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