Myeloma Facts

March 13, 2024 
This page was reviewed under our medical and editorial policy by Michael Rosenzweig, M.D., Chief, Division of Multiple Myeloma, City of Hope Duarte

Myeloma is a relatively rare disease, representing about 1.8% of all new cancer cases. Approximately 36,000 new myeloma diagnoses occur in the United States each year.

What Is Myeloma?

Accounting for around 10% of blood cancer cases, myeloma is a type of cancer that develops in plasma cells. These are the white blood cells that grow in bone marrow. Because the disease typically affects bone marrow in multiple parts of the body, it's also known as multiple myeloma. Although myeloma grows within bone, it is not considered bone cancer.

Parts of the body involved in myeloma include:

• Bone marrow: Spongy blood-producing tissue inside the bones. This is where all of the blood in the body is produced and where malignant (abnormal) plasma cells grow.
• Plasma cells: Produced in the bone marrow and a part of the immune system, these are types of white blood cells. They play an important role in creating antibodies that fight infection. In myeloma, plasma cells are abnormal.
• Immunoglobulins: Another word for antibodies, these proteins are produced by plasma cells. They form a crucial part of your immune response. They bind to infectious agents, like bacteria or viruses, which identify them for destruction by other immune system cells.
• Bone cells: Specifically, osteoblasts that make bone and osteoclasts that dissolve bone. Myeloma cells produce a substance that stimulates the breakdown of bone by osteoclasts. It also hinders the activity of osteoblasts, producing holes in the bone called lytic lesions.
• The nervous system can cause myeloma. Nerve damage may lead to the toxic, abnormal proteins produced by myeloma cells. 

What Causes Myeloma?

Myeloma develops when plasma cells become abnormal and grow and divide uncontrollably to become tumors.  Plasma cells are infection-fighting blood cells in the immune system.

During a normal immune response, B cells mature and change into healthy plasma cells. Those plasma cells then create antibodies that help the immune system recognize and fight the infection.

Myeloma occurs when a damaged B cell develops into an abnormal plasma cell. Instead of helping the immune system fight disease, myeloma cells grow quickly and crowd out healthy blood cells. Over time, this process can lead to conditions such as anemia (low hemoglobin) and thrombocytopenia (low platelets or blood clotting cells). Because the immune system is impaired, patients with myeloma are at increased risk of infection.

Myeloma cells produce abnormal antibodies called monoclonal proteins, or M proteins. These proteins build up in the body, leading to the health problems associated with myeloma.

Asymptomatic vs. Symptomatic Myeloma

This condition is categorized based on myeloma type, whether the patient is experiencing symptoms and how quickly it develops. The care team may use the terms listed below to describe the patient's status.

Asymptomatic myeloma: Also called smoldering myeloma. This develops slowly and has none of the characteristic symptoms, such as bone pain, anemia or kidney damage. Patients diagnosed with smoldering myeloma also have fewer plasma cells and abnormal proteins in their bone marrow compared with those who have symptomatic myeloma.

Symptomatic myeloma: Also called active myeloma, this has observable symptoms, such as bone disease, kidney damage and anemia.

Following the myeloma diagnosis process, the care team will develop a personalized myeloma treatment plan. They'll take into account such factors as the type and stage, the patient's overall health and his or her preferences.

Myeloma Risk Factors

Things that may put patients at higher risk for developing myeloma are called risk factors. Doctors don't fully understand what causes most cases of myeloma. Even defined risk factors don't have strong associations with developing myeloma.

Factors that may increase the risk for developing myeloma are listed below.

Age: As with most types of cancer, older age puts people at a higher risk of myeloma. Most people who are diagnosed with myeloma are older than 50. 

Gender: Myeloma is more common among men than women.

Race: African Americans are about twice as likely as other groups to develop myeloma.

Radiation exposure: Patients who have experienced radiation exposure have a higher risk for developing myeloma.

Chemicals: People who have been exposed to certain chemicals, such as pesticides, may have an increased risk of myeloma.

Certain conditions: Chronic inflammation may be involved with myeloma. A small subset of patients (around 1%) diagnosed with a condition called MGUS, monoclonal gammopathy of undetermined significance, develop myeloma.

Obesity: Being overweight or obese is considered the only known modifiable risk factor for developing myeloma.

Certain genetic factors: Genetic factors such as abnormally developing genes may increase risk of myeloma.