Occupational solar ultraviolet radiation and incidence of non-melanoma skin cancer in a nationwide cohort

Non-melanoma skin cancer (NMSC) is the most common cancer worldwide. Solar ultraviolet radiation (UVR) is the primary risk factor. Consequently, outdoor workers face a potential long-term occupational hazard, but little is known about the extent to which occupational UVR exposure affects the risk of NMSC. We aimed to quantify the exposure-response relation between occupational solar UVR exposure and NMSC incidence in a nationwide cohort. We conducted a register-based cohort study of the entire Danish workforce 1977-2015 assessing the association between occupational UVR exposure and the incidence of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) as recorded in the Danish Cancer Register. Exposure was measured in standardised erythema dose (SED) based on a newly developed European UVR job exposure matrix. We analysed confounder-adjusted incidence rate ratios of NMSC with a discrete-time hazard model and modelled the shape of the exposure-response relation with restricted cubic splines. Of the 2,943,463 workers followed for a median of 20 years, 26,958 were diagnosed with BCC and 1,132 with SCC. Median cumulative exposure was 5.99 SED-years. We observed a positive exposure-response relation between occupational solar UVR and BCC, with an adjusted incidence rate ratio of 1.58 (95 % CI: 1.47-1.70) in the highest exposure quartile compared with the lowest. Results for SCC suggested a similar exposure-response pattern, although not reaching statistical significance. We observed a strong exposure-response relation between occupational solar UVR exposure and the risk of NMSC in Danish workers. These findings underscore the need for implementing preventive strategies. TRIAL REGISTRATION NUMBER: j.no.: 1-16-02-196-17.