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. But sometimes multiple myeloma develops in people who don’t have any of the risk factors described below.

More men than women are diagnosed with multiple myeloma. The risk for 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.

History of monoclonal gammopathy of undetermined significance (MGUS)

Family history of multiple myeloma

Obesity and overweight

Farming

Weakened immune system

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

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 makes antibodies to help the body fight infection. Many of the known and possible risk factors for MGUS are the same as for multiple myeloma.

It is difficult to diagnose multiple myeloma early. Often it causes no symptoms until it is more advanced. People with MGUS may have regular blood work to monitor for 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 show that there is a stronger risk in families of African ancestry. But most people with multiple myeloma have no family history of the disease.

Multiple myeloma occurs more often in people with a high body mass index (BMI) than in those who have a healthy weight.

Many studies show that people who work on a farm have a higher risk of developing multiple myeloma. We need more research to understand what it is about farming that causes the increase in risk. Some studies suggest that being exposed to certain pesticides used in farming explains the increased risk. Pesticides include a large number of different chemicals, but only some pesticides are linked to multiple myeloma risk. Research also shows that working with farm animals, especially sheep, may increase your risk. It may be that it is the combination of being exposed to pesticides, animals or other factors that increases a person’s chance of developing multiple myeloma.

People with a weakened immune system (immunosuppression) have a higher risk of developing multiple myeloma. This includes people with HIV or AIDS and people who have had an organ transplant and must take medicines to suppress their immune system.

The following factors have been linked with multiple myeloma, but there is not enough evidence to show for sure that they are risk factors. More research is needed to clarify the role of these factors for multiple myeloma:

• autoimmune conditions
• viral infections such as hepatitis B and C
• working in occupations such as petroleum production, machinery production or carpentry, which expose you to chemicals such as benzene, coal or wood dust

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