Mortality after the 9/11 terrorist attacks among world trade center health registry enrollees with cancer

Abstract

Background While several studies have reported the association between 9/11 exposure and cancer risk, cancer survival has not been well studied in the World Trade Center (WTC) exposed population. We examined associations of 9/11‐related exposures with mortality in WTC Health Registry enrollees diagnosed with cancer before and after 9/11/2001. Patients and Methods This is a longitudinal cohort study of 5061 enrollees with a first‐ever primary invasive cancer diagnosis between 1995 and 2015 and followed through 2016. Based on the timing of first cancer diagnosis, pre‐9/11 (n = 634) and post‐9/11 (n = 4427) cancer groups were examined separately. 9/11‐related exposures included witnessing traumatic events, injury on 9/11, and 9/11‐related post‐traumatic stress disorder (PTSD). Associations of exposures with all‐cause mortality were examined using Cox proportional hazards regression. In the post‐9/11 group, cancer‐specific mortality was evaluated by enrollee group (WTC rescue/recovery workers vs. non‐workers) using Fine and Gray's proportional sub‐distribution hazard models, adjusting for baseline covariates, tumor characteristics, and treatment. Results In the pre‐9/11 group, 9/11‐related exposures were not associated with all‐cause mortality. In the post‐9/11 group, increased risk of all‐cause mortality was associated with PTSD (adjusted HR = 1.35; 95% CI = 1.11–1.65), but not with injury or witnessing traumatic events. Cancer‐specific mortality was not statistically significantly associated with 9/11‐related exposures. In rescue/recovery workers, increased non‐cancer mortality risk was associated with PTSD (aHR = 2.13, 95% CI = 1.13–4.00) and witnessing ≥3 traumatic events (aHR = 2.00, 95% CI = 1.13–3.55). Conclusions We did not observe associations between 9/11‐related exposures and cancer‐specific mortality. Similar to findings in the non‐cancer WTC exposed population, PTSD was associated with increased risk of all‐cause mortality in cancer patients.