• U M Frieling, D A Schaumberg, T S Kupper, J Muntwyler, and C H Hennekens.
• Division of Preventive Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass, USA.
• Arch Dermatol. 2000 Feb 1; 136 (2): 179-84.

ContextAlthough basic research provides plausible mechanisms for benefits of beta carotene supplementation on nonmelanoma skin cancer (NMSC) primarily consisting of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), observational studies are inconsistent. Randomized trial data are limited to 1 trial of secondary prevention that showed no effect of beta carotene on the incidence of NMSC after 5 years.ObjectiveTo test whether supplementation with beta carotene reduces the risk for development of a first NMSC, including BCC and SCC.DesignRandomized, double-blind, placebo-controlled trial with 12 years of beta carotene supplementation and follow-up.SettingPhysicians' Health Study in the United States.ParticipantsApparently healthy male physicians aged 40 to 84 years in 1982 (N = 22 071).InterventionBeta carotene, 50 mg, on alternate days.Main Outcome MeasureRelative risk (RR) and 95% confidence interval (CI) for a first NMSC, BCC, and SCC.ResultsAfter adjusting for age and randomized aspirin assignment, there was no effect of beta carotene on the incidence of a first NMSC (RR, 0.98; 95% CI, 0.92-1.05), BCC (RR, 0.99; 95% CI, 0.92-1.06), or SCC (RR, 0.97; 95% CI, 0.84-1.13). There was also no significant evidence of beneficial or harmful effects of beta carotene on NMSC by smoking status (current, past, or never).ConclusionThis large-scale, randomized, primary prevention trial among apparently healthy well-nourished men indicates that an average of 12 years of supplementation with beta carotene does not affect the development of a first NMSC, including BCC and SCC.

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