Breast Cancer: Science vs. Emotion
Image by LittleMissCupcakeParis via Flickr
I won’t try to settle the mammogram controversy here. But I did want to make just a couple of points about the screwed up the reaction to the new United States Preventive Services Task Force recommendations that most women not get regular mammograms in their 40s.
First off, I don’t think I’ve seen any TV news outlet give a report on this issue that was even half-comprehensible. The immediate reaction, society-wide, seems to have been: HOW DARE YOU SUGGEST WOMEN GET FEWER MAMMOGRAMS YOU INSENSITIVE BREAST-HATING BASTARDS I’M GOING TO STAB YOU ARRGHGHGHGH!?!?!? Thus, every news report has come from a position of sputtering anger, tempered by breaks to ridicule the qualifications of the task force members.
One might be left to wonder: How on Earth could this task force have recommended something so monstrous?
The answer, of course, is: statistics. The task force did a statistical analysis that found regular mammograms in women’s 40s came with more costs than benefits, overall. How could this be?
I’m not here to endorse the panel’s conclusions — to do that, I’d have to really be able to take apart their statistical analysis and know quite a bit about radiology and oncology. But I can, I think, tell you a little bit about the biases that are making people go apeshit in response to this report.
First and foremost, I think that people find it virtually impossible to conceive of the idea that mammograms could have any negative effects whatsoever. Of course, like everything ever, they do. Here’s the report on that question (You can look at the task force’s full report here [PDF]):
Harms of Detection and Early Intervention
The harms resulting from screening for breast cancer include psychological harms, unnecessary imaging tests and biopsies in women without cancer, and inconvenience due to false-positive screening results. Furthermore, one must also consider the harms associated with treatment of cancer that would not become clinically apparent during a woman’s lifetime (overdiagnosis), as well as the harms of unnecessary earlier treatment of breast cancer that would have become clinically apparent but would not have shortened a woman’s life. Radiation exposure (from radiologic tests), although a minor concern, is also a consideration.
Adequate evidence suggests that the overall harms associated with mammography are moderate for every age group considered, although the main components of the harms shift over time. Although false-positive test results, overdiagnosis, and unnecessary earlier treatment are problems for all age groups, false-positive results are more common for women aged 40 to 49 years, whereas overdiagnosis is a greater concern for women in the older age groups.
There is adequate evidence that teaching BSE is associated with harms that are at least small. There is inadequate evidence concerning harms of CBE.
Secondly, even with these downsides, people are still relatively sure that, on the whole, mammograms are a “good” thing. And we have a very hard time with the concept that there can be an optimal level of a good thing — more is better, less is worse (at least in our minds). But, of course, if that were the case, why not screen starting at 30? Or 20? Or 16? And why not screen two times a year? Three times? Once a month? Sure, this is pushing into the absurd — but if we’re not willing to believe that there’s a cost-benefit analysis to be done, where’s the logical stopping point?
But if there is a cost-benefit analysis to be done, why is it so inconceivable that the correct age to start regular mammograms is 50 instead of 40? Age 40, after all, was just a number set by another task force at another time. But, since it’s the number we’re used to, our status quo bias has set in.
Wait, you say. What about all the women whose lives have been saved by mammograms in their 40s? I’ve seen them on TV all week. What more proof could anyone need that 40 is the right age? Here, we’re up against our availability bias — first, in the media (these are the people who will get on TV this week), second, when we remember this week’s TV guests in our minds. Of course, the people not getting on TV this week are the ones who’ve suffered unnecessary mastectomies, unnecessary biopsies, excess radiation, etc.
Again, the task force’s recommendations may be imperfect — in fact, they’re certainly not perfect. They’re engaging in a very tricky cost-benefit analysis in a very emotionally charged area. But what we need to recognize is there’s nothing crazy or corrupt or irresponsible about trying to determine the most beneficial guidelines for a medical question like when to advise the average woman to begin having regular mammograms. So long as there’s a guideline, it has to be set somewhere.
