Impact of healthcare services on thyroid cancer incidence among World Trade Center‐exposed rescue and recovery workers

Abstract

Background A recent study of World Trade Center (WTC)‐exposed firefighters and emergency medical service workers demonstrated that elevated thyroid cancer incidence may be attributable to frequent medical testing, resulting in the identification of asymptomatic tumors. We expand on that study by comparing the incidence of thyroid cancer among three groups: WTC‐exposed rescue/recovery workers enrolled in a New York State (NYS) WTC‐medical monitoring and treatment program (MMTP); WTC‐exposed rescue/recovery workers not enrolled in an MMTP (non‐MMTP); and the NYS population. Methods Person‐time began on 9/12/2001 or at enrollment in a WTC cohort and ended at death or on 12/31/2015. Cancer data were obtained through linkages with 13 state cancer registries. We used Poisson regression to estimate rate ratios (RRs) and 95% confidence intervals (CIs) for MMTP and non‐MMTP participants. NYS rates were used as the reference. To estimate potential changes over time in WTC‐associated risk, change points in RRs were estimated using profile likelihood. Results The thyroid cancer incidence rate among MMTP participants was more than twice that of NYS population rates (RR = 2.31; 95% CI = 2.00–2.68). Non‐MMTP participants had a risk similar to NYS (RR = 0.96; 95% CI = 0.72–1.28). We observed no change points in the follow‐up period. Conclusion Our findings support the hypothesis that no‐cost screening (a benefit provided by WTC‐MMTPs) is associated with elevated identification of thyroid cancer. Given the high survival rate for thyroid cancer, it is important to weigh the costs and benefits of treatment, as many of these cancers were asymptomatic and may have been detected incidentally.

Cancer risk among World Trade Center rescue and recovery workers: A review

“…Finally, 225 thyroid cancers were identified among 224 participants. 35 Although thyroid cancer rates were approximately twice those of the NYS reference population throughout the study follow-up period (HR, 2.3; 95% CI, 2.0-2.7), we observed no change in the rate of thyroid cancer incidence.…”

“…Thyroid cancer was elevated primarily among RRWs who were participating in medical monitoring and treatment programs, suggesting the impact of medical surveillance. 35 In internal analyses comparing those who first worked on the WTC effort on September 11, 2001, with those who started after September 17, 2001, there was an increased risk for prostate cancer (hazard ratio [HR], 1.61; 95% CI, 1.33-1.95) and thyroid cancer (HR, 1.77; 95% CI, 1.11-2.81), with an exposure-response trend for both cancers. Selfreported exposure to the dust cloud itself was also associated with an increased risk of prostate cancer (HR, 1.30; 95% CI, 1.14-1.49), but not of other cancer sites.…”

“…Selfreported exposure to the dust cloud itself was also associated with an increased risk of prostate cancer (HR, 1.30; 95% CI, 1.14-1.49), but not of other cancer sites. 35 Internal analyses were restricted to cancer sites that had significant SIRs in the primary analysis, and additional subtypes of cancer were not investigated.…”

“… 34 Nine cases of mesothelioma were observed, yielding a SIR of 1.38 (95% CI, 0.63‐2.62). Thyroid cancer was elevated primarily among RRWs who were participating in medical monitoring and treatment programs, suggesting the impact of medical surveillance 35 …”

“…In internal analyses comparing those who first worked on the WTC effort on September 11, 2001, with those who started after September 17, 2001, there was an increased risk for prostate cancer (hazard ratio [HR], 1.61; 95% CI, 1.33‐1.95) and thyroid cancer (HR, 1.77; 95% CI, 1.11‐2.81), with an exposure‐response trend for both cancers. Self‐reported exposure to the dust cloud itself was also associated with an increased risk of prostate cancer (HR, 1.30; 95% CI, 1.14‐1.49), but not of other cancer sites 35 . Internal analyses were restricted to cancer sites that had significant SIRs in the primary analysis, and additional subtypes of cancer were not investigated.…”