[Editor Note: This is a greatly expanded version of my initial thoughts on a study about mammography published in the New England Journal of Medicine last week on my not-so-super-secret other blog. It’s such an important topic that I thought SBM should see my discussion too, and I couldn’t just cut and paste it. You deserve original material.]
I knew it. I just knew it. I knew I couldn’t get through October, a.k.a. Breast Cancer Awareness Month, without a controversial mammography study to sink my teeth into. And I didn’t. I suppose I should just be used to this now. I’m referring to the latest opus from H. Gilbert Welch and colleagues that appeared in the New England Journal of Medicine last week, “Breast-Cancer Tumor Size, Overdiagnosis, and Mammography Screening Effectiveness.” Yes, it’s about overdiagnosis, something I’ve blogged about more times than I can remember now, but it’s actually a rather interesting take on the issue.
Before 2008 or so, I never gave that much thought to the utility of mammographic screening as a means of early detection of breast cancer and—more or less—accepted the paradigm that early detection was always a good thing. Don’t get me wrong. I knew that the story was more complicated than that, but not so much more complicated that I had any significant doubts about the overall paradigm. Then, in 2009, the United States Preventative Services Task Force (USPSTF) dropped a bombshell with its recommendation that mammographic screening beginning at age 50 rather than age 40 for women at average risk of breast cancer. Ever since then, there have been a number of studies that have led to a major rethinking of screening, in particular screening mammography and PSA testing for prostate cancer. It’s a rethinking that affects discussions even up to today, with advocates of screening arguing that critics of screening are killing patients and skeptics of screening terming it useless. Depending on the disease being screened for, the answer usually lies somewhere in between. Basically, screening is not the panacea that we had once hoped for, and the main reason is the phenomenon of overdiagnosis. Before I go on, though, remember that we are talking about screening asymptomatic populations. If a woman has symptoms or a palpable lump, none of this discussion applies. That woman should undergo mammography.