What Is Multiple Myeloma?

For additional information, please visit the National Cancer Institute.

Multiple myeloma is a type of cancer that affects plasma cells, which are a type of white blood cell. Plasma cells and other white blood cells are part of the immune system, which helps the body protect itself from infection and disease. All white blood cells develop in the bone marrow, the spongy tissue that fills the centers of most bones. Some of these white blood cells remain in the bone marrow, and some migrate to other parts of the body. Some of the white blood cells, whether in the marrow or other parts of the body, develop into plasma cells when the immune system needs them to fight infection and disease.

Plasma cells are important to the immune system because they produce antibodies. Antibodies are proteins that move throughout the blood stream to fight foreign, harmful substances. Each type of plasma cell produces a specific antibody to fight a specific foreign substance. Since the body has many different types of plasma cells, it can respond to, or fight against, many different foreign substances.

When plasma cells become cancerous, they reproduce uncontrollably. These excess abnormal plasma cells are all alike; they are referred to as "monoclonal," meaning that they all have a common origin.

The tremendously increased number of plasma cells in multiple myeloma crowd out healthy red and white blood cells, preventing them from functioning as effectively as they should. The malignant plasma cells produce osteoclast activating factors which cause calcium to be leached out of the bones. This leaching of calcium can result in dangerously high levels of calcium in the bloodstream, known as hypercalcemia, and holes in bones, known as osteolytic lesions. Some patients experience vertebral collapse or spontaneous fractures. The malignant plasma cells also produce excessive monoclonal immunoglobulin, a type of protein, referred to as an M-protein. This protein can overload the kidneys, leading to abnormal kidney function and even renal failure. Sometimes malignant plasma cells congregate in clumps, causing isolated tumors, or plasmacytomas.

Early myeloma may cause no overt symptoms, but as tumor mass increases and excess protein is produced, symptomatic disease develops. Typical symptoms include bone pain, anemia, and renal failure. Frequent infections are also common, because the immune system is compromised when healthy white blood cells are crowded out by the malignant myeloma cells.

There is no known cure for multiple myeloma, although lengthy remissions can often be achieved. The immediate goal in treating multiple myeloma is to get the disease under control and to keep the patient in remission with a good quality of life for as long as possible. Disease control can be complicated by a tendency for myeloma cells to become resistant to chemotherapeutic agents.

Multiple myeloma typically affects middle-aged or elderly persons. It accounts for 15% of all hematological malignancies. Approximately 15,000 new cases are diagnosed each year. Multiple myeloma is more common in men than women, and in African Americans than Caucasians. Over 50,000 Americans are currently living with Multiple Myeloma. The median survival rate for patients in the United States is roughly 2.5 to 3 years, but this varies according to the extent of the disease at diagnosis, adequacy of support measures, and response to drugs. The Myeloma Institute has achieved a median survival rate of 6 to 7 years.

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