A nested case-control study of the effectiveness of screening for prostate cancer: research design.

Although prostate-specific antigen (PSA) and digital rectal examination (DRE) are commonly used to screen for prostate cancer, available data do not confirm that either test improves survival. This report describes the methodological aspects of a nested case-control study addressing the question of whether PSA screening, with or without DRE, is effective in increasing survival. Potential sources of bias are discussed, as well as corresponding strategies used to avoid them. Results are expected in the year 2002.