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

RATIONALE: Monoclonal antibodies, such as rituximab, can block cancer growth in different ways. Some find cancer cells and kill them or carry cancer-killing substances to them. Others interfere with the ability of cancer cells to grow and spread. Drugs used in chemotherapy, such as methotrexate, leucovorin, vincristine, procarbazine, dexamethasone, and cytarabine, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Giving rituximab together with combination chemotherapy may kill more cancer cells. PURPOSE: This phase II trial is studying how well giving rituximab together with combination chemotherapy works in treating patients with primary central nervous system (CNS) 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.