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The Mammogram Post-Mortem

The Mammogram Post Mortem
Steve Novella whimsically opined on a recent phone call that irrationality must convey a survival advantage for humans. I’m afraid he has a point.
It’s much easier to scare people than to reassure them, and we have a difficult time with objectivity in the face of a good story. In fact, our brains seem to be hard wired for bias – and we’re great at drawing subtle inferences from interactions, and making our observations fit preconceived notions. A few of us try to fight that urge, and we call ourselves scientists.
Given this context of human frailty, it’s rather unsurprising that the recent USPSTF mammogram guidelines resulted in a national media meltdown of epic proportions. Just for fun, and because David Gorski nudged me towards this topic, I’m going to review some of the key reasons why the drama was both predictable and preventable.  (And for an excellent, and more detailed review of the science behind the kerfuffle, David’s recent SBM article is required reading. http://www.sciencebasedmedicine.org/?p=1926 )
Preamble
In an effort to increase early detection of breast cancer, American women have been encouraged to get annual screening mammograms starting at age 40. Even though mammograms aren’t as sensitive and specific as we’d like, they’re the best screening test we have – and so with all the caveats and vagaries associated with what I’d call a “messy test,” we somehow collectively agreed that it was worth it to do them.
Now, given the life-threatening nature of breast cancer, it’s only natural that advocacy groups and professional societies want to do everything in their power to save women from it. So of course they threw all their weight behind improving compliance with screening mammograms, and spent millions on educating women about the importance of the test. Because, after all, there is no good alternative.
However, the downside of an imprecise test is the false positive results that require (in some cases) invasive studies to refute them.  And so this leaves us with 2 value judgments:  how many women is it acceptable to harm (albeit it mildly to moderately) in order to save one life? Roughly, the answer is a maximum of 250 over 10 years (I came up with that number from the data here: http://www.sciencebasedmedicine.org/?p=565 if as many as half of women receive a “false alarm” mammogram over a period of 10 years of testing, and half of those undergo an unnecessary biopsy). And second: how many tests are we willing to do (this is more-or-less an economic question) to save 1 life? The answer is roughly 1900.
So when the USPSTF took a fresh look at the risks and benefits of mammography and recommended against screening average risk women between 40-50 (and reducing mammogram frequency to every other year for those over 50), what they were saying is that they would rather injure fewer women and do fewer costly tests for the trade off of saving fewer lives. In fact, their answer was that they were willing to perform 1300 mammograms to save 1 life, not 1900 (as has been our standard of care).
This value judgment is actually not, in and of itself, earth shattering or irresponsible. But it’s the societal context into which this judgment was released that made all the difference.
1. Timing Is Everything: Or, why not to bring a party hat to a funeral
First of all, it’s almost amusing how bad the timing of the USPSTF guidelines really were. The country was in the midst of trying to pass our country’s first serious healthcare reform bill in decades (at least, the house reform bill was being voted upon the week that the USPSTF guidelines were released) and opponents of the bill had already expressed vehement concern about arbitrary government rationing of healthcare services.
What worse time could there have been to announce that a government agency is (against the commonly held views of the rest of the medical establishment) recommending reduction in frequency  of a life-saving screening test for women? The fact that the guidelines leader said she hadn’t thought about the greater context when she scheduled the press release is quite astonishing. On the one hand, I suppose it shows how disconnected from potential political bias the workgroup really is. On the other hand, it is violates Public Relations 101 so completely as to call into question the judgment of those making… er… judgments.
2. You Can’t Replace Something With Nothing: Or How To Take Scissors From A Baby
Let’s just say for a moment that we all agree that mammograms aren’t the greatest screening test for breast cancer. They’re rather expensive, and wasteful perhaps one might even argue that in a healthcare system with limited resources, one healthy woman’s screening test is another woman’s insulin.  But – it’s all we have. And they do save lives… occasionally.
Anyone who’s seen a child pick up something harmful realizes that the only way to take it from them without tears is to replace it with something harmless. You can’t just take away mammograms from women who have come to expect it, without offering them something more sensible. If there is nothing, then I’m afraid that discontinuing them will result in considerable outrage which you may or may not wish to engage. Given the size and power of the breast lobby – I’d say it’s pretty much political suicide.
3. Know Your Opposition: Or Don’t Bring A Knife To A Gun Fight
And that brings me to point #3. The breast cancer movement is one of the most powerful and successful disease fighting machines in the history of medicine. And bravo to all the women and men who made it such a visible disease. The amount of funding, research, and PR that this cancer gets is astounding – it dwarfs many other worthy diseases (like pancreatic cancer or lymphoma), and is a force to be reckoned with.
Which is why, before you undermine a cherished tenet of such a group, you take a long hard look at what you’re going to say… Because it will be shouted from the hilltops, scrutinized from every conceivable angle, and used to rally all of Hollywood, the medical establishment, and everyone in Washington to its cause. Yeah, you better be darn sure you’re “right” (whatever that means in this context) before attempting to promote a service cut back to this group.
4. Know Who You Are: Or Unilateral Decision Making Is Not A Great Idea – Especially For Government
And finally, it’s important not only to know who you’re dealing with, but to know your mission in society so you can be maximally effective. The US government exists to honor the will of the people and serve its citizens. The best way to do that is to listen to them carefully, engage in consensus-building, and try to be a good steward of resources. When government behaves in ways counter to our expectations, it provokes some legitimate negativity.
So, for example, when a small group of civil servants hole themselves up in a room to create guidelines that will potentially take preventive health services away from women – resulting in a larger number of deaths each year… and they don’t invite input from key stakeholders, and announce their views in the midst of a firestorm about “rationing”
In summary
The new USPSTF guidelines for mammogram screenings debacle serves as a perfect public relations case study in what not to do in advancing healthcare reform. It was the perfect storm of high profile subject, bad timing, poor argument preparation, and lack of back up planning. Though we could have had a rational discussion about the cost/benefit analysis of this particular screening test, what we got instead was the appearance of a unilateral rationing decision by an out-of-touch government organization, devaluing women to the point of death. Throw that chum in the water of human frailty and you’ll get the same result every time: a media feeding frenzy that makes you regret the moment that guideline development became a twinkle in your task force eye.

