The Safety and Effectiveness of 4R-CHOP+4R vs 6R-CHOP+2R in Newly Diagnosed Patients With DLBCL in Low Risk

Inclusion Criteria: * Pathologically confirmed CD20 positive DLBCL based on 2016 WHO classification who achieved CR after 4 cycles of RCHOP therapy (examined by PET-CT, Deauville score 1-2) * Treatment naïve * IPI=0,1 * Age ≥ 14 or ≤75 years * non-mass (The length of the lesion\<7.5cm) * ECOG=0,1 * Life expectancy\>6 months * Informed consented Exclusion Criteria: * Have received systemic or local treatment including chemotherapy in the past * Have received autologous stem cell transplantation in the past * Past medical history of other malignant tumors, except basal cell carcinoma of the skin and cervical cancer in situ * Accompanied by uncontrolled cardiovascular and cerebrovascular diseases, coagulopathy, connective tissue diseases, severe infectious diseases and other diseases * Primary skin, primary central nervous system lymphoma * Left ventricular ejection fraction ≦50% * Other concurrent and uncontrolled situation which will affect the patient's medical status based on researchers decision * Laboratory test value during screening: (unless it is caused by lymphoma) Neutrophils \<1.5\*109/L Platelet\<80\*109/L Hemoglobin \<100g/L ALT or AST is 2 times higher than the upper limit of normal, AKP and bilirubin are 1.5 times higher than the upper limit of normal E. Creatinine level is higher than 1.5 times the upper limit of normal * Psychiatric patients or other patients who are known or suspected to be unable to fully accomplish with the research protocol * Pregnant or lactating women * Patients with positive HbsAg test results need to undergo HBV-DNA test and can be admitted to the group after turning negative. In addition, if the HBsAg test result is negative, but the HBcAb test is positive (regardless of the HBsAb status), HBV-DNA is also required；if the result is positive, patients also need to be treated to become negative before entering the group * Patients living with HIV * Patients with TP53 mutations or those who have not undergone DLBCL hot spot gene screening