Inclusion Criteria:

   - Patients must have histologically confirmed diagnosis of diffuse large cell lymphoma

   - Patients must be stage I or II (Modified Ann Arbor staging)

   - Baseline measurements and evaluations must be obtained within 4 weeks of registration
   to the study; abnormal PET scans will not constitute evaluable disease unless verified
   by CT scan or other appropriate imaging; patients must have at least one objective
   measurable disease parameter (a lesion with at least 1 dimension > 1.5 cm); or if they
   are stage 1

   - Stage I patients must have at least one of the following risk factors:

      - Age >= 60 years

      - Bulky disease (>= 5 cm in at least one dimension)

      - Elevated Lactate Dehydrogenase (LDH) above institutional upper limit of normal

      - Eastern Cooperative Oncology Group (ECOG) performance status = 2

   - Eastern Cooperative Oncology Group (ECOG) performance status 0-2

   - Absolute neutrophil count >= 1500/mm^3 (includes neutrophils and bands)

   - Platelet count >= 100,000/mm^3

   - Creatinine < 2.0 mg/dl

   - Total bilirubin < 2 mg/dl (may be up to 3.0 mg/dl if due to liver involvement by
   lymphoma); patients with elevated total bilirubin should have a direct bilirubin
   checked; if the direct bilirubin is normal there is no need for a dose reduction

   - Patients must have left ventricular ejection fraction (LVEF) of > 45%

   - Patients must be tested for hepatitis B (HBV) surface antigen within 2 weeks of
   registration

      - NOTE: Patients who test positive will be allowed to participate but must be
      followed closely for clinical and laboratory signs of active HBV infection and
      for signs of hepatitis

Exclusion Criteria:

   - Prior chemotherapy, radiation therapy, radioimmunotherapy, or immunotherapy; a short
   course (=< 14 days prior to registration) of corticosteroids is allowed

   - Evidence of other malignancy:

      - Prior chemotherapy or prior radiation therapy for other malignancies

      - Currently receiving hormone therapy or chemotherapy for another malignancy even
      if the treatment is being provided in the adjuvant treatment setting, i.e. with
      no evidence of the original other malignancy

      - Adjuvant hormonal therapy must have been discontinued > 3 months before entering
      this study

      - Patients are eligible if they meet the following conditions: (a) treated
      carcinoma-in-situ of the cervix; (b) treated squamous cell or basal cell skin
      cancer; or (c) any other surgically cured malignancy from which the patient has
      been disease free for at least 3 years

   - Pregnant or breast feeding, as there would be radiation exposure to the fetus or
   child; a negative pregnancy test is required =< 1 week prior to registration for women
   of childbearing potential (WOCBP). Women of childbearing potential and sexually active
   males must be strongly advised to use an accepted and effective method of
   contraception

   - Known central nervous system (CNS) lymphoma, testicular lymphoma, or vitreous lymphoma

   - Known HIV infection. The safety of Zevalin™ in this population has not been tested at
   this time

   - Serious coexisting medical condition or active infection which would compromise the
   ability to deliver standard R-CHOP chemotherapy

   - Evidence of myelodysplasia on bone marrow aspiration and biopsy