Liposomal Doxorubicin and Gemcitabine in Treating Women With Metastatic Breast Cancer

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed metastatic breast cancer Measurable disease Hormone receptor status: Not specified PATIENT CHARACTERISTICS: Age: 18 and over Sex: Female Menopausal status: Not specified Performance status: Karnofsky 60-100% Life expectancy: At least 3 months Hematopoietic: Platelet count at least 100,000/mm^3 Hemoglobin at least 9 g/dL Absolute neutrophil count at least 1,500/mm^3 No impaired bone marrow function Hepatic: Bilirubin no greater than 2 mg/dL AST and ALT no greater than 2 times upper limit of normal (ULN) Alkaline phosphatase no greater than 2 times ULN (unless attributed to tumor) No impaired hepatic function Renal: Creatinine no greater than 2.5 mg/dL OR Creatinine clearance at least 60 mL/min No impaired renal function Cardiovascular: No prior cardiac disease within the past 5 years OR LVEF at least 50% Other: No prior uncontrolled seizures No uncontrolled systemic infection No anthracycline resistance No other malignancy within the past 5 years except curatively treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: No prior trastuzumab (Herceptin) Chemotherapy: Prior adjuvant therapy with anthracycline of no more than 320 mg/m^2 allowed Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy to more than 1/3 of hematopoietic sites Surgery: Not specified Other: At least 30 days since prior investigational medications and recovered No more than 1 prior treatment regimen for metastatic disease