DISEASE CHARACTERISTICS: Histologically or cytologically proven unresectable, locally recurrent, or metastatic breast cancer not amenable to surgery or radiotherapy of curative intent No inflammatory breast cancer unless evidence of metastatic disease No bone metastases, pleural effusion, or ascites as the only site of disease Clinically measurable disease outside previously irradiated area Relapse after 1 prior adjuvant or neoadjuvant chemotherapy regimen containing anthracycline unless clinically contraindicated No known or suspected brain metastases or recurrence requiring steroids or radiotherapy Hormone receptor status: Not specified

PATIENT CHARACTERISTICS: Age: 18 and over Sex: Female Menopausal status: Not specified Performance status: Karnofsky 70-100% Life expectancy: At least 12 weeks Hematopoietic: Absolute granulocyte count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hemoglobin at least 9.0 g/dL Hepatic: ALT and AST no greater than 2 times upper limit of normal (ULN) Bilirubin no greater than 1.5 times ULN Renal: Calcium no greater than 1.2 times ULN Creatinine no greater than 1.5 times ULN Cardiovascular: No active uncontrolled cardiac disease and/or myocardial infarction within the past 6 months Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 3 months after completion of study No other prior malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix No other serious systemic disorder precluding study No active infection No severe psychiatric disease No history of hypersensitivity reactions to polyoxyethylated castor oil-based drugs

PRIOR CONCURRENT THERAPY: Biologic therapy: No prior bone marrow transplantation or autologous stem cell infusion following high-dose adjuvant chemotherapy for metastatic disease No concurrent immunotherapy (including humanized anti-HER2 antibody) Chemotherapy: See Disease Characteristics See

Biologic therapy No prior chemotherapy for metastatic breast cancer No prior gemcitabine or taxane No other concurrent chemotherapy Endocrine therapy:

See Disease Characteristics Prior antitumoral hormonal therapy allowed No concurrent hormonal therapy excluding contraceptives and replacement steroids Radiotherapy: See Disease Characteristics At least 2 weeks since prior radiotherapy and recovered No concurrent radiotherapy Surgery: See Disease Characteristics Other: Recovered from prior therapy At least 30 days since prior investigational drugs No concurrent investigational drugs Concurrent bisphosphonate therapy allowed if not begun or stopped within 4 weeks before study