Capecitabine, Vinorelbine, and Trastuzumab in Treating Patients With Metastatic Breast Cancer

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed invasive breast cancer * Metastatic disease * HER2/neu-positive by immunohistochemistry (3+ by HercepTest\^™ or equivalent) OR positive for amplification by fluorescent in situ hybridization * Testing may be performed in the primary tumor or the metastatic site * Received prior anthracycline or taxane as adjuvant therapy or for metastatic disease * Measurable disease * At least one measurable lesion ≥ 2.0 cm by CT scan or MRI OR ≥ 1.0 cm by spiral CT scan * The following are considered non-measurable disease: * Bone lesions * Leptomeningeal disease * Ascites * Pleural/pericardial effusion * Inflammatory breast disease * Lymphangitis cutis/pulmonis * Abdominal masses that are not confirmed and followed by imaging techniques * Cystic lesions * No bone metastases as the only evidence of metastasis * Previously treated CNS metastases allowed provided disease has been stable for ≥ the past 3 months * Hormone receptor status: * Not specified PATIENT CHARACTERISTICS: Age * 18 and over Sex * Female or male Performance status * ECOG 0-2 Life expectancy * At least 12 weeks Hematopoietic * Absolute neutrophil count ≥ 1,500/mm\^3 * Hemoglobin ≥ 8.0 g/dL * Platelet count ≥ 100,000/mm\^3 * No known uncontrolled coagulopathy Hepatic * Bilirubin ≤ 3.0 times the upper limit of normal (ULN) * One of the following must be true: * AST or ALT ≤ 5 times ULN AND alkaline phosphatase normal * Alkaline phosphatase ≤ 5 times ULN AND AST or ALT normal * Alkaline phosphatase ≤ 2.5 times ULN AND AST or ALT ≤ 1.5 times ULN * INR ≤ 1.5 times ULN Renal * Calcium ≤ 11.5 mg/dL * Creatinine ≤ 1.5 times ULN * Creatinine clearance ≥ 30 mL/min Cardiovascular * LVEF ≥ 50% by MUGA or echocardiogram * No clinically significant (i.e., active) cardiac disease * No congestive heart failure * No symptomatic coronary artery disease * No myocardial infarction within the past 12 months * No cardiac arrhythmia not controlled with medication Gastrointestinal * Able to take oral medication * No lack of physical integrity of the upper gastrointestinal tract * No clinically significant malabsorption syndrome Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception during and for 30 days after study participation * No history of allergy or hypersensitivity to study drugs, drug product excipients, including polysorbate 80, or chemically similar agents * No prior unanticipated severe reaction to fluoropyrimidine therapy * No know hypersensitivity to fluorouracil * No known dihydropyrimidine dehydrogenase deficiency * No history of uncontrolled seizures or CNS disorders * No clinically significant psychiatric disability that would preclude giving informed consent or study compliance * No other serious uncontrolled infection or disease * No other malignancy within the past 5 years except cured basal cell skin cancer, carcinoma in situ of the cervix, or contralateral breast cancer PRIOR CONCURRENT THERAPY: Biologic therapy * Prior adjuvant trastuzumab (Herceptin\^®) allowed as adjuvant or first-line therapy for metastatic disease * No concurrent immunotherapy Chemotherapy * See Disease Characteristics * No more than 1 prior chemotherapy regimen in the advanced or metastatic (non-adjuvant) setting * No prior continuous (≥ 24 hours) fluorouracil infusion * No prior capecitabine * No prior oral fluoropyrimidines (e.g., eniluracil and fluorouracil, uracil and tegafur, S1, or emitefur) Endocrine therapy * At least 1 day since prior hormonal therapy * No concurrent hormonal therapy Radiotherapy * More than 4 weeks since prior radiotherapy to the axial skeleton (i.e., skull, spinal column, sternum, or ribs) * No concurrent radiotherapy Surgery * More than 4 weeks since prior major surgery * No prior organ allografts requiring immunosuppressive therapy Other * More than 4 weeks since prior investigational drugs * No concurrent sorivudine or its chemically related analogues (e.g., brivudine) * No concurrent allopurinol, metronidazole, or cimetidine * No other concurrent cytotoxic agents * No other concurrent investigational drugs * No other concurrent anticancer therapy