INTRAOPERATIVE RADIATION-THERAPY IN INTEGRATED TREATMENT OF RECTAL CANCERS - RESULTS OF PHASE-II STUDY

PURPOSE: Risk of local recurrence of rectal cancer remains high despit e extensive therapeutic strategies, many of which have been tried to a chieve better local control (i.e., external beam radiation therapy (EB RT)). Recently, intraoperative radiation therapy (IORT) has been intro duced in clinical protocols to boost the areas at risk of local recurr ence. METHODS: Between April 1990 and December 1995, 44 patients with ''high risk'' (T3,N0-2 primary tumors) extraperitoneal rectal tumors a nd 24 patients with ''locally advanced'' (2 T3,N3 and 11 T4,N0-3 prima ry tumors; 11 local recurrences) tumors entered a protocol that includ ed preoperative EBRT (38 Gy), surgery plus IORT (10 Gy) in the high-ri sk group, and preoperative EBRT (45-48 Gy) and concomitant computerize d tomography (5-fluorouracil plus mitomycin C), surgery plus IORT (10- 15 Gy), and postoperative adjuvant computerized tomography (5-fluorour acil plus folinic acid) in the locally advanced group. RESULTS: In the high-risk group, acute Grade 3 (Radiation Therapy Oncology Group scal e) skin toxicity, attributable to preoperative treatment, involved one patient (2.2 percent); among locally advanced cases, Grade 3 hematolo gic toxicity was observed in one patient (4.1 percent). Treatment was discontinued in no patients. On average, IORT prolonged surgery by 48 minutes. There was no mortality. Four anastomotic leakages, one pelvic infection, and five wound infections were observed. No chronic IORT-r elated toxicity occurred. After mean follow-up periods of 28.3 and 25. 9 months, 41 and 15 patients in the high-risk and locally advanced gro ups, respectively, are alive and disease-free. In one high-risk patien t, an anastomotic recurrence occurred. In four patients with locally a dvanced tumors (1 T4 primary, 3 local recurrences) an unresectable tum or relapse developed locally. Distant metastases occurred in two high- risk patients and in eight patients with a locally advanced tumor. Thr ee-year actuarial survival was 100 percent in both high-risk and local ly advanced primary tumors and 68.2 percent in local recurrences. CONC LUSIONS: Results of this study suggest that multimodal treatment (incl uding IORT) in rectal cancer is safe, has no significant increase of m ortality and morbidity, and also shows a trend for local improvement. A longer term follow-up and larger numbers of patients could demonstra te the therapeutic efficacy of IORT in rectal cancer.