OBJECTIVES: Primary * Determine the 2-year and overall progression-free survival of patients with newly diagnosed, previously untreated primary systemic (AL) amyloidosis treated with risk-adapted melphalan followed by thalidomide and dexamethasone. Secondary * Determine plasma cell disease response in these patients at 3, 12, and 24 months after treatment with this regimen. * Determine amyloid-related disease response in these patients at 12 and 24 months after treatment with this regimen. * Determine the prognostic significance of immunoglobulin light-chain variable-region germline gene expression by AL plasma cell clones in patients treated with this regimen. * Determine whether there is molecular minimal residual disease at 12 and 24 months in patients achieving a complete hematologic response after treatment with this regimen. OUTLINE: Patients are stratified according to the extent of amyloid-related disease (low-risk vs high-risk). * High-risk disease: Patients receive 2 courses of low-dose melphalan IV, dexamethasone, and filgrastim (G-CSF). After 3 months, patients receive thalidomide and dexamethasone if plasma cell disease persists. * Low-risk disease: Patients receive 1 course of high-dose melphalan IV and G-CSF. Patients then receive thalidomide and dexamethasone as in high-risk disease regimen. Patients are followed at 3, 12, and 24 months. PROJECTED ACCRUAL: A total of 82 patients will be accrued for this study.
DISEASE CHARACTERISTICS: * Diagnosis of primary systemic (AL) amyloidosis within the past 12 months * High- or low-risk disease, determined by the extent of systemic organ involvement with disease and patient age PATIENT CHARACTERISTICS: Age * 18 and over Performance status * SWOG 0-3 Life expectancy * Not specified Hematopoietic * Not specified Hepatic * Not specified Renal * Not specified Cardiovascular * No New York Heart Association class III or IV congestive heart failure * No restrictive cardiomyopathy requiring oxygen * No myocardial infarction within the past 6 months * No symptomatic cardiac arrhythmia within the past 60 days Other * No other active malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, or adequately treated stage I cancer in complete remission PRIOR CONCURRENT THERAPY: Biologic therapy * Not specified Chemotherapy * No prior chemotherapy for AL amyloidosis Endocrine therapy * Not specified Radiotherapy * Not specified Surgery * Not specified Other * No other prior or concurrent therapy for AL amyloidosis