Vasectomy and prostate cancer: a case-control study in India.

ABSTRACT

BACKGROUND: The role of vasectomy in the development of prostate cancer remains controversial. In particular, there has been concern about detection bias and confounding in the previously published epidemiological studies examining this hypothesis. With the goal of minimizing detection bias, we have evaluated the relation between vasectomy and prostate cancer in a population without routine prostate cancer screening. METHODS: A case-control study consisting of 175 prostate cancer cases and 978 controls with cancer diagnoses other than prostate cancer was conducted at hospitals covered by the Bombay Cancer Registry in Bombay, India. History of vasectomy, demographic, and lifestyle factors were obtained by structured interview. Multiple logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI). RESULTS: Standardizing by age, 8.7% of cases and 8.3% of controls had had a vasectomy. The OR for prostate cancer comparing men who had had a vasectomy to those who did not was 1.48 (95% CI 0.80-2.72) controlling for age at diagnosis, smoking status, alcohol drinking, and other demographic and lifestyle factors. Risk of prostate cancer associated with vasectomy appeared to be higher among men who underwent vasectomy at least two decades prior to cancer diagnosis or who were at least 40 years old at vasectomy. CONCLUSIONS: Although not statistically significant, the results of this hospital-based case-control study are consistent with the hypothesis of a positive association between vasectomy and prostate cancer. Because routine prostate cancer screening is not common in this population, detection bias was unlikely to account for this association.

ABSTRACT

PIP Although several studies have detected an association between vasectomy and subsequent prostate cancer, the research has been marred by detection bias and confounding. This association was reassessed in a hospital-based case-control study conducted in India, where the absence of routine screening for prostate cancer eliminates the potential for detection bias. Enrolled from hospitals covered by the Bombay Cancer Registry were 175 prostate cancer cases and 978 controls with other types of cancers. 17 cases and 83 controls reported a history of vasectomy. After age was controlled, the odds ratio for prostate cancer was 1.31 (95% confidence interval (CI), 0.74-2.33) among vasectomized compared with nonvasectomized men. Further adjustment for confounding factors such as smoking, alcohol consumption, and marital status increased the relative risk to 1.48 (95% CI, 0.80-2.72). Compared with men without a vasectomy history, men who underwent the procedure more than 20 years earlier had 1.56 times the risk (95% CI, 0.79-3.08) of prostate cancer. Men who were 40 years of age or older at vasectomy had a relative risk of prostate cancer of 2.10 (95% CI, 1.02-4.31) compared with controls; this risk was not elevated in younger men. Overall, these findings confirm the hypothesis of a small but positive association between prostate cancer and vasectomy.