Vinorelbine With or Without Trastuzumab in Treating Women With Progressive Metastatic Breast Cancer

DISEASE CHARACTERISTICS: * Histologically confirmed breast cancer * Clinical evidence of metastatic disease * HER2-positive tumor, as indicated by one of the following methods: * HER2 gene amplification by fluorescence in situ hybridization * HER2 protein overexpression (3+) by immunohistochemistry * Disease progression during or after prior taxane therapy (single-agent paclitaxel, docetaxel, or taxane-containing combination chemotherapy) in combination with trastuzumab (Herceptin®) as first- or second-line chemotherapy for metastatic disease * Patients who received maintenance therapy with single-agent trastuzumab after acheiving a response or stable disease to prior taxane/trastuzumab combination therapy are eligible provided disease has progressed * Measurable or nonmeasurable disease * No effusions or ascites as the only sites of disease * No leptomeningeal disease or lymphatic pulmonary metastases * Brain metastases allowed provided disease is stable for \> 3 months after completion of prior radiotherapy to the brain * Hormone receptor status: * Not specified PATIENT CHARACTERISTICS: Age * 18 and over Sex * Female Menopausal status * Not specified Performance status * Zubrod 0-1 Life expectancy * Not specified Hematopoietic * Absolute neutrophil count ≥ 1,500/mm\^3 * Platelet count ≥ 100,000/mm\^3 * Hemoglobin ≥ 9 g/dL Hepatic * Bilirubin ≤ 2.0 mg/dL * SGOT or SGPT ≤ 2.5 times upper limit of normal (ULN) (\< 5 times ULN in the presence of liver metastases) * Alkaline phosphatase ≤ 3 times ULN (\< 5 times ULN in the presence of liver or bone metastases) Renal * Creatinine ≤ 2.0 mg/dL * Calcium ≤ 11.0 mg/dL Cardiovascular * No history of significant symptomatic cardiac disease * LVEF ≥ 50% of the lower limit of normal by MUGA or ECG Other * No pre-existing clinically significant (≥ grade 2) motor or sensory neuropathy except for abnormalities due to cancer * No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, or adequately treated stage I or II cancer in complete remission * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy * See Disease Characteristics * At least 28 days since prior trastuzumab * No concurrent filgrastim (G-CSF) Chemotherapy * See Disease Characteristics * No more than 2 prior chemotherapy regimens for metastatic breast cancer * Prior adjuvant/neoadjuvant chemotherapy allowed, for a total of 3 prior regimens * No prior vinorelbine * No other prior chemotherapy after progression on a taxane/trastuzumab regimen * No prior cumulative dose \> 360 mg/m\^2 of anthracycline-based chemotherapy Endocrine therapy * No prior hormonal therapy after progression on a taxane/trastuzumab regimen * Prior exogenous hormonal therapy for stage IV disease and/or as adjuvant therapy allowed Radiotherapy * See Disease Characteristics * No prior radiotherapy to \> 50% of the marrow-bearing bone Surgery * At least 4 weeks since prior major surgery (2 weeks for minor surgery) and recovered Other * Concurrent bisphosphonates allowed for bone metastasis