RATIONALE: Drugs used in chemotherapy use different ways to stop cancer cells from dividing so they stop growing or die. Combining more than one drug may kill more cancer cells. Monoclonal antibodies can locate cancer cells and either kill them or deliver cancer-killing substances to them without harming normal cells.

PURPOSE: Phase II trial to study the effectiveness of combination chemotherapy followed by monoclonal antibody therapy in treating patients who have newly diagnosed follicular non-Hodgkin's lymphoma.

OBJECTIVES: I. Determine the 2 year failure free survival rate of patients with newly diagnosed follicular lymphoma treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) followed by iodine I 131 monoclonal antibody anti-B1. II. Determine the complete and partial response rates of these patients after this therapy. III. Evaluate the toxicity of this regimen in these patients. IV. Determine the rate of disappearance of cells with clonal t(14;18)/bcl2 rearrangements from the peripheral blood and bone marrow after this therapy in these patients.

OUTLINE: Patients receive cyclophosphamide IV over 15 minutes, doxorubicin IV, and vincristine IV on day 1 and oral prednisone on days 1-5. Treatment is repeated every 21 days for up to 6 courses. Within 4-8 weeks after the last course of chemotherapy, patients who achieve at least a partial response and have less than 25% bone marrow involvement begin immunotherapy. Patients receive unlabeled monoclonal antibody anti-B1 (MOAB anti-B1) IV over 1 hour, then iodine I 131 MOAB anti-B1 IV over 20 minutes on day 1. This regimen is repeated on day 8. Patients are followed every 6 months for 2 years, then annually thereafter.

PROJECTED ACCRUAL: A total of 80 patients will be accrued for this study within 1 year.

DISEASE CHARACTERISTICS: Histologically confirmed follicular non-Hodgkin's lymphoma No prior treatment Bulky stage II, stage III, or stage IV Must express cluster of differentiation antigen 20 (CD20) antigen Bidimensionally measurable disease No Central Nervous System (CNS) involvement

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: SWOG 0-2 Life expectancy: Not specified Hematopoietic: Granulocyte count at least 1500/mm3 Platelet count at least 100,000/mm3 Hepatic: Not specified Renal: Not specified Cardiovascular: No arrhythmias (except sinus arrhythmia or infrequent premature ventricular contractions) No history of impaired cardiac status (severe coronary artery disease, cardiomyopathy, congestive heart failure, or serious arrhythmia Ejection fraction at least normal Other: HIV negative No prior malignancy within past 5 years except adequately treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix No pregnant or nursing Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: No prior monoclonal antibodies Chemotherapy: No prior chemotherapy for lymphoma Endocrine therapy: Not specified Radiotherapy: No prior radiotherapy for lymphoma Surgery: Not specified