Chemotherapy Plus Interferon Alfa Alone or With Radiation Therapy and Peripheral Stem Cell Transplantation in Treating Patients With Stage III or Stage IV Follicular Non-Hodgkin's Lymphoma

OBJECTIVES: I. Compare the progression free and overall survival, toxicity, and mortality of marrow ablative chemo/radiotherapy in addition to peripheral blood stem cell transplantation and interferon alfa maintenance therapy versus interferon alfa maintenance therapy alone in patients with follicular non-Hodgkin's lymphoma. OUTLINE: This is a randomized study. All patients receive 8 courses of cyclophosphamide/vincristine/prednisone (CVP) chemotherapy. Cyclophosphamide and vincristine IV are given on day 1, along with oral prednisone on days 1-5. Courses are repeated every 3 weeks. Patients are randomized to receive one of two treatments 4 weeks after completion of CVP chemotherapy if a partial or complete response is achieved and there are less than 15% monoclonal B-lymphocytes in the bone marrow. Patients randomized to arm I receive interferon alfa subcutaneously 3 times per week for a maximum of 3 years. Patients randomized to arm II receive cyclophosphamide IV followed by subcutaneous filgrastim (granulocyte colony-stimulating factor; G-CSF). Leukapheresis begins after leukocyte, platelet, and CD34+ levels recover and lasts 3-4 hours on 2-3 consecutive days. If an insufficient number of stem cells are collected from the peripheral blood, bone marrow harvesting is performed. After stem cell collection, a conditioning regimen consisting of cyclophosphamide IV on days -4 and -3 and total body irradiation on day -1 is administered. Stem cells are infused on day 0. If granulocyte and platelet counts recover within 8 weeks, patients receive interferon alfa maintenance therapy as in arm I. Patients are followed every 4 months until death. PROJECTED ACCRUAL: A total of 469 patients will be accrued for this study within 5 years.