Rituximab and Combination Chemotherapy in Treating Patients With Stage II, Stage III, or Stage IV Diffuse Large B-Cell Non-Hodgkin's Lymphoma

INCLUSION CRITERIA:

* Diffuse large B-cell non-Hodgkin's lymphoma

  * Bulky stage II (bulk defined as any lesion ≥ 10 cm) or stage III or IV disease
  * The following lymphoma types are excluded:

    * Primary central nervous system lymphoma
    * Transformed low-grade lymphoma (prior history of low-grade lymphoma or clear presence of low-grade lymphoma on histologic sections)
    * Primary mediastinal B-cell lymphoma or testicular lymphoma (consolidative radiotherapy is usually indicated)
    * Immunodeficiency-related lymphoma (i.e., after organ or bone marrow transplant)
* Measurable disease

  * Patient must have at least one objective measurable disease site (i.e., measurable in at least 2 perpendicular parameters)
  * Measurable disease in the liver is required if the liver is the only site of lymphoma involvement
  * Abnormal positron emission tomography scans will not constitute evaluable disease, unless verified by CT scan or other appropriate imaging
* Eastern Cooperative Oncology Group (ECOG) performance status 0-3
* For patients \> 50 years of age, a normal ejection fraction by ECHO or Multigated Acquisition Scan (MUGA) is required within 6 weeks prior to registration
* Absolute neutrophil count ≥ 1,500/mm\^3
* Platelet count \> 100,000/mm\^3
* Creatinine \< 2.0 mg/dL
* Bilirubin \< 2 mg/dL (may be up to 3.0 mg/dL if due to liver involvement by lymphoma)

EXCLUSION CRITERIA:

* Prior chemotherapy or radiation therapy for lymphoma
* Prior anthracyclines or platinum compounds used as systemic chemotherapy
* Prior radiation therapy to the mediastinum or to ≥ 25% of the bone marrow
* Concurrent pentostatin or trastuzumab (Herceptin®)
* Pregnant or nursing
* Prior malignancy within the past 5 years unless it was in situ OR was treated with curative intent AND the patient has remained relapse-free
* HIV positive