Two recent double blind randomised, placebo controlled trials using 5-alpha reductase inhibitors confirm that prostate cancer can be prevented in high risk individuals.
The Prostate Cancer Prevention Trial (PCPT) randomised 18 882 men to Finasteride or placebo and found a 24.8% reduction in prostate cancer in those randomised to finasteride. Urinary symptoms improved and those taking finasteride had prostates 24% smaller at the end of the study.
The REDUCE trial randomised men to dutasteride or placebo and performed biopsies at 2 and 4 years with an overall risk reduction of 23%. These effects were seen as early as year 2 (22.5% relative risk reduction) and persisted at year 4 (23.5%). The risk reduction was largest in those patients with a positive family history of prostate cancer found to have a 32% risk reduction.
Furthermore, patients treated with dutasteride had more than a 70% reduction in the risk of acute urinary retention or surgery for benign enlargement including TURP. Prostate volume reduction and symptom improvement occurred commonly in those in the treated arm of the study. Both dutasteride and finasteride were well tolerated with infrequent and generally self limiting side effects.