Think twice about mammography screening programs: The Swiss Medical Board

In a perspective published in The New England Journal of Medicine, members of the Swiss Medical Board – an independent health technology assessment initiative – presented a thorough review of mammography screening programs. The board, which included a clinical epidemiologist, a medical ethicist, a pharmacologist, a nurse scientist, an oncologic surgeon, a health economist and a lawyer, agreed that the downsides of mammography for breast screening in asymptomatic populations now outweigh any associated benefits. The following factors led to the board’s unanimous decision:

 

1.  Outdated clinical trials
According to the authors of the perspective, the ongoing debate surrounding mammography screening is “based on a series of reanalyses of the same, predominantly outdated trials.” The first trial, which started more than 50 years ago in New York City, and the most recent trial, which occurred nearly 25 years ago in the United Kingdom, did not take place “in the era of modern breast cancer treatment, which has dramatically improved the prognosis of women with breast cancer.”

 

2.  The benefits of mammography screening do not outweigh the harms
The authors were struck by how “nonobvious it was that that the benefits of mammography screening outweighed the harms.” In an effort to substantiate their claim, the authors added: “The relative risk reduction of approximately 20% in breast cancer mortality associated with mammography that is currently described by most expert panels came at the price of a considerable diagnostic cascade, with repeat mammography, subsequent biopsies and overdiagnosis of breast cancers.”

 

3.  Skewed perceptions
The authors referred to a survey about U.S. women’s perceptions of the benefits of mammography screening, and of the 1,003 participants questioned, 717 (71.5%) said they believed mammography reduced the risk of breast cancer by half. Seventy-two per cent of women believed “at least 80 deaths would be prevented per 1,000 women who were invited for screening.” However, the authors note, mammography may offer a relative risk of 20% and prevent only one breast cancer death per 1,000 women.