The prostate specific antigen. Its use as a tumor marker for prostate cancer.

The prostate specific antigen (PSA) has had an enormous impact on the diagnosis and management of prostate cancer. Use of the PSA has strikingly increased the diagnosis of prostate cancer since its introduction and widespread application in clinical practice. This article examines the assay characteristics of PSA, its utility in early detection of prostate cancer, and its use in facilitating treatment decisions.