Study of S1 Efficacy and Toxicity as Second-line Treatment on Inoperable or Advanced Gastric Cancers

Inclusion Criteria: 1. Histologically confirmed, inoperable or advanced gastric cancer patients who received at most 1st line treatment 2. Aged 18 years or older 3. KPS performance status of ≥ 70. 4. Anticipated life expectancy of ≥ 3 months. 5. Adequate organ function, including bone marrow, kidney and liver. * ANC ≥ 1.5×109/L and hemoglobin ≥ 8g/dL and platelet count ≥ 100×109/L * Serum total bilirubin ≤ 1.5 x ULN, Serum ALT and AST ≤ 2.5 x ULN (Serum ALT and AST ≤ 5 x ULN, if liver metastases are present) * Serum creatinine ≤ 1.5 x ULN and CLcr \> 60 ml/min 6. Written informed consent can be obtained prior to their participation in the trial. Exclusion Criteria: 1. History of severe drug allergy , or an allergy to any components of S1 2. Subjects who have received chemotherapy, immunotherapy or radiotherapy within two weeks 3. Alimentary tract hemorrhage, diarrhea or aphagosis at the present stage 4. Subjects with uncontrolled CNS metastasis or epilepsia or severe psychiatric disorders. 5. Subjects who are regarded to be unsuitable for this trial by the investigator. 6. Subjects who are participating in other clinical trials 7. Subjects with ascites draining or severe infection 8. Pregnant or breast-feeding women