Any procedure that involves sandwiching your naked breast between hard glass plates is personal. Very. But it’s becoming ever more clear that getting a mammogram also holds an element of personal decision. Medical authorities put out broad guidelines, but then you and your doctor can customize them, based in part on your own breast cancer risk and preferences.
How? Before we get into that, a paper just out in the Journal of the American Medical Association takes a sweeping look at a half century of mammogram data, and offers this big picture: mammograms do save lives, “but those benefits are not enormous,” said Dr. Nancy Keating of Brigham and Women’s Hospital and Harvard Medical School, the paper’s co-author. While the potential harms — that a woman will undergo cancer treatment for a tumor that never would have actually harmed her — have tended to be underestimated.
Here, Dr. Keating lays out the mammogram numbers that I found most helpful:
“If we take 10,000 women who are at average risk at age 40, over the course of ten years about 190 will be diagnosed with breast cancer. Most of these women will do well and would have done well regardless of screening. About five of those 10,000 women will have their life saved by the mammogram. Another 30 of those women will die regardless of the mammogram because unforutunately some breast cancers are so aggressive that they’re destined to be deadly despite the mammogram.
So there is benefit, five out of 10,000 women have their lives saved, but there are also these harms. One harm is false positives and unnecessary biopsies,: Of 10,000 women, about 6,000 will have at least one false positive. At this point, I say to patients, ‘You should expect that you’ll have some false positives, and don’t worry when they call you back.’ The over-diagnosis harm, we estimate: about 36 of those 190 cancers that were diagnosed could be over-diagnosed, and so those women will be treated — because we can’t currently tell the difference between the cancers we need to worry about and those that might not be so concerning, so we treat them all the same. So those women are then subjected to the harms of treatment without gaining any benefits.
So how to customize? How do you help create your own risk-benefit analysis? I asked the Informed Medical Decisions Foundation for helpful tools, and they suggested three:
On the questions Dr. Keating sought to answer in her review: Continue reading