Combination Chemotherapy Plus Radiation Therapy in Treating Patients With Primary CNS Lymphoma

DISEASE CHARACTERISTICS: Histologically proven non-Hodgkin's lymphoma of the central nervous system (CNS) including leptomeninges and the spinal cord No Burkitt's lymphoma or low grade T-cell lymphoma Must have at least 1 measurable lesion No AIDS-related primary central nervous system lymphoma (PCNSL) No disease confined to the eye without other localization in the CNS

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

PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent treatment with immunosuppressive drug Chemotherapy: No prior chemotherapy Endocrine therapy: Corticosteroid use for less than 3 weeks allowed Radiotherapy: Not specified Surgery: No prior organ transplantation