Noninferiority of S-1 to UFT/LV as adjuvant chemotherapy for stage III colon cancer: A randomized phase III trial (ACTS-CC).

3518 Background: The ACTS-CC trial is a phase III trial designed to validate non-inferiority of S-1 to UFT/LV, a standard treatment in Japan as adjuvant chemotherapy for stage III colon cancer. This is the first report which evaluated the efficacy of S-1 as adjuvant therapy for colon cancer. Methods: 20-80 aged patients with stage III colon cancer who underwent curative surgery were randomly assigned to receive S-1 (80, 100, or 120 mg/day according to BSA on days 1 to 28, followed by 14 days rest, 4 courses) or UFT/LV (UFT: 300 to 600 mg/day according to BSA and, LV: 75 mg/day on days 1 to 28, followed by 7 days rest, 5 courses). Primary endpoint was DFS. Sample size was 1,480 determined with one-sided alpha of 0.05, power of 0.80, and non-inferiority margin of hazard ratio (HR) of 1.29. Results: Among 1535 enrolled patients between Apr. 2009 and Jun. 2010, 1518 patients (758 in S-1 group, 760 in UFT/LV group) were included in the efficacy analysis. Median follow-up was 41.3 months, the mean age at enrollment was 64.5 years, wide lymph node dissection (D3) was done in 79.8%, the median number of dissected lymph nodes was 17, and stage IIIA/IIIB/IIIC were 15%/71%/14%. The 3-year DFS rate was 75.5% in S-1 group and 72.5% in UFT/LV group. The HR of DFS was 0.85 (95%CI: 0.70-1.03) and non-inferiority of S-1 was demonstrated (p<0.0001). The completion rate of the protocol treatment was 76.5% in S-1 group and 72.5% in UFT/LV group. The overall incidence of grade ≥3 adverse events (AEs) in S-1 group and UFT/LV group were 16.0% and 14.4%: 4.4% and 5.5% for diarrhea, 4.9% and 3.5% for anorexia, 0.7% and 0.4% for leucopenia, 0.9% and 0.1% for anemia, 0.1% and 0.4% for thrombocytopenia, 1.2% and 1.5% for hyperbilirubinemia, 0.8% and 2.1% for AST elevation, and 1.1% and 3.3% for ALT elevation, respectively. Conclusions: Adjuvant therapy of S-1 for stage III colon cancer was demonstrated to be non-inferior in DFS to that of UFT/LV. Although AE profiles differed between S-1 group and UFT/LV group in this trial, incidence and degree of AEs were acceptable, and the completion rate of the protocol treatment was high. Adjuvant chemotherapy using S-1 will be a treatment option for stage III colon cancer. Clinical trial information: NCT00660894.