Study Comparing Zevalin Regimen With no Further Treatment in Patients With Diffuse Large B-cell Lymphoma.

Inclusion Criteria: Histologically confirmed, Ann Arbor stage II, III, or IV Diffuse large B-cell lymphoma (DLBCL) according to the Revised European American Lymphoma(REAL)/World Health Organization (WHO) classification . Central pathology review confirming the DLBCL diagnosis and Cluster of differentiation 20 (CD20) positivity, and no evidence of DLBCL in bone marrow First-line treatment of DLBCL must have been 6 or 8 cycles of standard CHOP chemotherapy in combination with rituximab . Complete remission(CR) or unconfirmed complete remission(CRu) according to the International Workshop Response Criteria for Non Hodgkins Lymphoma (NHL) described by Cheson et al and modified for this study after first-line treatment with CHOP-R. Computerised Tomography (CT) scans of chest, abdomen, pelvis, and neck (if applicable) must have been performed within 6 weeks after the last dose of the last course of CHOP-R. Applicability of the neck CT means that the patient had involvement of the neck region by palpation / physical examination at first diagnosis (pre-CHOP-R). Central radiographic review of the CT scans from before and after first-line treatment with CHOP-R fulfilling the radiological requirements for CR/CRu Patients 60 years of age or older at time of randomization WHO performance status (PS) of 0 to 2 within 1 week of randomization Absolute neutrophil count greater than or equal to 1.5 x 10^9/L within 1 week of randomization Hemoglobin greater than or equal to 10 g/dL within 1 week of randomization Platelets greater than or equal to 150 x 10^9/L within 1 week of randomization Life expectancy of 3 months or longer Written informed consent obtained according to local guidelines Exclusion Criteria: Presence of any other malignancy or history of prior malignancy except non-melanoma skin tumors or stage 0 (in situ) cervical carcinoma Prior radioimmunotherapy, radiation therapy, or any other NHL therapy except first-line CHOP-R Presence of gastric, central nervous system or testicular lymphoma at first diagnosis Histological transformation of low-grade non-Hodgkin's lymphoma (NHL) Known seropositivity for hepatitis C virus or hepatitis B surface antigen Known history of Human Immunodeficiency virus (HIV) infection Abnormal liver function: total bilirubin > 1.5 x upper limit of normal (ULN) or Alanine Aminotransferase > 2.5 x ULN within 1 week of randomization Abnormal renal function: serum creatinine > 2.0 x ULN within 1 week of randomization Nonrecovery from the toxic effects of CHOP-R therapy Known hypersensitivity to murine or chimeric antibodies or proteins Granulocyte Colony Stimulating Factor (G-CSF) or Granulocyte Macrophage Colony Stimulating Factor (GM-CSF) therapy within two weeks (or four weeks if pegylated) prior to screening laboratory sampling Concurrent severe and/or uncontrolled medical disease (e.g., uncontrolled diabetes,congestive heart failure, myocardial infarction within 6 months of study, unstable and uncontrolled hypertension, chronic renal disease, or active uncontrolled infection) which could compromise participation in the study Male and female patients of child-bearing potential unwilling to practice effective contraception during the study and unwilling or unable to continue contraception for 12 months after their last dose of study treatment Female patients who are pregnant or are currently breastfeeding Treatment with investigational drugs less than 4 weeks before the planned Day 1 or nonrecovery from the toxic effects of such therapy Surgery less than 4 weeks before the planned Day 1 or nonrecovery from the side effects of such surgery Concurrent systemic corticosteroid use for any reason except as premedication in case of known or suspected allergies to contrast media or as premedication for potential side effects of rituximab treatment Unwillingness or inability to comply with the protocol