O-324 Incidence of potentially exposure-related cancer sites among Norwegian firefighters: 58 years of follow-up

Introduction Firefighters are exposed to a variety of known and suspected carcinogens through their work, and previous studies have found elevated risk for a number of cancer sites among firefighters. Objectives The aim was to examine cancer incidence among Norwegian firefighters in sites with established associations to known carcinogenic occupational exposures. This included sites within the respiratory, urinary, and lympho-haematopoietic systems, as well as the skin and all sites combined. Methods A newly established historical cohort of 3881 Norwegian firefighters who worked within the period 1950–2018 was linked to the Cancer Registry of Norway for incident cancers occurring in the period 1960–2018. We calculated standardized incidence ratios (SIR) with rates for the national male population as reference, and stratified SIR analyses by period of first employment, duration of employment, and time since first employment. Results Elevated risk was seen for all sites combined (SIR 1.15, 95% confidence interval 1.07–1.23). Elevated risk of urinary tract cancer was observed among firefighters who began working before 1950, and with observation ≥40 years since first employment. With ≥40 years since first employment, risks of mesothelioma and laryngeal cancer were also elevated. Conclusions Our patterns of increased incidence in cancer sites somewhat differs from observations in other studies, which may reflect that firefighting is a complex exposure that differs between countries, and that exposures have likely changed alongside changing fire contents, firefighting techniques, and equipment. However, our observed associations between firefighting and urinary tract cancer, laryngeal cancer, and mesothelioma have been observed in some studies previously, and may be related to carcinogenic occupational exposures. Differences in risk by period of employment potentially reflect improved quality and use of personal protective equipment, while stratification by time since first employment suggests that some cancers may have yet to develop among more recently employed firefighters.