Association of Prediagnostic Serum Vitamin D Levels with the Development of Basal Cell Carcinoma

We investigated the association between serum 25-hydroxyvitamin D (25(OH) D) levels and basal cell carcinoma (BCC) risk in a nested case-control study at Kaiser Permanente Northern California (KPNC). A total of 220 case patients with BCC diagnosed after serum collection were matched to 220 control subjects. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) using conditional logistic regression. Fully adjusted models included body mass index (BMI), smoking, education, sun-exposure variables, X-ray exposure, and personal history of cancer. For each measure of serum 25(OH) D (continuous, clinically relevant tertiles, quintiles), we found an increased risk of BCC in unadjusted models (OR = 1.03, 95% CI 1.00-1.05, P<0.05; OR = 3.98, 95% CI: 1.31-12.31, deficient vs. sufficient, test for trend P-value <0.01; OR = 2.32, 95% CI: 1.20-4.50, 1st vs. 5th quintile, test for trend P-value 0.03). In fully adjusted models, the values attenuated slightly (OR = 1.02, 95% CI 1.00-1.05, P<0.05; OR = 3.61, 95% CI: 1.00-13.10, deficient vs. sufficient, t-trend P = 0.03; OR = 2.09 1st vs. 5th quintile, 95% CI: 0.95-4.58, t-trend P = 0.11). Our findings suggest that higher prediagnostic serum 25(OH) D levels may be associated with increased risk of subsequent BCC. Further studies to evaluate the effect of sun exposure on BCC and serum 25(OH) D levels may be warranted.