Evidence from the Prostate Cancer Prevention Trial (PCPT), the European Randomized Study of Screening for Prostate Cancer derived Prostate Risk Indicator (SWOP-PRI) and the Montreal cohort studies demonstrated that variables including age, ethnicity, family history of prostate cancer, prostate volume and digital rectal examination (DRE) could improve the positive predictive value of PSA [6]–[8]. The gene discussed is KLK3; the disease is prostate cancer.