S9628 Dexamethasone Plus Interferon Alfa in Treating Patients With Primary Systemic Amyloidosis

DISEASE CHARACTERISTICS: * Histologically diagnosed primary systemic amyloidosis based on the following: * Deposition of fibrillary protein with Congo red positive stain or characteristic electron microscopic appearance * Monoclonal light chain protein (Bence-Jones protein) in serum or urine or immunohistochemical studies * Evidence of tissue involvement other than carpal tunnel syndrome * Diagnostic histologic material available for central pathology review * Confirmation of tissue diagnosis at all sites of organ dysfunction encouraged * No senile, secondary, localized, dialysis-related, or familial amyloidosis * No known therapy-related myelodysplasia PATIENT CHARACTERISTICS: Age: * Adult Performance status: * SWOG 0-4 Hematopoietic: * Not specified Hepatic: * Not specified Renal: * Not specified Cardiovascular: * No NYHA class IV status Other: * No uncontrolled diabetes * No active peptic ulcer disease * No medical condition that precludes high-dose steroids * No second malignancy within 5 years except: * Adequately treated nonmelanomatous skin cancer * In situ cervical cancer * Adequately treated stage I/II cancer in complete remission * Not pregnant or nursing * Effective contraception required of fertile patients * Blood/body fluid analyses within 14 days prior to registration * Imaging/exams for tumor measurement within 28 days prior to registration * Other screening exams within 42 days prior to registration PRIOR CONCURRENT THERAPY: Biologic therapy * No prior interferon alfa Chemotherapy * Prior melphalan allowed, but recovered from effects * At least 4 weeks since cytotoxic therapy and recovered Endocrine therapy * Prior prednisone allowed, but recovered from effects * At least 4 weeks since prior glucocorticoids * No prior dexamethasone * No planned or concurrent dexamethasone or other therapy for primary systemic amyloidosis Radiotherapy * Not specified Surgery * Not specified