PRIOR CONCURRENT THERAPY: Biologic therapy: No prior biologic therapy or immunotherapy No concurrent immunotherapy Chemotherapy: No prior chemotherapy for metastatic disease At least 4 weeks since prior adjuvant chemotherapy No prior adjuvant cyclophosphamide, methotrexate, or fluorouracil No other concurrent chemotherapy Endocrine therapy: No concurrent hormone therapy Radiotherapy: See Disease Characteristics At least 14 days since prior radiotherapy Surgery: At least 2 weeks since prior surgery