The impact of 5-fluorouracil and intraoperative electron beam radiation therapy on the outcome of patients with locally advanced primary rectal and rectosigmoid cancer.

Objective: To analyze the effects of 5-fluorouracil (5-FU) chemotherapy combined with preoperative irradiation and the role of intraoperative electron beam irradiation (IOERT) on the outcome of patients with primary locally advanced rectal or rectosigmoid cancer.

Methods: From 1978 to 1996, 145 patients with locally advanced rectal cancer underwent moderate- to high-dose preoperative irradiation followed by surgical resection. Ninety-three patients received 5-FU as a bolus for 3 days during the first and last weeks of radiation therapy (84 patients) or as a continuous infusion throughout irradiation (9 patients). At surgery, IOERT was administered to the surgical bed of 73 patients with persistent tumor adherence or residual disease in the pelvis.

Results: No differences in sphincter preservation, pathologic downstaging, or resectability rates were observed by 5-FU use. However, there were statistically significant improvements in 5-year actuarial local control and disease-specific survival in patients receiving 5-FU during irradiation compared with patients undergoing irradiation without 5-FU. For the 73 patients selected to receive IOERT, local control and disease-specific survival correlated with resection extent. For the 45 patients undergoing complete resection and IOERT, the 5-year actuarial local control and disease-specific survival were 89% and 63%, respectively. These figures were 65% and 32%, respectively, for the 28 patients undergoing IOERT for residual disease. The overall 5-year actuarial complication rate was 11%.

Conclusions: Treatment strategies using 5-FU during irradiation and IOERT for patients with locally advanced rectal cancer are beneficial and well tolerated.