Multiple Myeloma: Causes, Symptoms and Treatment
Multiple myeloma is a cancer of the plasma cells, a type of white blood cell found in the bone marrow. The cancer is a result of abnormal plasma cell growth, which interferes with normal blood cell production. The abnormal plasma cells tend to gather together in the bone marrow, creating tumors. Multiple myeloma occurs when multiple tumors of abnormal plasma cells are found in the bone marrow. If only one tumor is found in the bone marrow, though, the condition is called a plasmacytoma.
The Cause of Multiple Myeloma
The exact cause of multiple myeloma is not known, though researchers are beginning to suspect a genetic cause. Currently, researchers are studying the DNA of the abnormal plasma cells, and while they have not discovered the exact cause, they have identified certain irregularities common in the abnormal plasma cells, such as an irregularity in chromosome 13. Many abnormal plasma cells have been found to be missing all or part of chromosome 13, making the cells much more aggressive and more difficult to treat.
Many of the irregular plasma cells also have an abnormal translocation or switching of chromosomes, which may also result in the cancer.
Multiple Myeloma Statistics
Currently,
about 50,000 Americans have been diagnosed with multiple myeloma. The
cancer is growing at an alarming rate: over 15,000 new cases are
diagnosed every year. Unfortunately, multiple myeloma has a relatively
low five-year survival rate of approximately thirty percent. |
Multiple Myeloma: A Bone Cancer?
Multiple
myeloma often affects the bones and has symptoms such as pain and
destruction of the bone, but the cancer itself is not a bone cancer.
Multiple myeloma is a cancer of the blood. It originates in the bone
marrow and is a result of the growth of abnormal plasma cells. |
Certain risk factors are known to increase a person's chance of developing multiple myeloma, such as:
- age: Some 99 percent of all multiple myeloma cases are diagnosed over the age of 40. The average age of diagnosis is 68.
- gender: Men are more likely to develop multiple myeloma than women.
- race: African Americans are at the highest risk of developing the disease—twice as likely as Caucasians.
- exposure on the job: People who work in agricultural, chemical and radiological industries are at higher risk.
- family history: People with relatives with multiple myeloma are at higher risk.
- other plasma cell disorders: People who have monoclonal gammopathy of undetermined significance (MGUS) or plasmacytoma are at an increased risk of developing multiple myeloma.
Signs and Symptoms of Multiple Myeloma
People with multiple myeloma at an early stage often display no symptoms. Symptoms of multiple myeloma generally develop as the cancer progresses, and are usually vague at first. One of the first signs of multiple myeloma is the presence of abnormal proteins (called monoclonal or M proteins) produced by the abnormal plasma cells.
People with multiple myeloma tend to have high blood calcium. This is a result of the destruction of the bone due to the tumors, and may result in a wide variety of symptoms, including:
- excessive thirst
- loss of appetite
- constipation
- drowsiness
- nausea.
Other symptoms of multiple myeloma include:
- anemia
- bone pain
- bone fractures
- repeated infections
- weakness
- weight loss.
Keep in mind that symptoms tend to vary from one person to another.
Complications of Multiple Myeloma
Plasma cells generally make up less than five percent of all the cells in the bone marrow. In multiple myeloma, abnormal plasma cells multiply uncontrollably and do not die, so they begin to crowd out normal cells. Plasma cells often make up more than ten percent of all the cells in the bone. This can lead to a number of complications, such as lower production of red blood cells, white blood cells and platelets.
A lower number of red blood cells can lead to anemia. This causes a number of problems, such as impaired organ function, weakness and shortness of breath.
A decrease in the number of normal white blood cells leaves the body vulnerable to infection by various germs. While the abnormal plasma cells created in multiple myeloma do produce antibodies (also known as immunoglobulins), those antibodies do not help protect the body in any way. These cells and antibodies only take up space, meaning fewer functioning white blood cells are available to fight infection.
A decreased platelet count may result in bleeding problems.
The tumors in the bone marrow may cause bone destruction. People with multiple myeloma experience bone pain and have weakened bones that are more likely to fracture. If the bones in the spine are affected, compression of the spinal cord may occur. As a result, patients may experience numbness, pain or even paralysis.
The destruction of the bones increases the calcium levels in the blood. Elevated levels of calcium, called hypercalcemia, combined with the high number of monoclonal proteins, may damage the kidneys and ultimately cause kidney failure.
Diagnosing Multiple Myeloma
Blood tests are usually performed first if multiple myeloma is suspected. One specific blood test, called a serum protein electrophoresis, separates the various blood proteins to detect the presence of monoclonal immunoglobulins. If the M proteins are detected, additional blood tests may be required to measure blood cell counts and blood calcium levels.
An MRI (magnetic resonance imaging) or CT scan may be required. The doctor may also perform a biopsy to examine the bone marrow.
Staging and Progression of Multiple Myeloma
Multiple myeloma is often staged using the Durie-Salmon system, which assigns a stage based on four factors: the amount of monoclonal immunoglobulin in the blood and urine, the amount of calcium in the blood, the extent of bone damage and the amount of hemoglobin in the blood.
| Stage |
Criteria |
5-year survival rate |
| I |
|
50%
(median survival time is over 5 years) |
| II |
- moderate number of myeloma cells present
- levels of hemoglobin, blood calcium and monoclonal immunoglobulin are between the levels found in stage I and stage III
|
40%
(median survival time is about 3 years, 6 months) |
III |
- large number of myeloma cells present
- low levels of hemoglobin (less than 8.5 g/dL)
- severe bone damage—three or more sites of bone destruction
- high blood calcium levels (more than 12 mg/dL)
- large amount of monoclonal immunoglobulin found in the blood and urine
|
10 to 25%
(median survival time is about 23 months) |
*Information provided by American Cancer Society.
Blood Disorders