The effect of finasteride as a chemopreventive agent has been established in the critical analysis of the Prostate Cancer Prevention Trial (PCPT) study by Goetzl and Holzbeierlein.[51] In the PCPT study, healthy men aged 55 years or older with a normal digital rectal examination and a PSA level of 3 ng/ml or lower were enrolled and a total of 18,882 men were randomized to receive either finasteride 5 mg/day or placebo for seven years. The gene discussed is KLK3; the disease is prostate cancer.