Doctors assign multiple myeloma a stage as a concise way of describing where the cancerous cells are, whether and where they have spread, and whether they are affecting other parts of the body. As with other cancers, the purpose of staging multiple myeloma is to help doctors determine the best treatment and prognosis (chance of recovery). Different types of cancer rely on different staging systems. The staging system used for multiple myeloma is different from the kind used for breast cancer, for instance. Multiple myeloma is a cancer of the plasma cells in the bone marrow, but it can impact everything from bone density to kidney function. Staging the disease involves considering all these possible complications — a complex task. RELATED: What Are Mycosis Fungoides and Sezary Syndrome? Symptoms, Causes, Diagnosis, Treatment, and Prevention
Describing Myeloma as Symptomatic or Not
Usually the first job in staging multiple myeloma is categorizing the cancer as symptomatic or asymptomatic. Physicians can take a quantitative approach to symptoms, looking at the results of blood and urine analyses, imaging scans, and other diagnostic tests. Doctors use the acronym CRAB as a shorthand to describe the criteria they’re looking at:
C — calcium elevation (high levels of calcium in the blood)R — renal insufficiency (poor kidney function)A — anemia (low red blood cell count)B — bone abnormalities (lesions and thinning) (1)
Multiple myeloma that does not cause these symptoms is called smoldering multiple myeloma (SMM). People with SMM have a high blood level of an antibody produced by abnormal plasma cells. This antibody goes by a number of names, including monoclonal protein (M protein). SMM patients also have large amounts of plasma cells in the bone marrow and light chains (small protein segments) in the blood and urine. But these patients will also have normal blood counts, calcium levels, and kidney function, no bone or organ damage, and no signs of a condition called amyloidosis (amyloid is a protein that builds up in tissues of some patient with multiple myeloma). Doctors typically take a watch-and-wait approach to SMM, moving to treatment only when the cancer advances and begins to cause symptoms. (2) RELATED: Cancer News Digest: Latest Developments in Cancer Research and Treatment for June The system focuses on four key considerations:
Amount of albumin in the blood Albumin is an important protein produced by the liver and an indicator of overall health. It plays a role in fighting infections and building or repairing muscle tissue.Amount of beta-2 microglobulin in the blood This is a protein produced by myeloma cells. High levels in the blood suggest the cancer is at an advanced stage.Amount of LDH in the blood Lactate dehydrogenase is an enzyme found in tissues throughout the body. High levels in the blood may reveal tissue damage or disease.Specific gene abnormalities (cytogenetics) of the cancer Certain chromosome changes, such as the loss of a piece of chromosome 17, make multiple myeloma more dangerous.
The RISS translates this information into three multiple myeloma stages:
Stage 1 Serum beta-2 microglobulin is less than 3.5 milligrams per liter (mg/L); albumin level is 3.5 grams per deciliiter (g/dL) or greater; cytogenetics are considered “not high risk”; and LDH levels are normalStage 2 Not stage 1 or 3Stage 3 Serum beta-2 microglobulin is 5.5 mg/L or greater and cytogenetics are considered “high risk” or LDH levels are high (3)
Durie-Salmon Staging System
This multiple myeloma staging system, introduced in 1975 and updated in 2006, remains in use by physicians who find it helpful in determining the extent of the disease. The system uses stages 1, 2, and 3 and relies on specific measurements of red blood cells, blood calcium levels, M protein levels in the blood and urine, and bone lesions. Each stage is further classified as A or B, with B signifying serious kidney damage (a factor that typically relates to a poorer overall prognosis):
Stage 1 Patients may not show symptoms because there are only a limited number of myeloma cells in the body. The number of red blood cells is within or slightly below normal range; there’s a normal amount of calcium in the blood; and there are low levels of M protein in the blood and urine.Stage 2 Not Stage 1 or Stage 3. More myeloma cells are present in the blood.Stage 3 Many myeloma cells are present in the blood. Red blood cell counts are low (anemia); blood calcium levels are high; there’s advanced bone damage (three or more bone lesions); and there are high levels of M protein in the blood or urine. (4)
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Restaging Multiple Myeloma That Comes Back
Multiple myeloma may return after treatment or a period of remission. This kind of myeloma is called recurrent or relapsed. Since multiple myeloma is not yet curable, most patients will relapse at some point. When this happens doctors may need to restage the cancer using one of the systems above. (4)
How Staging Corresponds to Survival Rates
Doctors use staging as one way to assess a multiple myeloma patient’s odds of survival. Survival rates typically indicate what percentage of people with the same type and stage of cancer are still alive five years after diagnosis. Generally people with early-stage multiple myeloma face better odds than people at later stages. Still, cancer stage doesn’t tell the whole story. An individual’s chance of survival also depends on factors that aren’t part of staging systems. These include the patient’s age and overall health, and how well the cancer responds to treatment. (5)
