Influence of preoperative combined radiochemotherapy on surgical outcome and colonic anastomotic healing: Experimental study in the rat

Purpose: To study the influence of combined preoperative hyperfractionated irradiation with intraperitoneal 5-fluorouracil (5-FU) on surgical outcome and colonic anastomotic healing in a rat model. Methods: Male Wistar rats were given 41.6 Gy of preoperative radiotherapy ( RT) or sham irradiation, with intraperitoneal 5-FU at low dose (10 mg/kg) o r high dose (20 mg/kg). Animals were arranged in 6 groups: RT + low-dose 5- FU (RCT-L), RT + high-dose 5-FU (RCT-H), sham RT + low-dose 5-FU (CT-L), sh am RT + high-dose 5-FU (CT-H), RT alone (R), and a control group (sham RT intraperitoneal saline). Side-to-side colonic anastomoses were constructed from one irradiated and one nonirradiated limb 4 days after radiochemother apy. Animals were sacrificed 10 days after surgery. Results: Compared to controls, more complications occurred in group RCT-H ( 50% versus 0%, p = 0.01). Adhesion formation was more intense in groups RCT -H and CT-H (p < 0.001 and p = 0.001, respectively). After therapy, white b lood cell counts dropped significantly in all irradiated animals (p < 0.01) , and platelet counts decreased significantly in group RCT-H (p = 0.01). No significant differences were noticed in anastomotic bursting pressure when the treated groups were compared to each other or to the control group. Conclusions: Neoadjuvant radiochemotherapy has no adverse effect on the str ength of colonic anastomotosis in this rat model. However, the combined RT with high-dose 5-FU does increase operative morbidity and adhesion formatio n. (C) 2001 Elsevier Science Inc.