SERUM BETA(2)-MICROGLOBULIN FOR STAGING AND MONITORING OF MULTIPLE MYELOMAS AND OTHER NON-HODGKIN LYMPHOMAS

Background: In lymphoproliferative disorders serum beta(2)-microglobulin (beta(2)m) can be useful as a clinical marker. Material and Methods: beta(2)m measurements were carried out with a new assay of Hoffmann-La Roche, which is a one-step solid-phase enzyme immunoassay with competitive inhibition. Sera of 81 healthy subjects, 42 patients with renal failure, 108 patients with monoclonal gammopathies [3 monoclonal gammopathies of undetermined significance (MGUS), 91 multiple myeloma (MM), 14 macroglobulinemia (MG)], and 11 patients with non-Hodgkin lymphoma (NHL) were tested. In addition beta(2)m was determined during follow-up of 29 patients with myeloma and lymphoma. Results: beta(2)m values of normal sera ranged from 1.0 to 3.0 mg/l in 97.5%. Patients with renal malfunction had the highest beta(2)m concentrations (60 mg/l) with significant correlation (p<0.01) to serum creatinine (r=0.45). 57% of the patients with MM and NHL had raised beta(2)m levels when compared to healthy controls. Serum beta(2)m values did not correlate with the serum levels of monoclonal immunoglobulins. Using the myeloma staging system of Durie and Salmon, a strong association of pretreatment serum beta(2)m with advanced stage of disease was found. In stages II and III, beta(2)m levels were significantly higher than in stage I (p<0.001). Seven patients with smoldering myeloma showed beta(2)m concentrations within the normal range. No association with histologic cell types of myeloma was found. In the follow-up of patients with myeloma, beta(2)m values decreased with response to chemotherapy and were low in stable remission. At relapse very high beta(2)m concentrations were associated with a poor prognosis. Conclusion: Serum beta(2)m appears to be a good prognostic marker in MM independent of the paraprotein concentration. In MM and also in other NHL, beta(2)m determination helps to optimize therapy.