This study examines whether insufficient ultraviolet B (UVB) irradiance, a marker of vitamin D inadequacy, might contribute to lung cancer incidence.
The association of latitude and UVB irradiance with age-adjusted incidence rates of lung cancer in 111 countries was investigated. Independent associations with UVB irradiance, cloud cover, anthropogenic aerosols, and cigarette smoking, were assessed using multiple regression.
Latitude was positively related to incidence rates in men (R(2) = 0.55, p<0.01) and women (R(2) = 0.36, p<0.01). In men, cigarette consumption (p<0.001) was positively related to risk, whereas UVB irradiance was inversely associated (p = 0.003). There were positive associations with UVB absorbers, in particular cloud cover (p = 0.05) and aerosol optical depth (p = 0.005). The R(2) for the model was 0.78 (p<0.001). UVB irradiance was also inversely associated with incidence rates in women (p = 0.0002), whereas cigarette consumption (p<0.001), total cloud cover (p = 0.02) and aerosol optical depth (p = 0.005) were positively associated. The R(2) for the model was 0.77 (p<0.001).
Lower levels of UVB irradiance were independently associated with higher incidence rates of lung cancer in 111 countries.