It's a holiday week. But when the New York Times published another op-ed by Dr. H. Gilbert Welch of the Dartmouth Institute on yet another, misleading two-author analysis of breast cancer screening by him and one other scientist, I thought it worth noting some concerns.
The issue is that educated, middle-aged women are being nudged, and frightened, and even charmed into not going for mammography. Nudged, by papers like the current Journal of the American Medical Association JAMA paper, which acknowledges controversy about statistics and then goes on to report a low range for how many lives are saved by screening. Frightened, by headlines that highlight the risks of overdiagnosis, a statistical concept. If a woman finds out she has an early-stage breast tumor, she and her doctor can decide how much therapy she should have based on the molecular subtype of her tumor, stage and other factors. And charmed, yes -- by the false notion that breast cancer is often nothing to worry about, that in many cases it can be let alone. That it might just disappear.
For now, let's examine the JAMA paper's hype about harms from false positives. The authors state that among 1,000 U.S. women age 50 years who are screened annually for a decade, "490 to 670 will have 1 false alarm." But as detailed in Table 2, it turns out the range for women who undergo false-positive biopsies is far lower: between approximately 50 and 100 per thousand women, depending on the age group and study from which the authors draw the data. What this means, according to the numbers they've culled, is that fewer than 1 in 10 women would undergo a breast biopsy, and not have cancer, per decade of screening.
Welch and his colleague emphasize the frequency and anxiety produced by false alarms. They cite studies documenting that "anxiety may persist for at least 3 years and produce psychological morbidity..." But I firmly believe that if women and primary care physicians were sufficiently aware of the data supporting that in most cases breast cancer can be removed and metastatic disease avoided, years later, by early detection, many would choose and advise screening. Most adult women can cope with the emotional distress of not knowing the results of a medical test for a few days or even weeks, as compared to the consequences of not finding an early-stage tumor that advances to Stage 4 disease.
Years ago, mammography was widely considered an act of empowerment, a way for women to take control of their bodies, and to avoid the disfiguring and sadly lethal effects of late-stage breast cancer, besides the potential need for treatment until the end of life. Now, screening is more accurate and involves less radiation than ever before. Women might be demanding universal access to better, state-of-the-art facilities, rather than shying away from the test.
Dr. Welch and I agree on at least one point, that women should have access to information so they might make reasoned decisions. Near the end of his latest op-ed, which, incidentally, was published during the media embargo of the work, Welch suggests that the way to reduce uncertainty about breast cancer screening is to carry out randomized clinical trials. But I don't think it makes sense to initiate large randomized trials of mammography in the United States at this time.
It takes 15 - 20 years of follow-up in a trial to demonstrate that screening and early detection reduce breast cancer deaths. Long, randomized trials of mammography would be costly, and besides that they might prove worthless. It would be better to spend those hypothetical research dollars in finding how to prevent breast cancer. If in 20 years breast cancer is less common, as we all hope will be the case, screening of the population won't be needed. And if that doesn't happen, by 2034 the technology will have improved, or we might have a valid alternative to mammography for screening, and so the studies would be, again, out of date.
In 2014, we might instead invest in resources to improve the quality of all screening facilities, and assure universal access to those. That way, women who choose to have the procedure can be confident it's performed using modern equipment, by well-trained doctors and technicians. The machines should provide images using the lowest level of radiation exposure possible. The results should all be evaluated, carefully, by breast imaging radiology sub-specialists. Those improvements would reduce the risks of the procedure, lower the false positive rate, and make women less afraid to be screened.