ANTIOXIDANTS IN CHEMOPREVENTION OF COLORECTAL NEOPLASMS

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The association of carcinoma of the colon with identifiable geographic location, and more specifically with certain dietary habits has led to the supposition that manipulation of dietary factors may help to decrease the incidence of this disease. Antioxidants have been shown to decrease the incidence of chemically-induced cancers in experimental models and decrease the level of carcinogens present in the gastric secretions and urine of certain groups of humans. With the identification of fecal mutagens in groups of patients at high risk for colon cancer, it seems possible that a decrease in the level of these mutagens may lower the incidence of colon cancer. The actual effect of non-toxic supplementation of two antioxidants, ascorbic acid and alpha-tocopherol, on the levels of these compounds in various human tissues and excretions is not clearly defined. We plan to measure the change in tissue levels of ascorbic acid and alpha-tocopherol with various levels of dietary supplementation in normal patients. We then plan to identify a population of individuals with fecal mutagens and determine the effect of alpha-tocopherol and ascorbate supplementation upon these levels. Finally, patients who have undergone removal of colonic neoplasms are at high risk for developing recurrent or metachronous benign or malignant colonic neoplasms. We plan to identify such a population and in a prospective, randomized clinical trial treat them with either vitamin supplementation or placebo to determine whether such treatment will significantly decrease the incidence of these metachronous neoplasms.