Effects of calcium and vitamin supplementation on colon cell proliferation in colorectal cancer

Calcium and antioxidant vitamins, such as A, C, and E, have been shown to reduce colorectal epithelial proliferation and thereby to act as possible chemoprotective agents in colorectal cancer. We investigated the effects of an intervention with calcium and vitamins on cell proliferation in the colonic mucosa of patients operated on for colorectal cancer Patients with resected colorectal cancer Dukes' stage BC were randomized to receive daily 30,000 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 calcium daily or indistinguishable placebo for 6 months. At the rime of surgery 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 PCNA labeling index (PCNALI) was evident in both groups after 6 months (vitamins/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 significant in the treatment and placebo groups: 34% and 28%, respectively. A second control, 6 months after discontinuously of vitamin and calcium supplementation, showed a further decrease of,mean total PCNALI in both groups, bur this was not statistically. significant. Our. randomized trial showed that calcium and vitamin supplementation does not reduce cell kinetics of colon epithelium. Furthermore, this study suggests the need for extreme caution in the interpretation and publication of studies on chemoprotectants in colon cancer without a control group.