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. Am. J. Ind. Med. 59:722–730, 2016.