title: Vasectomy and prostate cancer.
abstract: OBJECTIVE
  Vasectomy has been associated with an increased risk of prostate cancer in some previous studies but not in others. We evaluated the association in a population based, case control study in Massachusetts.
  
  
  METHODS
  Included in our study were 1,216 patients younger than 70 years with newly diagnosed prostate cancer and 1,400 controls with no history of prostate cancer who were matched to patients by age and town of residence. Data on vasectomy and potential confounding factors were obtained by telephone interview, and confounding was controlled by conditional logistic regression analysis.
  
  
  RESULTS
  Overall 16% of patients and 15% of controls had undergone vasectomy. Compared with no vasectomy the odds ratio for ever having undergone vasectomy was 1.0 (95% confidence interval [CI] 0.8 to 1.3), which did not vary significantly by age at or interval since vasectomy. In men who reported urological symptoms and those without symptoms the odds ratio was 0.9 (95% CI 0.7 to 1.2) and 1.4 (1.0 to 1.9), respectively. In men younger than 55 years and those 55 years old or older at diagnosis of prostate cancer the odds ratio was 1.9 (95% CI 1.2 to 3.2) and 1.0 (0.8 to 1.3), respectively [corrected]. In the younger men with stages A or B and C or D disease the odds ratio was 2.3 (95% CI 1.2 to 4.3) and 1.3 (0.5 to 3.5), respectively.
  
  
  CONCLUSIONS
  Our findings do not support the hypothesis that vasectomy increases the risk of prostate cancer in men older than 55 years. Further study is needed to determine whether the observed association between vasectomy and prostate cancer in men younger than 55 years is due to chance, detection bias or a causal effect.
authors.affiliation: Slone Epidemiology Unit, School of Public Health, Boston University School of Medicine, Brookline, Massachusetts, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Lesko
authors.forename: C
authors.initials: C
authors.lastname: Louik
authors.forename: R
authors.initials: R
authors.lastname: Vezina
authors.forename: L
authors.initials: L
authors.lastname: Rosenberg
authors.forename: S
authors.initials: S
authors.lastname: Shapiro
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D016022:Case-Control Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011471:Prostatic Neoplasms / Q000453:epidemiology* / Q000209:etiology*; D014659:Vasectomy / Q000009:adverse effects*