A systematic review and meta-analysis found that PSA-based screening in men without a diagnosis of prostate cancer led to prostate-specific mortality in 2 of 1000 men in the screening group and 3 of 1000 men in the no screening group over 10 years (incidence rate ratio= 0.79, 95% CI 0.69–0.91, moderate quality evidence) [72]. This evidence concerns the gene KLK3 and prostate cancer.