Rituximab and Yttrium Y 90 Ibritumomab Tiuxetan in Treating Patients With Non-Hodgkin's Lymphoma

DISEASE CHARACTERISTICS: Histologically confirmed indolent non-Hodgkin's lymphoma (NHL), including 1 of the following histologic subtypes: Grade1 or 2 follicular lymphoma Small lymphocytic lymphoma (SLL) Marginal zone B-cell lymphoma CD20-positive disease confirmed by immunohistochemistry or flow cytometry Bidimensionally measurable disease At least 1 lesion measuring ≥ 2.0 cm in a single dimension by CT scan Less than 25% bone marrow involvement with lymphoma by bilateral iliac crest bone marrow aspiration and biopsy within the past 6 weeks No clinically significant impaired bone marrow reserve as evidenced by any of the following: Hypocellular marrow, as evidenced by 1 of the following: ≤ 15% cellularity Marked reduction in bone marrow precursors Platelet count < 100,000/mm^3 Absolute neutrophil count < 1,500/mm^3 History of failed stem cell collection Prior myeloablative therapy No greater than 5,000/mm^3 circulating tumor cells in peripheral blood Requires antilymphoma therapy, as indicated by any of the following: Systemic symptoms B symptoms Cytopenias Malaise Organ compromise Discomfort Pain Disfigurement Rapidly progressive disease Undue anxiety related to not receiving treatment No transformation to intermediate or high-grade NHL No known brain metastases or CNS involvement by lymphoma NOTE: A new classification scheme for adult non-Hodgkin's lymphoma has been adopted by PDQ. The terminology of "indolent" or "aggressive" lymphoma will replace the former terminology of "low", "intermediate", or "high" grade lymphoma. However, this protocol uses the former terminology. PATIENT CHARACTERISTICS: Age Over 18 Performance status ECOG 0-2 OR WHO 0-2 OR Karnofsky 70-100% Life expectancy More than 3 months Hematopoietic See Disease Characteristics WBC ≥ 3,000/mm^3 Absolute neutrophil count ≥ 1,500/mm^3 Platelet count ≥ 100,000/mm^3 Lymphocyte count < 5,000/mm^3 (for patients with SLL ) Hepatic Bilirubin ≤ 2.0 mg/dL AST and ALT ≤ 2.5 times upper limit of normal Renal Creatinine ≤ 2.0 mg/dL OR Creatinine clearance > 60 mL/min Cardiovascular No symptomatic congestive heart failure No unstable angina pectoris No cardiac arrhythmia Immunologic No anti-murine antibody reactivity (in patients with prior exposure to murine antibodies or proteins) No ongoing or active infection No history of allergic reaction attributed to compounds of similar chemical or biologic composition to yttrium Y 90 ibritumomab tiuxetan Other Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for at least 1 year after study treatment No other active malignancy except non-melanoma skin cancer No other serious nonmalignant disease that would preclude study participation No psychiatric illness or social situation that would preclude study compliance No other uncontrolled illness PRIOR CONCURRENT THERAPY: Biologic therapy More than 4 weeks since prior pegfilgrastim More than 2 weeks since prior filgrastim (G-CSF) or sargramostim (GM-CSF) Chemotherapy No prior chemotherapy Endocrine therapy Not specified Radiotherapy No prior external beam radiotherapy to > 25% of active bone marrow (involved field or regional) Surgery More than 4 weeks since prior major surgery except diagnostic surgery Other No prior systemic antilymphoma therapy No concurrent combination antiretroviral therapy for HIV-positive patients No other concurrent anticancer therapy No other concurrent investigational agents No other concurrent antilymphoma therapy