ARM B: Patients receive vincristine sulfate, carmustine, and melphalan as in the induction phase, high-dose cyclophosphamide IV on days 1-4 and prednisone PO on days 1-4 during courses 3 and 5. Patients receive VBMCP as in the induction phase during even numbered courses. Patients receive recombinant interferon alfa-2b subcutaneously (SC) on days 1, 3, 5, 8, 10, 12, 15, 17, 19, and 22 during odd courses beginning course 7. Treatment repeats every 35 days for courses 3-5, every 21 days for even courses beginning course 6, and every 22 days for odd courses beginning course 7 in the absence of disease progression or unacceptable toxicity.