Consolidation Treatment With Y90-Ibritumomab Tiuxetan After R-CHOP Induction in High Risk Patients According to Follicular Lymphoma International Prognostic Index (FLIPI) With Follicular Lymphoma

Inclusion Criteria: * Signature of the written informed consent by the subject or his/her legal representative before initiation of any trial specific procedure. * Patients older than 18. * Histologic diagnosis of CD20+, grade 1-3a follicular lymphoma as per the WHO classification. * High-risk patients according to FLIPI before initiation of induction chemotherapy. * Stage II-IV prior to initiation of induction treatment, or any stage in patients with grade 3 follicular lymphoma. * Complete or partial response to the induction scheme. * ECOG scale performance status 0 - 2. * Life expectancy greater than 3 months. * In women of childbearing age, use of a reliable contraceptive method. * A suitable bone marrow reserve: * Lower than 25% Bone marrow infiltration by lymphoma. * Hb 10 g/dL. PMN leukocytes 1,500 cel/mm3, platelets 100,000/mm3 * Suitable hepatic, renal and cardiac function: * creatinine \<2,5 x UNL (upper normality limit). * bilirubin or ALT/AST \< 2,5 x UNL Exclusion Criteria: * Patients with no objective clinical response to induction chemotherapy. * \> 25% bone marrow infiltration following induction chemotherapy. * Platelets \< 100,000 before radioimmunotherapy. * Severe and/or uncontrolled concomitant disease: * Hepatic, renal, cardiovascular, neurological or metabolic disease. * Cardiac failure, ischemic cardiopathy, ischemic cardiopathy with a history of myocardial infarction or angor, or major ventricular arrhythmia. * Positive regarding HBV, HCV, HIV. * Active acute or chronic infection. * Social, psychic or geographic disability to satisfy any of the treatment schemes. * Pregnant and/or breastfeeding women, or adult patients of childbearing age who are not using a safe birth control device throughout the study treatment and at least 12 months thereafter. * Known or suspected hypersensitivity, or confirmed or suspected adverse reaction to the study drugs and other related compounds (Rituximab, Ibritumomab tiuxetan, a history of sensitivity to murine proteins, dexametasone, cyclophosphamide and other anthracyclines, cytarabine).