Steve Novella whimsically opined on a recent phone call that irrationality must convey a survival advantage for humans. I’m afraid he has a point.

It’s much easier to scare people than to reassure them, and we have a difficult time with objectivity in the face of a good story. In fact, our brains seem to be hard wired for bias – and we’re great at drawing subtle inferences from interactions, and making our observations fit preconceived notions. A few of us try to fight that urge, and we call ourselves scientists.

Given this context of human frailty, it’s rather unsurprising that the recent USPSTF mammogram guidelines resulted in a national media meltdown of epic proportions. Just for fun, and because David Gorski nudged me towards this topic, I’m going to review some of the key reasons why the drama was both predictable and preventable.  (And for an excellent, and more detailed review of the science behind the kerfuffle, David’s recent SBM article is required reading.)

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Posted in: Cancer, Public Health, Science and the Media

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The USPSTF recommendations for breast cancer screening: Not the final word

Preface: On issues such as this, I think it’s always good for me to emphasize my disclaimer, in particular:

Dr. Gorski must emphasize that the opinions expressed in his posts on Science-Based Medicine are his and his alone and that all writing for this blog is done on his own time and not in any capacity representing his place of employment. His views do not represent the opinions of his department, university, hospital, or cancer institute and should never be construed as such. Finally, his writings are meant as commentary only and are therefore not meant to be used as specific health care recommendations for individuals. Readers should consult their physicians for advice regarding specific health problems or issues that they might have.

Now, on to the post…

“Early detection saves lives.”

Remember how I started a post a year and a half ago starting out with just this statement? I did it because that is the default assumption and has been so for quite a while. It’s an eminently reasonable-sounding concept that just makes sense. As I pointed out a year and a half ago, though, the question of the benefits of the early detection of cancer is more complicated than you think. Indeed, I’ve written several posts since then on the topic of mammography and breast cancer, the most recent of which I posted a mere two weeks ago. As studies have been released and my thinking on screening for breast cancer has evolved, regular readers have had a front row seat. Through it all, I hope I’ve managed to convey some of the issues involved in screening for cancer and just how difficult they are. How to screen for breast cancer, at what age to begin screening, and how to balance the benefits, risks, and costs are controversial issues, and that controversy has bubbled up to the surface into the mainstream media and public consciousness over the last year or so.

This week, all I can say is, “Here we go again”; that is, between downing slugs of ibuprofen for the headaches some controversial new guidelines for breast cancer screening are causing many of us in the cancer field.
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Posted in: Cancer, Politics and Regulation, Public Health

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Are one in three breast cancers really overdiagnosed and overtreated?

ResearchBlogging.orgScreening for disease is a real pain. I was reminded of this by the publication of a study in BMJ the very day of the Science-Based Medicine Conference a week and a half ago. Unfortunately, between The Amaz!ng Meeting and other activities, I was too busy to give this study the attention it deserved last Monday. Given the media coverage of the study, which in essence tried to paint mammography screening for breast cancer as being either useless or doing more harm than good, I thought it was imperative for me still to write about it. Better late than never, and I was further prodded by an article that was published late last week in the New York Times about screening for cancer.

