Methotrexate and Temozolomide Versus Methotrexate, Procarbazine, Vincristine and Cytarabine

Inclusion Criteria: * primary central nervous system lymphoma histologically confirmed by brain biopsy, CSF cytology or vitrectomy * KPS 40 or higher * Absence of systemic disease as evaluated by chest-abdomen-pelvis CT scan * Leucocytes\>3.500/mm3, platelets\>130.000/mm3, Bilirubin \< 2 mg, transaminases \< 2.5 N), creatinine \< 150 μM/l, creatinine clearance \> 40 ml/min * Age ≥ 60 years * Negative HIV test * Signature of informed consent Exclusion Criteria: * previous cranial radiotherapy * prior chemotherapy for primary central nervous system lymphoma * presence of another cancer (excepting basal cell carcinoma of the skin and cervical carcinoma in situ ) * systemic lymphoma (outside the CNS) * Isolated ocular lymphoma * Immunosuppressed patients (HIV , use of immunosuppressors) * Other uncontrolled or progressive disease compromising shot-term survival * Severe renal or hepatic disease * Patients not legally covered by the French Social Security * Inability to swallow the medication