Rituximab, Combination Chemotherapy, and 90-Yttrium Ibritumomab Tiuxetan for Patients With Stage I or II Non-Hodgkin's Lymphoma

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