C-reactive protein and β-2 microglobulin produce a simple and powerful myeloma staging system

Abstract

Multiple myeloma (MM) staging procedures are still inadequate for detection of the optimal therapeutic procedure for an individual patient. The Durie & Salmon staging system and serum β2-microglobulin (β2M) are used worldwide because of their easy clinical application. Other prognostic parameters, such as myeloma cell proliferative activity, are of exceeding importance, but are not as simple as standard methods. Recently, interleukin-6 (IL-6) has been shown to be a major growth factor for MM. IL-6 is a pleiotropic cytokine acting on several cell lineages, and, at the hepatocyte level, stimulates the synthesis of acute phase proteins, such as the well known C-Reactive Protein (CRP). Serum CRP concentration actually reflects the IL-6 activity. A survival analysis carried out in 162 MM patients at diagnosis showed that serum CRP level is a highly significant prognostic factor. Moreover, serum CRP was independent of serum β2M. This feature allowed stratification of MM patients into 3 groups according to CRP and β2M serum levels: (1) low risk group, CRP and β2M <6 mg/L (50% of patients); (2) intermediate risk group CRP or β2M ≥6 mg/L (35% of patients); (3) high risk group, CRP and β2M ≥6 mg/L (15% of patients). Survival was 54, 27, and 6 months, respectively (P < .0001). We thus propose a new and powerful myeloma staging system based on simple and reliable laboratory evaluations. © 1992 by The American Society of Hematology.