Asymptomatic screening using PSA is undertaken, and accepted in some countries, including the US, however the U.S. Preventative Services Task Force recommend a discussion on the potential benefits and harms of PSA screening, stating that screening offers a “small potential benefit of reducing the chance of dying of prostate cancer” but also highlighting that “many men will experience potential harms of screening” [2]. Here, KLK3 is linked to prostate cancer.