What are risk factors for progression of monoclonal gammopathy of undetermined significance (MGUS)?

Updated: Jul 15, 2019
  • Author: Dhaval Shah, MD; Chief Editor: Emmanuel C Besa, MD  more...
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Answer

Patients with non-IgM MGUS have a risk of progression to MM at rate of 1% per year. For these patients, risk factors for progression to MM are as follows:

  • M protein concentration > 1.5 g/dL
  • Non-IgG isotype
  • An abnormal free light chain (FLC) ratio

Patients with IgM MGUS have a risk of progression to Waldenstrom macroglobulinemia and less frequently lymphoma or amyloid light chain (AL) amyloidosis. IgM MGUS rarely progresses into MM. Light chain MGUS has a tendency to progress to light chain MM, AL amyloidosis, or light chain deposition disease.

A study by Wadhera et al examined secondary MGUS that developed in patients with MM. Of 1942 patients with MM, 128 (6.6%) developed a secondary MGUS at a median of 12 months from the diagnosis of MM. Overall survival was superior in patients with MM who developed secondary MGUS compared with the rest of the cohort. [13]


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