Occupation as a firefighter and cancer mortality in a population-based cohort in the United States.

Background: A 2022 International Agency for Research on Cancer (IARC) Working Group concluded that occupational exposure as a firefighter causes mesothelioma and bladder cancer. Evidence for causality of other cancers was considered limited or inadequate, but methodologic limitations may have contributed to inconsistent or null findings from previous studies. The present analysis uses data from >470 000 men enrolled in a general population, prospective cohort to assess associations between occupation as a firefighter and cancer mortality.

Methods: Multivariable hazard ratios (HR) and 95% confidence intervals (CI) were used to compare survival time among firefighters (n = 3085) to other male participants in the American Cancer Society Cancer Prevention Study-II Cohort. Data were obtained from surveys taken by cancer-free individuals with 36 years of mortality follow-up (1982-2018). Occupations were categorized according to 1980 Census Bureau groups and cancer deaths according to the International Classification of Disease.

Results: Occupation as a firefighter compared to career professional was associated with most cancers, but strongest for skin (HR = 1.72, 95% CI: 1.14-2.60) and kidney (HR = 1.39, 95% CI: 0.92-2.09) cancer mortality. Suggestive increases in prostate and colorectal cancer mortality were observed with more years as a firefighter. An association with lung cancer was only apparent after three decades of follow-up. Most associations attenuated with control for confounders and changes in referent group to include all nonfirefighter occupations, but associations with skin and kidney cancers persisted.

Conclusions: These results support additional associations for occupation as a firefighter and cancer mortality beyond those reported in the most recent IARC evaluation.