Prostate-specific antigen and biomarkers for prostate cancer

Prostate-specific antigen (PSA) is a kallikrein serine protease secreted by the prostate to liquefy the ejaculatory coagulum. Changes in the blood/prostate barrier allows PSA to enter the circulation in men with prostate cancer and other inflammatory prostatic diseases. The commonest method for detection of men at risk of prostate cancer is PSA testing, which is typically used in an opportunistic screening setting. The widespread use of PSA testing leads to overdiagnosis and overtreatment of many men with low-risk prostate cancer, but can allow the identification of those with significant disease requiring radical treatment. This lack of specificity for high-risk prostate cancer has led to the need for more accurate biomarkers or methods to improve the use of PSA testing.