Mammography Revisited: Research and Rationalization

I'm 63 and have never had a mammogram. When I wrote about my reasons 17 years ago in Z Magazine, I got mixed and impassioned reactions: grateful, relieved support of my position that mammographies are neither safe nor effective and frightened or enraged opposition. How dare I, some demanded, discourage women from pursuing this life-saving, preventive measure?

Closer to home, my friends heard me out, then most succumbed to their doctors' insistence. But a growing number of doctors and researchers who have promoted and profited from this questionable procedure are calling for caution. Several recent studies speak directly to my 1992 argument that mechanically compressing and irradiating our breasts does not protect them—and may well do great harm.

In a meta-analysis of eight major studies to evaluate the effectiveness of mammographic screening that appeared in the prestigious British medical journal the Lancet in 2000, the researchers concluded: "Screening for breast cancer with mammography is unjustified...there is no reliable evidence that screening decreases breast-cancer mortality." A 2009 study in the open-access journal BMC Medical Informatics and Decision Making found that, "To save one life, 2,970 women have to be tested."

Moreover, their conclusions were based on studies in Europe, where, beginning at age 50, women get only one scan of each breast every two years. This is in dramatic contrast to the American Cancer Society's (ACS) recommended two scans per breast every year from age 40.

In October 2009, a front-page New York Times article told us that the very same ACS is "quietly working on its message" about mammography to emphasize the risks of overdiagnosis and overtreatment. Dr. Otis Brawley, ACS chief medical officer, admitted that, "American medicine has overpromised when it comes to screening." And Dr. Barnette Kramer, associate director for disease prevention, National Institutes of Health, said "overdiagnosis is pure unadulterated harm."

The British beat us to it. A 2008 letter by a group of physicians and researchers printed in the Times of London stated that the mammography handouts given to women do not "come close to telling the truth," but overstate benefits and minimize risks. In response, the British National Health Service has agreed to rewrite them. In a pamphlet, "Screening for Breast Cancer with Mammography," intended as a model for new leaflets, breast cancer researcher Peter Gotzsche wrote in 2008, "If 2,000 women are screened regularly for ten years, one...will avoid dying from breast cancer. At the same time, 10 healthy women…will [have] either a part of their breast or the whole breast removed and they will often receive radiotherapy and sometimes chemotherapy...[and] about 200 healthy women will experience a false alarm. The psychological strain until one knows whether or not it was cancer, and even afterwards, can be severe."

Over time the risks of false positives become even more striking. A 1998 study of 2,400 American women published in the New England Journal of Medicine estimated that after 10 screenings 49 percent of women will have at least one false positive test, resulting in repeated mammograms and possible biopsies. And a 2009 British Medical Journal article estimates that one in three breast cancers detected by mammography are "over-diagnoses," which are defined as detections of cancers that will never cause death or even symptoms.

 
It's becoming increasingly clear that what women get from mammography's marketing blitz is an almost-imperceptible clinical benefit and frequent diagnostic errors. The urgent message of this new research is that mammograms are, at best, questionably effective. But a separate and more far-reaching question remains—are they safe?

A 2008 study in the American Medical Association's Archives of Internal Medicine came to some shocking conclusions: invasive breast cancer rates went up in four Norwegian counties after mammograms were performed every two years for six years. A large control group of women who received only one mammogram at the end of 6 years was found to have 22 percent fewer cases of invasive breast cancer than the screened group. That is, over the course of 6 years, 1,909 out of 100,000 screened women had developed breast cancer, but only 1,564 out of 100,000 unscreened women had done so.

These figures become even more disturbing in light of the authors' convoluted reasoning: "...the natural course of some screen-detected invasive breast cancers is to spontaneously regress." They conclude that there is a much higher rate of spontaneous remission of invasive breast cancers than was ever before suspected, that 22 percent of undetected and untreated invasive breast cancers will spontaneously disappear. The disparity between the two groups continued after the six years. The women who got fewer mammograms got fewer cancers, both during the period of screening and after. This large-scale, well-designed study means either that some combination of the radiation, compression, and stress of waiting for bad news caused these excess cancers or that many more cancers would have spontaneously healed if left to their "natural course."

The National Cancer Institute estimates there will be more than 194,000 new breast cancer cases and almost 41,000 deaths this year, but very little is known about remission or regression. In a 1999 Danish international survey, researchers Larsen and Rose concluded that spontaneous remission of breast cancer is "very rare and the natural course is very variable."

The notion that nearly a quarter of serious breast cancers might just evaporate on their own allows researchers to ignore the obvious, because it's also the unthinkable: that mammography promotes breast cancer. There's no reason to believe the unscreened group ever developed those 345 cancers that inexplicably healed. To suggest that they did without even considering the more alternative of iatrogenesis, the medical origin of these cancers, demonstrates psychological denial, not scientific method. Both interpretations of the data call into serious question our highly profitable, but apparently neither effective nor safe, mammography screening program.

Too many researchers and physicians have bet their reputations and income on mammography and have pushed, threatened, and scared patients into getting scans early and often "for their own good." So when these turn out to be neither safe nor effective, researchers engage in guilt-driven rationalizations to conceal the truth from themselves as much as from others.