PATIENT CHARACTERISTICS: Age: 30 and under Performance status: ECOG 0-2 Life expectancy: Not specified Hematopoietic: Absolute neutrophil count at least 1,000/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 times normal SGOT no greater than 3 times normal Renal: Creatinine normal Phosphate at least 3.0 mg/dL without supplementation Cardiovascular: Shortening fraction at least 28% by echocardiogram If echocardiogram unsatisfactory, must have ejection fraction at least 50% No history of pericarditis or myocarditis No symptomatic arrhythmia or symptomatic cardiac conduction disturbances