Prostate specific antigen: clinical use in the diagnosis and management of prostate cancer.

Prostate specific antigen (PSA) has replaced prostatic acid phosphatase as the preeminent clinical tumor marker in the management of patients with prostate cancer. Serum PSA levels have been shown to be proportional to clinical and pathologic stage of prostate cancer and in particular to correlate closely with prostate cancer volume. Serum levels of PSA thus serve as a useful adjunct in the initial clinical staging of men with prostate cancer. Serum PSA values provide a unique and valuable tool in monitoring prostate cancer progression over time and its response to surgical, radiation, and/or hormonal therapies. Unfortunately, its lack of specificity for prostate cancer leaves many questions unanswered as to the efficacy and advisability of using PSA as a screening test for this cancer.