Serum carotenoids and alpha-tocopherol and risk of nonmelanoma skin cancer.

BACKGROUND: Carotenoids and tocopherols have been hypothesized to protect against cancer. METHODS: We prospectively evaluated associations of several carotenoids and alpha-tocopherol with risk of nonmelanoma skin cancer using serum collected at baseline from 302 subjects in the Isotretinoin-Basal Cell Carcinoma Prevention Trial. All subjects had at least two BCCs in the 5 years prior to randomization. During 5 years of follow-up, 70 subjects did not develop a nonmelanoma skin cancer, 221 developed a BCC, and 85 developed a squamous cell carcinoma (SCC). Cox proportional hazards models were used to estimate risk ratios. Models were stratified by clinical center and gender and adjusted for age, solar damage, skin type, number of prior BCCs and/or SCCs, treatment group, body mass index, and serum low-density lipoprotein-cholesterol and high-density lipoprotein-cholesterol. RESULTS: Risk of developing a subsequent BCC was not related to serum levels of any of the carotenoids measured or to alpha-tocopherol. Serum levels of alpha-carotene, beta-carotene, lycopene, and alpha-tocopherol also were not independently related to risk of a subsequent SCC. However, serum lutein, zeaxanthin, and beta-cryptoxanthin were positively related to SCC risk; risk ratios for subjects in the highest versus lowest tertiles of these micronutrients were 1.63 [95% confidence interval (95% CI) 0.88-3.01; P for trend = 0.01], 2.40 (95% CI 1.30-4.42; P for trend = 0.01), and 2.15 (95% CI 1.21-3.83; P for trend = 0.09), respectively. CONCLUSION: Additional research is needed on the relationship of carotenoids to SCC risk in the general population and in subsets of the population who are at increased risk.