Chemotherapy is an important therapeutic method for patients with advanced gastric cancer. However, there is currently no established standard chemotherapeutic regimen in the preoperative or neoadjuvant treatment setting. The aim of our study was to compare the efficacy and toxicity between SEEOX and SOX regimens. The investigators estimate that combined intravenous and intra-arterial intensified SEEOX preoperative chemotherapy may be a safe and promising regimen for locally advanced or initially unresectable gastric cancer patients.

Gastric cancer patients who will receive neoadjuvant chemotherapy would be included in this study. They would receive combined intravenous and intra-arterial intensified SEEOX neoadjuvant chemotherapy or SOX regimen at random. The efficacy and toxicity of these two regimens would be compared.

Inclusion Criteria:

• Eastern Cooperative Oncology Group(ECOG) score 0-2
• Ambulatory males or females, aged 30-70 years.
• Unresectable gastric cancer (Tumors with bulky nodal metastases surrounding the celiac artery and its branches or invasion of adjacent structures such as pancreas, omentum, esophagus, and aorta were considered unresectable)
• Life expectancy more than 3 months
• Give written informed consent, with the understanding that the patient has the right to withdraw from the study at any time, without prejudice.
• Normal hepatic, renal, and bone marrow function (GPT<2 fold of upper limit value; white blood cell count>4000/dl, Tbil<1.5mg/dl, Cr<1.5 fold of upper limit value)

Exclusion Criteria:

• Patients can not bear surgical procedure.
• Pregnant or lactating women.
• Previous cytotoxic chemotherapy, radiotherapy or immunotherapy.
• History of another malignancy within the last five years.
• History of uncontrolled seizures, central nervous system disorders or psychiatric disability judged by the Investigator to be clinically significant precluding informed consent or interfering with compliance for oral drug intake.
• Clinically significant (i.e. active) cardiac disease e.g. symptomatic coronary artery disease, New York Heart Association (NYHA) grade II or greater congestive heart failure or serious cardiac arrhythmia requiring medication or myocardial infarction within the last 12 months.
• Organ allografts requiring immunosuppressive therapy.
• Serious uncontrolled intercurrent infections or other serious uncontrolled concomitant disease.
• Moderate or severe renal impairment: serum creatinine > 1.5 x upper limit of normal (ULN).
• Hypersensitivity to any drug of the study regimen.
• With abdominal cavity implantation metastasis or distant metastasis.
• Unwilling or unable to comply with the protocol for the duration of the study.