PRIOR CONCURRENT THERAPY: Biologic therapy: At least 14 days since prior immunotherapy No prior trastuzumab (Herceptin) No other concurrent immunotherapy Chemotherapy: See Disease Characteristics Prior cytotoxic chemotherapy allowed in adjuvant setting Prior cumulative doxorubicin exposure no greater than 300 mg/m2 At least 1 year since prior taxane therapy No other concurrent chemotherapy Endocrine therapy: At least 14 days since prior hormonal therapy No concurrent hormonal therapy (e.g., tamoxifen, megestrol acetate, fluoxymesterone, or aminoglutethimide) Radiotherapy: At least 14 days since prior radiotherapy No concurrent radiotherapy to target lesions Surgery: Not specified Other: At least 30 days since other prior investigational agent or procedure No other concurrent investigational agents