A U.S. nested case-control study of 220 patients diagnosed with basal cell carcinoma (BCC) between 1968 and 1970 evaluated prediagnostic serum vitamin D levels and BCC risk. The patients were matched with 220 control subjects. Adjusted models for risk included body mass index, smoking and education status, sun-exposure variables, X-ray exposure and personal cancer history. In a fully adjusted model, the odds ratio (OR) of BCC risk increased with increasing vitamin D levels, from an OR of 2.30 (with insufficient levels; 10 to < 30 ng/mL) to an OR of 3.61 for sufficient levels (30 ng/mL or greater; P = 0.03). Similar findings were seen with an unadjusted or partly ...