PRIOR CONCURRENT THERAPY: Biologic therapy: No prior biologic or immunotherapy for recurrent or metastatic disease No concurrent biologic therapy Chemotherapy: No prior chemotherapy for recurrent or metastatic disease except as radiosensitizer No other concurrent chemotherapy Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy for recurrent or metastatic disease except as adjuvant therapy At least 4 weeks since prior radiotherapy to greater than 25% of bone marrow No concurrent radiotherapy except for CNS therapy Surgery: See Disease Characteristics At least 3 weeks since prior major surgery