The role of Prostate - Specific Antigen in the clinical evaluation of prostatic disease

Prostate Specific Antigen has truly revolutionized all aspects of the management of men with prostatic carcinoma. Its most important application is of course in the early detection or screening for this most common of all human malignancy. Prostate Specific Antigen has resulted in identifying men at risk for cancer and identifying such malignancies at a curable stage. Despite impressive results in the initial early detection screening studies, PSA is not the perfect tumor marker. The sensitivity is quite impressive. Approximately, 75 % of men with clinically significant prostate cancers have an elevation greater than 4.0 ng/ml. Specificity is, however, a problem. In fact, most series demonstrate that only 25-30 % of men with an abnormal PSA who undergo biopsy will be shown to have carcinoma. Thus considerable efforts are underway to make PSA more specific. Clinicians should be aware of the assays that their laboratorians are utilizing and the laboratorians should ideally define the performance of each free to total PSA assay in their patients setting prior to utilizing this test clinically. Finally, the free to total PSA may help stratify those men who have carcinoma despite an initial negative biopsy.