Y 90 Ibritumomab Tiuxetan &Rituximab Relapsed or Refractory Diffuse Large B-Cell Non-Hodgkin's Lymphoma

DISEASE CHARACTERISTICS: Histologically confirmed diffuse large B-cell non-Hodgkin's lymphoma, including any of the following: B-cell diffuse large cell variant Immunoblastic Mediastinal (thymic) large cell T-cell/histiocyte-rich Anaplastic large B-cell Intravascular large B-cell Lymphomatoid granulomatosis Relapsed or refractory disease after at least 1 prior chemotherapy regimen and requires further treatment Relapsed disease, defined as the following: Appearance of any new lesion OR increase of at least 50% in the size of a previously involved site 50% increase in greatest diameter of any previously identified node greater than 1 cm in the short axis OR in the sum of the perpendicular diameter (SPD) of more than 1 node Progressive disease, defined as the following: 50% increase from nadir in the SPD of any previously identified abnormal node Appearance of any new lesion during or at the end of therapy CD20-positive disease by immunohistochemistry Bidimensionally measurable disease At least 1 lesion at least 2.0 cm by CT scan Less than 25% bone marrow involvement by lymphoma No transformed lymphoma from indolent to aggressive No HIV- or AIDS-related lymphoma No hypocellular bone marrow No marked reduction in bone marrow precursors of 1 or more cell lines (e.g., granulocytic, megakaryocytic, or erythroid) No CNS lymphoma Ineligible for myeloablative therapy OR refused transplantation Ineligible for any other open yttrium Y 90 ibritumomab tiuxetan investigational protocols PATIENT CHARACTERISTICS: Age 18 and over Performance status WHO 0-2 Life expectancy At least 3 months Hematopoietic Absolute neutrophil count at least 1,500/mm^3 Lymphocyte count no greater than 5,000/mm^3 (for patients with small lymphocytic lymphoma) Platelet count at least 100,000/mm^3 Hepatic Bilirubin no greater than 2.0 mg/dL Renal Creatinine no greater than 2.0 mg/dL Other Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 1 year after study participation No concurrent serious nonmalignant disease or infection that would preclude study participation No human antimurine antibody reactivity PRIOR CONCURRENT THERAPY: Biologic therapy See Disease Characteristics No prior autologous bone marrow transplantation No prior peripheral blood stem cell rescue No prior failed stem cell collection Prior rituximab within the past 90 days allowed provided patient has fludeoxyglucose-avid disease that is also indium In 111 ibritumomab tiuxetan-avid disease in at least 1 lesion More than 2 weeks since prior filgrastim (G-CSF) or sargramostim (GM-CSF) Chemotherapy See Disease Characteristics Endocrine therapy Not specified Radiotherapy No prior radioimmunotherapy No prior external beam radiotherapy (involved field or regional) to more than 25% of active bone marrow Surgery More than 4 weeks since prior major surgery (except diagnostic surgery) Other Recovered from all prior therapy More than 4 weeks since prior therapy for lymphoma More than 8 weeks since prior phase II investigational drugs No other concurrent antineoplastic therapy