Beta-2-microglobulin levels in patients with extranodal B-cell lymphoma ofthe mucosa-associated lymphoid tissue (MALT)-type: A retrospective analysis

Background: Serum levels of beta-2 microglobulin (B2M) have been reported a s a predictor of clinical outcome, prognosis and tumor burden in patients w ith various types of lymphomas. In case of lymphoma of the mucosa-associate d lymphoid tissue (MALT) - type, no clear data exist to define the role of B2M in terms of staging or prognosis. In a retrospective analysis we invest igated the serum B2M-levels in patients suffering from histologically verif ied MALT-type lymphoma in correlation to stage and response to treatment. P atients and Methods: All patients admitted to our institution since 1996 wi th a diagnosis of MALT-type lymphoma were retrospectively evaluated for sta ging procedures and measurements of serum B2M levels. Patients with a stagi ng work-up including otorhinolaryngologic evaluation, gastroscopy with mult iple biopsies, endosonography of the upper GI-tract, enteroclysis, colonosc opy, CT of thorax and abdomen and bone marrow biopsy were analysed, while s taging was performed according to the Ann Arbor system as modified by Mussh off. In addition, only patients with histologic samples amenable to re-asse ssment by a reference pathologist were included. Results: A total of 68 pat ients with a diagnosis of MALT-type lymphoma were identified from our recor ds. However, only in 32 patients exact staging according to our inclusion c riteria had been performed and serum B2M-levels prior to the initiation of therapy were available in all these patients. Twenty-five patients; suffere d from gastric lymphoma, while the remaining 7 patients had extragastric ma nifestations. In total, 13 out of 32 patients presented with stage I diseas e, 17 patients were rated as stage II and 2 patients suffered from stage II I disease. Nineteen patients had elevated B2M-levels prior to therapy: 6 pa tients were rated as stage I, 11 had stage II and two had stage III disease . Five patients still had elevated B2M-Ievels following treatment despite r adiologically and histologically verified complete remission. Conclusion: I n this series, no correlation between serum B2M levels, tumor burden and cl inical outcome was apparent in patients with MALT-type lymphomas. While the number of patients with disseminated disease was small we could not demons trate a difference for B2M-levels between stage I and stage II. While we ca nnot rule out that B2M might be different in patients with stage IN disease as compared to more advanced disease, further investigations are necessary to determine the role of this marker in patients with MALT-type lymphoma.