OBJECTIVES: I. Compare the overall and progression-free survival and remission rates in patients with refractory multiple myeloma treated with dexamethasone, cyclophosphamide, etoposide, cisplatin, and filgrastim (G-CSF) with or without thalidomide. II. Compare the qualitative and quantitative toxic effects of these regimens in these patients.

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.

PROJECTED ACCRUAL: A total of 320 patients will be accrued for this study within 4 years.

DISEASE CHARACTERISTICS: Histologically or cytologically confirmed stage I, II, or III multiple myeloma with protein criteria present Quantifiable M-components of IgG, IgA, IgD, IgE AND/OR Urinary kappa or lambda light chain excretion No IgM peaks Quantifiable monoclonal proteins Received at least 1, but no more than 4 prior treatment regimens, including the following: Chemotherapy Bone marrow transplantation Biologic therapy Radiotherapy Interferon therapy or steroid pulsing given as maintenance therapy after transplantation or chemotherapy is not considered a separate treatment regimen Progressive disease

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Zubrod 0-2 (3-4 allowed if due solely to bone pain) Life expectancy: At least 3 months Hematopoietic: Absolute granulocyte count at least 1,000/mm3 Platelet count at least 50,000/mm3 (at least 50% plasma cells in bone marrow) Hepatic: Bilirubin no greater than 2.5 times upper limit of normal (ULN) SGOT or SGPT no greater than 2.5 times ULN Renal: Creatinine no greater than 2.0 mg/dL OR Creatinine clearance at least 60 mL/min Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use 2 methods of effective contraception for 4 weeks before, during, and for 4 weeks after study No other prior or concurrent malignancies within the past 5 years except adequately treated basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, or any other adequately treated stage I or II cancer in complete remission No grade 2 or greater preexisting peripheral neuropathy

PRIOR CONCURRENT THERAPY: Biologic therapy: See Disease Characteristics Prior thalidomide allowed if received less than 3 months of therapy Recovered from prior biologic therapy Chemotherapy: See Disease Characteristics At least 3 weeks since prior chemotherapy and recovered No other concurrent chemotherapy Endocrine therapy: See Disease Characteristics No concurrent hormonal therapy Radiotherapy: See Disease Characteristics At least 3 weeks since prior extensive or limited radiotherapy and recovered No concurrent radiotherapy Surgery: Not specified