Dose response to preoperative irradiation in rectal cancer: implications for local control and complications associated with sphincter sparing surgery and abdominoperineal resection.

Sixty patients with locally advanced adenocarcinoma of the rectum have been treated with preoperative high dose pelvic irradiation at the University of Virginia and Rockingham Memorial Hospital. Fifty-six patients showed no evidence of distant metastases at surgery. A dose response was observed with a 67% incidence of local control with 4000 cGy vs. 91% incidence with 5000 cGy. For the 52 patients who received curative surgery, there has been no local failure alone; 6 of these patients have had local plus distant failure and 16 have had distant failure only. Forty-three percent had anterior resection (AR) and 57% had abdominoperineal resections (APR). The major complication rate was 5% and the minor 14%. No increase in complications or decrease in local control was found between APR and AR. Five-year actuarial survival was 64% for lesions limited to the bowel wall, 59% for node negative lesions with disease extending through the wall, and 23% for node positive patients.