PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent colony stimulating factors during the first course of study therapy Chemotherapy: See Disease Characteristics One prior chemotherapy regimen for metastatic disease allowed Prior neoadjuvant or adjuvant chemotherapy regimen allowed if the interval between this therapy and the first therapy for metastatic disease was at least 6 months At least 4 weeks since prior chemotherapy Endocrine therapy: Not specified Radiotherapy: At least 4 weeks since prior radiotherapy Surgery: Not specified Other: No other concurrent investigational agents No HIV positive patients receiving antiretroviral therapy