In 2005, a new staging system was developed by the IMF's research division, the International Myeloma Working Group (IMWG). Clinical and laboratory data were gathered on 10,750 previously untreated symptomatic myeloma patients from 17 institutions, including sites in North America, Europe, and Asia. Potential prognostic factors were evaluated using a variety of statistical techniques. Serum β2 microglobulin (Sβ2M), serum albumin, platelet count, serum creatinine, and age emerged as powerful predictors of survival and were then further analyzed.
A combination of Sβ2M and serum albumin provided the most powerful, simple, and reproducible three-stage classification. This system, the International Staging System (ISS), was further validated by demonstrating effectiveness
- in patients in North America, Europe, and Asia;
- in patients younger and older than age 65 years;
- with standard therapy or auto transplant; and
- in comparison with the Durie-Salmon Staging System.
International Staging System (ISS) for Multiple Myeloma
| Stage | VALUES (β2M = Serum β2 microglobulin; ALB = serum albumin |
| I | Sβ2M < 3.5 mg/L; serum albumin ≥ 3.5 g/dL |
| II | Sβ2M < 3.5 mg/L; serum albumin < 3.5 g/dL; or β2M 3.5 to 5.5 mg/L, irrespective of serum albumin |
| III | Sβ2M > 5.5 mg/L |
In August 2015, the IMWG published the Revised International Staging System (R-ISS) for multiple myeloma to incorporate two further prognostic factors: genetic risk as assessed by fluorescence in-situ hybridization (FISH), and level of lactate dehydrogenase level (LDH).
Revised International Staging System (R-ISS)
| Stage | Criteria |
| I |
Sβ2M < 3.5 mg/l |
| II | Not R-ISS stage I or III |
| III |
Sβ2M ≥ 5.5 mg/L and either |
What's Next?
If you are a newly diagnosed myeloma patient, learn when and if to begin treatment. Also, if you have undergone an induction therapy, learn about maintenance therapy and other new interventions.
The International Myeloma Foundation medical and editorial content team
Comprised of leading medical researchers, hematologists, oncologists, oncology-certified nurses, medical editors, and medical journalists, our team has extensive knowledge of the multiple myeloma treatment and care landscape. Additionally, Dr. Brian G.M. Durie reviews and approves all medical content on this website.
Last Medical Content Review: August 24, 2021