The Use of Proton Pump Inhibitor on the Prevention of Gastric Cancer Bleeding

Inclusion Criteria: * Histologically proven primary gastric adenocarcinoma * Age ≥18 years * Plan for 1st line or 2nd line palliative chemotherapy * Cancer staging: metastatic (TxNxM1) or locally advanced unresectable gastric cancer (T4NxMx with unresectable), or T2-3NxMx with inoperable condition * Performance status (PS) of 0 to 2 on Eastern Cooperative Oncology Group (ECOG) scale * Adequate organ functions defined as indicated below: (a) WBC \> 3000/mm3, (b) Hb 9.0 g/dL regardless of any transfusion history, (c) Platelet ≥100,000/mm3, (d) AST/ALT ≤ 2.5 x UNL (≤ 5 x UNL if liver metastases are present) (e) Total bilirubin ≤1.5x UNL (f) Cr ≤1.5 x UNL * Written informed consent Exclusion Criteria: * Other malignancy within the past 3 years except adequately treated non-melanomatous skin cancer or carcinoma in situ of the cervix * Patients with significant or uncontrolled gastrointestinal bleeding in the past two weeks without evidence of resolution documented by endoscopy or colonoscopy * Previous subtotal gastrectomy or total gastrectomy * Patient with a plan for neo-adjuvant chemotherapy * Lack of physical integrity of the upper gastrointestinal tract or malabsorption syndrome, or inability to take oral medication * Allergy history to proton pump inhibitor * Serious concurrent infection or nonmalignant illness that is uncontrolled or whose control may be jeopardized by complications of study therapy * Inadequate cardiovascular function: (a) New York Heart Association class III or IV heart disease, (b) Unstable angina or myocardial infarction within the past 6 months, (c) History of significant ventricular arrhythmia requiring medication with antiarrhythmics or significant conduction system abnormality * Requirement for therapeutic anticoagulant therapy, aspirin or non-steroidal anti-inflammatory agents except COX-2 selective inhibitor * Requirement for therapeutic corticosteroid; the use of dexamethasone as anti-emetics or a premedication of chemotherapy-associated hypersensitivity is not an exclusion criteria * Need for PPI maintenance treatment for uncontrolled reflux esophagitis or active peptic ulcer * Psychiatric disorder that would preclude compliance * Pregnant or breast-feeding women * Untreated folate or vitamine B12 deficiency anemia * Bone marrow metastasis, or evidence of microangiopathic hemolytic anemia (MAHA)