July 8, 2015
By Shannon Brownlee, MSc
When I turned 35, I dutifully went to my doctor to get a “baseline” mammogram. As a senior medical writer at U.S. News & World Report at the time, I knew getting a baseline was thought to provide a way for one’s doctor to look at subsequent mammograms and determine if any little white spots on the film were getting bigger and might indicate a cancer. When another medical reporter at the magazine told me there was growing concern that the radiation of mammograms themselves might cause some cancers, I was dubious. Everybody knew mammograms save lives. A tiny few additional cancers was surely offset by mammography’s life-saving power of catching cancers early.
That faith in screening was shaken in 2001, when the Cochrane Collaboration published the first systematic review of mammography.
The Cochrane study, which got front page play in the New York Times, set off a ferocious international debate because it found no evidence that mammograms save lives. At least one mammographer accused anybody who took the study seriously of “risking the lives of women.” Many breast cancer advocacy groups, the most powerful of which is the Susan G. Komen Foundation, continue to argue that mammograms are a no-brainer — you’d have to be crazy or stupid not to get one.
Now here we are, more than a decade later, still debating ferociously. Last year, a Canadian group published the longest and largest randomized trial of mammography ever done, finding no reduction in breast cancer mortality, and plenty of harm associated with biopsies and unnecessary treatment. A mammographer from Harvard, Daniel B. Kopans, accused the Canadian study’s lead author of “corrupted” research on public radio. (Nobody on the show pointed out that Kopans might have a bias: he’s named on numerous patents for mammographic technology.)
Now here comes yet another mammography study, co-authored by a bunch of terrific researchers, and I’m sure it too will be dismissed by many on the pro-mammography side. This study uses an “ecological method” to search for evidence of a link between rates of mammography in different US counties and rates of death from breast cancer. It found no link, suggesting more mammograms don’t lead to lives saved.
My bottom line is this: If mammography were a slam dunk, the studies wouldn’t be so equivocal, and the scientific community would not still be arguing about it. The same ecological method showed clearly that Pap smears reduce the death rate of cervical cancer. I get Pap smears. I don’t do mammograms. Not every woman should make the same choice, but as long as the evidence is so debatable, for me the downsides of mammograms outweigh the up.