This study is a multicentric, phase II, open-label, non-randomized trial evaluating the efficacy of O-miniCHOP in patients aged over 80 years with non previously treated CD20+ diffuse large B-cell lymphoma (age-adjusted IPI=0 to3), stage I, II, III or IV with a performance status ECOG from 0 to 4.

The anticipated study dates (start / end) are: 2010 - 2013. The study will evaluate a cohort of 120 patients (approximately 95 in France, 15 in Belgium, 5 in Switzerland and 5 in Portugal).

Patients will be recruited over 30 months and followed at least one year after the last patient has been included.

The duration of the treatment period is approximately 20 weeks.

Inclusion Criteria:

Patient with histologically proven CD20+ diffuse large B-cell lymphoma (DLBCL) (WHO classification 2008) including clinical subtypes (primitive mediastinal, intravascular, etc.) May also be included : de Novo Transformed DLBCL from low grade lymphoma (Follicular, other...) and DLBCL associated with some small cell infiltration in bone marrow

• Or CD20+ B-cell lymphoma, with intermediate features between DLBCL and Burkitt or with intermediate features between DLBCL and classical Hodgkin lymphoma
• Or CD20+ Follicular lymphoma grade 3B
• Or CD20+ Aggressive B-cell lymphoma unclassifiable Aged over 80 years. Ann Arbor stage I, II, III or IV. All aaIPI Patient non previously treated. All ECOG performance status With a minimum life expectancy of 3 months. Negative HIV, HBV and HCV serologies test < 4 weeks (except after vaccination). Patient able to give his consent and having previously signed a written informed consent.

Patient affiliated to social security system, if applicable

Exclusion Criteria:

Any other histological type of lymphoma, Burkitt included. Any history of treated or non-treated small-B cell lymphoma. Central nervous system or meningeal involvement by lymphoma. Contra-indication to any drug contained in the chemotherapy regimens. Any serious active disease (according to the investigator's decision). Poor renal function (creatinin level>150µmol/l), poor hepatic function (total bilirubin level>30mmol/l, transaminases>2.5 maximum normal level) unless these abnormalities are related to the lymphoma.

Poor bone marrow reserve as defined by neutrophils <1.5 G/l or platelets <100 G/l, unless related to bone marrow infiltration.

Any history of cancer during the last 5 years with the exception of non-melanoma skin tumors or stage 0 (in situ) cervical carcinoma. Patients previously diagnosed with prostate cancer are eligible if (1) their disease was T1-T2a, N0, M0, with a Gleason score <7, and a prostate specific antigen (PSA) <10 ng/mL prior to initial therapy, (2) they had definitive curative therapy (ie, prostatectomy or radiotherapy) >2 years before Day 1 of Cycle 1, and (3) at a minimum 2 years following therapy they had no clinical evidence of prostate cancer, and their PSA was undetectable if they underwent prostatectomy or <1 ng/mL if they did not undergo prostatectomy.

Treatment with any investigational drug within 30 days before planned first cycle of chemotherapy and during the study.

Prior treatment with anti-CD20 monoclonal antibody or alemtuzumab within 3 months prior to start of therapy Adult patient under tutelage.