Multiple myeloma is a cancer of the plasma cells, a kind of white blood cell that is found in the bone marrow. It affects the bones, the immune system, the kidneys, and the red blood cell count.
Multiple myeloma is also known as myeloma or plasma cell myeloma.
The American Cancer Society (ACS) estimates that the risk of developing multiple myeloma over a lifetime is 1 in 143 or 0.7 percent.
Contents of this article:
What happens in multiple myeloma?
Multiple myeloma is a type of cancer. Cancer starts when the structure of the DNA in a cell changes. This is called a genetic mutation. The mutation can cause rapid cell growth, it and can also stop unwanted cells from dying. This leads to a buildup of mutated cells, and these form tumors.
Multiple myeloma is a type of cancer that affects certain types of white blood cells.
Plasma cells are a type of white blood cells. White blood cells are produced in bone marrow, the soft, spongy tissue that is found in the middle of most bones. These white blood cells produce antibodies called immunoglobulin. Immunoglobin helps to fight off infections.
In multiple myeloma, there are too many plasma cells inside the bone marrow. Normally, less than 5 percent of bone marrow consists of plasma cells, but in multiple myeloma, plasma cells can make up more than 10 percent of the marrow.
In this type of cancer, a group of abnormal white blood cells, called myeloma cells, are produced, and they multiply in the body. This causes the levels of immunoglobulin to become too high.
The abnormal myeloma cells start in the bone marrow of the spine. From there, they enter the bloodstream and travel to other parts of the body, affecting the bone marrow there.
They collect in the bone marrow and in the hard, outer part of the bones. As they collect in the different bones, they can cause multiple tumors. This is multiple myeloma.
Unlike many cancers, multiple myeloma is thought to spread through the bloodstream. It can spread quickly to different parts of the body, making it very hard to cure.
Symptoms of multiple myeloma
The signs and symptoms of multiple myeloma depend on the stage and the patient's general health. There may be no symptoms in the early stage.
Sometimes a routine blood or urine test will show up abnormal proteins, called monoclonal proteins (M proteins). This can indicate multiple myeloma.
Other symptoms include bone pain, especially in the back, pelvis, ribs and skull, and high calcium levels in the blood, as calcium from the bones dissolves into the bloodstream.
High blood calcium levels can cause:
- Excessive thirst and frequent urination
- Loss of appetite
- Nausea and vomiting
- Abdominal pain.
Changes in red and white blood cell and platelet levels can cause:
- Fatigue, tiredness, and lethargy
- Repeated infections
- Easily bruised skin
- Nosebleeds, bleeding gums, or other unusual bleeding.
Other types of damage that can occur include kidney damage and spinal cord compression, potentially leading to numbness, weakness, and tingling in the legs, among other things.
Who is most at risk of multiple myeloma?
Scientists are unsure exactly what causes multiple myeloma, but the following may be risk factors:
- Age increases the risk, with 96 percent of cases occurring in people over 45 years of age, and 75 percent in those over 70 years.
- Genetic inheritance, for example, having a close relative with the disease, increases the risk.
- Obesity increases the odd of developing many cancers, including multiple myeloma.
- A diet with a low intake of fish and green vegetables may have an impact.
- HIV/AIDS puts people at greater risk
- Occupational exposure may be a factor, affecting people involved in agriculture, leather, cosmetology, and petroleum.
- Exposure to certain chemicals and products, such as heavy metals, some hair dyes, plastics, various dusts including wood dust, asbestos, herbicides, insecticides and petroleum products may be linked to it.
- Radiation exposure is thought to be a factor, and there is a significantly higher incidence of multiple myeloma among survivors of the Hiroshima and Nagasaki atomic bomb explosions.
- Some autoimmune disorders, such as rheumatoid arthritis, have been associated with it.
- Monoclonal gammopathy (MGUS) has been linked to the condition, with 1 percent of people with MGUS in the US developing multiple myeloma each year. People with MGUS have higher levels of M proteins in the blood.
How is multiple myeloma diagnosed?
Diagnosis will involve blood tests.
A staging system called the Durie-Salmon system is used to check which stage the disease has reached.
The system looks at four factors:
- Red blood cell count
- Calcium levels in the blood
- M proteins in the blood
- The state of the patient's bones.
At stage 1, blood calcium levels are normal, red blood cell levels are either normal or slightly low, there are low levels of M proteins, and the bones show little or no damage. Most patients have no symptoms.
At Stage 2, the levels of calcium and red blood cell levels are close to normal, there are low levels of M proteins, and there may be damage to one or two bones. There may also be damage to the kidneys.
At Stage 3, red blood cell levels are lower, and there may be symptoms of anemia. Blood calcium levels have risen, M protein levels are high, and there is damage to two or three bones. Damage to the kidneys is likely.
Treatment options for multiple myeloma
Most patients in Stage 1 will not receive immediate treatment, but changes will be monitored.
Patients in Stages 2 and 3 usually receive chemotherapy and treatment to help control symptoms.
The aims of treatment are to bring the cancer under control by removing the cancer cells from the bone marrow, and then to ensure that they do not return for as long as possible.
Treatment also aims to relieve symptoms such as pain, anemia, and kidney damage.
Bringing the cancer under control
Chemotherapy is used to kill the myeloma cells. Examples of drugs used include vincristine (Oncovin) and doxorubicin (Doxil), taken either orally or intravenously over a period of months.
Side effects of chemotherapy include nausea, vomiting, diarrhea, fatigue, skin rashes, infertility, and hair loss, but these normally disappear once treatment is over. Hair normally returns within 3-6 months after treatment is finished.
Stem cell transplantation is another option. Following a high-dose of chemotherapy, the patient receives a transfusion of stem cells, or immature blood cells, either from the patient or a donor.
The feasibility of this option depends on how the disease is progressing and the patient's age and general state of health.
Following initial treatment, corticosteroids are often prescribed, usually one tablet a day. This is thought to encourage the immune system to stop new cancerous cells from growing in the bone marrow, but how it works is unclear.
Thalidomide (Thalomid) is an approved treatment for multiple myeloma, usually taken orally once a day. Thalidomide appears to stop the cancerous cells from coming back by targeting the blood vessels that the cells need to multiply and grow.
Interferon alpha stimulates the body's immune system to attack any cancer cells that may remain in the bone marrow. Most patients need three injections per week, and they learn how to inject themselves.
All of these drugs have potential side effects.
Patients may need to receive treatment for other symptoms and complications of multiple myeloma. These include back pain, kidney problems, which may require dialysis, infections due to low levels of white blood cells, bone loss, and anemia.
Outlook for people with multiple myeloma
Multiple myeloma is treatable but rarely curable, and the median survival is 45 to 60 months. A solitary myeloma may be cured.
Younger patients, people with normal kidney function, and those in better overall health, without other chronic diseases, can expect a better outcome.