If there’s one aspect of medicine that causes more confusion among the public and even among physicians, I’d be hard-pressed to come up with one more contentious than screening for disease, be it cancer, heart disease, or whatever. The reason is that any screening test is by definition looking for disease in an asymptomatic population, which is very different from looking for a cause of a patient’s symptoms. In the latter case, the patient is already being troubled by something that is bothering him. There may or may not be a cause in the form of a disease or syndrome that is responsible for the symptoms, but the very existence of the symptoms clues the physician in that there may be something going on that requires treatment. The doctor can then narrow down range of possibilities for what may be the cause of the patient’s symptoms by taking a careful history and physical examination (which will by themselves most often lead to the diagnosis). Diagnostic tests, be they blood tests, X-rays, or other tests, then tend to be more confirmatory of the suspected diagnosis than the main evidence supporting a diagnosis.
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Posted in: Cancer, Clinical Trials, Public Health, Science and Medicine, Science and the Media

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Screening Tests – Cumulative Incidence of False Positives

It’s easy to think of medical tests as black and white. If the test is positive, you have the disease; if it’s negative, you don’t. Even good clinicians sometimes fall into that trap. Based on the pre-test probability of the disease, a positive test result only increases the probability by a variable amount. An example: if the probability that a patient has a pulmonary embolus (based on symptoms and physical findings) is 10% and you do a D-dimer test, a positive result raises the probability of PE to 17% and a negative result lowers it to 0.2%.

Even something as simple as a throat culture for strep throat can be misleading. It’s possible to have a positive culture because you happen to be an asymptomatic strep carrier, while your current symptoms of fever and sore throat are actually due to a virus. Not to mention all the things that might have gone wrong in the lab: a mix-up of specimens, contamination, inaccurate recording…

Mammography is widely used to screen for breast cancer. Most patients and even some doctors think that if you have a positive mammogram you almost certainly have breast cancer. Not true. A positive result actually means the patient has about a 10% chance of cancer. 9 out of 10 positives are false positives.

But women don’t just get one mammogram. They get them every year or two. After 3 mammograms, 18% of women will have had a false positive. After ten exams, the rate rises to 49.1%. In a study of 2400 women who had an average of 4 mammograms over a 10 year period, the false positive tests led to 870 outpatient appointments, 539 diagnostic mammograms, 186 ultrasound examinations, 188 biopsies, and 1 hospitalization. There are also concerns about changes in behavior and psychological wellbeing following false positives.

Until recently, no one had looked at the cumulative incidence of false positives from other cancer screening tests. A new study in the Annals of Family Medicine has done just that. (more…)

Posted in: Clinical Trials

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Do over one in five breast cancers detected by mammography alone really spontaneously regress?

ResearchBlogging.orgIt figures.

Last Wednesday, right before the four-day Thanksgiving holiday weekend, as I was far more interested in preparing to have family over the next day than in what was going on in the medical news or the blogs, the results of a most fascinating study hit the news. In Medscape, the title of the news report was Mammography Study Suggests Some Breast Cancer May Spontaneously Regress; on WebMD, the story ran under the title Can Breast Cancer Disappear?; on Medical News Today, Mammograms May Identify Cancers That Would Otherwise Just Regress by Drs. Per-Henrik Zahl, Jan Maehlen, and H. Gilbert Welch. Not surprisingly, the study found its way out of the medical news and into mainstream media outlets as well, given how provocative the findings seemingly are. From the Medscape report on this study:

A mammography study from Norway has come up with the controversial proposal that one fifth of breast cancer detected on screening may spontaneously regress. But there is no easy way to verify whether this is the case, say experts.

The study was published in the November 24 issue of the Archives of Internal Medicine. It found that the cumulative incidence of invasive breast cancer in a cohort of women, aged 50 to 64 years, who received 3 mammograms over 6 years was 22% higher than in a control group of age-matched women who received only 1 mammogram at the end of a 6-year period.

In their review of possible explanations for the difference in the breast cancer rates between the 2 groups — which had similar risk factors for breast cancer — the researchers write that the “natural course for some screen-detected breast cancers may be to spontaneously regress.”

“I anticipate that many clinicians will react negatively to the possibility of spontaneous regression, said coauthor Jan Maehlen, MD, PhD, professor of pathology at the Ulleval University Hospital, in Oslo, Norway, in an interview with Medscape Oncology.

Before I discuss the study itself, let me briefly discuss why clinicians may have a bit of a problem with the implications of this study, if they accurately reflect the biology of breast cancer.
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