PATIENT CHARACTERISTICS: Age: No greater than 21 at diagnosis Performance status: 0-2 Life expectancy: At least 2 months Hematopoietic: Cytopenias from marrow involvement eligible with study chairman approval ANC at least 1,000 Platelets at least 100,000 (transfusion independent) Counts between 70,000-100,000 allowed provided: Autologous bone marrow or peripheral stem cells available for rescue Study chairman approves entry Hemoglobin at least 8 g/dL (may transfuse) Hepatic: Bilirubin no greater than 1.5 times normal AST/ALT less than 2.5 times normal Renal: Creatinine no greater than 1.5 times normal OR Creatinine clearance or radioisotope GFR at least 70 mL/min per 1.73 square meters Pulmonary: No history of dyspnea at rest No exercise intolerance Other: No active infection requiring hospitalization No pregnant or nursing women Negative pregnancy test required of fertile women Effective contraception required of fertile patients during and for 2 months after study Patients unable to receive blood products due to religious reasons may receive buthionine sulfoximine alone