Effect of Vitamin A, C, and E Supplementation on Rectal Cell Proliferation in Patients With Colorectal Adenomas

Studies suggest that cell proliferation abnormalities of the colorectal mucosa are associated with risk of neoplasia, and most cancers of the large bowel are thought to arise from adenomas, The results of other studies suggest that vitamins A, C, and E have chemopreventive efficacy against colon cancer in animal models. This study evaluates the effect of dietary vitamin supplementation on cell kinetics in uninvolved rectal mucosa in patients with colorectal adenomas. Twenty patients with colorectal adenomas were given vitamins A, C, and E for 6 months after complete polypectomy, and 21 patients with adenomas received placebo. In each patient, six biopsy specimens were taken from normal-appearing rectal mucosa before treatment and after 3 and 6 months of treatment and were incubated with tritiated thymidine ([3H]thymidine), and the [3H]thymidine-labeled cells were counted by use of autoradiography. Two parameters of cell proliferation were evaluated: 1) the ratio of the number of cells to the total number of cells (thymidine labeling index) and 2) the ratio of the number of labeled cells in the upper 40% of the crypt to the total number of labeled cells in the crypt (Φh). The latter index reflects abnormal expansion of the proliferative compartment and is thought to be an intermediate biomarker of cancer risk. In patients receiving vitamins, Φh decreased progressively from baseline values, with increasing statistical significance (P