Cancer Incidence Among Swedish Seafarers Between 1985 and 2020.

BACKGROUND: Several studies from different countries have shown that merchant seafarers have an increased cancer risk compared to the general population. The aim of this study was to provide updated information on cancer incidence in a cohort of Swedish seafarers. METHODS: A cohort consisting of all Swedish seafarers from the Swedish Seafarers' Register 1985-2013 was linked to the Swedish Cancer Register 1985-2020. Seafarers with at least 5 years of sea service (N = 38,030; 76% men and 24% women) were included in the analyses. Standardized incidence ratios (SIR) were calculated for cancer by specific site, period of first signing, job category, type of vessel, and gender, using cancer incidence in the general population as reference. RESULTS: In seafarers who had worked on different types of vessels (not solely passenger ferries), there were 5076 cases of cancer during the follow-up period, and total cancer risk was increased (SIR 1.14; 95% confidence interval [CI] 1.11-1.17). Most cases occurred in seafarers who had their first signing before 1985. The risk of lung cancer was increased in all job categories, especially in engine room crew members (SIR 1.98; 95% CI 1.53-2.57). There were 16 mesothelioma cases in engine officers (SIR 3.75; 95% CI 2.30-6.12). CONCLUSIONS: This cohort study of seafarers in Sweden confirms that Swedish seafarers had an increased overall cancer risk compared with the general population, particularly those signing before 1985 and working on different types of vessels.