Vasectomy and risk of prostate cancer: a systematic review and meta-analysis of cohort studies.

The results of published literature focusing on the association between vasectomy and the incidence of prostate cancer are often inconsistent. We conducted a meta-analysis to provide a quantitative assessment of the association between vasectomy and the risk of prostate cancer. We identified all cohort studies by searching the PubMed, Embase, and Cochrane Library before August 2014. The quality of the studies was evaluated using the Newcastle-Ottawa Scale checklist. Summary effect estimates with 95% confidence intervals (CI) were derived using a fixed or random effects model, depending on the heterogeneity of the included studies. Nine cohort studies that spanned across two continents involving 1 127 096 participants (ages 20-75) with 7539 cases of prostate cancer cases were included in the meta-analysis. The overall combined relative risks for men with the reference group were 1.08 (95% CI: 0.87-1.34) in a random effects, however, the association was not statistically significant (p = 0.48). Estimates of total effects were generally consistent in the sensitivity and subgroup analyses. No evidence of publication bias was observed. This meta-analysis indicated that vasectomy may not contribute to the risk of prostate cancer. The conclusion might have a far-reaching significance for the public health, especially in countries with high prevalence rates of vasectomy.