• Compare progression-free survival rates of patients treated with CHOP chemotherapy alone, CHOP with rituximab, or CHOP followed by iodine-131 anti-CD20 antibody by Kaplan Meier survival curves at 2 or 5 years [ Designated as safety issue: No ]
  

• Compare response rates (confirmed and unconfirmed complete and partial responses) by Cheson criteria at 4 weeks and 6 months after completion of therapy and then annually [ Designated as safety issue: No ]
  
• Compare toxicities by NCI CTC at 4 weeks and 6 months after completion of therapy and then annually [ Designated as safety issue: Yes ]
  

OBJECTIVES:

• Compare the progression-free survival and overall survival of patients with newly diagnosed follicular non-Hodgkin's lymphoma treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) with or without either rituximab or iodine I 131 tositumomab (monoclonal antibody anti-B1). (CHOP chemotherapy alone arm closed to accrual as of 12/15/02)
• Compare the response rate of these patients treated with these regimens.
• Compare the toxic effects of these regimens in these patients.
• Compare the molecular remission rates of this patient population treated with these regimens.
• Determine the incidence and time to development of human anti-mouse antibody positivity.

OUTLINE: This is a randomized, multicenter study. Patients are stratified according to whether microglobulin is greater than upper limit of normal (yes vs no). Patients are randomized to 1 of 3 treatment arms. (Arm I closed to accrual as of 12/15/02)

• Arm I (CHOP only): Patients receive cyclophosphamide IV over 15 minutes, doxorubicin IV over 5-20 minutes, and vincristine IV over 5-15 minutes on day 1. Patients also receive oral prednisone daily on days 1-5. Treatment continues every 21 days for up to 6 courses in the absence of disease progression or unacceptable toxicity. (Arm I closed to accrual as of 12/15/02)
• Arm II (CHOP + rituximab): Patients receive cyclophosphamide IV over 15 minutes, doxorubicin IV over 5-20 minutes, and vincristine IV over 5-15 minutes on days 8, 29, 50, 71, 92, and 113. Patients also receive oral prednisone daily on days 8-12, 29-33, 50-54, 71-75, and 113-117 and rituximab IV over 4-6 hours on days 1, 6, 48, 90, 134, and 141.
• Arm III (CHOP + tositumomab): Patients receive chemotherapy as in arm I and tositumomab (monoclonal antibody anti-B1) IV over 1 hour followed by iodine I 131 tositumomab IV over 20 minutes on days 134 and 141.

Patients are followed on day 200, at 1 year, every 6 months for 2 years, and then annually thereafter.

PROJECTED ACCRUAL: Approximately 500 patients (250 per treatment arm) will be accrued for this study within 5.5 years. (Arm I closed to accrual as of 12/15/02)