Smoldering multiple myeloma: to treat or not to treat

Smoldering multiple myeloma (SMM) is an asymptomatic disorder characterized by the presence of ≥ 30 g/l serum M-protein and/or ≥ 10% bone marrow plasma cell infiltration. The progression risk to active multiple myeloma (MM) is not uniform, and several prognostic parameters are useful for identifying patients at high risk of progression. A watch-and-wait approach has been the standard of care up to now. However, recently, it has been demonstrated that a subset of high-risk cases can benefit from early treatment with new drugs.

In this editorial, we focus on SMM and evaluate the diagnostic work-up and the prognostic factors predicting progression to symptomatic MM. We also review the studies in which the role of early treatment has been evaluated for patients with SMM.

After the update performed by the International Myeloma Working Group regarding MM diagnosis, it is now time to change the therapeutic paradigm for this disease. While "ultra high-risk" myeloma should now be considered as active MM, for low-risk patients the "watch-and-wait" strategy is still recommended. More caution is needed for the high-risk group: physicians should continue monitoring patients using every tool now available while waiting for results from ongoing trials that will establish if this group will benefit from an early intervention.