S-1 + Cisplatin (arm A)
DrugS-1 will be administered orally, twice daily from Day 1 through Day 14 followed by a recovery period from Days 15 through Day 21. Initial dose of S-1 will be determined according to the patient's body surface area (80 to 120 mg/day). On Day 1, Cisplatin 50 mg/m2 will be administered intravenously (IV). This regimen is to be repeated every 3 weeks.