Cancer incidence in World Trade Center-exposed and non-exposed male firefighters, as compared with the US adult male population: 2001-2016.

OBJECTIVE: To compare cancer incidence in Fire Department of the City of New York (FDNY) firefighters who worked at the World Trade Center (WTC) site to incidence in a population of non-WTC-exposed firefighters, the Career Firefighter Health Study (CFHS) cohort, and to compare rates from each firefighter cohort to rates in demographically similar US males. METHODS: FDNY (N=10 786) and CFHS (N=8813) cohorts included male firefighters who were active on 11 September 2001 (9/11) and were followed until death or 31 December 2016. Cases were identified from 15 state cancer registries. Poisson regression models assessed cancers in each group (FDNY and CFHS) versus US males, and associations between group and cancer rates; these models estimated standardised incidence ratios (SIRs) and adjusted relative rates (RRs), respectively. Secondary analyses assessed surveillance bias and smoking history. RESULTS: We identified 915 cancer cases in 841 FDNY firefighters and 1002 cases in 909 CFHS firefighters. FDNY had: higher rates for all cancers (RR=1.13; 95% CI 1.02 to 1.25), prostate (RR=1.39; 95% CI 1.19 to 1.63) and thyroid cancer (RR=2.53; 95% CI 1.37 to 4.70); younger median ages at diagnosis (55.6 vs 59.4; p<0.001, all cancers); and more cases with localised disease when compared with CFHS. Compared with US males, both firefighter cohorts had elevated SIRs for prostate cancer and melanoma. Control for surveillance bias in FDNY reduced most differences. CONCLUSIONS: Excess cancers occurred in WTC-exposed firefighters relative to each comparison group, which may partially be explained by heightened surveillance. Two decades post-9/11, clearer understanding of WTC-related risk requires extended follow-up and modelling studies (laboratory or animal based) to identify workplace exposures in all firefighters.

Assembling the Career Firefighter Health Study cohort: A methods overview.

BACKGROUND: Studies of World Trade Center (WTC)-exposed rescue/recovery workers report the increased occurrence of health conditions after work at the WTC disaster site. However, the extent to which these associations are due to WTC exposure is unclear, in part due to the lack of suitable comparison groups. Accordingly, we identified a previously assembled National Institute for Occupational Safety and Health (NIOSH) cohort of career firefighters from three US cities (n = 29,992). Here, we document the challenges in establishing this non-WTC-exposed firefighter cohort for the goal of tracking and comparing cancer and chronic health conditions in WTC-exposed and non-WTC-exposed firefighters. METHODS: Follow-up process included institutional review board applications, data use agreements, state cancer registry linkages and vital status determination for the NIOSH firefighter cohort. After completion of these steps, we undertook outreach to the three original city fire departments and union officials, before contact tracing and direct recruitment of 14,566 living firefighters to complete a confidential health survey. We staggered recruitment efforts by the city, using letters, postcards, emails, videos, and telephone outreach. Participants who completed the survey received $10. RESULTS: A total of 4962 of 14,566 alive firefighters responded to the baseline survey (34.1% response rate). Respondents were older and more likely to be non-Hispanic white than nonrespondents. CONCLUSIONS: We provide an overview of the process for the first survey to collect information on physical and mental health conditions among US firefighters. The data collected will have an important impact on studies of WTC rescue/recovery work, firefighting, and related health conditions.