Gefitinib and Capecitabine in Treating Patients With Advanced Solid Tumors

Inclusion Criteria: * Histologically confirmed advanced solid tumor that is refractory to standard therapy or for which no standard therapy exists * No uncontrolled brain metastases, including symptomatic lesions or lesions requiring treatment (e.g., glucocorticoids and/or anticonvulsants) * Performance status - ECOG 0-2 * At least 12 weeks * WBC at least 3,000/mm\^3 * Absolute neutrophil count at least 1,500/mm\^3 * Platelet count at least 100,000/mm\^3 * Hemoglobin at least 9 g/dL * Bilirubin no greater than 1.5 mg/dL * AST and ALT no greater than 2.5 times upper limit of normal (5 times ULN if liver metastases present) * Creatinine no greater than 1.5 mg/dL * Creatinine clearance at least 60 mL/min * No active infections * No other serious concurrent systemic disorders that would preclude study participation * No other malignancy * No prior hypersensitivity to sulfonamide-based drugs, nonsteroidal anti-inflammatory drugs, or fluorouracil * No documented dihydropyrimidine dehydrogenase deficiency * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No concurrent immunotherapy * At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin) and recovered * No concurrent hormonal therapy * At least 28 days since prior radiotherapy * No concurrent radiotherapy * At least 4 weeks since prior investigational agents * No other concurrent experimental medications * No concurrent drugs known to induce cytochrome P450 3A4 (e.g., rifampin, phenytoin, carbamazepine, or barbiturates)