If you have lived in the U.S. in the last few decades, the answer from every area of modern health has been yes. Mammograms detect breast cancer, and that leads to earlier treatment and less death. It’s a simple equation: more testing = more detection= less death. Too bad it’s all wrong.
Let’s be clear. The study they just published on mammograms is the end of the test. There will be a lot of hand waving, and it’s likely that docs will fight it, but in the end, it’s really hard to argue with numbers.
Here’s the study link. The study was large: over 89,000 women. It was long: over twenty-five years of follow-up. And it was definitive: mammograms do not prevent death from cancer. If you look at the equation above, that was the point of mammograms. It wasn’t the detection of breast cancer, it was the prevention of death.
But, the argument will go, we might detect breast cancer earlier for this specific person. Even though mammograms do not prevent cancer overall, there might be a reason to use a mammogram in this family or with these patients. We still might detect more cancers in certain subgroups of women and save lives that way.
Well, that wasn’t what the study found. In fact, mammograms resulted in 22% false positives, leading to unnecessary treatments. So while certain women might benefit from mammograms, we have to balance that against the very real one in five chance that the cancer detected was a false positive that resulted in unnecessary surgery and other treatments.
A huge amount of money (37 million tests a year at $100 each) and professional prestige has gone into the promotion of mammograms. But earlier studies showing some benefit did not use gold standard randomization, and failed to account for the increased use of drugs like Tamoxifen, which makes early detection less necessary (this from the NYT article). So unless someone else has another twenty-five year study handy, this one should make mammograms an optional rather than a mandatory medical test. Mind you, it won’t come without a fight from every major medical group that has promoted the test for decades.
But someone who isn’t invested in the system might ask whether our focus on unnecessary testing in prostate cancer and now in breast cancer has hindered our efforts to make really positive changes in our lives. How many people just get tested rather than start doing things to help themselves avoid the illness? If we could use all the money spent on mammograms to get women walking, wouldn’t that have been money better spent?