There are two classifications of multiple myeloma. The cancer is classified according to whether or not it is causing symptoms.
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Asymptomatic (“without symptoms”) multiple myeloma - This is a relatively mild, early form of the disease. You might have low levels of M protein in your blood, as well as an increase in abnormal bone marrow plasma cells (the type of white blood cell from which the cancer develops).
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Symptomatic (“with symptoms”) multiple myeloma - This occurs when the disease is progressing and causing symptoms. You not only have the M protein and increased numbers of plasma cells, but also are experiencing symptoms of the disease, such as hypercalcemia (excess blood calcium), bone lesions, anemia, and possibly kidney failure.
Once your multiple myeloma has been classified, it will be staged. “Stage” is the term used to describe how far your cancer has advanced. Along with the classification, this is important information to have in making decisions about treatment. It also can be used to help predict prognosis, which is the likely course of your disease.
How Multiple Myeloma is Staged
Doctors can use one of two methods to determine the stage of multiple myeloma: the Durie-Salmon Staging System or the International Staging System. Both methods attempt to estimate how many myeloma cells are in the body.
The Durie-Salmon Staging System stages myeloma based on four pieces of information:
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Abnormal antibodies in the blood or urine - Myeloma cells produce abnormal antibodies called M proteins. They are different from normal healthy antibodies, which help the body defend itself against infection and disease. High levels of abnormal antibodies show that many myeloma cells are present.
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Calcium levels in the blood - Bones contain large amounts of the mineral calcium. The more damaged they are, the higher your calcium levels are likely to be.
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The degree of bone damage - Multiple areas of bone damage, as shown by x-rays or other imaging tests, would indicate that the myeloma is at a more advanced stage.
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Hemoglobin levels in the blood - Hemoglobin is the substance in red blood cells that carries oxygen. Low hemoglobin levels show that the myeloma cells are crowding the bone marrow, keeping it from making enough red blood cells.
Taken together, these four factors can help your doctor estimate the number of myeloma cells in the body.
He or she also may further classify the cancer as “A” or “B,” based on how much of a chemical called serum creatinine is in the blood. Healthy kidneys usually remove this chemical from the body. The creatinine level tends to rise when the kidneys are damaged, suggesting more advanced multiple myeloma.
Instead of using the Durie-Salmon Staging System, many doctors have begun using a newer approach called the International Staging System. Not only is it simpler to use, but recent studies suggest that it may be more accurate. This stages the myeloma based on two factors:
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The amount of a protein called beta-2-microglobulin in the blood - Beta-2-microglobulin is another protein that is released by myeloma cells. High levels indicate that many myeloma cells are present. They also can be a sign of the kidney damage that occurs in some people with multiple myeloma.
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The level of serum albumin - This is a blood protein made by the liver. It is needed to maintain the right volume of blood in the body. Lower levels suggest that multiple myeloma is at a more advanced stage.
Your doctor also may use additional tests and other information to help determine what stage your cancer is. For example, he or she might send out a sample of the myeloma cells for testing. The results would show how quickly the myeloma cells are growing. Special testing may be done to look at the genetic makeup of the cancer cells. This can help doctors classify the disease as “high-risk” (more aggressive and likely to spread) or “low-risk” (less aggressive). Check with your doctor to see what he or she recommends.
Stages of Multiple Myeloma
Multiple myeloma can be categorized into one of three stages:
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Stage I - This means that you have a low number of myeloma cells in your body. Myeloma cells are the abnormal plasma cells produced in the bone marrow. Healthy plasma cells are a type of white blood cell that helps the body defend itself against germs and other substances. Stage I multiple myeloma does not require treatment. It is sometimes referred to as “smoldering” multiple myeloma.
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Stage II - This means that there are a moderate number of myeloma cells in your body. Stage II multiple myeloma requires treatment. It is sometimes referred to as “indolent” multiple myeloma.
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Stage III - In stage III multiple myeloma, there is a high number of myeloma cells in your body. Stage III also requires treatment.
Sometimes the myeloma cells can collect at one site in the body, such as a bone or soft tissue. This single tumor is called a solitary plasmacytoma. Before making this diagnosis, your doctor has to make sure that there is no evidence of disease anywhere else in your body.
Other terms are often used to describe multiple myeloma after treatment begins:
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Relapsed multiple myeloma - This is multiple myeloma that has returned following successful treatment.
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Refractory multiple myeloma - Myeloma that does not respond to treatment. This can be first-time treatment or treatment for relapsed disease.