Geographic variation in urinary tract and genital cancers in Iran: a hypothesis involving exposure to solar radiation

OBJECTIVE: Sunlight and vitamin D intake are considered as essential elements for human health. Insufficient intake of this vitamin is one of the causes of various cancers and some other diseases. The aim of this study was to investigate the relation between bladder, prostate, cervical and ovarian cancers with solar ultraviolet exposure in Iran. In this ecological study, data from 30 provinces were studied and analyzed by correlation and linear regression tests in SPSS software version 22. Physical activity, gender, human development index, lung cancer and altitude were adjusted at population level. RESULTS: The incidence of bladder cancer in both sexes was inversely related to ultraviolet radiation, but it was significant only in men. Unlike bladder cancer, the incidence of cervical cancer showed a positive relation with ultraviolet radiation. No relation was found between the incidence of prostate and ovarian cancers with ultraviolet radiation. Among the adjusting variables, the incidence of lung cancer (surrogate for smoking) in women had the highest coefficient in the linear regression model.