ABSTRACT
PURPOSE: To determine the optimal scheme of postoperative chemoradiotherapy in rectal cancer by comparing survival, patterns of failure, toxicities in early and late radiotherapy groups using a phase III randomized prospective clinical trial. MATERIALS AND METHODS: From January 1996 to March 1999, 307 patients with curatively resected AJCC stage II and III rectal cancer were assigned randomly to an 'early (151 patients, arm I)' or a 'late (156 patients, arm II)' and were administered combined chemotherapy (5-FU 375 mg/m2/day, leucovorin 20 mg/ m2, IV bolus daily, for 3 days with RT, 5 days without RT, 8 cycles with 4 weeks interval) and radiation therapy (whole pelvis with 45 Gy/25 fractions/5 weeks). Patients of arm I received radiation therapy from day 1 of the first cycle of chemotherapy and those of arm II from day 57 with a third cycle of chemotherapy. The median follow-up period of living patients was 40 months. RESULTS: Of the 307 patients enrolled, fifty patients did not receive scheduled radiation therapy or chemotherapy. The overall survival rate and disease free survival rate at 5 years were 78.3% and 68.7% in arm I, and 78.4% and 67.5% in arm II. The local recurrence rate was 6.6% and 6.4% ( p=0.46) in arms I and II, respectively, no significant difference was observed between the distant metastasis rates of the two arms (23.8% and 29.5%, p=0.16). During radiation therapy, grade 3 diarrhea or more, by the NCI common toxicity criteria, was observed in 63.0% and 58.2% of the respective arms ( p=N.S.), but most were controlled with supportive care. Hematologic toxicity (leukopenia) greater than RTOG grade 2 was found in only 1.3% and 2.6% of patients in each respective arm. CONCLUSION: There was no significant difference in survival, patterns of failure or toxicities between the early and late radiation therapy arms. Postoperative adjuvant chemoradiation was found to be a relatively safe treatment but higher compliance is needed.