Chidamide Plus R-CHOP in Elderly DLBCL

Inclusion Criteria: * Pathologically confirmed diffuse large B-cell lymphoma, CD20 positive * Age 61-75 years * ECOG 0,1,2 * Life expectancy\>6 months * Informed consented * IPI\>1 Exclusion Criteria: * Chemotherapy before * Stem cell transplantation before * History of malignancy except for basal cell or squamous cell carcinoma of the skin or carcinoma in situ of the cervix * Uncontrollable cardio-cerebral vascular, coagulative, autoimmune, serious infectious disease * Primary CNS lymphoma * LVEF≤50% * Lab at enrollment (Unless caused by lymphoma) Neutrophile\<1.5\*10\^9/L Platelet\<75\*10\^9/L ALT or AST \>2\*ULN,AKP or bilirubin \>1.5\*ULN Creatinine\>1.5\*ULN * Other uncontrollable medical condition that may that may interfere the participation of the study * Not able to comply to the protocol for mental or other unknown reasons * Pregnant or lactation * HIV infection * If HbsAg positive, should check HBV DNA, DNA positive patients cannot be enrolled. If HBsAg negative but HBcAb positive (whatever HBsAb status), should check HBV DNA,DNA positive patients cannot be enrolled.