Inclusion Criteria:

- All patients must have a histologic diagnosis of non-Hodgkin's lymphoma by brain
biopsy. Patients who have an inconclusive biopsy or who are not candidates for biopsy
may be eligible provided they have a typical cranial magnetic resonance imaging (MRI)
or computed tomography (CT) scan and meet at least one of the following two criteria:

- A positive cerebrospinal fluid (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

- A typical MRI/CT scan for primary intracranial lymphoma is defined as the presence of
hypo, iso, or hyperdense parenchymal contrast-enhancing (usually homogeneously) mass
lesion(s)

- Patients must be HIV-1 negative

- Patients must have a normal or negative pre-treatment systemic evaluation including:

- A bone marrow aspirate and biopsy

- CT scans of the chest, abdomen and pelvis

- Patients must have adequate bone marrow function (defined as peripheral
leucocyte count > 4000 cells/mm3 and platelet count > 100,000 cells/mm3), liver
function (bilirubin < 2.0 mg and SGOT < 2 times upper limit of normal), and
adequate renal function (serum creatinine < 1.5 mg/dl or creatinine clearance >
50 cc/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

Exclusion Criteria:

The following would exclude a patient from the study:

- 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