The purpose of this study is to determine whether combined chemotherapy [rituximab plus high dosage methotrexate, lomustine, and procarbazine] followed by maintenance therapy with procarbazine is effective in the treatment of cerebral Non Hodgkin lymphoma [PCNSL] in patients > 65 years.

Inclusion Criteria:

• first diagnosis of PCNSL, histologically confirmed
• age > 65 years
• written signed and dated informed consent of the legal representative and - if possible - of the patient

Exclusion Criteria:

• manifestations of further lymphoma outside the CNS
• sero-positive for HIV
• severe pulmonary, cardiac, hepatic, renal impairment
• uncontrolled infection
• neutrophil count < 1.500/µl, platelet count < 100.000/µl
• pulmonary disease with IVC < 55%, DLCO < 40%
• cardiac ejection fraction < 50%, uncontrolled malign arrhythmia
• creatinine > 1,5 mg% or creatinine-clearance < 50ml/min
• bilirubin > 2mg/dl
• ascites or pleural effusion (> 500ml)
• known hypersensitivity against methotrexate, lomustine, procarbazine, rituximab, leukovorin, or dexamethasone
• participation in another clinical trial within the last 30 days prior to the begin or parallel to this study
• known or current drug or alcohol abuse