Results of adjuvant radiation therapy in cancer of the rectum. Thomas Jefferson University Hospital experience.

From 1972 to 1981, 174 patients with cancer of the rectum surgically staged as B2 or C disease, underwent surgical resection of the tumors for cure. Eighty-eight patients received surgery only with no further adjuvant therapy, and the remaining 86 patients were treated with a combination of radiation and surgery. Twenty-nine patients received low-dose preoperative radiation (500 rad in one fraction); 26 patients received postoperative radiation (4500 rad in 5 weeks); and 31 patients received combined low-dose preoperative radiation (500 rad) and postoperative radiation (4500 rad in 5 weeks). This experience was analyzed to determine the patterns of failure and the impact of adjuvant therapy on survival. Patients undergoing surgery alone had a 26% incidence of local failure in the pelvis and a 57% incidence of distant metastasis. Patients receiving low-dose preoperative radiation had a reduction in the rate of distant metastasis (24%), but no effect on local failure (34%). On the other hand, patients receiving postoperative radiation had a reduction in the local failure rate (11%), with no effect on distant metastasis (50%). Patients who received the combined preoperative and postoperative treatment had a reduction in both the local recurrence rate (7%), and the rate of distant metastasis (13%), and these patients also had a substantial improvement in survival over surgery alone. Survival of patients undergoing surgery alone was 34% at 5 years and was not substantially different for patients undergoing low-dose preoperative irradiation (48%), or for patients receiving postoperative irradiation (29%). Survival in patients receiving combined preoperative and postoperative irradiation was substantially better (78%) than the other groups of patients.