NUTRITION AND LUNG-CANCER

Epidemiologic evidence on the relationship between nutrition and lung cancer is reviewed. Observational studies of diet and lung cancer, bot h prospective and retrospective, continue to suggest strongly that inc reased vegetable and fruit intake is associated with reduced risk in m en and women; in various countries; in smokers, ex-smokers, and never- smokers; and for all histologic types of lung cancer. Prospective stud ies of blood beta-carotene levels, arguably the best available biomark er of vegetable and fruit intake, indicate that low levels are predict ive of increased lung cancer incidence. However, in a randomized, plac ebo-controlled clinical trial in male smokers, lung cancer incidence a nd total mortality were increased significantly among the men receivin g beta-carotene supplements. If beta-carotene can prevent lung carcino genesis,which the trial cannot rule out, then the dosage, duration of use, method of administration, and/or subpopulation are critical. Ongo ing clinical trials, some of which include women, will provide much-ne eded information. Other carotenoids, other phytochemicals, and associa ted dietary patterns may explain the beneficial effects of vegetables and fruits and have not been explored adequately in epidemiologic work . Several observational epidemiologic studies, both prospective and re trospective, have indicated that diets high in fat, saturated fat, and cholesterol may increase the risk of lung cancer and that the effect is not mediated through vegetable and fruit intake. The relationship, although not yet established, merits further investigation. Since beta -carotene can function as an antioxidant, other micronutrients with th is potential, specifically vitamins E and C and selenium, also have be en proposed to reduce lung cancer risk. However, the totality of the e pidemiologic evidence is not, at present, persuasive for any one of th ese micronutrients.