[[-2] proPSA: A Novel Marker of Prostate Cancer]

Over the decades, prostate-specific antigen (PSA) has contributed to the early detection of and screening for prostate cancer (PCa). However, PSA is now in the spotlight due to issues of overdetection and subsequent overtreatment of PCa, causing a serious drawback in PSA-based screening. The challenge of a PSA assay for PCa detection is that the sensitivity is high, whereas the specificity is relatively low. With advancements in molecular biology and genomics, numbers of novel PCa markers has been discovered. One of the promising serum biomarkers is proPSA. proPSA is a pre-mature form of PSA. The molecules are fractions of free PSA, and [-2]proPSA contains 2 amino acids as N-terminus pro-peptides of PSA. Studies have shown the possibilities of using [-2] proPSA-related indices like the Prostate Health Index and %2PSA as tumor markers for diagnosis. [-2]proPSA-related indices have improved specificity compared to commonly used PSA and free PSA to detect PCa, while maintaining high-level sensitivity. Reports on clinical utilities of [-2]proPSA are rapidly increasing, and recent studies suggested the utility of [-2] proPSA-related indices for the enhancement of optimized treatment strategies and patient management. At present, several investigations which may reveal clinical utilities of [-2]proPSA are on-going in Japan. Attention: At the time of the submission of this article, [-2] proPSA had yet to be approved as an in vitro diagnostic test in Japan.