LOCALLY ADVANCED RECTAL-CARCINOMA - PELVIC CONTROL AND MORBIDITY FOLLOWING PREOPERATIVE RADIATION-THERAPY, RESECTION, AND INTRAOPERATIVE RADIATION-THERAPY

Purpose: To determine the impact of intraoperative radiation therapy ( IORT) combined with preoperative external beam irradiation and surgica l resection in patients with locally advanced, unresectable rectal car cinoma. Methods and Materials: Between 1982 and 1993, 40 patients with locally advanced colorectal cancer unresectable at initial presentati on were treated with preoperative external beam radiation therapy (med ian dose 50.4 Gy). Thirty patients received concurrent 5-fluorouracil. Twenty-seven patients had primary tumors and 13 had recurrent disease ; 1 patient had a solitary hepatic metastasis at the time of surgery. Four to 6 weeks after radiation, surgical resection was undertaken, an d if microscopic or gross residual disease was encountered, IORT was d elivered to the tumor bed. Patients with an unevaluable or high-risk m argin were also considered for IORT. IORT was delivered through a dedi cated 300-kVp orthovoltage unit. The median dose of IORT was 12.5 Gy ( range 8-20). The dose was typically prescribed to a depth of 1-2 cm. T he median follow-up was 33 months (range 5-100). Results: Thirty-three patients were able to undergo a curative resection (83%). Five patien ts had gross residual disease despite aggressive surgery. Seven patien ts did not receive IORT: six because of clear margins, and one with gr oss disease that could not be treated for technical reasons. The remai nder of the patients (26) received IORT to the site of pelvic adherenc e. The crude local control rates for patients following complete resec tion with negative margins were 92% for patients treated with IORT and 33% for patients without IORT. IORT was ineffective for gross residua l disease. Pelvic control was none of four in this setting. The crude local control rate of patients with primary cancer was 73% (16 of 22), as opposed to 27 % (3 of 11) for these with recurrent cancer. The 5-y ear actuarial overall survival and local control rates for patients un dergoing gross complete resection and IORT were 64% and 75%, respectiv ely. Seventeen of the 26 patients (65%) who received IORT experienced pelvic complications, as opposed to two patients (28%) who did not rec eive IORT. The incidence of complications was similar in the patients with primary versus recurrent disease. All cases were successfully tre ated with the placement of a posterior thigh myocutaneous flap. Of not e, no pelvic osteoradionecrosis was seen in this series. Conclusion: P atients with locally advanced carcinoma of the rectum were aggressivel y treated,vith combined modality therapy consisting of preoperative ex ternal beam radiotherapy, surgery, and IORT. The pelvic control rate w as 82% for patients with minimal residual disease. IORT failed to cont rol gross residual disease. The incidence of pelvic wound healing prob lems was 65% in this series; however, a reconstructive procedure which replaced irradiated tissue with a vascularized myocutaneous flap was successful in treating this complication. We believe that IORT has the rapeutic merit in the treatment of locally advanced rectal cancer, par ticularly in the setting of minimal residual disease. (C) 1997 Elsevie r Science Inc.