The war against breast cancer — or mammography?
The ongoing attacks directed against screening mammography remain sources of bitter disappointment for those of us focused on another war on a daily basis, that against a real killer — breast cancer. We have a powerful weapon in high-quality mammography: We know this based on real science, stemming from randomized controlled trials. The randomized controlled trials is the most valid measure of value of any test, and mammography screening has been measured by this method more than any test in the history of medicine.
The largest randomized controlled trials were conducted in Sweden from 1977 to 1985, and showed a 31 percent decrease in deaths from breast cancer among women offered mammograms versus those who were not. The benefit was actually much greater, with a decrease in mortality of 43 percent among women who actually had mammograms. Six other randomized controlled trials from the U.S. and Europe showed similar findings. This benefit was demonstrated in every age group beginning at age 40. As a result, screening mammography began in earnest worldwide in the 1980s.
Further validation came from worldwide organized, governmentrun, mammography-screening programs, which have now involved more than 20 million women. The results of every one of these programs showed a 30 percent to 50 percent decrease in breast cancer deaths. The explanation for this success: Screening lowers the rate of advanced, less controllable cancers.
However, those opposing early detection — largely pseudo-skeptics with no experience in screening — stubbornly refuse to acknowledge the huge benefits shown in randomized controlled trials and organized screening programs. Instead, they focus on so-called “harms” of mammography, most notably overdiagnosis and anxiety. Screening mammography actually reduces anxiety for the 90-plus percent of women who have a normal mammogram. For the vast majority of women, the screening mammogram is a “good news” examination!
The Danish authors of the most recent attack on mammography screening, the subject of the commentary by Robert Gebelhoff (“Be skeptical about mammograms,” Jan. 22) published in The Santa Fe New Mexican, focus on overdiagnosis, claiming that a large number of cancers detected by mammography would never kill. This issue was already addressed in numerous scientific publications, which showed that overdiagnosis exists in no more than 1 percent to 5 percent of the cases. Strangely enough, the anti-screening campaign focusing on harms of mammography originates in Denmark, a country with one of the highest breast-cancer death rates in Europe.
The United States Preventive Services Task Force also focused on so-called “harms” of screening mammography, especially anxiety and overdiagnosis. With no valid data to support their claims of “harms,” they made value judgments, not scientific judgments. They also refused to consider the powerful collected data from the multiple worldwide organized screening programs.
As a result, in 2009 and again in 2016, they recommended no screening mammography for women in their 40s or above age 74, and mammograms every two years for women 50-74. A recent study showed these recommendations would result in 6,500 additional deaths from breast cancer, every year! Even more perturbing, these have the power of law under the Affordable Care Act, and would have become guidelines for both government and private institutions, had Congress not passed a moratorium, allowing women to continue to have mammograms covered yearly beginning at age 40. This moratorium is due to expire at the end of 2017, so there is still concern that many women will lose affordable access to screening mammography.
We know that mammography is not a perfect test — there is no perfect test in all of medicine. However, we now have digital mammography, tomosynthesis, screening ultrasound and MRI, which are shown to find 40 percent to 50 percent more cancers. With prudent use of these tools, effectiveness of screening in decreasing breast cancer deaths should soar even higher. But screening mammography’s availability as our primary screening weapon must be maintained at this time – without its continued widespread use, breast cancer death rates will surely rise. We know we have better tools on the way — as they become more affordable and available, women will have an even greater chance of surviving and thriving, even in the face of this terrible disease.