Dr. Schlegel: Vasectomy and Risk of Prostate Cancer

Introduction and Objectives

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 or due to unaccounted for bias remains unclear. The Prostate, Lung, Colorectal, Ovarian (PLCO) Cancer Screening Trial provided a unique opportunity to assess the relationship between vasectomy and prostate cancer in a modern cohort of men who were uniformly screened for prostate cancer.

Methods 

A retrospective analysis of 13 year prostate cancer screening and outcomes data from the PLCO cancer screening trial. Vasectomy status was available for 73,180 subjects, of whom 19,965 (27.3%) reported a history of vasectomy. Analysis was stratified by study arm and age at vasectomy in order to assess, and control for, detection bias. Cox proportional hazards models adjusted for baseline demographics, including prior history of PSA screening and rectal examination were utilized. 

Results 

There was an increased risk of prostate cancer in men who had undergone vasectomy and were randomized to the usual care arm of the study (adjusted hazard ratio (HR) 1.11, 95% CI 1.03 to 1.20, p=0.008). There was no association between vasectomy and diagnosis of prostate cancer in men randomized to the screening arm. The association between vasectomy and prostate cancer was present only for Gleason 2-6 prostate cancers in the control arm, but not more aggressive cancers. Only men undergoing vasectomy at an older age in the control arm of the study were at increased risk of being diagnosed with prostate cancer (adjusted HR 1.10, 95% CI 1.04-1.17, p=0.002). 

Conclusions 

In a contemporary cohort, the association of vasectomy and prostate cancer is limited to low risk disease, and 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. 

Jonathan Shoag*, Sameer Mittal, Joshua Halpern, New York, NY, Daniel Shoag, Cambridge, MA, Daniel Lee, Padraic O'Malley, Bobby Najari, New York, NY, Brian Eisner, Boston, MA, Jim Hu, Douglas Scherr, Peter Schlegel, Christopher Barbieri, New York, NY