Maintenance Chemotherapy with S-1 Following SOX Regimen Chemotherapy Improves Prognosis of Stage 3 Gastric Cancer After D2 Gastrectomy: A 5-Year Analysis

OBJECTIVE: To assess the effectiveness and safety of treatment consisting of maintenance chemotherapy (MCT) with S-1 following S-1 plus oxaliplatin (SOX) chemotherapy for stage 3 gastric cancer (GC) after D2 gastrectomy. METHODS: In this retrospective study, we enrolled 255 patients with stage 3 GC who underwent D2 gastrectomy between February 2011 and May 2014. The SOX regimen chemotherapy was administrated to all of the patients as adjuvant therapy. The SOX regimen consisted of S-1 (for patients with a body surface area [BSA] of less than 1.25 m(2), 80 mg/d; 100 mg/d for BSA=1.25 m(2)- <1.5 m(2), and 120 mg/d for BSA≥1.5 m(2), in 2 divided doses for 14 d) and oxaliplatin (130 mg/m(2) given on Day 1), repeated every 21 d for 8 cycles. Following SOX chemotherapy, 122 of these patients received maintenance chemotherapy (the MCT group) with S-1, whereas 133 patients (the control group) received no MCT. The MCT consisted of S-1 (80, 100, or 120 mg daily based on BSA, in 2 divided doses for 14 d), repeated every 21 d for 8 cycles at most. The chemotherapy was discontinued if unacceptable toxicity or disease progression occurred or upon the request of the patient. All cases were followed up, and overall survival (OS), recurrence-free survival (RFS), and toxicities were compared. RESULTS: The MCT group exhibited a distinctly higher 5-year OS (P=0.0425) and RFS (P=0.0479) than those of the control group. The incidence of hand-foot syndrome was markedly greater in the MCT group (P=0.0026). No toxicity-related death occurred. CONCLUSION: Maintenance chemotherapy with S-1 following the SOX regimen chemotherapy provides significant survival benefit for stage 3 GC after D2 gastrectomy.