Three-year outcomes of a randomized phase III trial comparing adjuvant chemotherapy with S-1 plus docetaxel versus S-1 alone in stage III gastric cancer: JACCRO GC-07

The second planned interim analysis (median follow-up 12.5 months) in a phase III trial of postoperative adjuvant chemotherapy for stage III gastric cancer revealed significant improvement in relapse-free survival (RFS) for S-1 plus docetaxel over S-1 alone. Although enrollment was terminated on the recommendation of the independent data and safety monitoring committee, we continued follow-up and herein report on 3-year RFS, the primary endpoint. Patients with histologically confirmed stage III gastric cancer who underwent gastrectomy with D2 lymphadenectomy were randomly assigned to receive adjuvant chemotherapy with either S-1 plus docetaxel or S-1 alone. In the S-1 plus docetaxel group, S-1 was given orally for 2 weeks followed by 1 week of rest for seven courses, and docetaxel was given intravenously on day 1 of the second to seventh courses. The combination therapy was followed by S-1 monotherapy for up to 1 year. The 3-year RFS rate of the S-1 plus docetaxel group was 67.7%. This was significantly superior to that of 57.4% in the S-1 group (hazard ratio [HR] 0.715, 95% CI 0.587–0.871, P = 0.0008). This translated into a significant benefit in the 3-year overall survival (OS) rate in the S-1 plus docetaxel group (77.7% versus 71.2%, HR 0.742, 95% CI 0.596–0.925, P = 0.0076). On 3-year follow-up data, postoperative adjuvant therapy with S-1 plus docetaxel was confirmed to improve both RFS and OS and can be recommended as a standard of care for patients with stage III gastric cancer treated by D2 dissection.