PATIENT CHARACTERISTICS: Age: 55 and under Performance status: Karnofsky 70-100% OR Lansky 60-100% Life expectancy: Not specified Hematopoietic: See Disease Characteristics Hepatic: Bilirubin less than 2.5 mg/dL SGOT less than 3 times upper limit of normal Renal: Creatinine within normal range OR Creatinine clearance greater than 60 mL/min Cardiovascular: Asymptomatic OR Left ventricular ejection fraction at rest greater than 40% and improves with exercise Pulmonary: Asymptomatic OR DLCO greater than 45% Other: Not pregnant or lactating HIV negative No uncontrolled viral, bacterial, or fungal infection