KLK3 and prostate cancer: The benefits and harms of the prostate-specific antigen (PSA) screening test to reduce specific mortality have been debated for a long time.A recent Cochrane systematic review [2], combining data from five randomized clinical trials (RCT) with more than 340,000 participants, including two important recent RCTs in Europe [3] and USA [4], found that PSA screening did not reduce the specific mortality for prostate cancer, and tended to lead to over-diagnosis and consequent over-treatment.