In this study, the investigators will use P-HDFL, a regimen with high tumor remission rate (~ 60-70%) and with only modest treatment-associated toxicities, as induction chemotherapy for patients with non-resectable gastric cancer. For those patients who have achieved complete response (CR) or partial response (PR), DI will be used to "consolidate" the remission. For those patients who fail to achieve remission by P-HDFL, DI will be used as salvage chemotherapy. The efficacy and toxicities of DI in these two settings will be evaluated in this prospective study.