R-CHOP Versus R-CDOP as First-line Treatment for Elderly Patients With Diffuse Large-B-cell Lymphoma

Inclusion Criteria: * Pathologically confirmed diagnosis of CD20-positive diffuse large B-cell lymphoma * 60\~80 years old * Ann Arbor stage I\~IV * ECOG physical score of 0\~2 * Have not received previous treatment to lymphoma, including chemotherapy, radiotherapy, or biotherapy * Have at least one clinically measurable lesion: \>= 2cm under physical examination, or \>= 1.5cm under computed tomography (CT) or magnetic resonance (MR) * Life expectancy of \>= 3 months * Serum glutamic oxaloacetic transaminase (SGOT) and serum glutamate pyruvate transaminase and total bilirubin \<= 2 × upper limit of normal (ULN) * Glomerular filtration rate (MDRD method) \>= 30ml/min * No abnormalities in blood coagulative function * Generally normal bone marrow function: while blood cell \>= 3,000/μL, absolute neutrophil count \>= 1,500/μL, hemoglobin \>= 100g/L, platelet \>= 75,000/μL * No evidence of active hepatitis B or C virus, or human immunodeficiency virus infection * Left ventricular ejection fraction (LVEF) \>= 45% measured by two dimensional echocardiography or multi-gated acquisition (MUGA) scan * Cardiac function of class I-II in New York Heart Association (NYHA) classification Exclusion Criteria: * Patients with indolent lymphoma * Positive results for in situ hybridization for Epstein-Barr virus encoded RNA (EBER) * Serum Epstein-Barr virus DNA \>= 1,000 copies/ml * Double-hit lymphoma confirmed by fluorescence in situ hybridization (FISH) * Primary mediastinal B-cell lymphoma * Involvement of central nervous system * Bulky disease (\>= 10cm) * History of cardiac disease, including clinically significant ventricular tachycardia, atrial fibrillation, conduction block, myocardial infarction within 1 year, congestive heart failure, symptomatic coronary heart disease which needs medication * Known allergic reaction to any component of the agents used in the chemotherapeutic regimens that are used in the study * Previous exposure to anthracycline drugs, rituximab, or chemotherapy for lymphoma * History of malignant carcinoma within 5 years (except carcinoma in situ of the skin and uterine cervix, and prostatic carcinoma) * Currently enrolled in other clinical studies * Other conditions that the investigators consider as inappropriate for enrolling into this study