Like all cancers, multiple myeloma is caused by genetic mutations that allow cells to divide and grow in a disorganized way. Normal cells divide in a regular, ordered fashion, forming new cells that are exact copies to replace old ones. Certain genes in each cell are responsible for telling cells when to divide and when to stop dividing. Other genes identify and fix problems in DNA that is copied incorrectly, or cause cells with bad DNA to self-destruct rather than keep multiplying. If a genetic mutation causes one or more of these genes to turn off in some cells, the cells can divide at a faster rate without regulation or order, becoming more and more mutated. When these disordered cells begin to invade nearby tissues or break off and migrate to other locations, they are called cancer.
Since genetic mutations cause myeloma, risk factors for myeloma include anything that can encourage mutations. Myeloma is not the result of one genetic mutation alone; it requires many different genetic mutations for cancer to develop. Some genetic mutations are inherited from parents, while 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. In some people, inherited factors contribute to the development of myeloma. It is still unclear why some people develop myeloma and some people do not.
It is important to note that while science is good at finding correlations, or apparent relationships, between factors and disease, correlation does not prove that the factor causes the disease. Many risk factors for myeloma have been identified and are being studied for their role in the development of the disease.
The average risk for any American to develop myeloma is 1 in 132, or 0.76 percent. Other factors may increase or decrease an individual’s risk for myeloma.
Age is the most important factor in myeloma risk. The risk for developing myeloma increases with age. Less than 1 percent of myeloma cases are diagnosed in people under 35. Myeloma is most prevalent in people over 65.
Ethnicity has a significant influence over risk for myeloma. In the U.S., African Americans are more than twice as likely to develop myeloma as white people. Myeloma is also more prevalent in the Middle East, North Africa, and the Mediterranean region. People of Japanese and Mexican backgrounds have a lower-than-average risk for myeloma.
Men are about 40 percent more likely than women to develop myeloma. Some researchers theorize that female sex hormones may play a protective role against myeloma.
Myeloma does not have a strong pattern of inheritance among families. Only about 3 in 1,000 cases of myeloma are believed to involve genes passed down from parent to child. People with a first-degree relative — parent, child, or sibling — diagnosed with myeloma are 3.7 times more likely to be diagnosed with myeloma themselves than someone without a family history of myeloma. It is often difficult for researchers to separate genetic factors from shared environmental factors.
Researchers have identified a wide array of environmental factors linked to the development of myeloma. People who have been diagnosed with related disorders, such as monoclonal gammopathy of undetermined significance (MGUS) and solitary plasmacytoma, have an increased risk for progressing to multiple myeloma.
People diagnosed with MGUS who are obese have a higher risk for progressing to multiple myeloma. However, obesity does not appear to raise the risk for initially developing MGUS.
Having certain chronic health conditions increases the risk for developing myeloma. Conditions that weaken the immune system may allow abnormal cells to proliferate and become cancerous. Conditions that raise the risk for myeloma include autoimmune conditions, such as rheumatoid arthritis, lupus, pernicious anemia, and spondylitis, and viral infections, such as HIV and hepatitis B and C.
There is some evidence that taking certain medications may raise the risk for developing myeloma in some people. Drugs that have been linked to increased myeloma risk include erythromycin and phenytoin.
Exposure to radiation increases the risk for 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) or positron emission tomography (PET) scans, and radiation therapy. Although the levels of radiation most people are exposed to are low, the effects of radiation can accumulate over time, gradually causing mutations that lead to the development of 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 for developing myeloma.
Similarly, people who work with carcinogenic (cancer-causing) chemicals, such as benzene and petroleum, may be more likely to develop myeloma. Occupations that may carry a higher risk for myeloma include farming, firefighting, painting, and roles in the petroleum industry.
There is no certain way to avoid getting myeloma. Most risk factors, including age, genetic predisposition, and ethnicity, are beyond anyone’s control. If you are concerned you may have a high risk for developing 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.
General guidelines for cancer prevention recommend eating a healthy diet with plenty of fresh fruits, vegetables, and whole grains, and 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 for progression to multiple myeloma.
If you have been diagnosed with MGUS or smoldering myeloma, attend all scheduled follow-up screenings. If your condition progresses, identifying progression as early as possible will give you the best chance for effective treatment.