Table 2.

Definition of high-risk SMM

Clonal BMPCs ≥10% and any one or more of the following:
Serum M protein ≥30g/L
IgA SMM
Immunoparesis with reduction of 2 uninvolved immunoglobulin isotypes
Serum involved/uninvolved FLC ratio ≥8 (but <100)
Progressive increase in M protein level (evolving type of SMM; increase in serum M protein by ≥25% on 2 successive evaluations within a 6-month period)
Clonal BMPCs 50%-60%
Abnormal PC immunophenotype (≥95% of BMPCs are clonal) and reduction of ≥1 uninvolved immunoglobulin isotypes
t(4;14) or del(17p) or 1q gain
Increased circulating PCs
MRI with diffuse abnormalities or 1 focal lesion
PET-CT with focal lesion with increased uptake without underlying osteolytic bone destruction

The term SMM excludes patients without end-organ damage who meet the revised definition of MM; namely, clonal BMPCs ≥60% or serum FLC ratio ≥100 (plus measurable involved FLC level ≥100 mg/L), or >1 focal lesion on MRI scan. The risk factors listed are not meant to be indications for therapy; they are variables associated with a high risk of progression of SMM and identify patients who need close follow-up and consideration for clinical trials.

PET-CT, positron emission tomography with computed tomography.