What’s the Down Side?

The absurd controversy over mammograms.

The absurdity began in 1997, when the National Institutes of Health issued a “consensus statement” purporting to advise women about when to get a mammogram, the X-ray test for breast cancer. The NIH declared that an annual mammogram is extremely beneficial and definitely recommended for women ages 50-69. For women ages 40-50, it said, the evidence is unclear. Every woman should decide for herself, in consultation with her doctor.

This recommendation shares a flaw with many such pieces of statistically based advice we get from the government and other organizations dedicated to our well-being: It is detached from reality. It posits a world where risks and benefits change at a few discrete points (birthdays ending in zero), while the decision at hand allows for a variety of fine distinctions (mammogram definitely, mammogram maybe, mammogram probably not necessary, etc.). In reality, though, the opposite is true: The risks and benefits change gradually while the decision is a discrete yes-or-no.

How can the value of a mammogram to any particular woman be completely uncertain the day before her 50th birthday and overwhelmingly clear the day after? Ten years earlier, how can a mammogram be worthless or worse the day before her 40th birthday and possibly save her life the day after?

And how is a sensible woman supposed to act on the recommendation of “maybe”? Assuming that she doesn’t fall into some clarifying subcategory such as a family history of breast cancer, how are one patient and one doctor supposed to make an intelligent yes-or-no decision when the National Institutes of Health apparently cannot?

Last month the absurdity was compounded by two studies casting doubt on the validity of earlier studies that are the basis for believing that, for women over 50 at least, regular mammograms cut the risk of breast cancer by about 30 percent.

Every day, thousands of American women have mammograms and some of them discover tumors that would have killed them if the tumors hadn’t been discovered and removed. Almost everyone knows women who have survived breast cancer thanks to a mammogram. Many of the articles in the press about the latest mammogram controversy pause at some point to ask how it can possibly be that mammograms are a bad idea—whatever a statistical study may show. But the explanations they offer do not make sense.

Sure, the mere fact that a malignant tumor is caught by a mammogram doesn’t mean that a woman’s life has been saved: The tumor might have been discovered in time anyway, or something else might have killed her before the tumor could do its deadly work. But no one tries to deny that some tumors are caught and removed that would have been fatal and that some women are alive as a result. So there’s no serious case that mammograms have no benefit. The fancy explanations point to alleged disadvantages of mammograms that might possibly outweigh the benefits.

For example, almost all the tumors found in an initial mammogram—80 percent to 95 percent—turn out to be false alarms, and those women suffer what turns out to have been needless anxiety until further testing clears things up. But presumably they suffer the amount of anxiety appropriate to a 5-percent-to-20-percent chance of confirmed bad news—as do the unlucky minority for whom the news actually is bad. This group ought to be more anxious, if only they knew. If anxiety is proportional to the actual risk, there is no net increase in anxiety caused by false alarms. People probably are disproportionately anxious about a small risk of cancer, but it would be odd to tell women they shouldn’t have mammograms (and to allow some number of them to die as a result) because they will overreact if the news is bad.

Similarly, mammograms that indicate a tumor lead to biopsies, some of which turn out to be unnecessary. Biopsies that confirm the bad news lead to surgery, and even some of that turns out to have been unneeded when the actual tumor is examined and labeled benign. These are interpreted as “costs” of mammograms. But why blame the mammogram for someone’s conscious decision to have a biopsy or surgery? Why “blame” anyone for deciding sensibly that a large chance of saving your life is worth a small chance that it will turn out to have been unnecessary? It would be even odder to advise women not to have mammograms because it might lead them to take a risk that is perfectly rational.

The only reason for any individual woman not to have a mammogram is the actual financial cost, plus the cost in inconvenience and discomfort. At some point, the chance of detecting a tumor becomes so small that a mammogram really isn’t worth it. And since so much health care is paid for by third parties, society needs a policy about when mammograms are appropriate. But ask yourself: If the president were a woman in her 40s, would she be getting a regular mammogram? You get one too.