Rituximab and Combination Chemotherapy in Treating Patients With Primary Central Nervous System Lymphoma

OBJECTIVES: Primary * Determine the complete response rate. Secondary * Determine the progression-free survival of these patients. * Determine the proportion of progression-free and overall survival in these patients. * Determine rituximab cerebrospinal fluid pharmacokinetics (only in patients requiring intrathecal chemotherapy). OUTLINE: This is a multicenter study. Patients receive rituximab IV 3 times weekly in weeks 1-4; high-dose methotrexate IV over 2 hours in weeks 1, 3, 5, and 9; oral or IV leucovorin calcium every 6 hours for 12 doses beginning 24 hours after the start of methotrexate in weeks 1, 3, 5, and 9; vincristine IV in weeks 1, 3, 5, 7, and 9; oral procarbazine hydrochloride daily on days 1-7 in weeks 1, 5, and 9; oral dexamethasone daily in weeks 1-6; and cytarabine IV over 2 hours twice weekly in weeks 11 and 14. Patients with positive cerebrospinal fluid also receive methotrexate intrathecally and oral leucovorin calcium every 12 hours for 8 doses beginning 24 hours after the start of methotrexate in weeks 2, 4, 6, 8, and 10. After completion of study treatment, patients are followed periodically for 5 years. PROJECTED ACCRUAL: A total of 43 patients will be accrued for this study.