Although vasectomies do not increase your risk of dying from heart disease, another study shows an increased risk of cancer, mainly of the lung, among those who'd had their vasectomies done 20 years before.

This study of 28,000 men, half of whom had undergone vasectomy by 1976, showed that those who'd undergone the procedure were not at increased risk of atherosclerosis, or hardening of the arterial walls.

This was a concern because it is known that antibodies to sperm form in some two thirds of men who have undergone vasectomy and persist for many years.

The theory has been that immune complexes formed from these antibodies could injure the arterial walls and bring on hardening of the arteries. This theory seemed justified because advanced atherosclerosis has been observed after vasectomy in animals.

However, to date studies in humans haven't shown an increase in heart disease for up to 15 years after vasectomy.

This large study tended to confirm that finding, while throwing up a wild card result. Those men who'd had a vasectomy at least 20 years earlier were one and a half times more likely to have died from cancer, particularly lung cancer, even when adjustments were made for smoking habits, body size, alcohol consumption or even educational level. This cancer risk was primarily of the lung, although this study observed an increased risk of prostate cancer, as has been noted in other studies.

"Although the focus of research to date has been on cardiovascular disease, the immune response to sperm after a vasectomy may possibly influence carcinogenesis," said the study. 21 May 1992.