VI. Effect of Fc-Gamma Receptor III (FcyRIII) polymorphism genotype on outcome. OUTLINE: Patients receive rituximab intravenously (IV) on days 0, 1, 4, 8, and 15 of course 1; days 1, 8, and 15 of course 2; and day 1 of all subsequent courses. Patients also receive CHOP chemotherapy comprising cyclophosphamide IV, doxorubicin hydrochloride IV, and vincristine sulfate IV on day 1, and prednisone orally (PO) on days 1-5. Treatment repeats every 21 days for 6 courses in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up every 2-3 months for 2 years, every 6 months for 3 years, annually for up to 10 years.