What Is Multiple Myeloma?
Multiple myeloma is a cancer of the plasma cells that are found mainly inside of the bone marrow (the soft tissue in the center of most of your bones). The main function of the bone marrow is to make red blood cells, white blood cells, and platelets. Plasma cells are white blood cells that make antibodies, also called immunoglobulins, the immune system needs to protect you from germs that cause infection. This cancer is called multiple myeloma because the plasma cells begin to make abnormal cells that cause multiple tumors to grow in different locations of the body.
What Causes Multiple Myeloma?
Scientists do not know what is the exact cause of most cases of multiple myeloma. But they do have some understanding of how DNA changes can turn plasma cells into cancerous cells. DNA is the chemical that instructs cells on what to do and how to protect the body. Nevertheless, cancer is believed to start when normal plasma cells become cancerous and grow out of control. The cells are called myeloma cells at this point.
The overgrowth of myeloma cells interferes with healthy cells in the bone marrow tasked with making red blood cells, platelets, and other white blood cells. The plasma cells also stop producing the antibodies needed to fight infection. Instead, they produce abnormal proteins called monoclonal proteins, or M proteins. These are abnormal cells the body cannot use and will build up and eventually lead to complications such as kidney and bone damage.
Myeloma cells also show abnormalities in their chromosomes (found in DNA) such as extra or missing (deleted) chromosomes. Myeloma appears to be more aggressive and resistant to treatment in patients with deleted parts of chromosome number 17.
Types of Multiple Myeloma
There are two main subtypes of multiple myeloma:
- Hyperdiploid (HMM): This type makes up about 45% of multiple myeloma cases and is usually not as aggressive as non-hyperdiploid. The myeloma cells in people with HMM have extra chromosomes than normal.
- Non-hyperdiploid or hypodiploid: This type is more aggressive and affects about 40% of people with multiple myeloma. Myeloma cells in patients with non-hyperdiploid have fewer or missing chromosomes than normal. Pre-Myeloma Plasma Cell Disorders
There are other plasma cell disorders involving abnormal plasma cells but fall short of the criteria to be called active multiple myeloma. They include the following more common plasma cell disorders which may turn into multiple myeloma later on:
- Monoclonal gammopathy of uncertain significance (MGUS): A benign condition that involves the presence of the same M proteins produced in patients with multiple myeloma. In the case of MGUS, the levels of M proteins are not high enough to cause damage to the body.
- Smoldering multiple myeloma (SMM): This is an early stage or asymptomatic (no symptoms) myeloma that is not causing any trouble. Although asymptomatic, people with SMM may show certain signs of multiple myeloma if tested. Common signs are large amounts of plasma cells in the bone marrow, high levels of M protein in the blood, and high levels of light chains (small protein segments also called Bence Jones protein) in the urine. People with SMM are half as likely to develop multiple myeloma after about five years.
- Solitary plasmacytoma: Solitary plasmacytoma usually develops in the bone but can also start in tissues such as the lungs or other organs. Only one tumor appears instead of multiple tumors.
- Light chain amyloidosis: Abnormal plasma cells grow in the bone marrow because it makes an incomplete antibody or immunoglobulin known as a light chain antibody. However, the levels of abnormal plasma cells are lower than seen in patients with active multiple myeloma.
Although you may not need treatment for any of these pre-malignant disorders, your doctor may monitor you closely to see if multiple myeloma starts developing later.
Who Is at Risk of Multiple Myeloma?
Some individuals are more at risk of developing multiple myeloma based on gender, age, race, and exposure to radiation.
- Genetics: You have an increased risk of the disease if a parent or sibling has the disease.
- Gender: Men are more likely to be diagnosed with multiple myeloma than women.
- Old Age: Most diagnoses are made in adults 65 years or older.
- Race or ethnicity: African Americans are two times more likely to develop the disease.
- Personal history of an MGUS: Multiple myeloma almost always begins as MGUS, and increases your chance of developing blood cancer.
Multiple Myeloma Signs and Symptoms
Multiple myeloma does not always cause symptoms and may continue to fly under the radar as it progresses. The disease is often discovered when the person does a blood or urine test for another condition and the results show a higher than normal level of proteins in the samples. When symptoms do show they may vary from person to person The following are common signs and symptoms and may occur when the cancer is in its advanced stage:
- Bone pain (usually occur in your chest or spine)
- Bones that break easily
- Unexplained fever
- Frequent infections
- Excessive thirst
- Mental fogginess or confusion
- Loss of appetite or weight loss
- Bruising or bleeding easily (due to low levels of blood platelets)
- Weakness or numbness in your arms or legs
When to See a Doctor
These symptoms can be a sign of other medical conditions. Talk to your doctor if your symptoms persist or grow worse.
Types of complications include:
- Frequent infections: Myeloma cells make an antibody that prevents your body from fighting infections.
- Low blood count: A drop in blood count can arise from myeloma cells overgrowing and crowding out normal blood cells. This can cause anemia (shortage of healthy red blood cells), low blood platelets (thrombocytopenia), or low white blood cells (leukopenia).
- Bone problems: Abnormal plasma cells can also affect bone cells responsible for bone breakdown and repair. This can lead to bone pain, thin bones, and bones that break easily.
- Kidney problems: Myeloma cells make an antibody that may harm the kidney or cause kidney damage or kidney failure.
How is Multiple Myeloma Diagnosed?
Your doctor may order one or more of the following tests or procedures if he or she suspects multiple myeloma based on your signs and symptoms. Routine diagnostic tests and procedures include:
- Blood tests: A lab test of your blood may detect abnormal proteins produced by myeloma cells such as M proteins. Tests are also done to assess blood cell counts, kidney function, and the levels of calcium and uric acid in your blood.
- Urine tests: A urine analysis is done to screen for M proteins produced by myeloma cells.
- Bone marrow exam: A sample of your bone marrow may be sent to the lab to test for myeloma cells. Fluorescence in situ hybridization (FISH) test can detect these abnormal cells.
- Imaging tests: An X-ray, MRI, CT scan, or positron emission tomography (PET) may be needed to screen you for bone problems caused by multiple myeloma.
If you're diagnosed with multiple myeloma, your doctor will use the details of the various diagnostic tests to determine the stage of the disease. The cancer is grouped into stage I, stage II, or stage III. Stage I is the least aggressive stage. Understanding the disease stage and risks helps your doctor provide a prognosis and recommend suitable treatment options.
Multiple Myeloma Treatment Options
The need for urgent treatment will depend on the stage of the disease. You may not need treatment if you have no symptoms, the disease is in its early stage, or it is slow-growing. Your doctor will monitor you and perform regular tests to check for signs the disease is progressing. The following standard treatments (or combination treatments) can begin if signs and symptoms develop or the disease starts to progress:
- Targeted therapy: Drug treatments will focus on killing cancer cells by blocking abnormalities within the cells.
- Immunotherapy: Immunotherapy works by interfering with the ability of cancer cells to produce proteins that hide them so your immune system cannot detect and destroy them.
- Chemotherapy: Chemotherapy drugs work by killing fast-growing cancer cells.
- Corticosteroids: Corticosteroid medications control inflammation in the body so your immune system can function better.
- Bone marrow transplant: A bone marrow or stem cell transplant involves removing diseased bones in your body and replacing them with healthy bone marrow. Blood-forming stem cells collected from your blood before the transplant are infused into your body to help rebuild your bone marrow.
- Radiation therapy: Radiation therapy uses beams of intense energy to kill cancer cells from sources such as X-rays and protons. It is also useful for shrinking myeloma cells in a specific area.
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