Some current issues in breast cancer screening.

Randomized trials of mammography have demonstrated the efficacy of mammographic screening for breast cancer in terms of preventing deaths, but various issues of particular interest remain, including: quantification of overdiagnosis; evaluation of service screening outside the research setting; absolute benefit in terms of number needed to screen per life saved; which types of tumours benefit most from early detection; use of screening data to investigate tumour biology and natural history. This paper describes examples of approaches to the above issues, along with some important results.