Oxaliplatin and Capecitabine in Treating Patients With Advanced Esophageal Cancer or Stomach Cancer

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed adenocarcinoma of the esophagus, gastroesophageal junction, or gastric cardia for which no potentially curative or significant palliative therapy exists * Unresectable disease * Gastric cardia is defined as no more than 5 cm from the gastroesophageal junction into the stomach * Measurable disease * No known CNS metastases PATIENT CHARACTERISTICS: Age: * 18 and over Performance status: * ECOG 0-2 Life expectancy: * At least 12 weeks Hematopoietic: * Absolute neutrophil count at least 1,500/mm\^3 * Platelet count at least 100,000/mm\^3 Hepatic: * Bilirubin no greater than upper limit of normal (ULN) * AST no greater than 3 times ULN * Alkaline phosphatase no greater than 2 times ULN Renal: * Creatinine no greater than 1.5 times ULN * Creatinine clearance at least 60 mL/min Cardiovascular: * No New York Heart Association class III or IV heart disease Other: * Able to swallow capecitabine * No unresolved gastrointestinal bleeding * No uncontrolled infection * No chronic debilitating disease * No peripheral neuropathy grade 2 or greater * No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer or adequately treated noninvasive carcinoma * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: * No prior immunotherapy or biological therapy for re…