Staging of myeloma

MM

Early Active Myeloma

HR SMM

LR SMM

MGUS

CRAB Criteria

Myeloma-de ning events (MDE) Bone marrow plasma cells ≥ 60% Ratio of monoclonal to normal light chains ≥100 >1 focal lesion on MRI

Spanish Criteria Mayo Criteria

MM Multiple Myeloma Early Active Myeloma Ultra-High-Risk Smoldering Myeloma HR SMM High-Risk Smoldering Multiple Myeloma LR SMM Low-Risk Smoldering Multiple Myeloma MGUS Monoclonal Gammopathy of Undetermined Signi cance

When myeloma is diagnosed, the stage of the disease varies from patient to patient.

In 1975, the Durie-Salmon Staging System (DSS) was introduced to classify patients with myeloma. The DSS demonstrated the correlation between the amount of myeloma and the damage caused by it. In some patients who produce a lot of M-protein, the number of myeloma cells can be quite low. Conversely, in patients with low M-protein production, the number of myeloma cells can be high.

In 2005, the IMWG developed the International Staging System (ISS), which is based on prognostic factors and expected survival. The ISS assesses disease behavior that is most predictive of aggressive myeloma. The ISS is based on four highly predictive markers of aggressive disease: 1. Serum beta-2 microglobulin (S β2M), 2. Serum albumin (S ALB), 3. C-reactive protein (CRP), and 4. Serum lactate dehydrogenase (LDH).

In 2015, the IMWG published the Revised International Staging System (R-ISS), combining ISS with two tests for chromosomal abnormalities.

STAGE

STAGE I

(low cell mass)

Table 3. The Durie-Salmon Staging System (DSS)

CRITERIA MEASURED MYELOMA CELL MASS (myeloma cells in whole body)

All of the following: • Hemoglobin value > 10 g/dL • Serum calcium value normal or < 10.5 mg/dL • Bone X-ray, normal bone structure (scale 0), or solitary bone plasmacytoma only • Low M-protein production rates IgG value < 5 g/dL; IgA value < 3 g/dL • Urine light chain M-protein on electrophoresis < 4 g/24h 600 billion/m2

STAGE II

(intermediate cell mass) Fitting neither Stage I nor Stage III

STAGE III

(high cell mass) One or more of the following: • Hemoglobin value < 8.5 g/dL • Serum calcium value > 12 mg/dL • Advanced lytic bone lesions (scale 3) • High M-protein production rates IgG value > 7 g/dL; IgA value > 5 g/dL • Urine light chain M-protein >12 g/24h > 1,200 billion/m2

600 to 1,200 billion/m2

SUBCLASSIFICATION

(either A or B) • A: relatively normal renal function (serum creatinine value) <2.0 mg/dL • B: abnormal renal function (serum creatinine value) >2.0 mg/dL

Table 4. Standard risk factors for myeloma and the R-ISS

PROGNOSTIC FACTOR CRITERIA ISS Stage I Serum β2-microglobulin < 3.5 mg/L, serum albumin ≥ 3.5 g/dL II Not ISS stage I or III III Serum β2-microglobulin ≥ 5.5 mg/L CA by FISH High Risk Presence of del(17p) and/or translocation t(4;14) and/or translocation t(14;16) Standard Risk No high-risk CA LDH Normal Serum LDH < the upper limit of normal High Serum LDH > the upper limit of normal

A new model for risk stratification for multiple myeloma

R-ISS Stage I ISS stage I and standard-risk CA by FISH and normal LDH II Not R-ISS stage I or III III ISS stage III and either high-risk CA by FISH or high LDH

Abbreviations: CA, chromosomal abnormalities; FISH, interphase fluorescence in situ hybridization; ISS, International Staging System; LDH, lactate dehydrogenase; R-ISS, Revised International Staging System.