How to use prostate-specific antigen.
OBJECTIVE: To determine if prostate-specific antigen (PSA) is the most effective analyte for diagnosing, staging, and monitoring prostatic carcinoma. METHODS: This article reviews what PSA is and how it can be used to detect clinically significant carcinomas as well as its application in managing patients after radical prostatectomy, radiation therapy, and androgen deprivation therapy. RESULTS: PSA screening results in increased detection of localized disease. In individual patients a serum PSA level is not a good indicator of pathologic stage; however, a serum PSA level of greater than 10 ng/mL is associated with a higher incidence of extracapsular disease. Asymptomatic patients with newly diagnosed untreated prostate cancer and a serum PSA level less than 10 ng/mL do not need to undergo staging radionuclide bone scan. Elevated serum PSA is generally the first indicator of "persistent disease" after radical prostatectomy and radiation therapy. In androgen deprivation the PSA nadir is an important indicator of response to therapy. CONCLUSIONS: PSA is the most accurate tumor marker in oncology. This analyte can be successfully used to diagnose, stage, and monitor prostatic carcinoma.