Impact of the New AJCC Staging System and Adjuvant Treatment in Rectal Cancer / Journal of the Korean Cancer Association, 대한암학회지

ABSTRACT

PURPOSE: The combination of chemoradiation and fluorouracil based chemotherapy has been the standard adjuvant treatment for colorectal cancer patients. The aim of this study was to evaluate treatment outcome of patients classified by the new AJCC staging system and to compare treatment outcome of oral doxifluridine and the standard Mayo Clinic regimen after chemoradiation in advanced rectal cancer patients. MATERIALS AND METHODS: One hundred nine patients underwent curative surgical resection and chemoradiation followed by chemotherapy. 45 Gy pelvic irradiation was given to the entire pelvis and the boost radiation with 50.4 to 54 Gy, and simultaneously 5-fluorouracil (5-FU) 375 mg/m2/day was given on day 1~3 and 26~28. After the completion of chemoradiation, patients were given either 6 cycles of the Mayo Clinic regimen (5-FU 425 mg/m2 plus leucovorin 20 mg/m2 intravenous bolus infusion on day 1~5, every 4 weeks) or oral doxifluridine (600 mg/m2/day) for 1 year. RESULTS: The median follow-up duration was 30 months. Among 102 evaluable patients, 38 patients (37.3%) relapsed the locoregional recurrence in 10 patients (9.8%) and systemic relapse in 28 patients (27.5%). The systemic relapse rate was 15.6% in the stage IIA, 25.0% in the stage IIIB, and 59.1% in the stage IIIC (p=0.048). The 5-year disease-free survival (DFS) rate was significantly higher in the IIA and IIIA patients than the IIIB and IIIC patients (72% and 100% vs 48.1% and 11.2%, respectively. p<0.001). The 5-year overall survival (OS) rate was also significantly different between in the IIA/IIIA patients and the IIIB/IIIC (67.3%/100% vs 48.4%/22.3%. p<0.001). However, the difference in DFS or OS between the oral doxifluridine group and the Mayo Clinic regimen group was not significant. Cox regression multivariate analyses showed that the new AJCC stage and tumor differentiation were significant independent prognostic factors in DFS and OS. CONCLUSION: These results support that the new AJCC staging system is superior to Dukes' staging system in the prognostic stratification. Regarding DFS and OS, oral doxifluridine is comparable to the standard Mayo Clinic regimen in rectal cancer patients when combined with postoperative chemoradiation. Stage IIIC patients should be selected for aggressive therapy as they have a dismal prognosis.