In this landmark study 18,882 men aged 55 years or older with a PSA < 3 ng/mL and a normal rectal exam were randomized to either 5 mg finasteride (proscar) daily or placebo, and underwent prostate needle biopsy if either PSA > 4 ng/mL or the rectal exam became abnormal over the 7 years of the study. The main result was a 25% reduction in the prevalence of prostate cancer detected by needle biopsy in men who were given finasteride for 7 years. However it is uncertain whether this means prostate cancer was prevented or whether finasteride delays prostate cancer being detected. Also the sexual side effects of finasteride are not tolerated by some men including less volume of ejaculate, loss of libido, gynecomastia, erectile problems. On the counter side finasteride also improved symptoms in men with large prostates and urinary complaints. In addition the treatment group had a slightly higher detection of high grade prostate cancer at biopsy. What this all means is that finasteride is a good drug for men above 55, with prostatic enlargement and who are also keen to reduce their risk of developing prostate cancer.