POF Versus FOLFOX Plus IP Paclitaxel in AGC

Inclusion Criteria: * 18-75 years old; * Patients must have histologically or cytologically confirmed metastatic or unresectable gastric or gastroesophageal junction (GEJ) adenocarcinoma. GEJ adenocarcinoma may be classified according to Siewert's classification type I, II, or III * Histological documentation of local recurrence or metastasis is strongly encouraged, unless the risk of such a procedure outweighs the potential benefit of confirming the metastatic disease. * If no histologic confirmation, then the metastases or recurrence will require documentation by a 2nd radiographic procedure (eg. PET/CT scan or MRI in addition to the CT scan). If the imaging procedure does not confirm recurrent or metastatic disease, biopsy confirmation will be required. * Patients must have ascites or peritoneal carcinomatosis confirmed by image (CT or MR or US or others) operation. * Patients may have received no prior chemotherapy for metastatic or unresectable disease. Patients may have received prior adjuvant therapy (chemotherapy and/or chemoradiation) if more than 6 months have elapsed between the end of adjuvant therapy and registration. * Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0-1; * An expected survival of ≥ 3 months; * Major organ function has to meet the following criteria; (1) For results of blood routine test: * Hemoglobin (HB) ≥ 80g / L, * ANC(absolute neutrophil count) ≥ 1.5 × 109 / L, * PLT(blood platelet) ≥ 75 × 109 / L, (2) For results of biochemical tests: * BLT（total bilirubin） ≤ 1.25 times the upper limit of normal (ULN), * ALT(Alanine aminotransferase) and AST(aspartate aminotransferase ) ≤ 2.5 × ·ULN, liver metastases, if any, the ALT and AST≤ 5 × ULN, * Serum Cr（creatinine）≤1ULN, Endogenous creatinine clearance rate \>50ml/min; * The patient has a PT（prothrombintime） (INR international normalized ratio) \< or = to 1.5 and an PTT（Partial Thromboplastin Time）\< than or = to 3 seconds above the upper limits of normal if the patientia t is not on anticoagulation. ·If a patient is on full-dose anticoagulants, the following criteria should be met for enrollment: * The patient must have an in-range INR (usually between 2 and 3) on a stable dose of warfarin or on stable dose of LMW(Low molecular weight) heparin * The patient must not have active bleeding or pathological conditions that carry high risk of bleeding (e.g. tumor involving major vessels, known varices) * Pregnancy test (serum or urine) has to be performed for woman of childbearing age within 7 days before enrolment and the test result must be negative. * Men and women of childbearing potential must be willing to consent to using effective contraception while on treatment and for at least 3 months thereafter. * Ability to understand informed consent and signing of written informed consent document prior to initiation of protocol therapy. Exclusion Criteria: \- Patients who have received previous chemotherapy for the treatment of metastatic or unresectable gastric or GEJ adenocarcinoma are ineligible. * Patients who have received previous pre- or post-operative chemotherapy or chemoradiation are ineligible if therapy was completed less than 6 months prior to study registration. Patients must have recovered from adverse events from any previous therapy. * Patients with a history of another neoplastic disease within the past three years, excluding basal cell carcinoma of the skin, cervical carcinoma in situ, or nonmetastatic prostate cancer. * Patients with brain or central nervous system metastases, including leptomeningeal disease. * Pregnant (positive pregnancy test) or breast feeding. * Serious, non-healing wound, ulcer, or bone fracture. * Significant cardiac disease as defined as: unstable angina, New York Heart Association (NYHA) grade II or greater, congestive heart failure, history of myocardial infarction within 6 months Evidence of bleeding diathesis or coagulopathy. * History of a stroke or CVA within 6 months * Clinically significant peripheral vascular disease. * Inability to comply with study and/or follow-up procedures. * Patients with any other medical condition or reason, in that investigator's opinion, makes the patient unstable to participate in a clinical trial.