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In the largest and most comprehensive study of its kind, researchers from Harvard School of Public Health in Boston, MA, find that vasectomy is associated with a small increased risk of prostate cancer, and a larger increased risk for advanced or lethal prostate cancer.
Prostate cancer is a major cause of cancer-related deaths in men in the US, where vasectomy is a common form of contraception, with around 15% of American men having the minor procedure, which blocks the tubes that carry sperm from the testicles to the penis.
“A man’s decision to opt for a vasectomy remains a highly personal one in which the potential risks and benefits must be considered with his physician,” said lead study author Lorelei Mucci, ScD, MPH, associate professor of epidemiology at Harvard School of Public Health in Boston. “We believe that our findings suggest continued epidemiological and experimental research into clarifying the association of vasectomy with prostate cancer.”
Mucci and coauthors followed 49,405 men in the US Health Professionals Follow-Up Study who were between the ages of 40 and 75 at the study’s initiation in 1986. During the more than 2-decade time frame of the study, 6,023 men were diagnosed with prostate cancer, including 811 who had lethal cases and 723 who had high-grade disease. One-quarter of the men in the study (12,321) underwent a vasectomy. The average age that a patient underwent a vasectomy on study was 38.6 years. Approximately 96% of study participants were Caucasian.
A history of a vasectomy was associated with a 10% increase in prostate cancer overall, and relative risk was 22% higher for high-grade prostate cancer (defined as prostate cancer with a Gleason score between 8 and 10).
Analyses suggested that the association of vasectomy with lethal prostate cancer was not linked to differences in sex hormone levels, sexually transmitted diseases, or therapies for cancer treatment.
Previous studies on the link between vasectomies and prostate cancer had conflicting results. According to Mucci, two initial reports published in 1993, including one of the same study cohort used for the current long-term analysis, showed an increased risk of prostate cancer among the men who had had a vasectomy. But, there were concerns that these prior results had a detection bias, Mucci told Cancer Network. In other words, in prior studies, those men who had had a vasectomy were more likely to have had closer follow-up medical care and prostate cancer screening.
“Given the high proportion of men who undergo vasectomy in the United States, we felt an updated and more comprehensive investigation of this question was needed,” said Mucci. “With 19 additional years of follow-up; more than 6,000 cases, including 800 with advanced disease; and the ability to control for PSA screening and other potential sources of bias, we felt that we could provide a more comprehensive investigation of the topic.”
Agencies/Canadajournal
