Current role of protatic specific antigen (PSA) and its by-products in the diagnosis of prostate cancer

Incorporation of prostatic specific anti-gen (PSA) to clinical practice was a revolution in the diagnosis and modified the epidemiology of prostate cancer (PCa). Although it lacks of many characteristics of an ideal tumor marker, it is the marker most used for diagnosis and follow up of any kind of cancer. It represents the best clinical tool we have available today for screening and staging of PCa. On the contrary, its greatest limitation is the lack of tumor specificity. The use of PSA by-products and molecular isoforms tries to solve, at least partially, its limitations. Indeed, the use of FreePSA ratio ([%]fPSA) ad PSA density (PSAD) increase significantly the specificity of the diagnostic test and, the use of derivatives that evaluate time kinetics of PSA (PSA velocity (PSAV) and PSA doubling time (PSADT)) represents a very useful tool for prognosis estimation during treatment and follow up of the disease. The greatest advance over the last years comes from the analysis of the predecessor isoform (-2) pPSA and the phi Index. Both markers have demonstrated to improve the sensitivity and specificity results obtained to date, resulting in a decrease of unnecessary biopsies. Probably, with the ongoing development of new markers for PCa , the role of PSA on disease diagnosis and staging would be modified in a few years.