Contrary to prior reports, men who undergo vasectomy do not appear to be at increased risk for developing prostate cancer, according to findings published in the June 19th issue of the Journal of the American Medical Association.

Concern about a possible link between vasectomy and prostate cancer first arose from reports published in 1990. Following analysis of additional data from these studies, researchers concluded that vasectomy was probably not a risk factor for prostate cancer. However, in 1993, the findings of two large cohort studies appeared to reaffirm the link.

Dr. Brian Cox and colleagues, from the University of Otago in Dunedin, New Zealand, decided to study the relationship in a population of men living in New Zealand, a country with the highest vasectomy rate in the world and with mandatory national reporting of cancer cases. The study included 923 men with prostate cancer and 1224 matched control subjects.

The researchers found no evidence of a link between vasectomy and prostate cancer, even 25 years or more after the procedure. In fact, a vasectomy history was actually less common among case patients than controls, but the difference was not statistically significant.

“The high prevalence of vasectomy and the large size of our case-control study provided a 99% statistical power to detect a relative risk of 1.5 or higher at the 5% level of significance,” the authors point out. “That no association between prostate cancer and vasectomy was found, even 25 years or more after vasectomy, strongly suggests that there is no increased risk of prostate cancer after this procedure.”