Breast cancer screening in younger women: evidence and decision making

Contrasting conclusions on the efficacy of routine breast cancer screening in younger women, under age 50, have been produced by expert and influential groups, particularly in the United States. In an international workshop in 1993, and again at a consensus development conference in 1997, the National Institutes of Health and the National Cancer Institute concluded that evidence for efficacy was uncertain, and routine screening could not be recommended. The 1997 conference concluded that the individual decision had to be made by each woman and her health care provider. In contrast, the American Cancer Society has advocated routine screening, despite accepting that the randomized trial evidence does not clearly support it. The decision of the 1997 NCI consensus conference has been rejected by the director of the NCI, and a similar controversy occurred in 1993. On two occasions, US Senate subcommittees have affirmed support for screening and criticized the conclusions of expert groups. In this paper, the arguments raised in these discussions, and the differing ways in which scientific evidence has been assessed, are discussed.