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Health See other Health Articles Title: Vasectomy Linked to Higher Risk for Lethal Prostate Cancer Medscape...A large cohort study has found that vasectomy is associated with a modest increase in the incidence of high-grade and lethal prostate cancer. However, vasectomy does not appear to be associated with a risk for low-grade or localized disease, according to a study published online July 7 in the Journal of Clinical Oncology. "The cumulative incidence of lethal prostate cancer during a 24-year follow-up was 1.6%; thus, these relative risks translate to small increases in absolute risk," conclude the researchers, led by Lorelei Mucci, MPH, ScD, associate professor of epidemiology at the Harvard School of Public Health in Boston. They note that previous studies have had mixed results, with some suggesting a link between vasectomy and prostate cancer and others suggesting no link. Vasectomy is a common form of contraception; the prevalence is about 15% in the United States. "The decision to opt for a vasectomy remains a highly personal one in which the potential risks and benefits must be considered," the researchers note. Study of Nearly 50,000 Men The prospective cohort study involved 49,405 participants in the Health Professionals Follow-up Study who were 40 to 75 years of age in 1986. By 2000, 12,321 men (25%) had undergone vasectomy. By 2010, after 24 years of follow-up, 6023 patients had been diagnosed with prostate cancer — 732 with high-grade disease and 811 with lethal disease. In men who had undergone vasectomy, compared with those who had not, the multivariable-adjusted relative risk (RR) for prostate cancer was 1.10. There was no significant association between vasectomy and the risk for low-grade cancer. Vasectomy was associated with a higher risk for lethal disease (RR, 1.19), advanced-stage disease (RR, 1.20), and high-grade disease (RR, 1.22). Small Risk, No Causal Relation "As is often the case in observational studies, there are contradictory findings," said David Miller, MD, MPH, assistant professor in the Department of Urology at the University of Michigan in Ann Arbor. "This study has a provocative finding of a slightly higher relative risk of prostate cancer among men who underwent a vasectomy." Time since vasectomy and age at vasectomy had no effect on the risk for prostate cancer. "The cancers that were observed were also considered more clinically significant, such as those that are high grade or lethal," he noted. That said, Dr. Miller emphasized that the overall risk for lethal prostate cancer is small. "While the relative risks are statistically significant, the absolute risk for an individual patient is very small," he said. "We're talking about 1% or less." He pointed out that the researchers attempted to account for possible biologic mechanisms underlying the association between vasectomy and lethal prostate cancer. They looked at differences in sex hormone levels, sexually transmitted infections, and cancer treatment. Although the researchers looked for mechanistic relation, they could not find one. "Why would having a vasectomy lead to a higher risk of prostate cancer?" he asked. "This is an important issue when thinking about causality." Dr. Miller said that he would not dissuade patients from undergoing vasectomy on the basis of current literature. "It is important to raise the issue with the caveats. I would synthesize it and allow them to make their own decision." We need to understand the possible mechanism underlying this relation "before we can say it's causal," he explained. Subgroup of Highly Screened Men In their study, Dr. Mucci and colleagues analyzed a subgroup of highly screened men. They reasoned that because prostate-specific antigen (PSA) testing is one of the strongest predictors of a prostate cancer diagnosis, it could act as a confounder. There was a slightly higher rate of vasectomy in the subgroup of 13,901 men than in the entire cohort (27% vs 25%). There was also a higher rate of men reporting PSA testing (97% vs 75%). From 1996 to 2010, 1665 incident cases of prostate cancer were diagnosed; 179 of these were high-grade disease and 127 were lethal. Vasectomy was not associated with a risk for low-grade or localized prostate disease, but was associated with an increased risk for high-grade disease (RR, 1.28) and for a Gleason score of 7 (RR, 1.22). However, the risk for high-grade cancers was not statistically significant. The researchers point out that the men in this subgroup had a statistically significant 56% increased risk for lethal prostate cancer (RR, 1.56). This study was supported by grants from the National Cancer Institute/National Institutes of Health. The authors have disclosed no relevant financial relationships. J Clin Oncol. Published online July 7, 2014. Abstract Post Comment Private Reply Ignore Thread
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