Oncologists (doctors specializing in cancer) assign a stage to multiple myeloma as a way of expressing how advanced the cancer is and their prediction for how it will progress. Recommendations about myeloma treatment are based partly on the stage. Two different systems are used to stage multiple myeloma. Both systems recognize three stages and are based on the results of clinical tests rather than myeloma symptoms a person experiences.
Some doctors regard related precancerous conditions such as monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM) as early, asymptomatic stages of multiple myeloma. However, this article deals with how cancer is staged when multiple myeloma is first diagnosed or when it relapses. Read more about myeloma types and related disorders.
Systems for staging multiple myeloma
The two staging systems for multiple myeloma are based on measurements of different properties.
International Staging System (ISS)
The International Staging System was introduced in 2003, and many doctors consider it a more accurate assessment of the risk for multiple myeloma progression. The ISS does not take X-rays or bone lesions into account when staging multiple myeloma. Oncologists using the ISS perform a cytogenic study to examine the genes of cancer cells for traits connected with a high risk for progression. They also measure levels of different substances found in the blood:
Albumin – A common protein
Beta microglobulin – Protein produced by myeloma cells
Lactate dehydrogenase – Enzyme produced as cells turn glucose into energy
Durie-Salmon Staging System
First introduced in the 1970s, the Durie-Salmon staging system is still used by some doctors to stage multiple myeloma. Oncologists using the Durie-Salmon system look at X-rays and count bone lesions as well as measuring levels of certain substances in the blood and urine:
Hemoglobin – a protein that transports oxygen in the blood
Calcium – a mineral released when bones are breaking down
M-proteins – abnormal fragments of antibodies made by the immune system
Light chains – abnormal fragments of antibodies made by the immune system
If there is a relapse after multiple myeloma has been effectively treated, the oncologist may re-stage the cancer based on the same criteria.