RESUMO
BACKGROUND: The study of a possible relationship between vasectomy and prostate cancer has yielded mixed results. Data from developing countries are limited. STUDY DESIGN: We conducted a hospital-based case-control study in China, Nepal and the Republic of Korea to evaluate the risk of prostate cancer after vasectomy. RESULTS: Prostate cancer in 294 cases (confirmed by independent pathologists) and 879 matched controls were included. The odds ratio of prostate cancer in men with a history of vasectomy was 1.21 [95% confidence interval (95% CI)=0.79, 1.87]. No significant trend was observed in risk by time since vasectomy or age at vasectomy. The odds ratio for localized disease was 1.02 (95% CI=0.53, 1.95); the odds ratio for later stages was 1.41 (95% CI=0.78, 2.53). No confounding factor was identified. The study illustrated differential misclassification of disease by vasectomy status; reference pathologists determined that 28% of men with a history of vasectomy, compared with 17% of men without a history of vasectomy, were misdiagnosed with prostate cancer by local pathologists. CONCLUSION: Vasectomy is not associated with an increased risk of prostate cancer in developing countries where the rate of the disease is low.