Early Treatment Stratification Based on PET Scan Response to Chemotherapy in Patients With Diffuse Large B-cell Lymphoma

Inclusion Criteria: 1. follicular lymphoma grade III diagnosed patients, diffuse large B-cell lymphoma, histologically confirmed with CD20+ 2. aged between 18 and 65 years. Patients aged from 65 to 70 years can be included according to the investigator's criteria regarding the patients' global health status and the absence of excluding comorbidity. 3. IPI adjusted to the age over 1 or a-IPI and beta2-microglobulin equal or higher than 3 mg/dl 3. Punctuation in the ECOG grade from 0 to 4 4. Life expectancy over 12 weeks 5. Written informed consent form 6. New diagnosed patient without any previous treatment Exclusion Criteria: 1. Existence of severe cardiac, pulmonary, neurologic, psychiatric and metabolic diseases not caused by the lymphoma. 2. uncontrolled high blood pressure (diastolic pressure in rest \> 115 mmHg) 3. Altered hepatic function (bilirubin or AST/ALT superior or equal at 2 times the superior limit of normality) or renal (creatinine equal or superior at 1.5 times the superior limit of normality) not caused by the lymphoma. 4. other malignant neoplasias along the past 5 years, except skin tumors, excluded melanoma or carcinoma in situ of cervix 5. patients positive for HIV 6. patients with transformed follicular lymphoma 7. pregnant women or in nursing; women of childbearing age who do not use an adequate contraceptive method before being included in the study 8. ventricular ejection fraction inferior to 50% 9. patients with severe psychiatric diseases which can interfere with their ability for understanding the study (including alcoholism or drug addiction)