The purpose of this study is to determine the safety of this new treatment offered in this study. PCNSL can be cured in less than half of patients with standard treatment, a combination of chemotherapy and brain radiation. Also, the combination of chemotherapy and brain radiation may result in serious lasting side effects. Most patients older than age 60 develop memory problems, difficulty walking or inability to control their bladder. Some patients younger than age 60 also develop these side effects.

Inclusion Criteria:

• All patients must have non-Hodgkin's lymphoma involving the brain, as demonstrated by CT or MRI and histologic confirmation by one of the following: A positive CSF cytology for lymphoma or a monoclonal lymphocyte population as defined by cell surface markers.

A biopsy of the vitreous or uvea demonstrating non-Hodgkin's lymphoma. Brain biopsy.

• Patients must be HIV-1 negative.
• Patient must have left ventricular ejection fraction ≥ 50%.
• Patients must have no evidence of systemic lymphoma. This must be demonstrated by a CT scan of the chest, abdomen and pelvis prior to registration.
• Patients must have adequate bone marrow function (defined as peripheral leucocyte count >3000 cells/mm3 and platelet count > 100,000 cells/mm3), liver function (bilirubin < 2.0 mg%), and adequate renal function (serum creatinine < 1.5 mg/dl or creatinine clearance > 50cc/min/1.73M2).
• Men and women of reproductive potential must agree to use an acceptable method of birth control during treatment and for six months after completion of treatment.
• Patients must be between 18 and 72 years-old.
• Patients must sign an informed consent.

Exclusion Criteria:

• Prior cranial irradiation
• Other active primary malignancy with the exception of basal cell carcinoma of the skin and cervical carcinoma in situ.
• Pre-existing immunodeficiency such as renal transplant recipient.
• Prior treatment with chemotherapy for CNS lymphoma.