Colonic healing: the effect of irradiation and chemotherapy - an experimental study, resembling adjuvant therapy for colorectal carcinoma

Adjuvant treatment of colon and rectal carcinoma is of major interest. Irradiation and chemotherapy are modalities used widely. The purpose of this study was to evaluate the effect of preoperative irradiation and postoperative intraperitoneal 5-fluorouracil treatment on colonic healing. In rats preoperative irradiation of the lower abdominal region by 10 + 10 Gy four days apart caused inflammatory reaction in the colon as evaluated by histology and determination of myeloperoxidase activity. The inflammatory reaction reached its peek within a week of the second irradiation. When standard used colonic resections and anastomes were performed within the irradiate part of the colon the anastomotic healing was not affected during the first week after operation as judged by complications and breaking strength. A lower breaking strength and an increase in myeloperoxidase activity two months after operation may indicate late changes within the intestinal wall. Intraperitoneal 5-fluorouracil in rat given immediately after colonic resection and repeated as daily injections caused a weight loss and marked reduction in breaking strength of the anastomosis as well as in the abdominal skin wound. A reduction in 5-fluorouracil concentration did not alter the negative wound healing effect of the chemotherapy. In a group of rats subjected to nutritional depletion, mimicking the weight curve of 5-fluorouracil treated animals, anastomotic breaking strength was not compromised to the same extent as when 5-fluorouracil was given. This indicated a direct toxic effect rather than an effect of reduced food intake caused by 5-FU treatment. Collagen synthesis and the formation of new tissue in the wound gap was reduced in 5-fluorouracil treated animals compared to controls as judged by in vivo incorporation of 3H-proline in the anastomotic segment and determination of anastomotic breaking strength after removal of sutures. 108 refs