Comparison of Free and Total Forms of Serum Human Kallilcrein 2 and Prostate-Specific Antigen for Prediction of Locally Advanced and Recurrent Prostate Cancer (Cancer Diagnostics‪)‬

Prostate-specific antigen (PSA [8]; human kallikrein 3 pro tein) is the protein product of the human KLK39 gene. Because of its remarkable tissue specificity in human males, PSA is the most valuable biomarker for prostate cancer (PCa). In addition to its established clinical application for early detection, PSA is a key variable in current prognostic models for clinically localized PCa (1-3). These models allow us to assess pathologic tumor stage and the risk of disease recurrence after local therapy. PSA concentrations in blood do not reflect only the presence of cancer, however; they are also driven by nodular hyperplastic or inflammatory processes. This lack of specificity limits the application of PSA as a predictor of stage and disease progression in populations in which PSA is regularly used for screening (4-6). Human kallikrein 2 (hK2), the product of the KLK2 gene, is a seriee protease with 80% sequence identity to PSA. The enzymes share the property of being expressed chiefly in the prostate under androgen regulation (7).