RATIONALE: Drugs used in chemotherapy, such as cyclophosphamide, doxorubicin, vincristine, and prednisone, use different ways to stop cancer cells from dividing so they stop growing or die. Radiation therapy uses high-energy x-rays to damage cancer cells. Monoclonal antibodies, such as rituximab and yttrium Y 90 ibritumomab tiuxetan, can locate cancer cells and either kill them or deliver radioactive cancer-killing substances to them without harming normal cells. Combining chemotherapy with radiation therapy and monoclonal antibody therapy may kill more cancer cells.

PURPOSE: This phase II trial is studying how well giving combination chemotherapy together with radiation therapy and monoclonal antibody therapy works in treating patients with stage I or stage II non-Hodgkin's lymphoma.

OBJECTIVES:

• Determine the 2-year progression-free survival of patients with aggressive high-risk stage I or IE or non-bulky stage II or IIE CD20-positive non-Hodgkin's lymphoma treated with cyclophosphamide, doxorubicin, vincristine, and prednisone and radiotherapy followed by rituximab and yttrium Y 90 ibritumomab tiuxetan.
• Determine the toxicity of this regimen in these patients.

OUTLINE: This is a multicenter study.

• Chemotherapy: Patients receive CHOP chemotherapy comprising cyclophosphamide IV over 1-2 hours, doxorubicin IV, and vincristine IV on day 1 and oral prednisone on days 1-5. Treatment repeats every 21 days for 3 courses in the absence of disease progression or unacceptable toxicity.
• Radiotherapy: Beginning 3 weeks after the completion of CHOP chemotherapy, patients undergo radiotherapy once daily 5 days a week for 4-5 weeks.
• Monoclonal antibody therapy: Beginning 3-6 weeks after the completion of radiotherapy, patients receive rituximab IV followed by indium In 111 ibritumomab tiuxetan IV over 10 minutes on day 1. Patients then undergo whole body imaging. If ibritumomab tiuxetan biodistribution is acceptable, patients receive rituximab IV and yttrium Y 90 ibritumomab tiuxetan IV over 10 minutes on day 7, 8, OR 9.

Patients are followed every 6 months for 2 years and then annually thereafter.

PROJECTED ACCRUAL: A total of 60 patients will be accrued for this study within 15 months.

DISEASE CHARACTERISTICS:

• Histologically confirmed aggressive non-Hodgkin's lymphoma of 1 of the following subtypes:

  • Diffuse large B-cell
  • Mantle cell
  • High-grade B-cell, Burkitt's, or Burkitt-like
  • Anaplastic large cell (B-cell phenotype only)

• Stage I, IE, or non-bulky* stage II or IIE disease by Ann Arbor classification

  • Patients who have bulky stage II or IIE disease are ineligible even if, after resection, the measurements are less than 10.0 cm NOTE: *Non-bulky disease defined as any tumor measuring less than 10.0 cm or occupying less than 1/3 of the chest diameter

• CD20-expressing disease by flow cytometry or immunoperoxidase staining

• Aggressive lymphomas must have at least 1 of the following adverse prognostic factors:

  • Non-bulky stage II or IIE disease
  • At least 60 years of age
  • Zubrod performance status of 2
  • Lactic dehydrogenase greater than upper limit of normal

• All disease must be encompassable in a single radiation port (including any site of resected disease) NOTE: A new classification scheme for adult non-Hodgkin's lymphoma has been adopted by PDQ. The terminology of "indolent" or "aggressive" lymphoma will replace the former terminology of "low", "intermediate", or "high" grade lymphoma. However, this protocol uses the former terminology.

PATIENT CHARACTERISTICS:

Age

• Over 18

Performance status

• Zubrod 0-2

Life expectancy

• Not specified

Hematopoietic

• Not specified

Hepatic

• Not specified

Renal

• Not specified

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix
• No medical contraindication to study chemotherapy, rituximab, or ibritumomab tiuxetan
• No known AIDS syndrome or HIV-associated complex

PRIOR CONCURRENT THERAPY:

Biologic therapy

• No prior monoclonal antibody therapy

Chemotherapy

• No prior chemotherapy for lymphoma

Endocrine therapy

• Not specified

Radiotherapy

• See Disease Characteristics
• No prior radiotherapy for lymphoma
• No concurrent intensity-modulated radiotherapy
• Planned involved-field radiotherapy must not encompass more than 25% of active bone marrow space

Surgery

• See Disease Characteristics

Other

• Concurrent participation in SWOG-8947 or SWOG-8819 allowed