Combination Chemotherapy and Rituximab in Treating Patients With Chronic Lymphocytic Leukemia or Lymphocytic Lymphoma

DISEASE CHARACTERISTICS: Diagnosis of B-cell chronic lymphocytic leukemia (CLL) or small B-cell lymphocytic lymphoma (SLL) with the following: Lymph node biopsy interpreted as SLL or consistent with CLL or all of the following: Peripheral lymphocyte count greater than 5,000/mm^3 with small to moderate peripheral lymphocytes and no more than 55% prolymphocytes Bone marrow aspirate containing at least 30% lymphoid cells Immunophenotypic evaluation of peripheral blood lymphocytes demonstrating monoclonality of B lymphocytes with all of the following: CD19 or CD20 coexpressed with CD5 antigen in the absence of other pan-T- cell markers (e.g., CD2 or CD3) Expression of CD23 on CLL cells or Dim B-cell expression of kappa or lambda light chains Measurable disease with any of the following: 1 or more lymph nodes at least 1.5 cm by CT scan Splenomegaly by CT scan Peripheral lymphocyte count greater than 5,000/mm3 with coexpression of CD5 and B-cell markers Bone marrow aspirate with at least 30% lymphoid cells No mantle cell lymphoma PATIENT CHARACTERISTICS: Age 18 and over Performance status ECOG 0-2 Life expectancy At least 2 years Hematopoietic See Disease Characteristics No immune thrombocytopenia No hemolytic anemia Hepatic Bilirubin no greater than 3 times upper limit of normal (ULN) SGOT no greater than 3 times ULN (unless due to hemolysis or CLL) No hepatitis Renal Creatinine no greater than 1.5 times ULN Cardiovascular No cardiac dysfunction No New York Heart Association class III or IV heart disease No myocardial infarction within the past month Other HIV negative No active acute or chronic infection No immunosuppressive diseases No autoimmune disorder No secondary malignancy that is projected to limit life expectancy Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy See Chemotherapy No prior rituximab At least 4 weeks since prior biologic therapy Chemotherapy At least 4 weeks since prior chemotherapy No prior combination chemotherapy and rituximab or other antibody therapy No prior combination chemotherapy comprising an alkylating agent and a purine nucleoside analog (i.e., cyclophosphamide or chlorambucil in combination with fludarabine, cladribine, or pentostatin) No prior pentostatin Endocrine therapy At least 4 weeks since prior corticosteroids No concurrent supra-physiologic doses of corticosteroids Radiotherapy At least 4 weeks since prior radiotherapy Surgery At least 4 weeks since prior major surgery Other No concurrent immunosuppressive therapy (e.g., cyclosporine)