148P - Efficacy of capecitabine and oxaliplatin versus S-1 as adjuvant chemotherapy in gastric cancer after D2 lymph node dissection according to lymph node ratio and N stage

Abstract

BackgroundThe purpose of this study was to compare Capecitabine and Oxaliplatin (XELOX) with S-1, based on disease-free survival (DFS) and overall survival (OS) in gastric cancer (GC). In addition, clinical impact of using lymph node ratios and compare it with N stage was investigated. MethodsPatients who had curative resection and received either S-1 or XELOX as adjuvant chemotherapy for advanced gastric cancer between Jan, 2011 and Dec, 2015, were analysed. Of the 412 patients enrolled, 301 received S-1 and 111 received XELOX. Lymph node ratio (LNR) groups were segregated as 0, 0-0.1, 0.1-0.25, and > 0.25 and named LNR 0,1,2 and 3, respectively. Propensity score matching (PSM) was used to minimize the influence of potential selection bias. The PSM compared DFS and OS in the two treatment groups, and enabled subgroup analysis according to clinical variables including the lymph node ratio group (LNR group) and N stage. ResultsIn PSM cohort, the sample size of each group was 86 patients and variables are well balanced. The XELOX group showed significantly better DFS (26.9% vs 59.3%, HR 0.43, 95% CI 0.20-0.90; p = 0.025) and better OS(30.8% vs 63.0%, HR 0.44, 95% CI 0.20-0.99; 0.045) in stage IIIC. The XELOX group showed significantly better DFS in all stage III. (54.7% vs 61.6%, HR 0.57,95% CI 0.33-0.99; p = 0.045). The N3 group showed significantly better DFS (40% vs 65.8%, HR 0.45, 95% CI, 0.23-0.86; p = 0.017) and better OS (44.7% vs 68.4%, HR 0.48, 95% CI, 0.24-0.97; p = 0.040) in the XELOX group. The LNR 3 group showed significantly better DFS in the XELOX group (26.3% vs 52.9% with HR 0.41 (95% CI, 0.17-0.97; p = 0.042). ConclusionsOur data suggested that current N staging and LNR could be a useful tool for selecting patients who can benefit from adjuvant XELOX after D2 gastrectomy when compared with S-1. When patients who are designated N3 or LNR > 0.25 or at stage IIIC, XELOX should be recommended over S-1. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.