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.

Purpose 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 and methods 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. Results 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). Conclusion 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.