FDG-PET Directed Treatment in Improving Response in Patients With Locally Advanced Stomach or Gastroesophageal Junction Cancer

Pre-registered patients receive standard pre-operative chemotherapy comprising epirubicin intravenously 50mg/m\^2 (IV) on day 1; oxaliplatin 130 mg/m\^2 IV or cisplatin 60 mg/m\^2 IV on day 1; and capecitabine 625 mg/m\^2 orally (PO) twice daily (BID) or fluorouracil 200 mg/m\^2/day IV continuously on days 1-21; and undergo FDG-PET following course 1 (days 15-19). Patients defined as FDG-PET non-responders are registered and randomized to 1 of 2 treatment arms. Primary objective To assess and compare the overall survival (OS) of patients with locally advanced gastric cancer classified as FDG-PET non-responders after one cycle of pre-operative chemotherapy randomly assigned to receive either salvage chemotherapy before and after surgery or immediate surgery followed by fluorouracil sensitized radiotherapy. Secondary objectives 1. To assess and compare progression-free survival (PFS) between the treatment arms (Arms A and B). 2. To assess and compare R0 resection rate between the treatment arms (Arms A and B). 3. To assess and compare pathologic complete response (pCR) rate between the treatment arms (Arms A and B). 4. To assess the adverse events (AE) profile and safety of each treatment arm (Arms A and B), including post-operative mortality rate, 30-day post-operative targeted adverse events (i.e., dehiscence, significant infection, and re-operation rate). 5. To examine the changes of FDG-PET SUV induced by pre-operative chemotherapy at different time points (from baseline to completion of one cycle of treatment before randomization, and 2 cycles of salvage treatment) in patients randomized to salvage treatment arm (Arm B). 6. To collect measurement of fatigue and overall perception of QOL at registration of the study (Alliance registration QOL assessment study).