Multiple myeloma is cancer of the plasma cells in bone marrow, a type of white cell normally responsible for producing antibodies.
In multiple myeloma, plasma cells grow out of control in the bone marrow and form tumors in areas of solid bone. The growth of these bone tumors makes it harder for the bone marrow to make healthy blood cells and platelets and results in sometimes severe anemia, with increased risk of infection and abnormal bleeding. Multiple myeloma primarily affects older adults.
The disease is more common in men and is twice as common in African-Americans than it is in Caucasians. Multiple myeloma is the least common hematological malignancy (blood cancer) and constitutes 1% of all cancers.
As cancer cells grow in the bone marrow, bone pain (most often in the ribs or back) may be present and worsen with activity. If the bones in the spine are affected, pressure on the nerves may result in numbness or weakness of the arms and legs. The breakdown of bone also leads to the release of excess calcium into the blood (hypercalcemia) which may result in kidney damage or failure, weakness, confusion and fatigue.
Most cases of myeloma are also characterized by the production of an abnormal antibody (a paraprotein) that can cause kidney problems and interfere with the production of normal antibodies. The result is immunodeficiency, or the inability of the body to fight infection – most commonly pneumonia and kidney infections.
Symptoms of multiple myeloma include:
- Pain in the back or ribs that worsens with activity
- Abnormal bleeding
- Fatigue due to anemia
- Shortness of breath due to anemia
- Fever with no known cause
- Unexplained broken bones
Because many organs can be affected by myeloma, the symptoms and signs vary greatly. A mnemonic sometimes used to remember the four common parts of myeloma is CRAB:
C = elevated calcium R = renal failure A = anemia B = bone lesions
Myeloma is generally thought to be incurable, but remissions may be induced with steroids, chemotherapy, thalidomide and bone marrow stem cell transplants. Radiation therapy is sometimes used to treat bone tumors that are causing symptoms. Survival of people with multiple myeloma depends on the patient’s age and the stage of disease at diagnosis. The disease may be very aggressive or take many years to develop.