Questions about the risks and benefits of mammography screening come up again and again. The latest study to draw attention to the mammography debates appears in the November 22nd New England Journal of Medicine. And, as you’ve probably heard or read, the study suggests that over the past 30 years, mammography has resulted in the over diagnosis of 1.3 million American women. In turn, yet again, we’ve returned to the same controversy: Should women start breast screening at age 40 or age 50?
Why can’t we come to some consensus about this topic and move on? There are several problems that get in the way. The first, and most significant, is that medicine is a work in progress and our understanding about breast cancer has changed significantly since mammography was introduced in the 1950’s. At that time the studies that showed that mammography reduced the risk of dying of breast cancer by 25 percent in women over 50 appeared to confirm the belief that all breast cancers grow at the same rate, and that finding tumors early would ensure that breast cancer deaths could be prevented. It was an exciting concept that led to extensive public campaigns promising “early detection was the best protection.”
Unfortunately when something seems too good to be true it usually is! Since then, more research has been done, raising questions about mammography’s benefits. Now, it appears that mammography will reduce breast cancer deaths only in a portion of women—not all. How can this be? Why isn’t mammography doing what we expected?
The clue is in the new scientific findings that have shown us that all breast cancer is not the same. We used to think that breast cancer was a single disease, and that all breast tumors grew at the same rate. But as we’ve learned, that’s not the case. There are some breast cancers that are never going to progress to a lethal disease, while others with a different molecular biology will spread very early on, way before a mammogram could even detect them. And then there are others, somewhere in the middle, that have the potential to spread if not caught early. Mammography can be life saving for women with this type of breast cancer.
In other words: Mammography screening will save some women’s lives—but it will also find tumors in women who would never have gone on to die of breast cancer whether or not they had had a screening mammogram, because the outcome would have been the same if the tumor had been detected at a later time.
It is one thing to have this conversation about populations of women and to compare a theoretical group of women’s risks and benefits, or to say that from a cost effectiveness basis mammography screening will cause more problems with over diagnosis than it will prevent. It’s another, though, to answer the question individual women face: What should I do? This is more complicated and less scientific. Some say you should look at your risk and decide for yourself, but that is very difficult to do. It does not take into account the fear of developing a disease that could be fatal, or the relief from hearing that your mammogram is normal. There is no way that any woman can know if her cancer was an over diagnosis or a cure. Whatever happens to you is 100%!
So what should we do with this recent study? We should take it under consideration and combine it with our own experiences and decide for ourselves whether to continue getting mammograms or not. While we all would like magic and certainty, it is rare. We make decisions every day based on inadequate information and this is just one more. Take this study for what it is. Another attempt to figure out the best public policy. And then join the Army of Women and the HOW study and help us find the cause of breast cancer so that it won’t happen in the first place!