OUTLINE: This is a multicenter study. Patients are assigned to one of two treatment arms: Arm I: Patients receive rituximab IV on day 0, and cyclophosphamide IV, doxorubicin IV, and vincristine IV on day 1, followed by oral prednisone on days 1-5. Arm II: Patients receive interferon alfa subcutaneously on days 22-26, and cyclophosphamide IV, doxorubicin IV, and vincristine IV on day 1, followed by oral prednisone on days 1-5. Treatment repeat every 28 days for up to 8 courses in the absence of disease progression or unacceptable toxicity. Quality of life is assessed at baseline and prior to chemotherapy for each course. Patients are followed every 3 months for 2 years, every 6 months for 2 years, and then annually for up to 10 years.