In 323 SMM patients (IMWG 2014 criteria, diagnosed at Memorial Sloan Kettering Cancer Center 2002–2019), this study evaluated whether serial M-protein and free light chain ratio (FLCr) changes during the first year after diagnosis could improve risk stratification beyond the static baseline 2/20/20 model.
An increase in M-protein ≥0.4 g/dL (eMP; HR 2.8, 95% CI 1.5–5.5) or FLCr ≥40% (eFLCr; HR 2.9, 95% CI 1.8–4.8) within year 1 were each independently associated with progression to MM; adding these to the 2/20/20 model raised the C-index from 0.70 to 0.79, and high-risk patients with evolving markers had 2- and 5-year progression rates of 41% and 83%, versus 8% at 5 years for low-risk patients without evolving disease.
Single academic center retrospective design introduces selection bias; the dynamic model requires one full year of follow-up and cannot flag the ~7–8% of patients who progress within the first 12 months; external prospective validation is still needed.
For SMM patients under active surveillance, check whether M-protein has risen ≥0.4 g/dL or FLCr has risen ≥40% by the 12-month visit — those who meet either threshold face roughly 3× higher progression risk and should be considered for earlier intervention or clinical trial enrollment. Conversely, low-risk patients by 2/20/20 who show no evolving markers at 1 year have a very indolent course (5-year progression ~8%) and may be candidates for less intensive monitoring.
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