Rituximab, Temozolomide, and Methylprednisolone in Treating Patients With Recurrent Primary CNS Non-Hodgkin's Lymphoma

RATIONALE: Monoclonal antibodies, such as rituximab, can block cancer growth in different ways. Some block the ability of cancer cells to grow and spread. Others find cancer cells and help kill them or carry cancer-killing substances to them. Drugs used in chemotherapy, such as temozolomide and methylprednisolone, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Rituximab may help chemotherapy kill more cancer cells by making cancer cells more sensitive to the drugs. Giving rituximab together with temozolomide and methylprednisolone may be an effective treatment for primary CNS non-Hodgkin's lymphoma. PURPOSE: This phase II trial is studying how well giving rituximab together with temozolomide and methylprednisolone works in treating patients with recurrent primary CNS non-Hodgkin's lymphoma.