PRIOR CONCURRENT THERAPY: Biologic therapy: No prior bone marrow transplantation No concurrent immunotherapy No concurrent myeloid colony stimulating factors (e.g., filgrastim (G-CSF), sargramostim (GM-CSF), interleukin-11) Chemotherapy: See Disease Characteristics At least 3 months since prior chemotherapy measured from day 1 of last course of front line therapy No prior high dose chemotherapy with marrow or stem cell rescue No more than 1 prior chemotherapy regimen No other concurrent chemotherapy Endocrine therapy: No concurrent hormonal therapy Radiotherapy: At least 2 weeks since prior radiotherapy No prior extensive radiotherapy (greater than 25% of bone marrow) No concurrent radiotherapy except for patients who are responding and develop brain metastases Surgery: Not specified Other: At least 30 days since prior investigational drugs No concurrent participation in another investigational trial No other concurrent experimental agents No other concurrent anticancer therapy No prophylactic oral or IV antibiotics for neutropenia