Breast cancer screening in “real world” situations is not effective in preventing mortality, says a US case control study. The study, one of the largest completed to date looking at the effectiveness of breast cancer screening, was published in the Journal of the National Cancer Institute (2005;97: 1035-43).

Randomised controlled studies have shown that breast cancer screening prevents deaths. Many organisations recommend screening by clinical examination and mammography every year or two for women aged 40 or older.

“We observed no appreciable association between breast cancer mortality and screening history, [regardless of age or risk level],” the authors write. “Our findings may, therefore, reflect a possible reduction in the accuracy of screening as it moves from highly controlled randomised …