Prostate-Specific Antigen: Critical Issues for the Practicing Physician

Serum prostate-specific antigen (PSA), when used in combination with existing detection methods, improves the clinician's ability to detect early and potentially curable prostate cancer. This report describes clinically important issues about use of the serum PSA concentration for detecting early prostate cancer. Other PSA-related factors—PSA density, PSA velocity, and age-specific reference ranges—seem to enhance the ability of clinicians to distinguish benign prostatic conditions from early prostate cancer. Because digital rectal examination only minimally affects the serum PSA concentration, delaying a determination after this examination is unnecessary. Finasteride therapy for benign prostatic hyperplasia should be initiated only after the prostate has been evaluated for cancer because this 5α-reductase inhibitor lowers the serum PSA value by approximately 50%; however, reassessment of the prostate for cancer is necessary if the PSA level fails to decrease as expected or increases to more than 2 ng/mL during finasteride treatment. Currently, PSA is the most important, accurate, and clinically useful tumor marker for prostate cancer.