Vasectomy and the Risk of Prostate Cancer

Abstract

An unexpected association between history of vasectomy and increased risk of prostate cancer emerged when multiple comparisons were carried out in data collected from 1976-1988 in a US hospital-based case-control study of many diseases and exposures. The association was assessed in detail in these data, in a comparison of 220 men with first episodes of prostate cancer with 571 noncancer controls and 960 cancer controls. The age-adjusted relative risk of prostate cancer was 5.3 (95% confidence interval 2.7-10) when noncancer controls were used and 3.5 (95 percent confidence interval 2.1-6.0) when cancer controls were used. The magnitude of the relative risk estimate appeared to be unrelated to the length of the interval after vasectomy. Allowance for several factors did not alter the estimates, but we did not have information on testosterone level or sexual activity, which may have been confounding factors. The association was stronger among men most likely to have been under more intensive medical surveillance; selective detection of asymptomatic cancer in such men would have led to an excess of cases. Further studies are needed to rule out chance, bias from medical surveillance, and uncontrolled confounding as explanations for the finding.

Regulatory T cells control tolerogenic versus autoimmune response to sperm in vasectomy

“…Well documented are the development of sperm antibody response in vasectomized men and animals (2, 3), and autoimmune orchitis in vasectomized animals (4). More alarming is a positive statistical correlation with prostate cancer in long-term vasectomized humans (5,6). Although not confirmed (4), the initial findings have continued to influence clinical decisions regarding vasectomy (7).…”

Vasectomy and risk of prostate cancer: population based matched cohort study

“…7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Potential biological mechanisms supporting an association between vasectomy and incident prostate cancer include increases in androgen levels, which are hypothesised to increase the risk of prostate cancer,31 and impaired secretory function of the prostate, which might prolong exposure of the prostate to carcinogenic factors 11. Although some studies have shown an increase in serum dihydrotestosterone and testosterone after vasectomy,32 33 34 others have found no statistically significant change in androgen levels 35…”

A cross-sectional study of vasectomy, time since vasectomy and prostate cancer

“…25 It is possible that vasectomized men were more likely to participate in prostate cancer screening during these years because of a perceived risk from vasectomy. Previous case-control studies 18,19 have been criticized because of low vasectomy prevalence rates among controls. 25±27 If there is selection bias in the current study, it should con®rm our ®ndings more conclusively.…”

“…14,15,17,21±23 One report of a positive association 18 later reversed its ®ndings. 28 Length of time between vasectomy and a diagnosis of prostate cancer has been more consistently reported as being associated with prostate cancer than vasectomy alone.…”