Serum beta-2 microglobulin in malignant lymphomas: an old but powerful prognostic factor.

Beta-2 microglobulin is synthesized in all nucleated cells and forms the light chain subunit of the major histocompatibility complex class I antigen. Despite its potential role as a convenient and non-invasive prognostic indicator in malignant lymphomas, the influence of serum β2 microglobulin is currently underestimated, and therapeutic decision making is rarely affected by this marker. Recent studies that included relatively large numbers of patients with specific histologic subtypes showed that serum β2 microglobulin is a potent prognostic marker in malignant lymphomas. In follicular lymphoma, this effort led to the incorporation of serum β2 microglobulin as an indicator in a new prognostic model. In this review, we summarize the current evidence supporting the role of serum β2 microglobulin as a prognostic factor in patients with malignant lymphoma and discuss perspectives for future investigations.