Population-based cohort study of association of use of 5-α reductase inhibitors and mortality after prostate cancer diagnosis

Inhibitors of 5-α reductase (5-ARIs) are approved for treating benign prostatic hyperplasia (BPH) and have been found to reduce prostate cancer (PCa) risk by approximately 25%. However, trials also have shown 5-ARIs to be associated with high-grade PCa. A population-based cohort study in Ontario (Canada) investigated long-term outcomes of clinically localized PCa arising in individuals taking 5-ARIs compared with nonusers. Among 19,938 PCa patients aged 65 years or older, 2112 (10.6%) were 5-ARI users. During a median follow-up of 8.96 years (IQR 6.28-12.17), 6053 participants (30.4%) died, including 1047 (5.3%) from PCa. After inverse probability of treatment weighting prediagnostic 5-ARI use was not associated with overall mortality or PCa-specific mortality. The authors conclude that in this population-based cohort study, prediagnostic use of 5-ARIs was not associated with all-cause or PCa-specific mortality. These results support the safety of 5-ARIs to treat BPH and prevent PCa.