Post-9/11 Cancer Incidence in World Trade Center-Exposed New York City Firefighters as Compared to a Pooled Cohort of Firefighters From San Francisco, Chicago, and Philadelphia (9/11/2001-2009)

Background We previously reported a modest excess of cancer in World Trade Center (WTC)-exposed firefighters versus the general population. This study aimed to separate the potential carcinogenic effects of firefighting and WTC exposure by comparing to a cohort of non-WTC-exposed firefighters. Methods Relative rates (RRs) for all cancers combined and individual cancer subtypes from 9/11/2001 to 12/31/2009 were modeled using Poisson regression comparing 11,457 WTC-exposed firefighters to 8,220 urban non-WTC-exposed firefighters. Results Compared with non-WTC-exposed firefighters, there was no difference in the RR of all cancers combined for WTC-exposed firefighters (RR = 0.96, 95% CI: 0.83-1.12). Thyroid cancer was significantly elevated (RR = 3.82, 95% CI: 1.07-20.81) from 2001 to 2009; this was attenuated (RR = 3.43, 95% CI: 0.94-18.94) and non-significant when controlling for possible surveillance bias. Prostate cancer was elevated during the latter half (2005-2009; RR = 1.38, 95% CI: 1.01-1.88). Conclusions Further follow-up is needed to assess the relationship between WTC exposure and cancers with longer latency periods. (C) 2016 Wiley Periodicals, Inc.