A two centers study of postoperative adjuvant chemotherapy with S-1 versus SOX/XELOX regimens for gastric cancer after D2 resection: a cohort study

Currently, radical surgery with D2 lymphadenectomy has become the standard operation mode of patients in East Asian countries who suffer from resectable gastric cancer. Our target is to compare the efficacy of postoperative adjuvant chemotherapy with S-1 versus SOX/XELOX regimens for gastric cancer after D2 resection. We selected 186 patients with gastric cancer who underwent D2 resection in Hangzhou First People’s Hospital and Hangzhou Cancer Hospital from June 2014 to June 2017. All patients were followed up for more than 3 years. The primary endpoint was disease-free survival (DFS), and the secondary endpoints were overall survival (OS) and toxicity. The 3-year DFS of monotherapy group and combined group were, respectively, 50.7% and 64.0%, while the 3-year OS were, respectively, 62.7% and 71.2%. The 3-year DFS and OS of the combined group were higher than the monotherapy group, but the differences had no statistical significance (3-year DFS: P = 0.071; 3-year OS: P = 0.224). Subgroup analysis showed that the DFS of patients with stage III gastric cancer in monotherapy group was significantly lower than the combined group, with the difference that had statistical significance (P = 0.030), while there was no significant difference in OS (P = 0.186). Most toxic and side effects seen in both groups had no significant differences, while the incidence of hand-foot syndrome and peripheral neurotoxicity in combined group was significantly higher than that in the monotherapy group (P < 0.001). For patients with advanced gastric cancer who underwent D2 resection, compared with S-1 regimen, there is prolonged disease-free survival trend with SOX/XELOX regimen, while there is no significant overall survival benefit.