<br>        Inclusion Criteria:<br><br>          -  Histologically or cytologically/immunocytologically confirmed primary non-Hodgkin's<br>             lymphoma of the CNS. A central reference pathological report will be made on<br>             inclusion into the study (Prof. Dr. Pietsch, Reference Center for Brain Tumors of the<br>             German Society for Neuropathology and Neuroanatomy, Institute of Neuropathology of<br>             the Bonn University Hospital). Histological diagnosis is usually performed by<br>             preferential stereotactic biopsy of suspicious lesions in the brain or spinal cord.<br>             The diagnosis from cerebrospinal fluid (CSF) requires the detection of malignant<br>             lymphocytes according to cytological and immunocytological criteria. There should be<br>             no more than 2 weeks between establishing the diagnosis and inclusion in the study.<br>             The availability of the reference pathological report is not absolutely necessary for<br>             inclusion in the study and beginning therapy.<br><br>          -  Aged > 18 years<br><br>          -  Life expectancy of at least 2 months<br><br>          -  Adequate bone marrow reserve with a peripheral granulocyte count of > 1,500/µl and<br>             thrombocyte count of > 100,000/µl; bilirubin in the normal range; GOT of < three<br>             times the upper normal limit and adequate renal function with a creatinine clearance<br>             of > 50 ml/min and serum creatinine in the normal range.<br><br>          -  Written informed consent<br><br>          -  In women of child-bearing age, pregnancy is excluded, effective contraception is<br>             necessary, and women should not be breast feeding.<br><br>        Exclusion Criteria:<br><br>          -  Manifestation of lymphoma outside of the CNS<br><br>          -  Severe diseases in other organs which would make performing intensive chemotherapy<br>             impossible; Karnofsky index > 50% due to previous diseases other than PCNSL.<br>             Karnofsky > 30 will be accepted only due to the PCNSL.<br><br>          -  Active infection<br><br>          -  HIV positivity<br><br>          -  Previous treatment of PCNSL other than with corticosteroids, antiepileptics or<br>             diuretics<br><br>          -  Previous radiotherapy of the brain<br><br>          -  Concomitant or previous malignant diseases in the last 5 years except for an<br>             adequately treated basal cell carcinoma or cervical carcinoma in situ<br><br>          -  Immunosuppression, concomitant immunosuppressive therapy, or organ transplantation<br><br>          -  Ongoing chemotherapy for another disease<br>