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Multiple myeloma

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Risk factors for multiple myeloma

A risk factor is something that increases the risk of developing cancer. It could be a behaviour, substance or condition. Most cancers are the result of many risk factors. Often, people with multiple myeloma don’t have any of the risk factors described below.

Most people diagnosed with multiple myeloma are men. The risk of multiple myeloma increases with age. People of African ancestry have a higher risk of developing multiple myeloma. The reasons for this increased risk are not known.

Risk factors are generally listed in order from most to least important. But in most cases, it is impossible to rank them with absolute certainty.

*You may wonder about a history of asthma or allergies. There is significant evidence showing that there is no association between these factors and multiple myeloma.

Known risk factors

There is convincing evidence that the following factors increase your risk for multiple myeloma.

History of monoclonal gammopathy of undetermined significance (MGUS)

MGUS is a plasma cell disorder that has the potential to develop into multiple myeloma. A plasma cell is a type of white blood cell that produces antibodies to help the body fight infection. Many of the known and possible risk factors for MGUS are the same as for multiple myeloma.

Family history of multiple myeloma

Multiple myeloma is more common in some families. The risk of developing multiple myeloma is nearly 4 times greater for a person who has a parent or sibling with multiple myeloma. Some studies have found that there is a stronger risk in families of African ancestry. However, most people with multiple myeloma have no family history of the disease.

Being overweight or obese

Multiple myeloma occurs more often in people with a high body mass indexbody mass indexA measure that relates body weight to height (calculated by dividing weight in kilograms by height in metres squared). (BMI) than in those who have a healthy weight. The risk is higher in people who are obese.


Many studies have found that people who work on a farm have a higher risk of developing multiple myeloma. Some studies have suggested that exposure to certain pesticides used in farming may explain the increased risk. Pesticides include a large number of different chemicals but only some pesticides have been linked to multiple myeloma risk. Research has shown that working with farm animals, especially sheep, may increase a person’s risk. The combination of several factors, including pesticides, animals or other exposures, may increase a person’s chance of developing multiple myeloma.

Possible risk factors

The following factors have been linked with multiple myeloma, but there is not enough evidence to show they are known risk factors. Further study is needed to clarify the role of these factors for multiple myeloma.

Occupational exposure

Some jobs and job-related exposures have been linked to a higher risk of developing multiple myeloma.


Painting – People who work with aerosol (spray) paint, rather than paint applied with a brush, have been found to have the highest risk of developing multiple myeloma.


Petroleum-related industries – People who are exposed to benzene or ethylene oxide have been found to have a higher risk.


Pesticides – People who work with pesticides, such as farmers and gardeners, have been found to have a higher risk.


Firefighters – Recent evidence from Nordic countries, like Sweden and Norway, showed that firefighters have a higher than average risk of developing multiple myeloma. It’s not clear why firefighters may have a higher risk, but it may be because of exposure to certain chemicals or doing shift work.


Wood-related industries – People in wood-processing and wood-working industries, such as sawmill workers and furniture makers, are exposed to wood dust and certain chemicals like wood preservatives that some studies show may increase the risk of multiple myeloma.

Autoimmune conditions

An autoimmune condition causes the body’s immune system to attack its own tissue. The following are autoimmune conditions that have been linked to an increased risk of multiple myeloma:

  • rheumatoid arthritis
  • polymyalgia rheumatica
  • pernicious anemia
  • systemic lupus erythematosus
  • ankylosing spondylitis

Viral infections

Some viral infections may increase the risk of developing multiple myeloma.

Hepatitis B and C infections

Hepatitis viral infections cause inflammation and scarring in the liver. Several research studies show that people who have had hepatitis B infection and those with a long-term (chronic) hepatitis C infection have a higher risk of multiple myeloma.


People with HIV (human immunodeficiency virus) and people with AIDS (acquired immunodeficiency syndrome) also appear to have a greater risk of developing multiple myeloma. HIV and AIDS weakens the body’s immune system. It’s not clear if these associations are due to a weakened immune system or the viruses themselves. People with HIV/AIDS also have a higher risk of developing some other types of cancer.

Gene mutations

Changes to a gene can stop the gene from working properly and cause cancer. Mutations of some genes have been linked to an increased risk of developing multiple myeloma. Researchers continue to study genes to find out which ones may be involved with the development of multiple myeloma.

Some types of medicines

Some medicines have been found to increase a person’s risk of developing multiple myeloma.

  • erythromycin
  • phenytoin (Dilantin)
  • laxatives
  • diazepam
  • ibuprofen (Motrin, Advil)
  • diet pills or stimulants
  • corticosteroids
  • acetaminophen (Tylenol)

Unknown risks

It isn’t known whether or not the following factors are linked with multiple myeloma. It may be that researchers can’t show a definite link or that studies have had different results. Further study is needed to see if the following are risk factors for multiple myeloma:

  • ionizing radiation
  • certain chemicals including styrene (used in the rubber industry), methylene chloride (dichloromethane), metalworking fluids and hair dye
  • asbestos
  • metals such as nickel
  • history of thyroid cancer
  • other viral and bacterial infections such as bronchitis, pneumonia and the stomach flu (called gastroenteritis)

Further study is needed to see if the following jobs increase the risk of multiple myeloma:

  • radiation technologist
  • rubber manufacturer
  • metalworker
  • cleaner
  • printer
  • butcher and other jobs that work with live or dead animals
  • auto mechanic (car repair worker)

Questions to ask your healthcare team

To make the decisions that are right for you, ask your healthcare team questions about risks.


Brock Taraba Brock has been cancer free for over a decade, thanks to the support we received from the Canadian Cancer Society.

Read Brock's story

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