blog, I noted that screening MRI for breast cancer and whole body CT scans intended to detect other cancers early were not scientifically supported and thus were far more likely to cause harm than good. That was well over ten years ago. Now we have a company offering what it refers to as a “liquid biopsy” for the early detection of cancer. I fear that this is the recipe for the ultimate in overdiagnosis. I will explain.

The problem, of course, is that disease progression, including cancer progression, is not always a linear process, in which the disease progresses relentlessly through its preclinical, asymptomatic phase to symptoms to complications to (depending on the disease) death. There is such a thing as disease that remains asymptomatic and never progresses (at which point it’s hard to justify actually calling it a disease). As I pointed out in my first SBM post on the topic, at least three-quarters of men over 80 have evidence of prostate cancer in autopsy series. Yet nowhere near three-quarters of men in their 80s die of prostate cancer—or ever manifest symptoms from it. This is what is meant by overdiagnosis, the diagnosis of disease that doesn’t need to be treated, that would never cause a patient problems.

When teaching medical students and residents, I frequently emphasize that overdiagnosis is different from a false positive because overdiagnosis does diagnose an actual abnormality or disease. For example, ductal carcinoma in situ (DCIS) diagnosed by mammography leading to a biopsy is a real pathological abnormality; it is not a false positive. We just do not know which cases of DCIS will progress to cancer and which will not, leading to a question of how DCIS should be treated or at the very least whether we should treat it as aggressively as we do now, particularly given that the apparent incidence of DCIS has increased 16-fold since the 1970s, all of it due to mammographic screening programs and the increased diagnosis of DCIS and early stage breast cancer has not resulted in nearly as much of a decrease in the diagnosis of advanced stage breast cancer as one would expect if early diagnosis were having an impact in reducing the diagnosis of late stage disease.

Overdiagnosis would not be such an issue if it didn’t inevitably lead to overtreatment. DCIS, for instance, is treated with surgery, radiation, and anti-estrogen drugs. Early stage prostate cancer used to be treated with radical prostatectomy, but now more frequently with radiation. Many of these men and women didn’t actually need treatment. We just don’t know which ones. This is why over the last six or seven years a significant rethinking of screening for breast and prostate cancer has occurred. There has been a backlash, of course, but the rethinking seems to have taken hold.

Not everywhere, of course. (more…)

Posted in: Basic Science, Cancer, Diagnostic tests & procedures, Public Health

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How should we treat DCIS?

How should we treat DCIS?

I’ve written more times than I can remember about the phenomenon of overdiagnosis and the phenomenon that is linked at the hip with it, overtreatment. Overdiagnosis is a problem that arises when large populations of asymptomatic, apparently healthy people are screened for a disease or a condition, the idea being that catching the disease at an earlier stage in its progression will allow for more successful treatment. Two prominent examples include—of course—screening for breast cancer with mammography and screening for prostate cancer with prostate-specific antigen (PSA) testing, and I’ve written about the problem of overdiagnosis with each of them on many occasions. Basically, overdiagnosis occurs when the screening test picks up what we call “preclinical” disease (i.e., disease that hasn’t become symptomatic) that, if left untreated, would never become symptomatic or endanger the health or life of the patient). Although intuitively, it seems to the lay public (and, truth be told, most doctors) that detecting cancer earlier must be inherently better, it turns out that it’s way more complicated than you think. There is a price to be paid for early diagnosis in the form of overtreatment of disease that doesn’t need treatment and for disease that is destined to threaten the life of the patient earlier treatment doesn’t always result in better outcomes. Also, whenever you screen for a condition in asymptomatic people, you will always—always—find much more of it, and the significance of those added diagnoses is not always clear, as a new study in JAMA Oncology shows.

