This is a prospective, randomized, controlled, multicenter, phase II clinical trial to evaluate the efficacy and safety of R-CMOP versus R-CHOP in the initial treatment of low-risk and medium-risk diffuse large B-cell lymphoma (DLBCL).

Key Inclusion Criteria:

1. Aged ≥18,≤80 years, both male and female.
2. Pathologically confirmed DLBCL
3. No prior treatment for DLBCL.
4. There must be at least one measurable or evaluable lesion that meets the evaluation criteria for Lugano 2014 lymphoma.
5. Eastern Cooperative Oncology Group (ECOG) performance status score of 0-
6. Expected survival ≥3 months.
7. International Prognostic Index (IPI) ≤ 2
8. Sufficient bone marrow, liver, and kidney function.

Key Exclusion Criteria:

1. Other types of LBCL:Primary Cutaneous Diffuse Large B-cell Lymphoma (Leg Type), Primary Mediastinal (Thymic) Large B-cell Lymphoma, Lymphomatoid Granulomatosis, ALK-positive Diffuse Large B-cell Lymphoma, Plasmablastic Lymphoma, Intravascular Large B-cell Lymphoma, T-cell/Histiocyte-rich Large B-cell Lymphoma, and others.
2. Transformed DLBCL.
3. Patients with central nervous system involvement, or those who require high-dose methotrexate for prevention.
4. The patients had previously received antitumor therapy.
5. Patients with the infection of human immunodeficiency virus (HIV) and/or acquired immunodeficiency syndrome.
6. Pregnant and lactating women and subjects of childbearing age who do not want to use contraception.
7. Mentally ill persons or persons unable to obtain informed consent.
8. The investigators think that the patient is not suitable for the study.