Screening mammography controversies: resolved, partly resolved, and unresolved

Since the 1960s, multiple randomized clinical trials have measured differences in breast cancer mortality between women 40 and 70 years of age who were offered screening mammography and control group women. This article describes briefly these trials, which nearly universally documented statistically significant reductions in breast cancer deaths. These trials also underestimated the benefit, regardless of age, due to screening parameters that were not optimized. In recent years, published articles analyzing studies of Swedish women have claimed that there is no reduction in overall mortality from breast cancer and other causes among women offered screening. Critical assessment of these articles noted that breast cancer deaths were less than 5% of all deaths and that no statistically significant reduction in overall mortality rates should be expected within the population that had been analyzed. The latest screening mammography controversies involve potential adverse consequences and risks, such as X-ray exposure, detection of ductal carcinoma in situ (DCIS), and "excessive" callback rates for additional imaging studies. Despite these controversies, the preponderance of scientific evidence continues to strongly support annual screening mammography for women 40 years of age and older.