Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed non-Hodgkin's lymphoma by brain biopsy

- Patients with inconclusive biopsy or patients who are not candidates for biopsy must
have typical CT scan or MRI of the brain AND meet ≥ 1 of the following criteria:

- Positive cerebrospinal fluid cytology for lymphoma OR a monoclonal lymphoid
population as defined by cell surface markers or immunoglobulin gene
rearrangement studies

- Biopsy-proven involvement of the vitreous or uvea if cells are apparent in the
posterior chamber or vitreous by ophthalmological examination

- Bideminsionally measurable disease, defined as contrast-enhancing tumor ≥ 1 cm by
pretreatment MRI/CT scan

- Meningeal or vitreous involvement constitutes evaluable but not measurable
disease

- If an excisional, rather than a needle biopsy was done, measurable disease must
be present on a postoperative scan

- PET-CT scan not allowed

- No systemic lymphoma (as determined by pre-registration CT scans and physical
examination)

PATIENT CHARACTERISTICS:

- ECOG performance status 0-3

- Absolute granulocyte count ≥ 1,500/mm³

- Platelet count ≥ 100,000/mm³

- Bilirubin ≤ upper limit of normal (ULN)

- SGOT ≤ 2.0 times ULN

- Creatinine clearance ≥ 50 mL/min

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- No HIV-1 positivity

- No other malignancy within the past 5 years except basal cell skin cancer or any
carcinoma in situ

- No pre-existing immunodeficiency

- No hepatitis B surface antigen positivity

PRIOR CONCURRENT THERAPY:

- No prior chemotherapy or radiotherapy for primary central nervous system lymphoma

- No prior organ or bone marrow transplantation