Prostate specific antigen: A decade of discovery - What we have learned and where we are going

Purpose: Many advances have occurred during the last decade in the clinical use of prostate specific antigen (PSA) for detecting, staging and monitori ng prostate cancer. We review the clinical usefulness and limitations of se rum PSA as a tumor marker of prostate cancer. Materials and Methods: The English language literature was reviewed with re spect to the major contributions and limitations of PSA in present clinical practice. Results: Although controversial, age specific PSA reference ranges can impr ove the sensitivity for prostate cancer detection in young men and the spec ificity in older men. Percent free PSA improves the specificity for prostat e cancer detection in men with PSA values between 4 and 10 ng./ml., and a P SA density of greater than 0.15 may better distinguish benign prostatic hyp erplasia from prostate cancer. PSA velocity can improve the ability to dete ct prostate cancer when 3 serial PSA values are measured during a 2-year pe riod. For prostate cancer staging PSA is most useful combined with clinical stage and Gleason score in multivariate analysis. Percent fr ee PSA may pr ove useful for staging prostate cancer but further clinical trials are need ed to determine its clinical usefulness. PSA is the most clinically useful means to monitor disease recurrence after treatment of prostate cancer. Wit h ultrasensitive PSA assays it is now possible to increase the lead time fo r detection of disease recurrence by several months. Conclusions: During the last decade much of the focus has been on improving the ability of this tumor marker to detect prostate cancer. PSA remains th e best and most widely used tumor marker in urology today.