Cigarettes: A Smoking Gun in Cancer Chemoprevention
9/21/2005 Susan T. Mayne, Scott M. Lippman Journal of the National Cancer Institute, Vol. 97, No. 18, 1319-1321, September 21, 2005 A growing body of literature indicates that chemopreventive agents may have very different effects in populations that differ by lifestyle or host factors. One such factor of paramount importance is smoking status, which has been shown to predict the effects of micronutrients such as beta-carotene or related compounds in smoking-related cancer prevention trials. Some nutrients that appear to reduce the risk of cancer in nonsmokers may actually increase the risk of cancer in smokers, whereas other preventive nutrients may work better in smokers than nonsmokers. Two landmark trials, the Alpha-Tocopherol Beta-Carotene (ATBC) Cancer Prevention Study and Carotene and Retinol Efficacy Trial (CARET), first revealed an important impact of smoking status on chemoprevention. The ATBC trial was a randomized 2 x 2 factorial prevention trial of daily -tocopherol and/or beta-carotene in more than 29 000 male smokers from Finland (1). Unexpectedly, the men who were randomly assigned to receive supplemental beta-carotene had a statistically significantly higher lung cancer risk than did men who did not receive beta-carotene. This harmful effect occurred in men who smoked 20 cigarettes or more per day but not in men who smoked less (all ATBC participants were smokers). Therefore, the ATBC suggested that smoking intensity modified the cancer preventive effect of a nutrient. Subsequently, the CARET of beta-carotene combined with retinol to prevent lung cancer in men and women smokers and/or asbestos workers found that [...]