Multiple myeloma is a type of cancer that occurs when a specialized white blood cell, a plasma cell, begins to grow and divide in an uncontrolled way. Normal plasma cells are a part of the immune system that produces antibodies to help fight against infections and keep us healthy. In multiple myeloma, these plasma cells produce antibodies that are ineffective.
Multiple myeloma occurs when the overgrowth of plasma cells takes place in multiple areas of the bone marrow. Bone marrow is the soft spongy tissue in the middle part of the bone where blood cells are formed.
The average age of those receiving a diagnosis of multiple myeloma is 65 years. In Canada, about 2,900 people are diagnosed with multiple myeloma every year. There is a 1 in 117 lifetime chance of developing multiple myeloma.
It is not known what causes myeloma. Normally, only 5% or less of the bone marrow is made up of plasma cells. When a plasma cell becomes abnormal and begins multiplying, the cells are then called myeloma cells. Some risk factors for developing multiple myeloma include:
- a family history of multiple myeloma
- being male
- being older than 60 years of age
- people of African descent
- people with monoclonal gammopathy of undetermined significance (MGUS) – a precancerous disease of the plasma cell
There are other possible risk factors, such as obesity, exposure to high dose radiation and chemicals, but these have not been proven.
Symptoms and Complications
During the early stage of the disease, you may not even be aware that you have multiple myeloma. Some symptoms of the disease include:
- bone pain in your back or ribs
- decreased kidney function
- frequent infections
- weakness in your legs
- weight loss
Signs of multiple myeloma may also include an increase of:
- proteins in your blood or urine – these proteins (also known as monoclonal proteins or M proteins) are produced by myeloma cells and may impair kidney function
- elevated calcium levels in your blood – this indicates that calcium from your bones is entering your blood due to damage caused by the myeloma cells
An increase of calcium in your blood may lead to such symptoms as:
- diminished appetite
- frequent urination
- increased thirst
- fatigue and tiredness
Overgrowth of myeloma cells disrupts the production of normal cells in the bone marrow. This causes an impaired immune system and a decrease in the number of red blood cells. Decrease in red blood cells can lead to anemia and fatigue, which is common in people with multiple myeloma. Bone fractures (broken bones) are another complication of multiple myeloma.
Making the Diagnosis
Diagnosis of multiple myeloma depends on a number of factors. Blood or urine test results following a routine doctor's visit may provide the first indication of multiple myeloma. The combination of these results along with other tests, as well as your symptoms, helps determine the presence or absence of the disease.
The blood and urine tests known as serum and urine protein electrophoresis can detect certain proteins (M proteins) produced by the myeloma cells. If the test results show the presence of
M proteins or parts of M proteins (Bence Jones proteins), further blood and urine testing may be done to measure the:
- beta-2-microglobulin level
- blood cell counts
- calcium level
- creatinine level
- levels of C-reactive protein
- levels of gamma globulins
- level of lactate dehydrogenase
- amount of light chains (a part of the M protein) in the blood
- amount of protein in the urine
If your doctor suspects or confirms that you have myeloma, bone imaging may be ordered. Your doctor may order an MRI, CT, PET/CT, or X-rays. Weakened areas of the bones are common with myeloma and may be visible in an X-ray.
Bone marrow tissue also needs to be removed for microscopic examination. This test is called a bone marrow biopsy. During this procedure, the doctor inserts a needle into the pelvic bone and removes some of the marrow along with a small piece of the bone, which is then viewed under a microscope to detect the abnormal myeloma cells.
Treatment and Prevention
Because it is not known what causes multiple myeloma, it is not possible to prevent this disease. However, you have a number of options for the treatment of multiple myeloma.
Multiple myeloma often develops slowly and may not always have signs or symptoms. For people with multiple myeloma who are not experiencing symptoms, they may not need to start treatment right away. However, they will need regular visits to their doctor to monitor the progression of the disease.
You may need treatment for the disease if:
- you develop symptoms
- there is a marked increase in the level of M protein in your blood or urine
- there is an increase in calcium in your blood
- your bones show signs of weakening
- you have problems with kidney function
- you have anemia
The different types of treatment include:
- chemotherapy (e.g., melphalan*, cyclophosphamide, doxorubicin)
- steroids (e.g., dexamethasone)
- novel therapies (e.g., lenalidomide, bortezomib, thalidomide)
- stem cell transplantation
- radiation therapy
- bisphosphonates (e.g., pamidronate, zoledronic acid)
Chemotherapy and newer therapies are common treatments for multiple myeloma. These medications directly damage and kill the abnormal myeloma cells. These medications are specifically designed to quickly attack multiplying cells, but they can also damage normal cells. To reduce the damaging effects and adverse events of these medications, your doctor will carefully determine the type and dose of the medication as well as the duration of treatment.
A person with multiple myeloma can take the medication by mouth or through intravenous injection. The medication must be taken over a period of time, often months. If the level of M proteins stabilizes, you may be able to stop chemotherapy treatment.
Stem cell transplantation involves a combination of chemotherapy to wipe out the diseased cells and the transfusion of a special type of cells called stem cells. Stem cells from you or a donor are transfused into your body to replace damaged bone marrow.
Radiation therapy uses high-energy X-rays that penetrate the body to destroy myeloma cells. The radiation targets a specific area, often where a tumour has developed. The treatment may be given for a few days or up to several weeks. It may also relieve bone pain.
Bisphosphonates are medications injected into the vein that reduce the likelihood of bones breaking from the myeloma. They may also lessen bone pain.
To treat the anemia that is often associated with multiple myeloma, a group of medications called erythropoietin stimulating agents may be prescribed. They cause the bone marrow to produce more red blood cells.