Multiple myeloma is a relatively rare cancer of the plasma cells. Plasma cells normally produce proteins, or antibodies, to help the immune system fight infection. Myeloma occurs when the body produces too many abnormal plasma cells, which are called myeloma cells.
These extra myeloma cells produce excess proteins in the blood. This can cause health problems. Myeloma cells also collect and grow in the bone marrow, the soft interior of the bone. This often results in decreased production of blood cells. The types of blood cells include:
When myeloma cells grow in more than one site, the disease is called multiple myeloma. A single tumor of abnormal plasma cells is called a solitary plasmacytoma.
The cause of multiple myeloma is not known. Doctors think exposure to toxins, radiation, or a virus may play a role. Inherited gene mutations may also lead to multiple myeloma. In nearly all cases, doctors have no idea why a particular person develops the disease.
According to the American Cancer Society, about 20,580 Americans are diagnosed with multiple myeloma each year. Slightly more men than women are affected. And 10,580 people with the disease die from it annually. Multiple myeloma affects older adults. The average age of people with this disease is 65 years. It is uncommon for myeloma to occur in people younger than 35.
Symptoms of early stage multiple myeloma include:
When the disease progresses, symptoms may include:
Complications of multiple myeloma typically relate to problems with blood function. These complications include the following:
As malignant plasma cells multiply, they produce enormous quantities of abnormal antibodies. These abnormal antibodies accumulate in the blood and urine. This can cause kidney damage and a weakened immune system. About 20% of patients with the disease develop kidney problems. Most find themselves more susceptible to infections. The antibodies can also cause the blood to thicken. This can, in turn, decrease circulation to the brain, which can result in stroke. Decreased circulation to other organs can cause death of tissues in those organs, as well.
The growing tumor may destroy the surrounding bone, which leads to bone pain. Bones may break as they weaken. The bones in the spine may collapse and put pressure on the spinal cord, creating a medical emergency. Destruction of the bone also leads to high levels of calcium in the blood. Too much calcium can cause weakness and confusion, which can mimic stroke or dementia.
Myeloma is also associated with amyloidosis. This is a rare condition in which abnormal proteins accumulate in various organs of the body. The accumulation of these proteins causes the involved organs (usually heart, muscle, nervous system, and intestines) to malfunction. Amyloidosis is the result of a malfunction in the plasma cells that make antibodies. It is sometimes associated with myeloma. Anyone diagnosed with amyloidosis probably needs to be evaluated for the presence of myeloma. Patients with myeloma will sometimes experience complications as a result of amyloidosis.
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What are the key statistics about multiple myeloma? American Cancer Society website. Available at: http://www.cancer.org/cancer/multiplemyeloma/detailedguide/multiple-myeloma-key-statistics. Updated May 2009. Accessed March 4, 2010.
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Last reviewed September 2014 by Mohei Abouzied, MD, FACP
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