Vasectomy and risk of prostate cancer.

Most studies do not support an association between vasectomy and prostate cancer, but a few have suggested a link. Vasectomy is a common birth control method, and prostate cancer is the most frequently diagnosed solid tumor in men, making this a major public health question. This study was specifically designed to determine whether or not vasectomy is associated with risk of prostate cancer. To examine this issue, we conducted a population-based case-control study in King County, Washington. Interviews were completed with men ages 40-64 years newly diagnosed with prostate cancer between January 1993 and December 1996 who were ascertained through the Seattle-Puget Sound Surveillance, Epidemiology, and End Results (SEER) cancer registry (n = 753) and with comparison men without prostate cancer identified from the same general population (n = 703). The odds ratio (OR) for prostate cancer in relation to vasectomy was assessed. The prevalence of vasectomy was similar in cases (39.4%) and controls (37.7%), resulting in no association (adjusted OR, 1.10; 95% confidence interval, 0.9-1.4). There was no consistent evidence that risk varied by the age at which vasectomy was performed, the time since vasectomy, or the calendar period when the vasectomy was performed. The OR in relation to vasectomy was higher in men with less aggressive prostate cancer. Risk estimates did not differ according to age, race, or family history of prostate cancer. This study suggests that vasectomy is not associated with the risk of developing prostate cancer. It also provides evidence that vasectomized men may be more likely to present with earlier-stage, lower-grade prostate tumors.