PATIENT CHARACTERISTICS: Age: At least 365 days to 17 years Performance status: Karnofsky 50-100% (for patients older than 10 years) Lansky 50-100% (for patients 10 years and younger) Life expectancy: At least 8 weeks Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 (transfusion independent) Hemoglobin at least 8.0 g/dL (RBC transfusion allowed) Hepatic: Bilirubin no greater than normal SGPT no greater than 2.5 times normal Albumin at least 2 g/dL Alkaline phosphatase normal Gamma glutamyl transferase less than 2.5 times normal Renal: Creatinine no greater than 1.5 times normal OR Creatinine clearance or GFR at least lower limit of normal Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception Creatine phosphokinase less than 2 times normal No uncontrolled infection Seizure disorder allowed if well controlled on anticonvulsants No CNS toxicity greater than grade II