Vasectomy and Risk of Prostate Cancer in a Screening Trial

Abstract

Vasectomy has been implicated as a risk factor for prostate cancer in multiple epidemiologic studies over the past 25 years. Whether this relationship is causal remains unclear. This study examines the association between vasectomy and prostate cancer in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial, which randomized men to usual care or annual prostate cancer screening. We performed a retrospective analysis of 13-year screening and outcomes data from the PLCO trial. Multivariable Cox proportional hazards regression stratified by study arm and age at vasectomy was performed. There was an increased risk of prostate cancer in men who had undergone a vasectomy and were randomized to the usual care arm of the study (adjusted HR, 1.11; 95% confidence interval, 1.03-1.20; = 0.008). There was no association between vasectomy and diagnosis of prostate cancer in men randomized to the prostate cancer screening arm. Only men undergoing vasectomy at an older age in the usual care arm of the study, but not the prostate cancer screening arm, were at increased risk of being diagnosed with prostate cancer. Vasectomy was not associated with prostate cancer risk among men who were screened for prostate cancer as part of a clinical trial, but was associated with prostate cancer detection in men receiving usual care. The positive association between vasectomy and prostate cancer is likely related to increased detection of prostate cancer based on patterns of care rather than a biological effect of vasectomy on prostate cancer development. .

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“…Vasectomy has been discussed as a putative risk factor for PCa development over recent decades, and some studies have supported an association with lethal PCa [100]. On the contrary, most recent studies found either no or only a weak association between vasectomy and overall PCa risk (closer to the null with increasingly robust study design) and no significant association with HGPCA, advanced-stage PCa, or fatal PCa, finally resulting in currently strong evidence rebutting a relationship between vasectomy and PCa [101][102][103][104][105].…”

Can there be consensus on whether vasectomy is a prostate cancer risk factor?

“…In our Health Professionals Follow-up Study (HPFS) [6], tightly controlling for confounding by restricting to a highly screened subcohort attenuated the relative risk and 95% confidence interval (RR 1.05, 0.94-1.17) compared to a simpler adjustment (RR 1.10, 1.04-1.17). Within the PLCO screening trial, the relative risk for vasectomy and prostate cancer was 1.11 (1.03-1.20) in the usual care arm compared to 1.03 (0.95-1.11) in the screening arm, minimally affected by confounding [7]. To our knowledge, no other individual study in the meta-analysis investigated screening's impact to such depth.…”

Vasectomy and Risk of Prostate Cancer: A Systematic Review and Meta-analysis

“…A total of 466 unique records were identified. Of these, 70 full-text articles were assessed for eligibility and 37 met the inclusion criteria for qualitative and quantitative analysis [4] , [6] , [7] , [8] , [9] , [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] , [30] , [31] , [32] , [33] , [34] , [35] , [36] , [37] , [38] , [39] , [40] , [41] , [42] , [43] , [44] . The reasons for exclusion are summarized in Figure 1 .…”

“…These discrepancies are due to the paucity of documented causal associations, and possible detection biases related to PCa screening and closer follow-up among vasectomy patients, and modest clinical significance with a relative risk very often close to 1. Recently, several large, high-quality reports demonstrated conflicting results [5] , [6] , [7] , [8] , [9] . A recent meta-analysis that included the most recent reports found that vasectomy was associated with localized and advanced PCa [10] .…”