From pro-prostate specific antigen, [-2]pro-prostate specific antigen to Beckman Coulter phi: the evolution of new biomarkers for early detection of prostatic carcinoma.

Prostate specific antigen (PSA) has a wide clinical use for the early detection of prostatic carcinoma (PCa); however, it has never been a perfect marker due to its low specificity and low positive predictive value which ranges between 4 ng/ml and 10 ng/ml. The discovery of different PSA molecular forms in serum in the early 1990s brought insight into searching for more specific markers. Since then free PSA (fPSA) has been used routinely to increase the specificity for PCa and to reduce unnecessary biopsies. More recently, promising data is emerging regarding one proenzyme molecular form of free PSA, proPSA, and a few truncated proPSA isoforms. The purpose of this article is to review the recent studies on clinical utility of proPSA, especially [−2]pPSA, an isoform of proPSA, and parameters involving [−2]pPSA as well as other PSA derivatives in early detection of PCa.