Capecitabine and Oxaliplatin in Treating Patients With Locally Advanced, Unresectable, or Metastatic Stomach Cancer

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed gastric cancer * Locally advanced, unresectable, or metastatic disease * Measurable disease, defined as at least 1 lesion that can be accurately measured in ≥ 1 dimension as ≥ 20 mm with conventional techniques or as ≥ 10 mm with spiral CT scan * No known brain metastases PATIENT CHARACTERISTICS: * ECOG performance status (PS) 0-2 or Karnofsky PS 60-100% * WBC ≥ 3,000/mm³ * Absolute neutrophil count ≥ 1,500/mm³ * Platelet count ≥ 100,000/mm³ * Bilirubin normal * AST/ALT ≤ 2.5 times upper limit of normal * Creatinine ≤ 1.5 mg/dL * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception during study and for 6 months after completion of study treatment * Able to swallow * No history of allergic reactions attributed to compounds of similar chemical or biologic composition to fluoropyrimidines or platinum chemotherapy agents * No uncontrolled intercurrent illness including, but not limited to the following: * Ongoing or active infection * Symptomatic congestive heart failure * Unstable angina pectoris * Cardiac arrhythmia * Psychiatric illness or social situations that would preclude study compliance PRIOR CONCURRENT THERAPY: * More than 4 weeks since prior chemotherapy or radiotherapy (6 weeks for nitrosoureas or mitomycin C) and recovered * At least 6 months since prior radiotherapy with capecitabine as a radioenhancer * No concurrent combination antiretroviral therapy for HIV-positive patients * No other concurrent chemotherapy * No concurrent palliative radiotherapy * No concurrent hormonal therapy except for the following: * Steroids for adrenal failure * Hormones for nondisease related conditions (e.g., insulin for diabetes) * Intermittent use of dexamethasone as an antiemetic * No other concurrent investigational agents * No other concurrent anticancer agents or therapies