Vasectomy (cont.)
Is there an increased risk for prostate cancer after a vasectomy?
Although the HSAM and a number of other studies showed no increase in cancer among vasectomized men, three separate hospital-based studies published in 1990 reported positive correlations between vasectomy and prostate cancer. However, a well-regarded 1991 study found no such relationship.
Because of the importance of the issue, all of this research has been carefully analyzed, and scientists have identified several potential problems in the studies. It is possible, for example, that men who choose vasectomy for contraception have above average access to health care. In particular, these men may be more likely than others to visit urologists -- physicians whose specialty includes the male reproductive organs, and they might thus be more likely to receive an accurate diagnosis of prostate cancer, a disease that often causes no symptoms and remains undiagnosed. If this were the case, vasectomy might falsely appear to increase the risk of this cancer.
In October 1991, the World Health Organization (WHO) sponsored a meeting of experts from around the world to evaluate the available evidence regarding a link between vasectomy and prostate cancer. Because additional concerns had been raised about a possible association between vasectomy and testicular cancer, evidence for such an association was also weighed at the meeting. The assembled experts concluded that a causal relationship between vasectomy and cancer of either the prostate or testis was unlikely. This conclusion was based in large measure on an overview of study results. But it was strengthened by the absence of a biological explanation of how vasectomy might product any form of cancer.
Following the WHO meeting, two additional studies of vasectomized men found no increased risk of either prostate cancer or all cancers combined. Subsequently, a study conducted in three regions of the United States suggested that the subgroup of men who had a vasectomy before age 35 might have a slightly increased risk of developing prostate cancer. However, the size of this subgroup was not large enough to make the result conclusive. The study did not find any increased cancer risk in men who underwent vasectomy after age 35.
In 1993, a noted team of Harvard epidemiologists published findings from two large studies in the Journal of the American Medical Association (JAMA). One of these studies was retrospective (backward-looking), while the other was prospective and followed new patients. Both found vasectomy to be associated with a moderately elevated relative risk of prostate cancer that increased with time after the procedure. After more than 20 years, a vasectomized man appeared to be twice as likely to develop prostate cancer as a nonvasectomized man of the same age. Although this conclusion may seem startling, scientists generally consider risk findings of this magnitude to be of doubtful significance.
The studies were examined by experts in several professional organizations as well as in a JAMA article. The authors of this article concluded that the studies could neither be relied upon nor ignored and that further research was essential.
These authors pointed out that, since the causes of prostate cancer remain unknown, it had been impossible to assure that risk factors for the illness were equally distributed between the vasectomized and nonvasectomized men. In one of the studies, the men who had undergone vasectomy had a lower overall death rate than the men who had not, supporting the likelihood that the two groups had different characteristics. Differences of this type might have affected prostate cancer risk, producing study results that misleadingly implicated vasectomy as a cause of prostate cancer.
Like others before them, these scientists also noted the lack of evidence for any biological mechanism that could link vasectomy with prostate cancer.
In 1993, NICHD convened a meeting at which an expert panel considered published data, preliminary results from studies in progress, and an analysis of eight epidemiologic studies, including the two reports mentioned above. The panelists concluded that the positive associations between vasectomy and prostate cancer found in some studies might or might not be valid. Scientists agree, however, that if any increased risk is caused by vasectomy, it is relatively small.
WHO is currently conducting a major study of vasectomy and prostate cancer in several developing countries, and three other studies are ongoing in the United States and Canada. Scientists expect these investigations to help resolve the issue.
In the interim, most physicians will be guided by NICHD's expert panel of 1993 which concluded there is insufficient basis for recommending any change in current clinical or public health practice. Providers should continue to offer vasectomy and to perform the procedure, the panel said. Vasectomy reversal is not warranted to prevent prostate cancer, and screening for prostate cancer should not be any different for men who have had a vasectomy than for those who have not undergone the procedure.
Vasectomy has been used for about a century as a means of sterilization. It has a long track record as a safe and effective method of contraception and is relied upon by millions of people throughout the world. On the basis of much evidence, experts believe that vasectomy can safely continue to be used as it has been in the past, while further research is carried out.
- Vasectomy is a simple procedure to induce infertility in the male.
- Vasectomy has a long track record as a safe and effective method of contraception.
- The procedure blocks the tube (the vas deferens) through which sperm pass.
- A vasectomy can be done even without a scalpel.
- Reversing a vasectomy is difficult, expensive, and often unsuccessful.
- Vasectomy offers no protection against HIV/AIDS or any other sexually transmitted diseases (STDs).
- Vasectomized men can develop harmless immune reactions to sperm.
- There has been concern about a possible increase in prostate cancer among vasectomized men. This risk (if it exists) is relatively small.
This article is based in part upon information from the National
Institutes of Health (NIH) and USA.gov.
Last Editorial Review: 4/19/2007
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