Association Between 5α-Reductase Inhibitors and Prostate Cancer Mortality: A Systematic Review and Meta-analysis.

Importance: Recently, several large, high-quality analyses have shown opposing results regarding the association between 5α-reductase inhibitor (5-ARI) use and prostate cancer (PCa) mortality.
Objective: To systematically evaluate the current evidence regarding 5-ARI use and PCa mortality.
Data Sources: A literature search began in and was conducted through August 2022 using PubMed/Medline, Embase, and Web of Science databases.
Study Selection: Studies were deemed eligible if they included male patients of any age who were 5-ARI users and were compared with those who were nonusers if they analyzed PCa mortality in randomized clinical trials and prospective or retrospective cohort studies.
Data Extraction and Synthesis: This study was reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline. Adjusted hazard ratios (HRs) were extracted from published articles. Data analysis was performed in August 2022.
Main Outcomes and Measures: The primary outcome was PCa mortality among 5-ARI users vs nonusers. The inverse variance method with adjusted HRs and random-effect models were used to determine the association between 5-ARI use and PCa mortality. Two subgroup analyses were performed to assess the effect of 2 main confounders: prostate-specific antigen level and PCa diagnosis at baseline.
Results: Among 1200 unique records screened, 11 studies met the inclusion criteria. A total of 3 243 575 patients were included: 138 477 users of 5-ARI and 3 105 098 nonusers. There was no statistically significant association between 5-ARI use and PCa mortality (adjusted HR, 1.04; 95% CI, 0.80-1.35; P = .79). No significant association was found when the analysis was restricted to studies that excluded patients with a diagnosis of PCa at baseline (adjusted HR, 1.00; 95% CI, 0.60-1.67; P = .99) or the analysis was restricted to prostate-specific antigen-adjusted studies (adjusted HR, 0.76; 95% CI, 0.57-1.03; P = .08).
Conclusions and Relevance: This systematic review and meta-analysis, which draws on 2 decades of epidemiologic literature and includes more than 3 million patients, found no statistically significant association between 5-ARI use and PCa mortality but provides important data to inform clinical care.