PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent colony stimulating factor therapy Chemotherapy: Prior chemotherapy (hydroxyurea, fluorouracil, metronidazole, cisplatin, or other platinum agent) allowed as a radiosensitizing agent only No other concurrent chemotherapy Endocrine therapy: Not specified Radiotherapy: See Disease Characteristics Prior radiotherapy allowed to less than 30% of the bone marrow only Recovered from toxic effects No concurrent radiotherapy Surgery: See Disease Characteristics Prior surgery allowed Recovered from effects of prior surgery Other: No prior systemic therapy for this disease