- Arm I: Patients receive R-CHOP immunochemotherapy comprising rituximab IV, cyclophosphamide IV over 15 minutes, doxorubicin hydrochloride IV, and vincristine IV on day 1 and oral prednisone once daily on days 1-5. Treatment repeats every 21 days for 3 courses in the absence of disease progression or unacceptable toxicity. Patients then undergo restaging of their disease. Patients with disease progression proceed to salvage therapy off study. All other patients receive 3 more courses of R-CHOP.