Reduced Chemotherapy in Low Risk DLBCL

Inclusion Criteria: * Histologically confirmed de novo diffuse large B-cell lymphoma, complete response after 4 cycles of standard R-CHOP21 * Age\>=14 y.o.,\<=75 y.o. * IPI=0-1 * non-bulky (largest diameter \<7.5cm) * ECOG =0-1 * Life expectancy\>6 months * Informed consented 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 cutaneous, CNS DLBCL * LVEF≤50% * Other uncontrollable medical condition that may that may interfere the participation of the study * Lab at enrollment(unless caused by lymphoma) Neutrophile\<1.5\*10\^9/L Platelet\<80\*10\^9/L Hemoglobulin\<100g/L ALT or AST \>2\*ULN,AKP or bilirubin \>1.5\*ULN Creatinine\>1.5\*ULN * Not able to comply to the protocol for mental or other unknown reasons * Pregnant or lactation * 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. * HIV infection