Inhibitory effect of calcium on carcinogenesis at the site of colonic anastomosis - An experimental study

PURPOSE: A study was made to assess the effect of oral calcium supplementation on colorectal carcinogenesis at the colocolic suture line and in the rest of the colon following administration of a carcinogen. METHODS: Fifty-nine rats were randomly divided into two groups: control (given a standard diet for rats and mice containing 0.8 percent calcium) and treatment (given the same diet as before but with 2 percent calcium). Carcinogenesis was induced by 26 weekly injections of 1,2-dimethylhydrazine. All animals were subjected to an end-to-end colonic anastomosis at the beginning of the experiment using five stitches of steel wire. RESULTS: The control group developed significantly more tumors per animal at both the anastomosis (P < 0.001) and in the rest of the colon (P < 0.001). In addition, the percentage of rats with tumors was significantly higher in the control group at both the anastomosis (chi-squared = 12; df = 1, P < 0.001) and in the rest of the colon (chi-squared = 7.12; df = 1, P < 0.01). The mean surface of tumors was likewise greater in the control group at the anastomosis (P < 0.001) and throughout the rest of the colon (P < 0.001). Finally, there were significantly more small-bowel tumors (excluding the duodenum) in the control group (P < 0.05). CONCLUSIONS: It is concluded that calcium supplementation decreases the tumor field at the site of end-to-end colonic anastomosis and in the rest of the colon and small bon el (excluding the duodenum).