Feasibility of neoadjuvant S-1 and oxaliplatin followed by surgery for resectable advanced gastric adenocarcinoma

In Japan, the administration of S-1 following D2 gastrectomy is a standard treatment for stage II/III gastric cancer (GC). However, the survival of stage IIIB/IIIC GC remains unsatisfactory. To improve this, we conducted a multicenter phase II study to evaluate the safety and efficacy of a neoadjuvant S-1 and oxaliplatin regimen (SOX) followed by surgery targeted at stage III GC. Oxaliplatin was administered intravenously (130 mg/m(2)) on day 1, and S-1 was administered orally (40 mg/m(2), twice a day) for 14 days followed by a seven-day rest period. After three cycles of therapy, D2 gastrectomy was performed. A total of 14 patients were enrolled and completed the protocol treatment. Grade 3/4 toxicities included thrombocytopenia (21.4 %), anorexia (14.3 %), and diarrhea (7.1 %). Seven patients (50 %) underwent total gastrectomy, and seven patients underwent distal gastrectomy. Grade 3/4 surgical complications included pancreatic fistula (21.4 %) and lung infection (7.1 %). The pathological response rate was 85.7 %. Although our data are limited and preliminary, neoadjuvant SOX followed by surgery can be performed safely with a high pathological response rate in patients with resectable advanced GC. Further investigation of this neoadjuvant approach is warranted.