A phase I/II trial of whole-abdominal plus pelvic irradiation for Astler-Coller stage beta 2, C colorectal cancer

From 1982 to 1986, after radical surgery (S) for carcinoma of the rectum and rectosigmoid colon, 25 consecutive patients were entered into a Phase I/II study exploring adjuvant radiation (RT). The latter was given with a single fraction of whole abdomen (mid-body) irradiation (MBI), followed by conventional whole pelvis irradiation (WPI). The minimum follow-up time was 12 months, and the maximum was 44 months. There was escalation of the single MBI dose: 5 Gy in 11 patients, 6 Gy in two patients, and 8 Gy in 10 patients. The 2-year survival rate has been 100 and 45% for Stages B2 and C patients. Only 1/7 Astler-Coller Stage B2 patients failed; this failure was in the lungs. Seven of 15 patients with Stage C failed: one locally, three in the liver, and three in the lungs. Single MBI doses greater than 5 Gy have yielded a high incidence of intestinal obstruction when combined with routine WPI. Consequently, this combination requires both some modification and careful attention if used in future trials exploring new treatment approaches for colorectal cancer.