Inclusion Criteria:

1. Histologically confirmed CD20 positive DLBCL

2. Age ≥ 70

3. Ann Arbor stage II, III and IV

4. No prior chemotherapy or radiotherapy for DLBCL

5. Performance status (Eastern Cooperative Oncology Group) ≤ 2

6. At least one or more bidimensionally measurable lesion(s)

- ≥ 2 cm by conventional computerized tomography (CT)

- ≥ 1 cm by spiral CT

- skin lesion (photographs should be taken) ≥ 2 cm

- measurable lesion by physical examination ≥ 2 cm

7. Cardiac ejection fraction ≥ 50% as measured by echocardiogram without clinically
significant abnormalities

8. Adequate renal function: serum creatinine level < 2 mg/dL (177 μmol/L)

9. Adequate liver functions:

10. Adequate bone marrow functions:

hemoglobin ≥ 9 g/dL absolute neutrophil count ≥ 1,500/μL and platelet count ≥
75,000/μL, unless abnormalities are due to bone marrow involvement by lymphoma

11. Life expectancy more than 6 months

12. Informed consent

Exclusion Criteria:

1. Other subtypes of non-Hodgkin's lymphoma

2. Patients who transformed follicular lymphoma or other indolent lymphoma

3. Primary Central Nervous System (CNS) DLBCL

4. CNS involvement by lymphoma or any evidence of spinal cord compression.

5. Patients with a known history of human immunodeficiency virus (HIV) seropositivity or
hepatitis C virus (+).

6. Any other malignancies within the past 5 years except curatively treated non-melanoma
skin cancer or in situ carcinoma of cervix uteri

7. Pregnant or lactating women, women of childbearing potential not employing adequate
contraception

8. Other serious illness or medical conditions