PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent hematopoietic stimulants Chemotherapy: See Disease Characteristics At least 35 days since prior chemotherapy Endocrine therapy: No concurrent androgen therapy No concurrent corticosteroids Radiotherapy: Not specified Surgery: Not specified Other: At least 35 days since any previous therapy for MDS (other than transfusion) No participation in any other experimental clinical trial within 35 days of entry into current trial