Inclusion Criteria:

- Histologically/cytologically confirmed recurrent or metastatic gastric or
esophagogastric junctional adenocarcinoma

- Between 18 and 80 years old

- Capable of oral intake

- Measurable disease as defined by Response Evaluation Criteria in Solid Tumors
(RECIST) criteria

- Karnofsky Performance Status (KPS) ≥ 70%

- Normal functions of heart, lung and bone marrow

- Adequate hematological profile： Hemoglobin ≥ 9.0 g/dL Absolute granulocyte count ≥
1,500/mm3 Platelet count ≥ 100,000/mm3

- Adequate hepatic function Total bilirubin level≤ 3.0 times the upper limit of normal
(ULN) Transaminases AST (SGOT) and ALT (SGPT) ≤ 2.5 times ULN

- Adequate renal function(normal serum creatinine level)

- A life expectancy≥ 2 months

- Informed consent signed

Exclusion Criteria:

- Current enrollment in another clinical study with an investigational agent. Patients
participating in surveys or observational studies are eligible to participate in this
study

- Any radiotherapy or surgery within the previous 4 weeks

- Symptomatic brain metastasis not controlled by corticosteroids

- Bone marrow metastasis

- Active infection

- Serious complications

- Receiving a concomitant treatment with drugs interacting with S-1. The following
drugs are prohibited because there may be an interaction with S-1: phenytoin,
potassium warfarin , flucytosine, cimetidine and folinic acid.

- Pregnant or lactation women, or women with known or suspected pregnancy and men who
want let to pregnancy

- Ineligible for the study at the discretion of investigators