Classifying Multiple Myeloma
This article first appeared on the Multiple Myeloma Research Foundation website and is reprinted here with their permission.
Multiple myeloma is classified into one of three categories. Classification of multiple myeloma is important because immediate disease-directed treatment is needed only for symptomatic myeloma. Knowing your classification is very important in deciding when it is appropriate to begin treatment. Classification also plays an important role in determining the stage of multiple myeloma.
The three categories of multiple myeloma are:** 1. Monoclonal gammopathy of undetermined significance (MGUS)**
MGUS is a benign condition that can lead to multiple myeloma. Approximately 1.5% of persons older than 50 years and 3% of the population older than 70 in the U.S. are living with MGUS. It involves an excess of M protein, but the plasma cells have not formed a tumor or multiple lesions, no symptoms have occurred, and other criteria for a myeloma diagnosis are absent. MGUS itself is benign, but over many years, approximately 16% of individuals with MGUS will progress to a malignant plasma cell disorder, such as multiple myeloma.
- Serum M protein level is < 3 g/dL (less than 3 grams per deciliter)
- Percentage of plasma cells in the bone marrow is < 10%
- Absence of anemia, renal failure, hypercalcemia, and ostolytic lesions
2. Asymptomatic myeloma (further subdivided into smoldering myeloma or indolent myeloma)
Individuals with smoldering myeloma (asymptomatic myeloma) have a slightly increased level of M protein and a slightly increased number of plasma cells in the bone marrow. Smoldering myeloma is characterized by a lack of multiple myeloma symptoms. Patients may have mild anemia and/or a few bone lesions, but they do not have renal failure and frequent infection, which characterize the active form of the disease. Instead, myeloma is static and may not progress for months or years. Asymptomatic multiple myeloma includes both smoldering multiple myeloma and indolent multiple myeloma.
The characteristics of smoldering multiple myeloma include:
- Serum M protein level of ≥ 3 g/dL and/or ≥ 10% plasma cells in bone marrow
- Absence of anemia (although slight anemia may occur), renal failure, hypercalcemia, and osteolytic lesions
- The characteristics of indolent multiple myeloma include
- Level of M protein in the serum and/or urine, ≥ 3 g/dL and stable over time
- Percentage of plasma cells in bone marrow, > 30%
- Mild anemia or a few small osteolytic lesions
Lack of symptoms
Individuals with asymptomatic multiple myeloma have “close follow-up” (also called observation), with visits to the physician and/or testing approximately every 3 months. Treatment with bisphosphonates is started for individuals who have osteolytic lesions, osteoporosis, or osteopenia. Treatment directed at myeloma is started once the disease has progressed to symptomatic myeloma. Participation in a clinical trial is also encouraged.
3. Symptomatic myeloma
When present, symptoms of multiple myeloma may be vague and similar to those of other conditions. Some myeloma symptoms are more common than others, and less common symptoms may be the result of complications that may occur. Treatment of symptomatic multiple myeloma includes immediate treatment with myeloma drugs, bisphosphonates for patients with bone loss, and options for clinical trials.
The characteristics of symptomatic multiple myeloma include the following:
- Elevated levels of M protein and plasma cells in the serum and/or urine
- Percentage of plasma cells in bone marrow, >30%
- Renal failure
- Osteolytic lesions
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