BACKGROUND: The current study was conducted to assess the long-term results of reirradiation in patients with recurrent rectal carcinoma. METHODS: One hundred and three patients with recurrent adenocarcinoma of the rectum underwent reirradiation with concurrent 5-fluorouracil-based chemotherapy. The initial radiation dose to the pelvis ranged from 3000 to 7400 centigrays (cGy) with a median dose of 5040 cGy. The median time from initial treatment to recurrence was 19 months. Irradiation techniques consisted of two lateral fields with/without a posterior pelvic field to include recurrent tumor with a margin of 2-4 cm only. The reirradiation doses ranged from 1500 to 4920 cGy with a median dose of 3480 cGy. Total cumulative doses ranged from 7060 to 1080 cGy with a median total dose of 8580 cGy. After the reirradiation, 34 patients also underwent surgical resection for residual disease. Fourteen patients underwent pelvic exenteration, 11 patients underwent abdominoperineal resection, 4 patients underwent transanal transabdominal proctosigmoidectomy, 2 patients underwent full thickness local excision, and 3 patients underwent a Hartmann resection. RESULTS: Follow-up ranged from 3 84 months with a median follow-up of 2 years. The median survival for the whole group was 26 months and the 5-year actuarial survival rate was 19%. The median interval and 5-year survival rate of patients undergoing surgical resection after reirradiation was 44 months and 22% compared with 14 months and 15% for patients treated with reirradiation only (P = 0.001). Treatment was generally well tolerated. Fifteen patients required a treatment break and early termination of treatment for Grade 3 and higher diarrhea, moist desquamation, or mucositis. Late complications were seen in 22 patients, including persistent severe diarrhea in 18 patients with 10 patients requiring long-term parental support, small bowel obstruction was seen in 15 patients, fistula formation in 4 patients, and coloanal stricture in 2 patients. There was no difference in incidence of acute or long-term complications by the total radiation dose delivered. CONCLUSIONS: In patients with recurrent rectal carcinoma, high doses of reirradiation can be delivered with acceptable risks without prohibitive long-term side effects. Surgical salvage and long-term survival of patients are possible. Copyright 2002 American Cancer Society.