PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior biologic therapy or immunotherapy No concurrent immunotherapy No concurrent filgrastim (G-CSF) or sargramostim (GM-CSF) Chemotherapy: More than 4 weeks since prior chemotherapy (6 weeks for mitomycin or nitrosoureas) and recovered Prior doxorubicin allowed if total dose less than 300 mg/m2 No other concurrent chemotherapy No more than 2 prior chemotherapy regimens for metastatic disease Endocrine therapy: No current steroid use of greater than 1.5 mg dexamethasone (or equivalent) per day Radiotherapy: At least 4 weeks since prior radiation therapy No radiation therapy to greater than 25% of bone marrow No concurrent radiotherapy Surgery: At least 4 weeks since prior major surgery