Today was back to school day at our house. Thank goodness. Those kids needed to go back to school. For all of the learning, of course. As it turns out, apparently I had a little learning to do myself. (And yes, that’s the dog’s head. She’s missing her playmates. And driving me crazy.)
When we went around the circle of parents left at the bus stop discussing the glorious plans we all had for the day, they were about what you’d expect. Jiffy Lube, Target, spider removal from a chandelier… My goal for the day: make some lists. You know I love me a good, long list with checkboxes. Got my list made. (Check.) Then I proceeded to start checking off the boxes. Of course, I started with the easy ones. Then I got down to a tougher one: the great mammogram debate. (Insert dramatic dun-dun-DUNNNNN music here.) After hearing a lot about overdiagnosis and the inability of mammography to reduce the number of advanced cancers, I’d heard something about a new study that contradicted it, and decided I needed to clear it up.
Now hold on tight folks, it’s about to get a little science-y up in here. But I think I can get you through it. If a screening protocol is working, then one would expect to see more diagnosis of early stage disease and fewer cases of advanced disease. If you’re “catching it early,” then it will be diagnosed before it advances. Make sense? A study published in the the New England Journal of Medicine (very reputable) by Bleyer and Welch in 2012 looked at deaths from breast cancer in a roughly thirty year period since the introduction of mammography, and found that while there was a significant increase in overall cases of breast cancer, there was only a marginal (read: tiny) decrease in advanced disease. This led the authors to conclude that mammography was leading to a significant overdiagnosis of breast cancer (leading to the treatment of disease that would otherwise not kill the patient) without substantially decreasing the incidence of advanced disease. Their takeaway: mammograms don’t catch advanced disease early and catch a lot of otherwise insignificant disease. (Their subtext: mammograms are more trouble than they’re worth.)
I have to be honest. I didn’t like this. This put mammography into the “non-evidence based” decisions in my mind, right up there with contralateral prohylactic mastectomy. The evidence didn’t point to its benefit, but I just couldn’t imagine that mammography didn’t have a place in helping breast cancer patients. Until today.
In today’s issue of Cancer (also reputable, published by the American Cancer Society), Helvie et al. (that’s scientist speak for “and others”– Helvie’s group) published another look at that same data set. But they made one little tweak to their analysis that made a big difference. They adjusted their data for “temporal trends,” the change in incidence of a disease over time independent of any screening. (They looked at pre-mammography data and data from countries without widespread use of mammography to determine that each year, the number of breast cancer cases rises between one and three percent.) When they adjusted the data for this increase, they found that there was a marked increase in early stage breast cancer diagnoses, but a significant decrease in the number of advanced cases. They mentioned that their data doesn’t take into account who had a mammogram and who didn’t– it’s just all of the breast cancer deaths in the mammogram era vs. the pre-mammogram era. This would indicate that number of advanced cases would be even lower if they were looking only at a population of screened women. Did you stick with me, folks? That’s huge! That means that mammograms are catching potentially deadly cancers while they are still treatable. This study validates mammography as a screening tool. For years, studies showed the benefits of mammograms, but the Bleyer and Welch paper called that into serious question. Fears of needless biopsies and unneeded chemo compounded with their data left many women encouraging others to skip the annual mammogram. Somehow, I doubt this will be the last word in the great mammogram debate. But it is a thoughtful review of an excellent data set that agrees with many other studies. That’s enough for me. I’ll climb back up onto the mammography soap box with confidence. They do make a difference, ladies. Stop making excuses.
And now that I’ve finished my homework for the day, I’ll climb down off my soapbox so that I can go pick up my kiddos. I can’t wait to hear what they learned today at school. Won’t they be surprised when I can tell them that I learned something, too?