KLK3 and prostate cancer: <h4>Background and objective</h4>The European Randomized Study of Screening for Prostate Cancer showed 20% reduction in prostate cancer (PC) mortality after 16 year follow-up of prostate-specific antigen (PSA) based screening, but effects varied: 9% in Finland (FinRSPC) vs 37% in Sweden (Göteborg-1) in screening vs control groups.