DCIS and mammography: Some background

Before I get to the meat of the study, from my perspective, nowhere is the problem of overdiagnosis and overtreatment in cancer screening as pronounced than in the condition known as ductal carcinoma in situ (DCIS). DCIS is commonly referred to as “stage 0” breast cancer and is characterized by milk duct cells that appear malignant but remain confined to the milk ducts. In other words, they haven’t invaded the tissue surrounding the ducts. In general, DCIS is treated similarly to breast cancer, with surgical excision, either by mastectomy or breast-conserving surgery, followed by radiation therapy if breast conserving surgery is used. Then, depending on its hormone receptor status, adjuvant treatment consists of blocking estrogen for five years. The rationale for this treatment is the view of DCIS as being a precursor to fully invasive breast cancer and that treating the DCIS will prevent the development of breast cancer. Over the last couple of decades, however, it has become clear that not all DCIS is created equal. Much of it will never progress to breast cancer in the lifetime of the woman (particularly if the woman is older, which means less time for fully malignant transformation to occur). Evidence suggesting this includes studies showing an increase in DCIS incidence by 16-fold since the 1970s, when mammography started to be introduced on a large scale, with little change in the incidence of invasive cancer. Today, 20-25% of mammography-detected breast cancer diagnoses are DCIS; forty years ago, DCIS was an uncommon diagnosis, except associated with an invasive cancer.
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Posted in: Basic Science, Cancer, Clinical Trials, Science and the Media

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The uncertainty surrounding mammography continues

Screening mammography

Mammography is a topic that, as a breast surgeon, I can’t get away from. It’s a tool that those of us who treat breast cancer patients have used for over 30 years to detect breast cancer earlier in asymptomatic women and thus decrease their risk of dying of breast cancer through early intervention. We have always known, however, that mammography is an imperfect tool. Oddly enough, its imperfections come from two different directions. On the one hand, in women with dense breasts its sensitivity can be maddeningly low, leading it to miss breast cancers camouflaged by the surrounding dense breast tissue. On the other hand, it can be “too good” in that it can diagnose cancers at a very early stage.

Early detection isn’t always better

While intuitively such early detection would seem to be an unalloyed Good Thing, it isn’t always. Although screening for early cancers appears to improve survival, the phenomenon of lead time bias can mean that detecting a disease early only appears to improve survival even if earlier treatment has no impact whatsoever on the progression of the disease. Teasing out a true improvement in treatment outcomes from lead time bias is not trivial. Part of the reason why early detection might not always lead to improvements in outcome is because of a phenomenon called overdiagnosis. Basically, overdiagnosis is the diagnosis of disease (in this case breast cancer but it is also an issue for other cancers) that would, if left untreated, never endanger the health or life of a patient, either because it never progresses or because it progresses so slowly that the patient will die of something else (old age, even) before the disease ever becomes symptomatic. Estimates of overdiagnosis due to mammography have been reported to be as high as one in five or even one in three. (Remember, the patients in these studies are not patients with a lump or other symptoms, but women whose cancer was detected only through mammography!) Part of the evidence for overdiagnosis includes a 16-fold increase in incidence since 1975 of a breast cancer precursor known as ductal carcinoma in situ, which is almost certainly not due to biology but to the introduction of mass screening programs in the 1980s.

As a result of studies published over the last few years, the efficacy of screening mammography in decreasing breast cancer mortality has been called into question. For instance, in 2012 a study in the New England Journal of Medicine (NEJM) by Archie Bleyer and H. Gilbert Welch found that, while there had been a doubling in the number of cases of early stage breast cancer in the 30 years since mass mammographic screening programs had been instituted, this increase wasn’t associated with a comparable decrease in diagnoses of late stage cancers, as one would expect if early detection was taking early stage cancers out of the “cancer pool” by preventing their progression. That’s not to say that Bleyer and Welch didn’t find that late stage cancer diagnoses decreased, only that they didn’t decrease nearly as much as the diagnosis of early stage cancers increased, and they estimated the rate of overdiagnosis to be 31%. These results are in marked contrast to the promotion of mammography sometimes used by advocacy groups. Last year, the 25 year followup for the Canadian National Breast Screening Study (CNBSS) was published. The CNBSS is a large, randomized clinical trial started in the 1980s to examine the effect of mammographic screening on mortality. The conclusion thus far? That screening with mammography is not associated with a decrease in mortality from breast cancer. Naturally, there was pushback by radiology groups, but their arguments were, in general, not convincing. In any case, mammographic screening resulted in decreases in breast cancer mortality in randomized studies, but those studies were done decades ago, and treatments have improved markedly since, leaving open the question of whether it was the mammographic screening or better adjuvant treatments that caused the decrease in mortality from breast cancer that we have observed over the last 20 years.

Given that it’s been a while since I’ve looked at the topic (other than a dissection of well-meaning but misguided mandatory breast density reporting laws a month ago), I thought now would be a good time to look at some newer evidence in light of the publication of a new study that’s producing familiar headlines, such as “Mammograms may not reduce breast cancer deaths“.

