We don’t know what causes most cases of acute myeloid leukaemia (AML). But there are some factors that may increase your risk of developing it.
What is a risk factor?
Anything that can increase your risk of getting a disease is called a risk factor.
Different cancers have different risk factors. Having one or more of these risk factors doesn't mean you will definitely get that cancer.
AML is more common in older people. The risk of AML increases from around 50 years and is greatest in those aged between 85 and 89 years.
Smoking cigarettes can increase your risk of developing AML. There is benzene in cigarette smoke and this is likely to be a significant cause.
The risk of AML increases with the more cigarettes you smoke daily and the number of years you smoke.
Being overweight or obese
People who are overweight or obese have a slightly higher risk of AML than people who are not overweight. Being overweight means you have a body mass index of 25 to 29.9. Obesity means a body mass index or 30 or above.
We’ve known for a long time that exposure to high energy (ionising) radiation increases acute leukaemia risk. AML is one type of acute leukaemia.
For example, people who have had radiotherapy for cancer have an increased risk of acute leukaemia. This is because radiotherapy exposes you to a higher than normal level of radiation. But this risk is very small compared to the risk to your health of not treating the cancer.
Exposure to benzene at work
Exposure to the chemical benzene at work over a long time increases the risk of developing acute leukaemia. Workplaces where exposure is possible include oil refineries and chemical and petrochemical plants. In the UK, employers in these industries are required to prevent or control exposure to benzene as much as possible.
Certain inherited conditions, such as Fanconi anaemia can increase the risk of developing acute leukaemia. Children with Down’s syndrome are more likely to get acute myeloid leukaemia than other children.
People who have had treatment for Hodgkin lymphoma or breast cancer with particular chemotherapy drugs (such as chlorambucil, melphalan or cyclophosphamide) have a slightly increased risk of developing blood changes. These changes can lead to AML many years later. The amount of risk depends on how much treatment you had.
In the 10 years after treatment, survivors of childhood cancer have a higher risk of developing leukaemia than other people. But it is important to remember that this risk is still small compared to the risk to their health if the cancer wasn't treated. The risk also gets lower as time passes since the treatment.
Some types of blood disorder make you more likely to get leukaemia than people without those blood disorders. These include
• myelodysplastic syndrome
• myeloproliferative disorders such as polycythaemia rubra vera (PCV) and chronic myeloid leukaemia
People with these disorders still only have a small risk of developing AML.
Auto immune conditions
Auto immune disorders are diseases caused by the body producing an immune response against its own tissues. Research has found that people with particular immune disorders have an increased risk of AML.
The conditions include
- rheumatoid arthritis
- auto immune haemolytic anaemia
- ulcerative colitis
The amount that the risk increases depends on the condition you have. It is not known whether the increase in risk of AML is due to the auto immune conditions or the drugs used to treat them.
Other possible causes
Stories about potential causes are often in the media and it isn’t always clear which ideas are supported by evidence. There might be things you have heard of that we haven’t included here. This is because either there is no evidence about them or it is less clear.