A comparative analysis of histologic types of thyroid cancer between career firefighters and other occupational groups in Florida.

BACKGROUND

Florida Firefighters experience a higher risk of thyroid cancer than non-firefighters. This study examines whether the histologic types and tumor stage of thyroid cancer is different among firefighters compared to other occupational groups.

METHODS

Eligible cases were firefighters (n = 120) identified in a linkage of Florida Cancer Data System (FCDS) registry records (1981-2014) and Florida State Fire Marshal's Office employment and certification records, and non-firefighters classified into: blue-collar (n = 655), service (n = 834), white-collar (n = 4,893), and other (n = 1,789). Differences in thyroid histologic type (papillary, follicular, and rare/other less common forms of thyroid cancer), tumor stage, and age at diagnosis were evaluated using multinomial logistic regression models comparing blue-collar, service, white-collar, and other occupational groups with firefighters. Univariate odds ratios as well as odds ratios adjusted for age, gender, race, tumor stage, and year of diagnosis (aOR) and 95% confidence intervals (95%CI) were reported.

RESULTS

Service (aOR = 4.12; 95%CI: 1.25-13.65), white-collar (aOR = 3.51; 95%CI: 1.08-11.36), and blue-collar (aOR = 4.59; 95%CI: 1.40-15.07) workers had significantly higher odds of being diagnosed with rare histologic types of thyroid cancer vs papillary type compared to firefighters. Service (aOR = 0.42; 95%CI: 0.27-0.66), white-collar (aOR = 0.39; 95%CI: 0.26-0.59), blue-collar (aOR = 0.36; 95%CI: 0.23-0.56), and other (aOR = 0.34; 95%CI: 0.22-0.53) occupational groups have a significantly lower odds of being diagnosed with rare vs papillary type at a younger age (30-49 years) vs 50-69 years compared to firefighters. However, stage at diagnosis was not significantly different among occupational groups.

CONCLUSION

Firefighters diagnosed with thyroid cancer experience a higher odds of papillary compared to rare histologic types of thyroid cancer relative to other workers; there is no evidence of an increased odds of late-stage diagnosis in firefighters relative to other worker groups. Firefighters may benefit from routine screening and active surveillance of suspected thyroid tumors especially given the excellent treatment outcomes available for those diagnosed with early-stage papillary thyroid tumors.