Multicenter Phase II Study of a New Effective S-1 and Irinotecan Combination Schedule in Patients with Unresectable Metastatic or Recurrent Colorectal Cancer

Introduction: This multicenter phase II study determined the efficacy and safety of new daily oral S-1 and weekly irinotecan (CPT-11) combination schedule in patients with previously untreated advanced or recurrent colorectal cancer. Patients and methods: Patients received first-line chemotherapy comprising S-1 80 mg/m2/day given on days 3 to 7, 10 to 14, and 17 to 21 and 60 mg/m2 CPT-11 administered intravenously on days 1, 8, and 15 of a 28-day cycle. Results: A total of 45 eligible patients were enrolled in this study. The overall response rate was 48.9%. Median progression-free survival and median overall survival was 8.1 months and 20.9 months, respectively. The rates of grade 3 or 4 toxicity were as follows: neutropenia, 8.9%; anemia, 4.4%; anorexia, 6.7%; and diarrhea, 6.7%. Conclusions: This new S-1 and irinotecan combination schedule appeared to be an effective, well-tolerated, and convenient regimen in patients with advanced colorectal cancer as compared with conventional regimens such as FOLFIRI and IRIS.