Pentostatin, Cyclophosphamide, and Rituximab With or Without Bevacizumab in Treating Patients With B-Cell Chronic Lymphocytic Leukemia or Small Lymphocytic Lymphoma

RATIONALE: Drugs used in chemotherapy, such as pentostatin and cyclophosphamide, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. Monoclonal antibodies, such as rituximab and bevacizumab, 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. It is not yet known whether giving pentostatin and cyclophosphamide together with rituximab is more effective with or without bevacizumab in treating patients with B-cell chronic lymphocytic leukemia or small lymphocytic lymphoma. PURPOSE: This randomized phase II trial is studying the side effects of giving pentostatin and cyclophosphamide together with rituximab with or without bevacizumab and to see how well it works in treating patients with B-cell chronic lymphocytic leukemia or small lymphocytic lymphoma.