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iStopMM: Smouldering MM highly prevalent in general population

Presented by
Dr Sigrún Thorsteinsdóttir, University of Iceland, Iceland
ASH 2021
A large, population-based study showed that smouldering multiple myeloma (MM) is highly prevalent in individuals 40 years or older. Approximately 1 out of 3 patients with smouldering MM may progress towards MM. These results display a need to improve treatment policies and risk stratification in patients with smouldering MM [1].

Smouldering MM is an asymptomatic, preliminary condition of MM. Screening for smouldering MM is currently not recommended. Therefore, few patients with MM are diagnosed at the smouldering stage of the disease. Yet, evidence indicates that treatment initiation at the smouldering stage of MM may be beneficial for health outcomes [2,3].

Dr Sigrún Thorsteinsdóttir (University of Iceland, Iceland) and colleagues aimed to map the epidemiological and clinical characteristics of smouldering MM. The large, population-based iStopMM study (NCT03327597) screened 75,422 individuals for M-protein and abnormal free light chain ratio. In total, 3,725 participants displayed abnormal screening results and were randomised to 1 of 3 study arms: no further workup, guideline-recommended follow-up, or intensive follow-up.

Bone marrow sampling was performed in 1,503 participants, resulting in 180 diagnoses of smouldering MM (median age 70 years; 39% women). The most prevalent isotypes were IgG (57%), IgA (24%), and light chain (14%). The plasma cell burden was mostly low, with 73% of the participants showing plasma cell concentrations of 11–20%. The prevalence of smouldering MM in the total population was estimated at 0.53% in individuals 40 years or older, with increasing prevalence in older individuals (see Figure). The Mayo clinic 2018 risk stratification model for MM was used to classify participants into high risk (10%), intermediate risk (26%), or low risk (64%) of progression to MM.

Figure: Prevalence of smouldering MM according to age [1]

Dr Thorsteinsdóttir argued that treatment initiation at the smouldering MM stage may be included in the guidelines shortly. The high prevalence of smouldering MM in the general population showed the importance of better screening and risk management for this condition.

  1. Thorsteinsdóttir S, et al. Prevalence of Smoldering Multiple Myeloma: Results from the Iceland Screens, Treats, or Prevents Multiple Myeloma (iStopMM) Study. Abstract 151, ASH 2021 Annual Meeting, 11–14 December.
  2. Mateos MV, et al. N Engl J Med 2013;369(5):438–447.
  3. Lonial S, et al. J Clin Oncol. 2020;38(11):1126–1137.


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