Rituximab, Cyclophosphamide, Vincristine and Prednisone (R-CHOP) Plus Metformin in Diffuse Large-B-cell Lymphoma

Inclusion Criteria: * Patients with newly diagnosed nodal diffuse large-B cell non Hodgkin lymphoma according to the 2008 World Health Organization classification for lymphoid malignancies * No previous treatment other than prednisone or equivalent glucocorticoid up to 60 mg/m2 for 14 days * Good performance status (Eastern Cooperative Oncology Group scale 0-2) * Life expectancy \>6 months * Independently of the diagnosis of diabetes mellitus (any type) Exclusion Criteria: * History of intolerance or hypersensitivity reactions to metformin * Primary central nervous system lymphoma * History of other previous malignant neoplastic diseases \<5 years prior to enrollment * Evidence of systemic infection at the time of study * HIV, hepatitis C or B virus infection * Aspartate transaminase or alanine transaminase \>2x upper limit of normal, bilirubin \>2.5 times upper limit of normal * Serum creatinine \>1.5 mg/dL or chronic renal disease * Cardiac insufficiency (New York Heart Association scale \>1 or ejection fraction \<50%) * History of transformation from an indolent lymphoma * Pregnancy * History of lactic acidosis or alcoholism