An Association Between Vasectomy and Prostate Cancer?

A 30-year debate about the association of vasectomy with excess risk for prostate cancer has been fueled by studies of variable quality and with mixed results. In this meta-analysis, researchers addressed study quality: They evaluated 53 studies (16 cohort, 33 case-control, and 4 cross-sectional) that involved about 15 million patients; only 9 cohort studies, 7 case-control studies, and no cross-sectional studies were categorized as having low risk for bias.

When analyses of the cohort studies were restricted to those with low risk for bias, a barely statistically significant excess risk for incident prostate cancer of any type (relative risk, 1.05) was noted. Using the same criteria for case-control studies revealed no significant associati…