title: Prostate cancer and vasectomy: a hospital-based case-control study in China, Nepal and the Republic of Korea.
abstract: BACKGROUND
  The study of a possible relationship between vasectomy and prostate cancer has yielded mixed results. Data from developing countries are limited.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  Vasectomy is not associated with an increased risk of prostate cancer in developing countries where the rate of the disease is low.
authors.affiliation: Family Health International, Research Triangle Park, NC 27709, USA.
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Schwingl
authors.forename: Olav
authors.initials: O
authors.lastname: Meirik
authors.forename: Nathalie
authors.initials: N
authors.lastname: Kapp
authors.forename: Timothy M M
authors.initials: TM
authors.lastname: Farley