According to the recommendations of the American Urological Association, prostate specific antigen (prostate specific antigen, PSA) screening was generally carried out in the mid-1990s.[2] However, in recent years, many national guidelines have been updated and revised in accordance with the recommendations of U.S. Preventive Services Task Force (USPSTF), which recommended against PSA screening and pointed out that patients may be over diagnosed and over treated.[3] Nowadays PSA has not shown the ability to discriminate clinically important cancers from low-risk tumors. Here, KLK3 is linked to cancer.