PRIOR CONCURRENT THERAPY: Biologic therapy: No prior high-dose chemotherapy followed by bone marrow transplantation Chemotherapy: See Biologic Therapy At least 3 weeks since prior chemotherapy and recovered No prior doxorubicin HCl liposome or gemcitabine Prior neoadjuvant chemotherapy allowed At least 12 months since prior adjuvant anthracycline-based therapy and no evidence of anthracycline resistance (i.e., developed progressive disease while receiving adjuvant therapy or within 6 months of completing adjuvant therapy) Prior mitoxantrone allowed if total dose was no greater than 105 mg/m2 IV bolus or 140 mg/m2 IV continuous infusion Prior doxorubicin allowed if total dose was no greater than 300 mg/m2 IV bolus or 400 mg/m2 IV continuous infusion No prior chemotherapy for metastatic disease Endocrine therapy: Prior adjuvant and/or palliative hormonal therapy allowed Radiotherapy: See Disease Characteristics At least 3 weeks since prior radiotherapy and recovered Surgery: See Disease Characteristics Prior surgery allowed Other: At least 3 weeks since prior investigational study Concurrent pamidronate allowed if bone not the only site of disease