Is ultraviolet B irradiance inversely associated with incidence rates of endometrial cancer: an ecological study of 107 countries

Objective. The purpose of this study was to perform an ecological analysis of the relationship between low levels of ultraviolet B (UVB) irradiance and age-standardized incidence rates of endometrial cancer by country, controlling for known confounders. Methods. The contributions of UVB irradiance, cloud cover, intake of energy from animal sources, proportion of population overweight, skin pigmentation, per capita cigarette consumption, per capita health expenditure, and total fertility rates, to age-standardized incidence rates of endometrial cancer in 107 countries were assessed using multiple regression. Results. Incidence rates were higher at higher latitudes (R2 = 0.47, p < 0.01). According to multiple regression, UVB irradiance adjusted for cloud cover was negatively associated with incidence rates (p = 0.02), while proportion of population overweight (p = 0.004), intake of energy from animal sources (p = 0.01) and per capita health expenditure (p < 0.0001) were positively associated with incidence rates (overall R2 = 0.73, p < 0.0001). Conclusion. An association was found between low UVB irradiance, high intake of energy from animal sources, per capita health expenditure, proportion of population overweight, and incidence rates.