SERUM RETINOIC ACID LEVELS IN PATIENTS WITH RESECTED BENIGN AND MALIGNANT COLONIC NEOPLASIAS ON BETA-CAROTENE SUPPLEMENTATION

To determine whether patients with colon cancer metabolize beta-carote ne differently from benign colon polyp patients, a normal control grou p (n = 13) and groups of resected colon polyp patients (n = 29) or res ected colon cancer patients (Dukes A and B1, n = 21) were supplemented with placebo or beta-carotene (30 mg/day) taken with their morning me als for three months. Serum samples at zero and three months of the st udy were anlayzed blindly for retinoic acid and beta-carotene. The res ults showed that beta-carotene levels in the serum of colon polyp and colon cancer groups were 8- to 12-fold higher than in the untreated ce ntral or the placebo-treated groups. The benign polyp subjects (n = 17 ) receiving beta-carotene showed a significant rise in serum trans-ret inoic acid at three months compared with Time 0. The trans-retinoic ac id values from the colon cancer group receiving beta-carotene (n = 11) or placebo (n = 10) were significantly lower than the values from the beta-carotene-supplemented colon polyp group. It appears that trans-r etinoic acid levels in response to beta-carotene supplementation are d ifferent between treated cancer and benign patients because of differe nt body demands for retinoic acid.