Patients who have curative surgical resection will receive 6 cycles of adjuvant GOFL chemotherapy within 4 weeks after surgery and then followed up until tumor progression. Patients who are not feasible for curative resection, will receive continued chemotherapy of GOFL 3-4 weeks after chemoradiotherapy complete. The regimen will continue till disease progression. Patients who develop progressive disease during GOFL will shift to salvage chemotherapy.