The National Institute for Health and Clinical Excellence recommends that men are monitored under the START (Study of Active Surveillance versus Radical Treatement in Patients with Favourable-Risk Prostate Cancer) trial protocol, an ongoing trial where men have their PSA level measured regularly, and undergo prostate biopsy every 2 years (http://www.cancer.gov/clinicaltrials/CAN-NCIC-CTG-PR11). This evidence concerns the gene KLK3 and prostate carcinoma.