Prostate-Specific Antigen Comes of Age in Diagnosis and Management of Prostate Cancer

In the 6 years since the introduction of the first commercial immunoassays for prostate-specific antigen (PSA), this unique tissue-specific antigen has become established as the most useful serological marker for monitoring patients with prostate cancer. The antigen was originally isolated from semen by three indepen-dent laboratories searching for semen-specific antigens (1-3). Later, at Roswell Park Institute, the antigen was purified from normal prostate tissue, its natural source (4). This research group pioneered the use of PSA as a tumor marker to monitor patients with prostate cancer (5). Subsequent experience has shown that PSA is consid-erably more useful than prostatic acid phosphatase to monitor prostate cancer (6, 7). Serum concentrations o