Fluorouracil, Oxaliplatin, and Leucovorin in Treating Patients With Metastatic Stomach Cancer or Gastroesophageal Junction Cancer

Inclusion Criteria: * Patients must have histologically or cytologically confirmed adenocarcinoma of the stomach or gastroesophageal junction * Metastatic disease * Patients must have measurable disease, defined as at least one lesion that can be accurately measured in at least one dimension (longest diameter to be recorded) as ≥ 20 mm with conventional techniques or as ≥ 10 mm with spiral CT scan * No known active brain metastases * Patients with treated brain metastases are eligible if stable off steroids for at least 30 days PATIENT CHARACTERISTICS: * ECOG performance status ≤ 2 (Karnofsky performance status ≥ 60%) * Life expectancy ≥ 3 months * WBC ≥ 3,000/μL * Absolute neutrophil count ≥ 1,500/μL * Platelets ≥ 100,000/μL * Total bilirubin ≤ 1.5 x upper limit of normal (ULN) * AST or ALT ≤ 2.5 x ULN (\< 5 x ULN if known liver metastases) * Creatinine clearance ≤ 1.5 x ULN * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception during and for 21 days after completion of study treatment * No history of allergic reactions to fluorouracil or oxaliplatin * No concurrent uncontrolled illness including, but not limited to, ongoing or active infection or psychiatric illness/social situations that would limit compliance with study requirements PRIOR CONCURRENT THERAPY: * No prior therapy for metastatic disease * Prior neoadjuvant or adjuvant therapy is allowed if the disease-free interval has been longer than 6 months * No other concurrent chemotherapy * No concurrent combination anti-retroviral therapy for HIV-positive patients * No concurrent routine prophylaxis with filgrastim (G-CSF) * No other concurrent antineoplastic agents, including chemotherapy, radiation therapy, or biologic agents