Vasectomy and Risk of Prostate Cancer: A Systematic Review and Meta-analysis

CONTEXT: Previous reports have shown an association between vasectomy and prostate cancer (PCa). However, there exist significant discrepancies between studies and systematic reviews due to a lack of strong causal association and residual confounding factors such as prostate-specific antigen (PSA) screening. OBJECTIVE: To assess the association between vasectomy and PCa, in both unadjusted and PSA screen-adjusted studies. EVIDENCE ACQUISITION: We performed a systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses. The PubMed, Scopus, and Web of Science databases were searched in January 2022 for studies that analyzed the association between vasectomy and PCa. EVIDENCE SYNTHESIS: A total of 37 studies including 16 931 805 patients met our inclusion criteria. A pooled analysis from all studies showed a significant association between vasectomy and any-grade PCa (odds ratio [OR] 1.23; 95% confidence interval [CI], 1.10–1.37; p < 0.001; I(2) = 96%), localized PCa (OR 1.08; 95% CI, 1.06–1.11; p < 0.00001; I(2) = 31%), or advanced PCa (OR 1.07; 95% CI, 1.02–1.13; p = 0.006; I(2) = 0%). The association with PCa remained significant when the analyses were restricted to studies with a low risk of bias (OR 1.06; 95% CI, 1.02–1.10; p = 0.02; I(2) = 48%) or cohort studies (OR 1.09; 95% CI, 1.04–1.13; p < 0.0001; I(2) = 64%). Among studies adjusted for PSA screening, the association with localized PCa (OR 1.06; 95% CI, 1.03–1.09; p < 0.001; I(2) = 0%) remained significant. Conversely, vasectomy was no longer associated with localized high-grade (p = 0.19), advanced (p = 0.22), and lethal (p = 0.42) PCa. CONCLUSIONS: Our meta-analysis found an association between vasectomy and any, mainly localized, PCa. However, the effect estimates of the association were increasingly close to null when examining studies of robust design and high quality. On exploratory analyses including studies, which adjusted for PSA screening, the association for aggressive and/or advanced PCa diminished. PATIENT SUMMARY: In this study, we found an association between vasectomy and the risk of developing localized prostate cancer without being able to determine whether the procedure leads to a higher prostate cancer incidence.