Postoperative adjuvant therapy of rectal cancer: an analysis of disease control, survival, and prognostic factors.

Between 1976 and 1984, 139 patients with rectal cancer were treated with complete surgical resection and postoperative adjuvant pelvic radiation therapy with or without chemotherapy. In this group, tumor extended beyond the bowel wall or involved lymph nodes or both. Irradiation was begun between 15 and 182 days postoperatively (median delay, 42 days). The radiation was delivered with 4-, 6-, or 10-MV photons given 5 days per week at 1.8 to 2.0 Gy per fraction. Total doses ranged from 3.8 to 64.4 Gy (median, 50 Gy). The fields were AP:PA in 49 and AP:PA plus laterals in 90. Forty-four received concurrent chemotherapy: 5-fluorouracil and semustine in 37, and 5-fluorouracil alone in seven. Follow-up in survivors ranged from 2 to 10 years (median, 4.2 years). This analysis includes all failures, both initial and subsequent sites of failure. Local failure occurred in 30 (22%) of the 139 patients overall, 6 (18%) of 33 in Stage B-2, 1 of 3 in Stage B-3, 2 (10%) of 20 in Stage C-1, 20 (26%) of 76 in Stage C-2, and 1 (14%) of 7 in Stage C-3. Five-year actuarial survival was 59% overall, 82% in Stage B-2, 79% in Stages B-2 and B-3, 89% in Stage C-1, 41% in Stage C-2, and 42% in Stages C-2 C-3. The following prognostic factors were independently associated with poorer survival and increasing distant failure: lymph node involvement, tumor extension beyond the bowel wall, and high histologic grade. Use of chemotherapy was associated with a significant improvement in survival and decrease in distant failure. No single factor was significantly associated with local failure. Adequate perineal coverage after combined abdominoperineal resection yielded significantly fewer perineal failures. Overall, serious complications developed in 7%, but none was fatal. Treatment recommendations and optimal treatment techniques are discussed.