Epirubicin, Carboplatin, and Capecitabine in Treating Patients With Unresectable Locally Advanced, Metastatic, or Recurrent Solid Tumor

DISEASE CHARACTERISTICS: * Histologically confirmed solid tumor * Progressive disease on standard therapy, including: * Locally advanced, unresectable primary or recurrent tumor OR * Metastatic disease * Previously untreated metastatic cancer for which study regimen represents reasonable initial chemotherapy with palliative intent (e.g., metastatic gastric cancer, hepatobiliary cancer, or cancers for which no effective standard therapy exists) allowed * Phase II portion: * Diagnosis of cancer of the upper aerodigestive tract (head and neck, esophagus, stomach, or hepatobiliary) * No potential curative treatment options including surgery, radiotherapy, chemoradiotherapy, or combination chemotherapy * No leukemia or lymphoma * No primary CNS malignancies or CNS metastases PATIENT CHARACTERISTICS: Age: * 18 and over Performance status: * ECOG 0-2 Life expectancy: * Not specified Hematopoietic: * Absolute granulocyte count at least 2,000/mm\^3 * Platelet count at least 100,000/mm\^3 Hepatic: * Bilirubin no greater than 1.5 mg/dL * AST and ALT no greater than 2.5 times upper limit of normal Renal: * Creatinine no greater than 1.6 mg/dL Cardiovascular: * LVEF at least 50% * No symptomatic congestive heart failure * No unstable angina * No cardiac arrhythmia Other: * No serious concurrent medical illness that would preclude study participation * No active infections requiring IV antibiotic therapy * No history of allergy to platinum compounds, mannitol, or antiemetics used with study drugs * No history of severe intolerance to fluorouracil * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: * More than 4 weeks since prior immunotherapy and recovered Chemotherapy: * See Disease Characteristics * More than 4 weeks since prior chemotherapy (at least 6 weeks for nitrosoureas or mitomycin) and recovered * No prior cumulative doxorubicin dose of more than 300 mg/m2 Endocrine therapy: * Not specified Radiotherapy: * See Disease Characteristics * At least 2 weeks since prior radiotherapy and recovered * At least 8 weeks since prior strontium chloride Sr 89 Surgery: * See Disease Characteristics * Recovered from prior surgery Other: * At least 4 weeks since prior sorivudine or brivudine * No concurrent sorivudine or brivudine * No concurrent cimetidine * No concurrent antiretroviral therapy for HIV-positive patients