Efficacy Study of Paclitaxel Versus Irinotecan in Patients With Recurrent or Metastatic Gastric Cancer Who Progress Following First-line Therapy

Inclusion Criteria: * Histologically confirmed gastric adenocarcinoma in tissue/cell * Recurrent or metastatic gastric cancer that has progressed following first- line therapy * Patients must be ≥18 years of age. * ECOG performance status ≤ 2 * At least one lesion (measurable or non-measurable but evaluable) according to RECIST criteria * Normal organ and bone marrow function measured within 2 weeks prior to administration of study treatment as defined below: Haemoglobin ≥ 9.0 g/dL White blood cells (WBC) ≥ 3000/µL Absolute neutrophil count (ANC) ≥ 1500/µL Platelet count ≥ 100 x 103/µL Total bilirubin ≤ 1.5 x upper normal limit (UNL) Creatinine clearance ≥ 60 ml/min or Serum creatinine ≤ 1.5 x UNL AST (SGOT)/ALT (SGPT) ≤ 2.5 x UNL unless liver metastases are present in which case it must be ≤ 5x UNL * Life expectancy ≥ 12 weeks. * Written informed consent * Provision of informed consent for genetic research (In case of optional genetic research) Exclusion Criteria: * More than one prior chemotherapy regimen for the treatment of gastric cancer in the metastatic or recurrent setting. * Treatment with any investigational product during the last 14 days (or a longer period depending on the defined characteristics of the agents used). * Any previous treatment with a taxane, including paclitaxel and docetaxel or irinotecan, in the metastatic or recurrent setting. * Patients with second primary cancer, except: adequately treated non- melanoma skin cancer, curatively treated in-situ cancer of the cervix, or other solid tumors curatively treated with no evidence of disease for ≥5 years. * Patients receiving any systemic chemotherapy, radiotherapy (except for palliative reasons), within 2 weeks from the last dose prior to study treatment (or a longer period depending on the defined characteristics of the agents used). * Ongoing toxicities (\>CTCAE grade 2) caused by previous cancer therapy. * Clinically proven gastric outlet obstruction or CTCAE grade 3 or grade 4 upper GI bleeding * Medically uncontrolled, clinically significant heart disease or infection * Patients with symptomatic uncontrolled brain metastases. * Major surgery within 2 weeks of starting study treatment and patients must have recovered from any effects of any major surgery. * Women who have pregnancy potential or willing to pregnant. Pregnant and breastfeeding women. * Others Poor medical risk due to a serious, uncontrolled medical disorder, non- malignant systemic disease or active, uncontrolled infection Any psychiatric disorder that prohibits obtaining informed consent and regular follow-up. Inappropriate patient for subjects of this study on investigator's judgment