Capecitabine and Gemcitabine in Treating Patients With Metastatic Kidney Cancer

DISEASE CHARACTERISTICS: * Histologically confirmed renal cell carcinoma * Clinically confirmed metastatic disease (histologic documentation of metastatic disease not required) * Sarcomatoid renal cell carcinomas allowed * No pure sarcomas * No collecting duct (duct of Bellini) tumors, oncocytomas, or transitional cell tumors * Measurable disease * At least 20 mm by conventional techniques OR * At least 10 mm by spiral CT scan * Nonmeasurable lesions include the following: * Bone lesions * Leptomeningeal disease * Ascites * Pleural/pericardial effusion * Lymphangitis cutis/pulmonis * Abdominal masses that are not confirmed and followed by imaging techniques * Cystic lesions * Patients with known brain metastases are eligible if they have undergone prior surgical resection and/or cranial irradiation, they currently do not require steroids or anticonvulsants, and there is no progressive disease on CT scan or MRI at least 4 weeks after completion of radiotherapy PATIENT CHARACTERISTICS: Age * 18 and over Performance status * ECOG 0-2 Life expectancy * Not specified Hematopoietic * Granulocyte count at least 1,500/mm\^3 * Platelet count at least 100,000/mm\^3 Hepatic * Bilirubin no greater than 1.5 times upper limit of normal Renal * Creatinine clearance at least 30 mL/min Cardiac * No clinically significant cardiac disease * No congestive heart failure * No symptomatic coronary artery disease * No cardiac arrhythmias not well controlled with medication * No myocardial infarction within the past 12 months Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective barrier contraception during and for 3 months after study * No prior severe reaction to fluoropyrimidine therapy or known sensitivity to fluorouracil * No malabsorption syndrome or lack of physical integrity of the upper gastrointestinal tract that would preclude absorption of capecitabine PRIOR CONCURRENT THERAPY: Biologic therapy * Not specified Chemotherapy * At least 4 weeks since prior chemotherapy and recovered * No prior gemcitabine * No prior fluoropyrimidines (e.g., fluorouracil, floxuridine, capecitabine, or fluorouracil-uracil) * No other concurrent chemotherapy Endocrine therapy * See Disease Characteristics * At least 4 weeks since prior megestrol * No concurrent hormones (e.g., megestrol) except steroids for adrenal failure, hormones for nondisease-related conditions (e.g., insulin for diabetes), or intermittent dexamethasone as an antiemetic Radiotherapy * See Disease Characteristics * At least 4 weeks since prior radiotherapy and recovered * Prior radiotherapy to any lesion that may produce disability (e.g., unstable femur) allowed * No concurrent palliative radiotherapy Surgery * See Disease Characteristics * At least 4 weeks since prior major surgery and recovered Other * Any number of prior regimens allowed