Table 2 Risk stratification of smoldering multiple myeloma (SMM).

From: Smoldering multiple myeloma current treatment algorithms

Mayo 2018 Criteria (20-2-20 critieria)

 High risk SMM (2-year risk of progression 50%)

  Any 2–3 of the following high risk factors:

   Serum monoclonal protein > 2 gm/dL

   Serum free light chain ratio (involved/uninvolved) >20

   Bone marrow plasma cells >20%

 Intermediate risk SMM

   Any 1 high risk factor

  Low risk SMM

   No high risk factor

International Myeloma Working Group Scoring System for SMMa

  High Risk SMM (2-year risk of progression, 75%)

   Score >12

 High-Intermediate Risk SMM (2-year risk of progression, 50%)

   Score 9–12

 Low-Intermediate Risk SMM (2-year risk of progression, 25%)

   Score 5–8

 Low Risk SMM (2-year risk of progression, 5%)

   Score 1–4

  1. aInternational Myeloma Working Group Scoring includes 4 components. Serum free light chain assay: Score of 0, 2, 3, and 5 for serum free light chain ratio 0–10, 11–25, 26–40, and >40, respectively; Serum protein electrophoresis: Score of 0, 3, and 4 for monoclonal protein level (gm/dL) 0–1.5, 1.6–2.9, and >3, respectively; Bone marrow: Score of 0, 2, 3, 5, and 6 for bone marrow plasma cell percentage 0–15, 16–20, 21–30, 31–40, and >40, respectively; Fluorescent in situ hybridization: Score of 2 for presence any high risk cytogenetic abnormality (del 17p, t(4;14), gain 1q, or del 13).
  2. Derived from Lakshman A, et al. Risk stratification of smoldering multiple myeloma incorporating revised IMWG diagnostic criteria. Blood Cancer J 2018;8:59; and Mateos MV, et al. International Myeloma Working Group risk stratification model for smoldering multiple myeloma (SMM). Blood Cancer J 2020;10:102.
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