Risk factors for incident prostate cancer in a cohort of world trade center responders

Background: Despite a relatively young average age and no routine screening, prostate cancer is one of the most common cancers in men who worked at the World Trade Center (WTC) following the 9/11/2001 disaster. This study evaluated whether re-experiencing stressful memories of a traumatic event was associated with prostate cancer incidence. Methods: Participants were males from one clinical center that monitors the health of first-responders (N = 6857). Monitoring began in July 2002 and occurs annually but does not include prostate cancer screening. Severity of physical exposures and of re-experiencing memories and stress responses were measured at study enrollment using standardized and validated methods in all participants. The outcome was incidence of diagnosed prostate cancer after enrollment (n = 68). Bivariate analyses provided age-adjusted incidence rates (aIR). Cox proportional hazards modeling was used to calculate incidence; hazards ratios (HR) were reported. Results: The mean age of responders on 9/11/2001 was 37.9 years. Prostate cancer incidence was lowest in responders with no re-experiencing stress (aIR = 250.83/100,000 person-years, [233.41-268.25]) and highest in responders with severe re-experiencing stress (aIR = 818.49/100,000 person-years, [801.07-835.91]). Cox proportional hazards regression revealed that re-experiencing the stressful events of 9/11/2001 was associated with increased prostate cancer incidence (HR = 1.96 [1.26-3.05], P = 0.003), even upon adjusting for confounders. Conclusions: This is the first study to identify a positive association between re-experiencing a traumatic event and prostate cancer incidence. Our results are consistent with recent rodent model evidence demonstrating a direct biological link between stress pathways and prostate tumorigenesis and offer new hypotheses in the causality of prostate cancer.