The American Cancer Society estimates that 20,580 new cases of multiple myeloma were diagnosed in 2009--about 11,680 in males and 8,900 in females--and that 10,580 Americans died from the disease. Two systems are used to classify this cancer in terms of severity. For both, multiple myeloma is divided into three stages, with stage III representing the final stage. As the two systems employ different measures, health care practitioners typically use both to determine prognosis and treatment.
Durie-Salmon Staging System: Stage III
According to the American Cancer Society, the Durie-Salmon staging system defines stage III multiple myeloma based on four factors: a high level of M protein in the blood or urine, three or more bone lesions on X-rays, a high level of calcium in the blood and a low hemoglobin level. The blood calcium level in stage III multiple myeloma exceeds 12 mg/dL, while the hemoglobin level is below 8.5 g/dL. These indicators confirm that a large amount of myeloma cells are present throughout the body.
Durie-Salmon Staging System: IIIA and IIIB
The Durie-Salmon staging system further divides final-stage multiple myeloma according to kidney function, reports the Multiple Myeloma Research Foundation. Stage IIIA, a serum creatinine value less than 2.0 mg/dL, indicates that the kidney function is relatively normal. In contrast, stage IIIB, serum creatinine equal to or more than 2.0 mg/dL, denotes abnormal kidney function. Stage IIIB multiple myeloma mandates immediate treatment to recover kidney function, according to the MD Anderson Cancer Center.
International Staging System: Stage III
New diagnostic methods led to the development of the International Staging System, which was introduced by the International Myeloma Foundation's Working Group in 2005. This simple, reliable classification uses only one measure to denote stage III disease, a serum beta-2 microglobulin exceeding 5.5. The International Myeloma Foundation selected this blood marker for its prognostic accuracy, based on results in a large international database, and the availability of a simple, inexpensive laboratory test.
References
- American Cancer Society: What Are the Key Statistics About Multiple Myeloma?
- American Cancer Society: How is Multiple Myeloma Staged?
- Multiple Myeloma Research Foundation: Current and Emerging Trends in the Treatment of Multiple Myeloma.
- "International Staging System (ISS) for Multiple Myeloma"; Journal of Clinical Oncology. Greipp et al. 2005.
- MD Anderson Cancer Center: Multiple Myeloma.
