SOX regimen, consisting of oral S-1 and intravenous oxaliplatin, is the preferred regimen for perioperative chemotherapy for gastric cancer. The goal of this clinical trial is to compare the efficacy and safety between S-1 combined with oxaliplatin by arterial infusion, as neoadjuvant chemotherapy, and conventional SOX regimen, in locally advanced gastric cancer. The main question it aims to answer is: whether arterially infused oxaliplatin plus S-1 has the potential to be a better neoadjuvant option for patients with locally advanced gastric cancer.
Participants will be randomised, and receive:
* 3 cycles of conventional SOX chemotherapy plus PD-1 antibody or arterial infused oxaliplatin plus S-1 and PD-1 antibody, as neoadjuvant chemotherapy;
* Adequate gastric resection along with D2 lymph node dissection;
* 3 cycles adjuvant chemotherapy using SOX regimen plus PD-1 antibody.
* Administration of S-1 regularly till 1 year after surgery.
Researchers will compare Major pathological response rate (MPR) ，pathologic complete response rate（pCR）,the 2-year overall survival (OS) rates, 2-year disease free survival (DFS), R0 resection rates, and adverse events, to see if the modified perioperative chemotherapy improve the prognosis of patients with locally advanced gastric cancer.