Intraoperative radiation therapy in integrated treatment of rectal cancers. Results of phase II study.

PURPOSE : Risk of local recurrence of rectal cancer remains high despite extensive therapeutic strategies, many of which have been tried to achieve better local control (i.e., external beam radiation therapy (EBRT)). Recently, intraoperative radiation therapy (IORT) has been introduced in clinical protocols to boost the areas at risk of local recurrence. METHODS : Between April 1990 and December 1995, 44 patients with high risk (T3,N0-2 primary tumors) extraperitoneal rectal tumors and 24 patients with locally advanced (2 T3,N3 and 11 T4,N0-3 primary tumors ; 11 local recurrences) tumors entered a protocol that included preoperative EBRT (38 Gy), surgery plus IORT (10 Gy) in the high-risk group, and preoperative EBRT (45-48 Gy) and concomitant computerized tomography (5-fluorouracil plus mitomycin C), surgery plus IORT (10-15 Gy), and postoperative adjuvant computerized tomography (5-fluorouracil plus folinic acid) in the locally advanced group. RESULTS : In the high-risk group, acute Grade 3 (Radiation Therapy Oncology Group scale) skin toxicity, attributable to preoperative treatment, involved one patient (2.2 percent) ; among locally advanced cases, Grade 3 hematologic 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-related 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 groups, respectively, are alive and disease-free. In one high-risk patient, an anastomotic recurrence occurred. In four patients with locally advanced tumors (1 T4 primary, 3 local recurrences) an unresectable tumor relapse developed locally. Distant metastases occurred in two high-risk patients and in eight patients with a locally advanced tumor. Three-year actuarial survival was 100 percent in both high-risk and locally advanced primary tumors and 68.2 percent in local recurrences. CONCLUSIONS : Results of this study suggest that multimodal treatment (including IORT) in rectal cancer is safe, has no significant increase of mortality and morbidity, and also shows a trend for local improvement. A longer term follow-up and larger numbers of patients could demonstrate the therapeutic efficacy of IORT in rectal cancer.