XELOX Versus FOLFOX for Advanced Gastric Cancer (AGC)

Inclusion Criteria: 1. Age :older than 20 2. A patient with at least one measurable primary lesion of which the diameter is confirmed to be 10mm in Spiral CT or multidetector CT (MD CT), or 20 mm or longer in conventional CT (it should be used by a consistent method during the study period). (RECIST v1.1) \*but, patients who does not have measureable lesion with metastatic resected M1 lymph node or bone metastasis or ascites could be enrolled. 3. No prior palliative chemotherapy (relapse 1 year later after end of adjuvant treatment available) 4. Eastern Cooperative Oncology Group (ECOG) performance status 0 -2 5. The following laboratory test results: ① absolute neutrophil count (ANC) ≥1,500/micro Liter (uL), Platelet ≥ 100,000/uL, ② aspartate aminotransferase (AST) ≤ 3 x Upper limit of normal (ULN), alanine aminotransferase (ALT) ≤ 3 x ULN , Total bilirubin ≤ 2.0 mg/dL (in case of liver metastasis, 5 x ULN of AST, ALT) ③ Creatinine ≤ 1.5 mg/dL 6. A patient who signed the informed consent prior to the participation of the study and who understands that he/she has a right to withdrawal from participation in the study at any time without any disadvantages. Exclusion Criteria: 1. HER-2 Positive patients 2. Any other malignancies within the past 2 years except curatively treated non-melanoma skin cancer or in situ carcinoma of cervix uteri 3. Subjects who received radiotherapy within 4 weeks prior to randomization 4. Subjects who have chronic or acute infection need to treatment 5. Subjects who received major operation within 4 weeks prior to randomization 6. patients with clinically significant (i.e. active) heart disease (e.g. congestive heart failure, symptomatic coronary artery diseases, cardiac arrhythmias, etc) or myocardial infarction within past 12 months. 7. patient with epilepsy or psychiatric problem including central nervous system(CNS) metastasis. 8. Subjects who not be able to ingestion or have a malabsorption disorder 9. peripheral neuropathy accompany with functional loss 10. Prior history of allergic reaction to study treatment drugs 11. A patient with history of other clinical trial within 4 weeks 12. A patient of childbearing potential without being tested for pregnancy at baseline for positive. (A postmenopausal woman with the amenorrhea period of at least 12 months or longer is considered to have non-childbearing potential.) 13. subject who is decided by investigator decide exclusion with any other reasons