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FOR PEOPLE at high risk of lung cancer—notably current and former smokers and asbestos workers—the notion of being able to undo that risk by taking a vitamin supplement is an appealing one. But hopes of such a preventive magic bullet were recently dashed by the results of two large clinical trials aimed at determining whether taking high-dose supplements of beta carotene and vitamin A could reduce the risk of lung cancer in these high-risk individuals.
The trials, the Beta Carotene and Retinol Efficacy Trial (CARET) and the Physicians' Health Study, both showed the supplements conferred no benefit. In CARET, there was even evidence of the opposite effect—a lung cancer rate that was higher in at-risk patients who took high-dose supplements of beta carotene and vitamin A than in at-risk patients who took a placebo. In light of this evidence, the investigators terminated CARET 21 months before it was scheduled to
Marwick C. Trials Reveal No Benefit, Possible Harm of Beta Carotene and Vitamin A for Lung Cancer Prevention. JAMA. 1996;275(6):422-423. doi:10.1001/jama.1996.03530300006003