Testing the Addition of Radiotherapy to the Usual Treatment (Chemotherapy) for Patients With Esophageal and Gastric Cancer That Has Spread to a Limited Number of Other Places in the Body

PRIMARY OBJECTIVE: I. To establish superiority of consolidative radiation therapy over continuation of systemic therapy alone in patients with oligometastatic esophageal and gastric adenocarcinoma (EGA) that does not progress on first-line therapy. OUTLINE: STEP 1 (INDUCTION PHASE): Patients are assigned to 1 of 2 arms. ARM A: Patients receive oxaliplatin intravenously (IV) over 1.5 hours, leucovorin IV over 1.5 hours, and 5-fluorouracil IV over 46-48 hours on days 1 and 15. Treatment repeats every 28 days for up to 4 cycles in the absence of disease progression or unacceptable toxicity. ARM B: Patients receive oxaliplatin IV over 2 hours on day 1 and capecitabine orally (PO) twice daily (BID) on days 1-14. Treatment repeats every 21 days for up to 6 cycles in the absence of disease progression or unacceptable toxicity. STEP 2: Patients are randomized to 1 of 4 arms. ARM C: One week post induction of patients in ARM A, patients undergo radiation therapy for up to 15 days. Within 2-4 weeks post radiation therapy, patients receive oxaliplatin, leucovorin, and 5-fluorouracil as in Arm A for 2 years in the absence of disease progression or unacceptable toxicity. ARM D: Post induction of patients in ARM A, patients continue oxaliplatin, leucovorin, and 5-fluorouracil as in Arm A for 2 years in the absence of disease progression or unacceptable toxicity. ARM E: One week post induction of patients in ARM B, patients undergo radiation therapy for up to 15 days. Within 2-4 weeks post radiation therapy, patients receive oxaliplatin and capecitabine as in Arm B for 2 years in the absence of disease progression or unacceptable toxicity. ARM F: Post induction of patients in ARM B, patients continue oxaliplatin and capecitabine as in Arm B for 2 years in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up periodically for up to 5 years from study entry. Patients experiencing disease progression are followed up every 3 months in years 1-2, and then every 6 months for up to 5 years from study entry.