Vasectomy
Some studies have raised questions about a possible relationship between having a vasectomy and an increased risk of developing prostate cancer. This would be a very important risk factor to be aware of because 1 out of 5 men over the age of 35 in the U.S. has had a vasectomy. It does appear that men who have had a vasectomy are a little more likely to be diagnosed with prostate cancer 20 years later, but there is absolutely no evidence of a cause-and-effect relationship. There is good reason to believe that it may be due in large part to the health behaviors of men who get vasectomies. They may be more likely to look after their health more, meaning more check-ups and therefore more prostate exams than men who do not get vasectomies. And it is well established that men who are screened more, are diagnosed more.
The strongest evidence for an association between vasectomy and prostate cancer came from the well-respected Health Professionals Follow-Up Study in 1993. This is a prospective study investigating the causes of cancer and heart disease in men. Researchers following 47,855 participants, of whom 10,055 had had a vasectomy, reported that men with vasectomies were one-and-one-half times as likely as men without vasectomies to develop prostate cancer. The number of years since the surgery seemed to be an important factor. Men who had had a vasectomy at least 22 years before had almost twice the risk of disease.
Several other prospective and retrospective studies have examined the relationship between vasectomy and prostate cancer with inconsistent results. Some have shown no relation, others a somewhat greater risk. But when the evidence from the 14 available studies (5 prospective and 9 retrospective) was systematically combined, the result was only a slightly increased risk. Since this review was published, a couple of large retrospective studies have been published that confirm that the effect of vasectomy on the risk of prostate cancer is small.
No convincing biological mechanism for how a vasectomy could cause prostate cancer has been presented. There still are a few questions about the possible relationship of vasectomy and early-stage prostate cancer in younger men; but if there is an increased risk, it is small.
The NCI is addressing the issue of vasectomy and prostate cancer in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Trial, which began in 1993. The PLCO Trial is evaluating screening procedures for prostate cancer and will prospectively examine potential risk factors, including vasectomy, associated with prostate cancer.
