S0115, High-Dose Melphalan and Autologous Peripheral Stem Cell Transplantation in Treating Patients With Multiple Myeloma or Primary Systemic Amyloidosis

DISEASE CHARACTERISTICS: * At least 1 of the following diagnoses: * Multiple myeloma * Stage II or III disease * At least 1 of the following must be present: * Serum M-protein of IgG, IgA, IgD, IgE greater than 1.0 g/dL * Urinary M-protein (Bence-Jones) at least 200 mg/24 hours * No IgM peaks except in patients who have physiologic criteria to support a diagnosis of multiple myeloma (e.g., bony lesions, myeloma kidney-cast nephropathy, absence of adenopathy \[unless pathology-proven to be plasma cell infiltration\]) * No monoclonal gammopathy of undetermined significance * No indolent or smoldering myeloma * No disease progression on prior thalidomide or dexamethasone * Histologically confirmed primary systemic amyloidosis * No senile, secondary, localized, dialysis-related, or familial amyloidosis * No severe cardiac involvement * No pre-exertional syncope, ventricular arrhythmia, or symptomatic pleural effusions associated with cardiac involvement * Light Chain Deposition Disease alone or in combination with multiple myeloma meeting the following criteria: * Deposition of granular material containing free light chains/immunoglobulins that did not bind Congo red * Evidence of plasma cell dyscrasia (i.e., monoclonal gammopathy in the serum or urine by immunofixation electrophoresis and/or clonal plasmacytosis) on bone marrow biopsy by immunohistochemistry and/or elevated serum-free light chain concentration * Must have been diagnosed within the past year * Concurrent enrollment in the myeloma repository protocol SWOG-S0309 must be offered PATIENT CHARACTERISTICS: Age * 18 and over (patients with amyloidosis only OR patients with amyloidosis and multiple myeloma OR patients with multiple myeloma only with poor renal function) OR * 70 and over (patients with multiple myeloma only with or without poor renal function) Performance status * Zubrod 0-2 Life expectancy * Not specified Hematopoietic * Absolute neutrophil count at least 1,000/mm\^3 * Platelet count at least 100,000/mm\^3 Hepatic * Bilirubin no greater than 2.5 times upper limit of normal (ULN) * SGOT or SGPT no greater than 2.5 times ULN Renal * No hemodialysis within 2 hours of melphalan or stem cell infusion Cardiovascular * See Disease Characteristics * Hemodynamically stable (i.e., systolic blood pressure \> 90 mm Hg in a lying position within the past 42 days) * No myocardial infarction within the past 6 months * No congestive heart failure * No arrhythmia refractory to medical therapy * LVEF greater than 45% by echocardiogram or MUGA Pulmonary * See Disease Characteristics * No history of chronic obstructive or chronic restrictive pulmonary disease * Pulmonary function studies (e.g., FEV\_1 and FVC) at least 50% of predicted * DLCO at least 50% of predicted * Normal high resolution CT scan of the chest and acceptable arterial blood gases (i.e., PO\_2 greater than 70) required for patients unable to complete pulmonary function tests due to bone pain or fracture Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * Multiple myeloma patients receiving thalidomide must use 2 methods of effective contraception for at least 4 weeks before, during, and for at least 4 weeks after discontinuation of thalidomide * HIV negative * No other concurrent significant medical condition * No concurrent uncontrolled life-threatening infection * No other 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 or II cancer currently in complete remission PRIOR CONCURRENT THERAPY: Biologic therapy * See Disease Characteristics Chemotherapy * See Disease Characteristics * Prior cumulative melphalan dose no more than 200 mg * No other concurrent chemotherapy Endocrine therapy * See Disease Characteristics * No concurrent hormonal therapy Radiotherapy * No concurrent radiotherapy Surgery * Not specified Other * Recovered from prior therapy * Prior or concurrent bisphosphonates allowed