MAYO 20/20/20SMM Progression Risk Score
The "20/20/20" Metrics
%
Threshold > 20%
Ratio
Threshold > 20
g/dL
Threshold > 2 g/dL
Awaiting SMM Biomarkers
Guidelines & Evidence
Verified
Last Review: 2026
When to Use
Clinical Use
Patients formally diagnosed with Smoldering Multiple Myeloma (serum M-protein ≥3 g/dL or bone marrow plasma cells 10-59%, with NO CRAB features or SLiM-CRAB biomarkers of active malignancy).
Used to determine the optimal frequency of laboratory and imaging surveillance.
Crucial for identifying candidates for clinical trials investigating early therapeutic intervention (e.g., lenalidomide, dexamethasone, or daratumumab) designed to delay the onset of end-organ damage.
How it Works
The 3 Biomarkers
Bone Marrow Plasma Cells (BMPC): > 20% (1 point)
Serum M-Protein: > 2 g/dL (1 point)
Serum Free Light Chain (FLC) Ratio (involved vs. uninvolved): > 20 (1 point)
Risk Stratification
| Risk Group | Risk Factors | Median Time to Progression |
|---|---|---|
| Low Risk | 0 factors | 110 months (~9 years) |
| Intermediate Risk | 1 factor | 68 months (~5.6 years) |
| High Risk | 2 or 3 factors | 29 months (~2.4 years) |
Clinical Pearls
Differentiating SMM from Active Myeloma
The 20/2/20 criteria MUST NOT be confused with the SLiM-CRAB criteria. If BMPC is ≥ 60%, or FLC ratio is ≥ 100, or MRI shows >1 focal lesion, the patient has *Active Multiple Myeloma* regardless of symptoms, and standard induction therapy is mandated, not observation or SMM-trial therapies.
Management Nuance
While high-risk SMM patients have a rapid progression curve, the standard of care outside of a clinical trial remains highly debated. Some guidelines support the use of single-agent lenalidomide or lenalidomide/dexamethasone for high-risk patients based on trials showing delayed progression, though overall survival benefits are still being maturely evaluated.
The Evidence
Key Reference
International Myeloma Working Group risk stratification model for smoldering multiple myeloma (SMM)
Mateos MV et al. • Blood Cancer Journal. 2020;10(10):102
Last Comprehensive Review: 2026