Healing of experimental colonic anastomoses: Effects of combined preoperative high-dose radiotherapy and intraperitoneal 5-fluorouracil

To study the effects of preoperative radiochemotherapy (RCT) on the healing of colonic anastomosis, the rectosigmoid colon in male Wistar rats was irr adiated up to an end dose of 41.6 Gy (RT) or sham-irradiated (SR). During t he last 5 days of the irradiation schedule, 5-fluorouracil (5-FU) was admin istered intraperitoneally in either a high dose (20 mg/kg, chemotherapy-hig h dose [CHI) or a low dose (10 mg/kg, chemotherapy-low dose [CLI). Animals were randomly arranged into six groups: group I, control (SR + saline intra peritoneally); group II, RT only; group III, SR + CL; group IV, RT + CL; gr oup V, SR + CH; group VI, RT + CH. Four days after RCT, a side-to-side anas tomosis was constructed between the irradiated rectosigmoid. and the nonirr adiated caecum. Animals were killed 10 days postoperatively. No significant differences were found in the anastomotic bursting pressure or the burstin g wall tension. In group VI, mitoses were less (P < 0.01) and mucosaI ulcer ation was more (P = 0.03) pronounced compared to group I. Sclerotic arterie s were seen in all irradiated groups and in animals that received high-dose S-FU alone. 5-FU administration in high or low dose, with or without RT, i nduced more inflammation in the submucosa compared to controls (P < 0.05). Conclusively, RCT has no detrimental effect on the mechanical strength of c olonic anastomosis in this rat model. However, RCT with high-dose 5-FU indu ces more histological alterations at the anastomotic site. (C) 2001 Wiley-L iss, Inc.