Multiple myeloma is a blood, or hematologic, cancer that can affect your bones and kidneys as well as your levels of healthy blood cells.
- What is multiple myeloma?
- Types of myeloma
- What causes myeloma?
- Next steps
What is multiple myeloma?
Myeloma, or multiple myeloma, is cancer of a certain type of white blood cell called a plasma cell, which is part of your immune system. Myeloma begins in the bone marrow, where blood cells are made.
What happens in healthy bone marrow?
Bone marrow is found in the soft, spongy center of certain bones. Myeloma can affect any bones where marrow is active. Usually in adults marrow is active in the skull, shoulders, spine, ribs, pelvis and hips.
Healthy bone marrow produces the three major types of blood cells our bodies need.
- White blood cells fight infection.
- Red blood cells carry oxygen.
- Platelets make the blood clot and stop bleeding.
Normally, when microorganisms (like bacteria or viruses) enter your body, white blood cells called B lymphocytes (B cells) turn into plasma cells. Then these plasma cells make antibodies to destroy the specific microorganism. Antibodies, also called immunoglobulins, are complex proteins.
What happens in myeloma?
In myeloma, plasma cells don’t reproduce normally. Instead, they become cancerous, and they divide and grow out of control.
- Your cancerous plasma cells, also called myeloma cells, build up in your marrow and crowd out other healthy blood cells. This can increase your risk of:
- Infection (due to low white blood cells)
- Anemia (due to low red blood cells)
- Blood-clotting problems (due to low platelets)
- Myeloma cells don’t make effective antibodies, so people with myeloma have lower immune function than normal.
- Instead of making effective antibodies, myeloma cells produce and release an abnormal protein, called M protein, and other chemicals. These substances can damage the immediate area and travel through your bloodstream to damage other parts of your body.
Typically, bone damage is one of the main effects of myeloma.
- Some of the chemicals released in myeloma interact with your bone cells, causing hard, structural areas of bone to dissolve.
- The damaged areas are called osteolytic lesions. They weaken the bone and can lead to fractures.
- When bone dissolves, calcium is released into your bloodstream. High blood calcium (hypercalcemia) can cause health problems, such as confusion and dehydration, and damage your kidneys.
M protein can also:
- Cause kidney damage, such as by harming the small tubes inside your kidneys
- Cause circulation problems because the proteins tend to stick to each other and to other tissues (like blood cells), which can thicken your blood
Why is it called “multiple” myeloma?
Most people with myeloma have myeloma tumors in several places in their body. That’s why this disease is often called multiple myeloma.
What is plasmacytoma?
Some people with myeloma have only a single tumor, called plasmacytoma.
- “Plasma” refers to the type of cell affected.
- “Cyte” is a general term for cell.
- “Oma” means tumor.
A plasmacytoma can form:
- In a bone (intramedullary disease)
- In soft tissue outside the bone (extramedullary disease)
People with a single plasmacytoma in a bone often develop multiple myeloma later on.
Types of myeloma
Doctors can detect various levels of myeloma-related changes in the bone marrow, including small changes that do not amount to cancer. Here are different forms of myeloma or related conditions:
MGUS, or monoclonal gammopathy of undetermined significance
- In this condition, there are some myeloma precursor cells in your bone marrow, but the percentage is low.
- The cells do not form a tumor or cause any disease or symptoms, and no treatment is needed. MGUS is not cancer, and it rarely turns into myeloma.
- Usually doctors discover this condition when a routine blood test detects unusual levels of protein in the blood.
- If you have MGUS, it’s important to see your doctor about every 6 months to be sure it’s not progressing.
Asymptomatic myeloma, also called smoldering or indolent myeloma
- In this condition, there are more myeloma cells than in MGUS. But there are still not enough to damage your body or cause symptoms.
- This form of myeloma may worsen over time, in some cases very slowly. Some people live symptom-free for many years.
- As with MGUS, there’s no immediate need to treat this type of myeloma. But it’s important to have regular exams to check whether the condition is getting worse.
- When the condition becomes symptomatic, then treatment starts.
- Watch a video featuring SCCA’s Edward Libby, MD, for more information on smoldering myeloma.
Symptomatic myeloma, also called active myeloma
- In this condition, there are usually more myeloma cells. The myeloma is causing symptoms, and you need treatment.
- In active myeloma, the myeloma cells are causing one or more of these problems:
- High levels of calcium in the blood (hypercalcemia)
- Kidney (renal) problems
- Anemia (low red blood count)
- Bone damage
Symptoms of myeloma
Symptoms of myeloma come from the build-up of myeloma cells in your marrow and from the M protein and chemicals that myeloma cells release.
Once symptoms begin, these symptoms are typical:
- Weakness and fatigue caused by anemia
- Swelling in the legs or weakness caused by kidney damage
- Bone pain from build-up of myeloma cells, often in the back or ribs
- Bone fracture, which may compress nerves or the spinal cord
- Confusion, tiredness, weakness, dehydration, unusual thirst, nausea, constipation or frequent urination caused by high blood calcium
- More frequent infection or trouble recovering from infection
- Excessive bleeding, including from minor injuries
The same symptoms can also be caused by other conditions. See your doctor if you have any symptoms that concern you.
To find out whether you have myeloma, your doctor will do a thorough physical exam and ask about your health history. You will also need:
- Blood tests — to measure your levels of blood cells (complete blood count), look for chemicals that can be abnormal in myeloma (blood chemistry) and check for abnormal protein.
- Bone marrow aspiration and biopsy — removing a small amount of bone marrow and a small piece of bone from your pelvis using a needle to check for cancer and determine the percentage of myeloma cells in your marrow.
- Imaging studies — to tell whether myeloma has damaged or weakened your bones. X-rays are the standard imaging study. If your doctor needs more detailed images, they may recommend magnetic resonance imaging (MRI), computed tomography (CT) scan or positron emission tomography (PET) scan.
Stages of myeloma
Your doctor will also determine the stage of your disease, or how far along it is. The stage depends on:
- The amount of myeloma cells in your body
- The amount of damage the myeloma cells have caused
Doctors use the International Staging System to classify your disease as stage I, II or III, with I being the least advanced and III being the most advanced.
What causes myeloma?
Doctors do not know what causes the cellular changes that lead to myeloma.
- The disease occurs only in adults, seldom before the age of 40 and usually after age 65.
- It’s more common in men than women, and it’s twice as common in African-Americans as in white Americans. It’s less common in people of Asian or Hispanic descent.
- Certain factors are linked to higher risk in some cases. For instance, exposure to some farming chemicals or radiation may increase risk. But in most people, doctors are not able to link the disease to any particular risk factors.
- Some families have more than one person with myeloma. But this is extremely unusual. It does not appear that myeloma runs in families.