OUTLINE: This is a multicenter study. Patients receive rituximab IV over 4-10 hours on day 1 followed by etoposide, vincristine, and doxorubicin IV continuously on days 4-7, cyclophosphamide IV over 5-30 minutes on day 8 and oral prednisone on days 4-8. Patients also receive sargramostim (GM-CSF) subcutaneously beginning on day 9 until blood counts recover. Treatment repeats every 21 days for a maximum of 8 courses in the absence of disease progression or unacceptable toxicity.