Meanwhile, women should consult with their personal physicians and make their own decisions as informed patients; if you have certain genetic risk factors, the guidelines already recommend you start screening earlier. And even without those risk factors, you may well decide that, for you, the possible drawbacks of earlier screening are outweighed by the benefits.
What doesn’t help is the entire media and political class freaking out and pretending that there are no trade offs in medicine or in life.
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As someone who has raised money for this cause and walked in two 2-day Avon Walks for Breast Cancer, the piece of this that folks are missing is the fact that many women aren’t getting screened at all, particularly the poor or recently unemployed who have no health insurance. The point is, “delay” may be translated by many into “not at all”. Yes, we spend too much money on unnecessary procedures, but we’ve all beentaught at an early age that prevention is the best medicine. Seems odd that they are now making a complete reversal on that wisdom.
Hello IMHO,
I think that when you thinking about the “costs” of mammograms you are thinking about the actual price of the procedure. However what the panel did was look at other “costs”, specifically increased risk to the patient. A mammogram exposes breast tissue to radiation (X-rays) which increases the risk of cancer, albeit a very small risk. So each mammogram is a balancing act, balancing the risk of exposure to x-rays vs. the risk of not detecting breast cancer early enough to effectively intervene. Additionally, a mammogram may detect a “lump” that is not a cancer (a “false positive”) which will result in biopsy. Biopsies are not risk free either and pose their own problems. For example it is not unheard of for infections to result from biopsies, to say nothing of internal bleeding and other complications. A biopsy is also a balancing act, balancing the risk from the biopsy itself vs. the risk of not identifying a cancer. It is these “costs” that are being considered.
On the other hand, if, as the panel believes, there are no benefits for women aged 40-49 from mammograms, then the above mentioned “costs”, risks from the testing procedures, are greater than the benefits. This is all very cold and clinical and contrary to previous practice, but that is the math and that is how health policy needs to be determined.
In response to another comment. See in context »I understand exactly what is meant by “costs”. And I respectfully submit that these are calculated risks for a woman to decide with her doctor. It’s risky to take oral contraceptives, too, but most women–assuming they’re healthy and non-smokers–are willing to take that risk to avoid unwanted pregnancy. My point is, statistics should be used as guidelines, not edicts.
In response to another comment. See in context »Hello IMHO,
You are quite correct, it is entirely a matter between the patient and the doctor. The panel in question merely provided recommendations which are in no way binding upon anyone. Patients should make those informed decision on their own and the recommendations of this panel do not change that.
In response to another comment. See in context »Mr. Sager,
I first want to not that this sort of determination is actually an entire field of study. One can go to grad school (usually in a School of Public Health) and get one’s degree studying when things like testing or immunization are effective and when they are not. The question of balancing the benefits of testing for example (prevented diseases and deaths) against costs of false positives and false negatives. In case of false positives with breast cancer, unnecessary biopsies and unnecessary radiation exposure. In the case of false negatives, expensive tests are performed with no accompanying life extending benefits. You can actually punch all of this into an equation and literally do the math on whether testing is warranted or not.
I think part of the problem is that when the question of “cost – benefit analysis” is discussed, there is a tendency to see the “costs” as simply the price of the test. Of course that is a consideration but the cost here is of unnecessary biopsies which can have serious health implications. If false positives from mammograms result in unneeded biopsies, which compromise the patients long term health, and the mammograms themselves produce no additional benefit to women 40 – 49, then the math is pretty simple.
AAA, 1% of all breast cancer deaths (440 per year in the US) are men.
Ryan,
I think that a lot of the hysteria is anti-science backlash. As davidlosangeles very capably explained, the guidelines presented are defensible, but the defense is only going to be understood by someone with some statistical background. There are far more people who can’t understand the term “cost-benefit analysis” then there are people who could perform one. Which group do you think the media will target?
But the pernicious effect is that the media defines the question. As the framing we get is aimed at a less and less educated populace, the entire public conversation becomes less rational, more emotional.
BTW, as IMHO shows, it’s perfectly possible to thoroughly understand the issues and come to a different conclusion; reasonable minds will disagree.
It`s terrible to live with a disease like breast cancer My aunt had one of her breasts removed because of it. Horrible