Tumor Prevention and Genetics

Anthony B. Miller, Miller, Anthony B.

The consensus that breast screening is effective for women aged 50-59 years was shattered when Gotzsche and Olsen suggested that there are no reliable data to support screening by mammography. In practice, their concerns have been difficult to address because for many studies purporting to show effectiveness, adequate data have not been published to confirm that they were valid. Further, the trials in Canada for which such data are available did not show effectiveness of screening mammography. Since the 1990s, there has been an unprecedented reduction in breast cancer mortality in many countries. However, the reductions have no clear link to screening, but are probably due to the implementation of adjuvant treatment with chemotherapy and tamoxifen. Whether screening will have an additional impact in the future is unclear. After reviewing the published evidence, I conclude that the additional contribution of mammography over screening by good breast physical examinations and breast self examination is to detect good prognosis breast cancers, as the benefit of screening derives from the earlier detection of relatively advanced breast cancers, providing good therapy is given. If women choose mammography screening, they should understand that their risk of dying in the next few years may not be reduced.