Here we go again.
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Posted in: Cancer, Public Health

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Recent Developments and Recurring Dilemmas in Cancer Screening: Colon, Lung, Thyroid

Cancer screening - lead time bias small

Screen detection and tumor growth rates. Cancers have different growth rates, which determine their potential to be detected by screening. Tumor A remains microscopic and undetectable by current technology (although more sensitive tests in the future might render it detectable). Tumor B eventually becomes detectable by screening (*), but its growth rate is so slow that it will not cause symptoms during the life of the individual; its detection will result in overdiagnosis. Tumor C is capable of metastasizing, but it grows slowly enough that it can be detected by screening (*); for some, this early detection will result in survival. Tumor D grows very quickly and therefore is usually not detected by screening. This will present as an interval cancer (i.e. detected clinically in the interval between screening examinations) and has a particularly poor prognosis. Note that of the four tumor types, only Tumor C has the potential to benefit from screening. Red dashed lines represent the natural history of a tumor in the absence of detection by screening. (Figure 1 from Gates, 2014).

A new stool DNA test was recently approved by the FDA for colon cancer screening. My first reaction was “Yay! I hope it’s good enough to replace all those unpleasant, expensive screening colonoscopies.” But of course, things are never that simple. I wanted to explain the new test for our readers; but before I could start writing, some other issues in cancer screening barged in and demanded to be included. They exemplify the dilemmas we face with every screening test. We have covered these issues before, but mainly in reference to mammography and prostate (PSA) screening. My article morphed into a CLT sandwich: colon, lung, and thyroid cancer screening.

The current issue of American Family Physician has a great article on cancer screening. It uses lucid graphics to illustrate lead time bias, length time bias, and overdiagnosis bias, as well the effect of varying tumor growth rates on screening success rates, all concepts that have been covered by Dr. Gorski here. Briefly, screening may do more harm than good if:

  1. It detects cancerous cells that never would have developed into invasive cancers or harmed the patient in any way;
  2. Early diagnosis and treatment decrease quality of life without reducing death rates; or
  3. The test falsely indicates cancer in patients who don’t have it or fails to indicate cancer in some who do. (more…)

Posted in: Cancer, Diagnostic tests & procedures

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Mammography and the acute discomfort of change

As I write this, I am attending the 2014 meeting of the American Association for Cancer Research (AACR, Twitter hashtag #AACR14) in San Diego. Basically, it’s one of the largest meetings of basic and translational cancer researchers in the world. I try to go every year, and pretty much have succeeded since around 1998 or 1999. As an “old-timer” who’s attended at least a dozen AACR meetings and presented many abstracts, I can see various trends and observe the attitudes of researchers involved in basic research, contrasting them to that of clinicians. One difference is, as you might expect, that basic and translational researchers tend to embrace new findings and ideas much more rapidly than clinicians do. This is not unexpected because the reason scientists and clinical researchers actually do research is because they want to discover something new. Physicians who are not also researchers become physicians because they want to take care of patients. Because they represent the direct interface between (hopefully) science-based medicine and actual patients, they have a tendency to be more conservative about embracing new findings or rejecting current treatments found not to be effective.

While basic scientists are as human anyone else and therefore just as prone to be suspicious and dismissive of findings that do not jibe with their scientific world view, they can (usually) eventually be convinced by experimental observations and evidence. As I’ve said many times before, the process is messy and frequently combative, but eventually science wins out, although sometimes it takes far longer than in retrospect we think it should have, an observations frequently exploited by advocates of pseudoscience and quackery to claim that their pseudoscience or quackery must be taken seriously because “science was wrong before.” To this, I like to paraphrase Dara O’Briain’s famous adage that just because science doesn’t know everything doesn’t mean you can fill in the gaps with whatever fairy tale that you want. But I digress (although only a little). In accepting the validity of science that indicates either that a medical intervention that was commonly used either doesn’t help, doesn’t help as much as we thought it did, or can even be harmful, they have to contend with the normal human reluctance to admit to oneself that what one was doing before might not have been of value (or might have been of less value than previously believed) or that, worst of all, might have caused harm. Or, to put it differently, physicians understandably become acutely uncomfortable when faced with evidence that the benefit-risk profile of common treatment or test might not be as favorable as previously believed. Add to that the investment that various specialties have in such treatments, which lead to financial conflicts of interest (COI) and desires to protect turf (and therefore income), and negative evidence can have a hard go among clinicians.
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Posted in: Cancer, Diagnostic tests & procedures, Public Health, Science and the Media

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