Souya Nunobe, MD, PhD, on Gastric Cancer: 5-Year Follow-up on S-1 Chemotherapy for Stage II Disease

Based on previous pivotal RCT, adjuvant chemotherapy of S-1 for one year for eight courses is standard treatment for pathological stage II patients who underwent D2 gastrectomy for gastric cancer. Survival of pathological stage II of patient was dramatically improved by S-1, achieving high five-year survival of 84%. So, we assume that four courses of S-1 may be a sufficient treatment and conducted JACOG1104 Phase III trial, which compared four courses and eight courses of S-1 adjuvant chemotherapy. At the first interim analysis in 2017, the present trial was terminated due to futility. Four courses of S-1 was inferior to eight courses of S-1 in terms of relapse-free survival. Here we report the final follow-up data. Between 2012 and 2017, 519 patient were enrolled and 295 patient were allocated to each group. When the present study was terminated at the interim analysis, 27 patients of four courses were receiving S-1. Among them, 22 patients accepted the proposal to continue until eight courses. As final survival result, the RFS at five years was 85.6% for four courses and 87.7% for eight courses. The overall survival at five years was 88.6% for four courses and 89.7% for eight courses. Four courses of S-1 was [inaudible 00:02:27] inferior to eight courses of S-1 in terms of relapse-free survival. In conclusion, this final follow-up data confirmed the primary result presented at the interim analysis. Adjuvant chemotherapy for one year or eight courses is highly recommended for pathological stage II gastric cancer.