Breast Cancer Screenings: What We Still Don’t Know

“Breast Cancer Screenings: What We Still Don’t Know.” by Dr. H. Gilbert Welch, The New York Times.

A COUPLE of months ago, JAMA Internal Medicine, a journal of the American Medical Association, published the findings of a brief online survey of middle-aged Americans. Most had previously been screened for either breast or prostate cancer. But the study found that about half said they would not choose to start screening if the test resulted in more than one overtreated person per one cancer death averted.

Different people in the same situation can rationally make different choices. But first, patients need some quantification of the benefits and harms. In a study to be published Monday, Dec. 30 in JAMA Internal Medicine, a colleague and I attempt to provide that data for women making the choice about screening mammography. Let’s be clear at the outset: There is a lot of uncertainty — and professional disagreement — about what the data are. So we provide a range of estimates, from optimistic to pessimistic.

So put it all together. Among a thousand 50-year-old American women screened annually for a decade, 3.2 to 0.3 will avoid a breast cancer death, 490 to 670 will have at least one false alarm and 3 to 14 will be overdiagnosed and treated needlessly. That may help some women choose whether to be screened or not. But it’s still not very precise, and it doesn’t answer the fundamental question: Now that treatment is so much better, how much benefit does screening actually provide? What we need is a clinical trial in the current treatment era.

Two randomized trials could begin to answer the central question of mammography interpretation: How hard should the radiologist look? … Putting the two trials together, we could finally learn what level of screening minimizes false alarms and overdiagnosis while saving the most lives. Most experts would say that it’s never going to happen. It would cost too much, take too long and need too many subjects. Maybe they are right. But maybe not. Sure, it would cost millions of dollars. But that’s chicken feed compared with the billions of dollars we spend on breast cancer screening every year. Sure, it would take 10 to 15 years. But it would help our daughters know more. Sure, it would take tens of thousands of women to participate. But maybe they would want to be part of the effort to help sort out the morass surrounding what is one of the most common medical interventions done to American women.

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