EFFECT OF AMBIENT SOLAR ULTRAVIOLET-RADIATION ON INCIDENCE OF SQUAMOUS-CELL CARCINOMA OF THE EYE

Background We have investigated the geographic distribution of squamou s-cell carcinoma of the eye to assess whether solar ultraviolet light is a risk factor for this disease. Methods We used routinely collected population-based cancer incidence data and published measurements of ambient solar ultraviolet light in our analysis. Findings The incidenc e of squamous-cell carcinoma of the eye declined by 49% for each 10 de grees increase in latitude (p<0.0001), falling from more than 12 cases per million per year in Uganda (latitude 0.3 degrees) to less than 0. 2 per million per year in the UK (latitude >50 degrees). Solar ultravi olet radiation decreases with increasing latitude, and the incidence o f squamous-cell carcinoma of the eye decreased by 29% per unit reducti on in ultraviolet exposure (p<0.0001). Interpretation Our results are compatible with the hypothesis that exposure to solar ultraviolet ligh t is an important cause of squamous-cell carcinoma of the eye.