S-1 and Irinotecan Combination Chemotherapy for Advanced Gastric Cancer

Inclusion Criteria: Pathologically proven unresectable adenocarcinoma of stomach With uni-dimensionally measurable disease (at least longest diameter 2 cm on conventional CT scan, x-ray or physical examination, or 1cm on spiral CT scan) Age 18 to 70 years old Estimated life expectancy of more than 3 months ECOG performance status of 2 or lower Adequate bone marrow function(absolute neutrophil count [ANC] ≥1,500/µL, hemoglobin ≥9.0 g/dL,and platelets ≥100,000/µL) Adequate kidney function (serum creatinine < 1.5 mg/dL) Adequate liver function (serum total bilirubin < 2 times the upper normal limit (UNL); serum transaminases levels <3 times [<5 times for patients with liver metastasis] UNL) No prior chemotherapy but prior adjuvant chemotherapy finished at least 6 months before enrollment was allowed. (but, prior adjuvant chemotherapy with capecitabine or S-1 or camptothecin analogues was excluded) No prior radiation therapy for at least 4 weeks before enrollment in the study Exclusion Criteria: Other tumor type than adenocarcinoma Central nervous system (CNS) metastases or prior radiation for CNS metastases Gastric outlet obstruction or intestinal obstruction Evidence of gastrointestinal bleeding The patient has bony lesions as the sole evaluable disease. Past or concurrent history of neoplasm other than stomach cancer, except for curatively treated non-melanoma skin cancer or in situ carcinoma of the cervix uteri Pregnant or lactating women, women of childbearing potential not employing adequate contraception Other serious illness or medical conditions Unstable cardiac disease despite treatment, myocardial infarction within 6 months prior to study entry History of significant neurologic or psychiatric disorders including dementia or seizures Active uncontrolled infection Other serious underlying medical conditions which could impair the ability of the patient to participate in the study Concomitant administration of any other experimental drug under investigation, or concomitant chemotherapy, hormonal therapy, or immunotherapy concomitant drug medication; The following drugs cause drug interaction with S-1. i. Warfarin, phenprocoumon: increase bleeding tendency ii. Increase blood concentration of phenytoin iii. sorivudine: inhibit DPD -> increase toxicity according to fluoropyrimidine iv. allopurinol : decrease activity of S-1