PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: One prior chemotherapy regimen as part of a locoregional treatment (e.g., induction/concomitant) allowed, either as primary treatment or as therapy for locoregional relapse, if relapse occurred more than 6 months later No other prior chemotherapy Prior chemoprevention agents (e.g., cisretinoic acid or other vitamin analogues) allowed Endocrine therapy: Not specified Radiotherapy: See Disease Characteristics At least 4 weeks since prior radiotherapy No prior radiotherapy to more than 50% of bone marrow-bearing bones Surgery: See Disease Characteristics