ZAR2007: R-CHOP in Folicular Lymphoma Patients no Treated Previously. Consolidation With 90Y Ibritumomab Tiuxetan (Zevalin®) Versus Maintenance Treatment With Rituximab (MabThera®)

Inclusion Criteria:

* Folicular Lymphoma CD20-positive, grade 1, 2 or 3a, confirmed in previous 4 months.
* Patients no treated previously.
* Ann Arbor Stage II, III o IV.
* Symptoms or signes wich indicate necesary treatment (GELF criteria):

  * Ganglionar or extraganglionar mass
  * B Symptoms
  * LDH or B2-microglobuline increased
  * 3 ganglionar territory afected (\> 3 cm)
  * Esplenomegalia
  * Compresive syndrome
  * Pleural/peritoneal effusion
  * Secondary medular insufiency due to infiltration
* Age\> 18 years and \<75 years.
* ECOG \< 2
* Adecuate hematological function: Hemoglobin \> 8,0 g/dl (5,0 mmol/L); RAN \>1,5 x 109/L; platelets \> 100 x 109/L
* No pregnant women. Women and man should use an appropiate anticonceptive method during the study and one year after
* Informed consent

Exclusion Criteria:

* Transformation in high grade lymphoma
* FL grade 3b.
* Skin or gastro-intestinal primary lymphoma
* History of CNS diseases ( or CNS lymphoma)
* Previous treatment
* Regulary treatment with corticosteroids (permited \< 20 mg/day prednisone or equivalent).
* Previous cancer diseases
* Major surgery in 28 days before inclusion in study.
* Creatinine \> 2,0 mg/dl (197 mmol/L)
* Bilirubin \> 2,0 mg/dl (34 mmol/L), AST (SGOT) \> 3 x upper normal limit.
* HIV infection or active infection VHB o VHC \< 4 weeks before inclusion.
* Other complicated diseases

Criteria investigador:

* Life expectancy \< 6 months.
* Hipersensibility to Ibritumomab tiuxetan, rituximab, other murines proteins or any excipients.
* Treatment in other experimental study in previous 30 days
* Any medical o psicologycal condition that can modify the capacity to give the consent