Phase III Study to Compare Perioperative Chemotherapy of Oxaliplatin Combined With S-1(SOX) Versus SOX or Oxaliplatin With Capecitabine (XELOX) as Post-operative Chemotherapy in Locally Advanced Gastric Adenocarcinoma With D2 Dissection

Peri-operative treatment of locally advanced gastric cancer (LAGC) has always been argued by eastern and western scholars. For patients with clinical stage of cT4b/N+M0, or cT4aN+M0, the prognosis is rather poor, and the primary lesions might not be resectable at the time of diagnosis. MAGIC study has showed that pre-and post-operative chemotherapy with 3 cycles of ECF has increased 13% on 5yOS compared with surgery alone; However, eastern studies such as ACTS GC or CLASSIC showed that TS-1 monotherapy or XELOX (oxaliplatin/capecitabine) combination given as adjuvant chemotherapy for stage II or III patients after D2 surgery could achieve the significant survival benefit. So whether perioperative or post operative therapy is more beneficial for LAGC patients lacks of data supported by prospective study. So in this prospective randomized phase III study, the investigators aim to compare the survival benefit as well as the safety for SOX (oxaliplatin/TS-1) as perioperative therapy versus SOX or XELOX as postoperative therapy after D2 dissection.