Multiple myeloma, like all cancers, begins with genetic mutations (changes) that disrupt the normal process of cell division. Typically, cells divide in an orderly way to replace old cells with healthy, exact copies. Specific genes control when cells should start dividing, repair any DNA errors, or trigger self-destruction if DNA is damaged.

However, when these genes mutate, they can lose control, leading to cancer. This loss of regulation allows cells to multiply unchecked, creating mutated cells that can form tumors. These tumors may invade nearby tissues or spread to other parts of the body — hallmarks of cancer.

Multiple myeloma develops when a type of white blood cell (a plasma cell) becomes cancerous. Plasma cells live in the bone marrow and produce antibodies that help the body fight infections. In myeloma, plasma cells develop abnormalities in their genes, leading them to grow out of control and build up in the bone marrow, forming tumors.

Because genetic mutations cause myeloma, risk factors for the condition include anything that can encourage mutations. Like most cancers, myeloma isn’t the result of one genetic mutation alone. It requires many genetic mutations for cancer to develop. Some genetic mutations are hereditary (inherited from parents), and others can be caused by factors in the environment — such as exposure to radiation or harmful chemicals.

Scientists believe that in most people, myeloma develops as a combination of environmental factors. Inherited factors can also contribute, but their overall effect on a person’s risk is very small. It’s still unclear why some people develop myeloma and others do not.

Risk Factors for Myeloma

Although science is good at finding correlations (apparent relationships) between factors and disease, correlation does not prove causation. Many risk factors for myeloma have been identified and are being studied for their role in the disease.

The average risk for a person in the United States to develop myeloma is 0.8 percent. Certain factors may increase or decrease this risk on an individual level.

Age is one of the most important factors in myeloma risk. The risk of developing myeloma increases with age. Less than 1 percent of myeloma cases are diagnosed in people under 35. Myeloma occurs most often in people over 65.

Demographic and Genetic Risk Factors

Race, ethnicity, and geographic region are associated with varying levels of risk for myeloma. In the United States, Black people are more than twice as likely to develop myeloma as white people, according to the American Cancer Society. Globally, regions with the highest incidence of myeloma are Australia, New Zealand, North America, and northern Europe. People of Asian or Pacific Islander backgrounds tend to have a lower-than-average risk.

Sex and gender may also influence risk. Men are slightly more likely than women to develop myeloma, according to Cancer Research UK. Researchers aren’t sure what causes this pattern.

Myeloma does not have a strong pattern of inheritance among families. People with a first-degree relative (parent, child, or sibling) who has myeloma are two to four times more likely to be diagnosed than someone without a family history of the condition. However, the majority of people who have relatives with myeloma won’t develop it, and most people who are diagnosed with myeloma have no family history.

Environmental Factors

Researchers have identified a wide array of environmental factors linked to myeloma. People who have been diagnosed with related disorders, such as monoclonal gammopathy of undetermined significance (MGUS) and solitary plasmacytoma, have an increased risk of progressing to multiple myeloma. A person with MGUS has about a 1 percent chance each year of developing multiple myeloma. This risk can vary based on factors such as age and specific lab findings.

People with MGUS who are diagnosed with obesity have a higher risk of progressing to multiple myeloma. An obesity diagnosis is based on a person’s body mass index (BMI), which is the ratio of their height to their weight. However, obesity doesn’t appear to raise the risk of initially developing MGUS.

Having certain chronic health conditions increases myeloma risk. Conditions that weaken the immune system may allow abnormal plasma cells to grow and become cancerous. Autoimmune conditions that raise the risk of myeloma include:

• Rheumatoid arthritis
• Lupus
• Pernicious anemia
• Spondylitis
• Viral infections like HIV

There is limited evidence that taking certain medications may raise some people’s risk of developing myeloma. Drugs that have been linked to increased risk include erythromycin and phenytoin.

Radiation exposure may increase the likelihood of developing myeloma. Everyone is exposed to low levels of radiation from natural sources like the sky and the earth. Many building materials naturally contain low levels of radiation. Some people are exposed to naturally occurring radon gas in their homes. Human-made sources of radiation include:

• X-rays
• Computed tomography (CT) scans
• Positron emission tomography (PET) scans
• Radiation therapy

Although the levels of radiation most people are exposed to are low, the effects can accumulate over time, gradually causing mutations that lead to myeloma in some people. People in jobs that expose them to higher levels of radiation — such as radiologists or workers in nuclear power plants — may have a higher risk of myeloma.

Similarly, people who work with carcinogenic (cancer-causing) chemicals, such as benzene, asbestos, and pesticides, may be more likely to develop myeloma. Occupations that may carry a higher risk include farming, firefighting, painting, and roles in the petroleum industry.

Can Myeloma Be Prevented?

There’s no certain way to avoid myeloma. Most risk factors, including age, genetic predisposition, and ethnicity, are beyond anyone’s control.

If you are concerned you may develop myeloma, focus on lowering your risk by changing the environmental factors within your control. If you work with radiation or carcinogenic chemicals, take every precaution to limit your exposure. Use protective equipment and follow safety procedures consistently. These measures may lower the chances that cancerous plasma cells will form.

General guidelines for cancer prevention recommend eating a healthy diet with plenty of fresh fruits, vegetables, and whole grains, as well as limiting your intake of red meat and processed meats. A balanced, nutritious diet can also encourage a healthy weight, which may help people with MGUS reduce the risk of progression to multiple myeloma.

If you have been diagnosed with MGUS or smoldering myeloma, attend all scheduled follow-up screenings. Your doctor will use blood tests or urine tests to help determine whether you’re experiencing any signs or symptoms of multiple myeloma. Identifying progression as early as possible will give you the best chance for effective treatment.

Talk With Others Who Understand

MyMyelomaTeam is the social network for people with myeloma. On MyMyelomaTeam, members come together to ask questions, give advice, and share their stories with others who understand life with myeloma.

What questions do you have about the causes of multiple myeloma? Share your experience in the comments below, or start a conversation by posting on your Activities page.