Abolishing Mammography Screening Programs? A View from the Swiss Medical Board

One of the leading public and international health institutes in Europe, the Swiss Medical Board, is a nongovernmental, independent health technology assessment initiative in Switzerland that functions under the auspices of the Swiss Medical Association, the Swiss Academy of Medical Sciences, and the Conference of Health Ministers of the Swiss Cantons. The Board is mandated “to contribute to the improvement of the health of populations internationally, nationally and locally through excellence in research, services and teaching and training.”

After the board was called to prepare a review of mammography screening (Jan. 2013), it released a report of its findings, which were made public on February 2, 2014. Based on the board’s review of available evidence, it concluded that:

  1. no new systematic screening mammography programs should be introduced,
  2. all forms of mammography screening must be evaluated for quality,
  3. women must be given clear and balanced information on the benefits and harms of screening,
  4. systematic mammography screening programs in Switzerland–due to the tool’s limited utility for reducing mortality and the increased likelihood of harm from overdiagnosis and overtreatment—should be phased out.

The board’s strong recommendation differs dramatically from the “early detection is the best protection” slogans that pervade many breast cancer awareness campaigns and public health promotion programs internationally. Weighed against the slight benefit of repeated screening were the harms of increased biopsies and the overdiagnosis of breast cancers that would never have produced symptoms in a person’s lifetime or become clinically relevant. Overdiagnosis can increase the impact of cancer on quality of life and longevity because it leads to overtreatment, exposing patients to potential harms without offering any benefits.

The authors explained further that evidence of no effect of screening on overall mortality coupled with evidence of harm was especially disturbing in light of the fact women tend to vastly overestimate the benefits of screening compared to what is actually expected in reality: 71.5 percent of women surveyed believed that mammography reduced risk of breast cancer death by at least one-half, and 72.1 percent believed that 80 deaths would be prevented for every 1,000 women invited for screening. In reality, studies have found at most a relative risk reduction for breast-cancer mortality of only 20 percent, making the actual effect of mammography screening on breast-cancer deaths only one death for every 1000 women invited for screening.

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The Swiss Medical Board argued that beliefs in screening, rather than evidence, were at issue:

“It is easy to promote mammography screening if the majority of women believe that it prevents or reduces the risk of getting breast cancer and saves many lives through early detection of aggressive tumors. We would be in favor of mammography screening if these beliefs were valid. Unfortunately, they are not, and we believe that women need to be told so.”

Interpretations and Implications

Indeed, calling for the eventual cessation of mammography screening programs would cause uproar in some circles, particularly from specialists who believe in the high-tech tool and worked to institutionalize it. However, the board’s conclusion is based on the ethical premise that there is little (to no) justification for a public health program that does not clearly produce more benefits than harms. Based on the available evidence, systematic mammography screening programs, simply, are not justifiable.

The Swiss Medical board’s recommendation against screening mammography programs follows on the heels of findings from the Canadian National Breast Screening Study, published just one week after the Swiss board’s iconoclastic pronouncement. The Canadian National Breast Screening Study confirmed its earlier results that mammography screening did not reduce breast cancer deaths for women ages 40-59. Instead, one in five of the screen-detected cancers would have posed no threat to the patients’ health.

Source: Nikola Biller-Andorno, Peter Jüni. 2014. “Abolishing Mammography Screening Programs? A View from the Swiss Medical Board,” The New England Journal of Medicine [Apr. 16].

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