OUTLINE: This is a randomized, multicenter study. Patients are stratified according to prior transplantation (yes vs no), prior treatment failure (resistant vs relapsing), prior treatment regimens (1-2 vs 3-4), and prior thalidomide (no vs some). Patients are randomized to one of two treatment arms. Arm I: Patients receive oral dexamethasone daily and cyclophosphamide, etoposide, and cisplatin (DCEP) IV continuously on days 1-4. Patients also receive filgrastim (G-CSF) subcutaneously daily beginning on day 5 and continuing until blood counts recover. Treatment continues every 3-4 weeks for 3 courses. Patients achieving stable disease or better proceed to maintenance chemotherapy with DCEP administered every 8 weeks for 3 additional courses. Arm II: Patients receive chemotherapy with DCEP as in arm I plus oral thalidomide daily. Thalidomide continues with maintenance chemotherapy and then continues after chemotherapy is completed until disease progression. Patients are followed every 3 months for 1 year, every 6 months for 1 year, and then annually for 3 years.