Men who have undergone a vasectomy have more than a five fold risk of developing prostate cancer.
That is the unexpected association which emerged from data collected from 1976 to 1988 in comparing 220 men with 571 controlled men free from cancer and 960 controls with prostate cancer.
In the study, the vasectomy group was three and a half times more likely to develop prostate cancer than were men with another form of cancer.
"The magnitude of the relative risk estimate appeared to be unrelated to the length of the interval after vasectomy," said the report from the Boston University School of Medicine School of Public Health. American Journal of Epidemiology, as reported in JAMA, 24 April 1991.