PATIENT CHARACTERISTICS: Age: 16 to 60 Performance status: Karnofsky 40-100% Neurological functional status 0-3 Life expectancy: Not specified Hematopoietic: Not specified Hepatic: No serious impairment of hepatic function Renal: No serious impairment of renal function Creatinine no greater than 1.5 mg/dL OR Creatinine clearance no less than 50 mL/min Cardiovascular: No serious impairment of cardiac function Other: HIV negative No congenital or acquired immunodeficiency syndrome No prior/concurrent systemic lymphoma No prior malignancy except: Adequately treated non-melanoma skin cancer Carcinoma in situ of the cervix uteri Not pregnant No severe uncontrolled infection