Effects of calcium and vitamin supplementation on colon cell proliferationin colorectal cancer

Calcium and antioxidant vitamins, such as A, C, and E, have been shown to r educe colorectal epithelial proliferation and thereby to act as possible ch emoprotective agents in colorectal cancer. We investigated the effects of a n intervention with calcium and vitamins on cell proliferation in the colon ic mucosa of patients operated on for colorectal cancer Patients with resec ted colorectal cancer Dukes' stage BC were randomized to receive daily 30,0 00 IU of axerophthol palmitate (vitamin A) plus I g ascorbic acid (vitamin C) pills 70 mg of dl-alpha-tocopherol acetate (vitamin E) and 2 g natural c alcium daily or indistinguishable placebo for 6 months. At the rime of surg ery and after 6 and 12 months of treatment, cell kinetics of normal colonic mucosa Ir ere assessed by using proliferating cell nuclear antigen (PCNA). Ninety patients,were enrolled and 77 were assessable: 34 in the treatment group and 43 in the placebo group. A significant reduction of mean total PC NA labeling index (PCNALI) was evident in both groups after 6 months (vitam ins/calcium, from 16.11 +/- 2.43 to 10.71 +/- 2.81; placebo, from 17.30 +/- 2.63 to 12.53 +/- 3.40). The difference in the percentage of reduction of mean PCNALI between baseline and after 6 months was nor statistically signi ficant in the treatment and placebo groups: 34% and 28%, respectively. A se cond control, 6 months after discontinuously of vitamin and calcium supplem entation, showed a further decrease of,mean total PCNALI in both groups, bu r this was not statistically. significant. Our. randomized trial showed tha t calcium and vitamin supplementation does not reduce cell kinetics of colo n epithelium. Furthermore, this study suggests the need for extreme caution in the interpretation and publication of studies on chemoprotectants in co lon cancer without a control group.