Preoperative irradiation in operable cancer of the rectum: report of the Toronto trial.

The authors have studied the value of preoperative radiotherapy in 125 patients with cancer of the rectum. The patients were divided into two groups, control (no irradiation) and experimental (irradiation), and according to Dukes' pathological stage. The crude survival indicated no difference between the two groups, but analysis by stage and group demonstrated that for patients with a Dukes' stage C lesion, 500 rads of cobalt-60 gamma irradiation a few hours before excision of the lesion approximately doubles the probability of survival at 5 years. The prospect of surgical cure is three times higher in cancers arising above the peritoneal reflection than in those arising below it. If the practice of abdominoperineal resection is to continue the authors recommend that preoperative irradiation become a routine procedure.