This is a clinical trial to compare the efficacy and safety of four cycles of R-CHOP followed by four cycles of Rituximab with six cycles of R-CHOP followed by two cycles of Rituximab in the treatment of de novo, low-risk, non-bulky diffuse large B-cell lymphoma.

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