Risks and causes for acute lymphoblastic leukaemia (ALL)

Your risk of developing cancer depends on many things. These can include environmental, lifestyle and genetic factors.

Anything that increases your risk of cancer is called a risk factor.

For most people with ALL, the doctor won't be able to identify any underlying risk factors. So you might not know what caused your leukaemia.

But there are some factors that may increase your risk of developing it. Having one or more risk factors doesn't mean that you will definitely get leukaemia.

The information on this page is about the risks and causes of adult ALL. You can find out more about the risks and causes for cancer in children in the link below.  

Risk factors for ALL include:

Genetic conditions

Certain rare, inherited conditions can increase the risk of acute leukaemia, including:

  • Down’s syndrome
  • Fanconi anaemia
  • ataxia telangiectasia
  • Bloom syndrome

Previous treatment with chemotherapy

People who have had certain chemotherapy drugs in the past have a slightly increased risk of developing leukaemia some years later. The risk depends on how much treatment you had. Some of the drugs include:

  • etoposide with cisplatin and bleomycin
  • thiotepa
  • busulfan
  • chlorambucil

It's important to remember that this risk is still very small compared to the risk to your health if the cancer had not been treated.

Ionising radiation exposure

High energy (ionising) radiation can cause cancer because it can affect your cells and damage the DNA Open a glossary item.

We know that exposure to very high levels of ionising radiation increases acute leukaemia risk. For example, people exposed to the atomic bomb explosions in Japan at the end of World War 2 had a higher risk of developing leukaemia.

A 20 year study has followed up workers who helped clean up after the Chernobyl nuclear power plant accident in 1986. It shows that even at low doses of ionising radiation there is an increased risk of all types of leukaemia.

CT scans and radiotherapy treatment also use ionising radiation. Research suggested that this could increase the risk of children developing leukaemia later in life. However, it's important to note that doctors make sure the benefits of having the test or treatment outweighs the risks.   

Exposure to benzene

Exposure to a chemical called benzene at work can increase the risk of developing ALL. Exposure to benzene may occur in:

  • petrol industry
  • chemical industry
  • pharmaceutical industry
  • rubber industry
  • shoe production
  • printing industry

The higher the level of exposure over many years, the greater the risk. 

Another study showed that you have an increased risk of developing ALL if your parents were exposed to benzene before and during pregnancy. 

Weakened immunity

A study looked at published research into people:

  • with HIV or AIDS
  • treated with medicines that lower immunity after an organ transplant

The researchers found that these people have a risk of leukaemia that is up to 3 times higher than people without these factors.

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.

Last reviewed: 
28 Jul 2021
Next review due: 
28 Jul 2024
  • List of Classifications by cancer sites with sufficient or limited evidence in humans, IARC Monographs Volumes 1 to 129*
    The Internal Agency for Research on Cancer (IARC), last updated March 2021
    Accessed July 2021

  • The fraction of cancer attributable to known risk factors in England, Wales, Scotland, Northern Ireland, and the UK overall in 2015
    KF Brown and others
    British Journal of Cancer, 2018. Volume 118 Issue 8, Pages 1130 to 1141

  • Ionising radiation and risk of death from leukaemia and lymphoma in radiation-monitored workers (INWORKERS): an international cohort study
    K Leuraud and others
    Lancet Haematology, 2015. Volume 2, Pages e276 – e 281

  • Principles and practice of oncology (11th edition)
    VT De Vita, S Hellman and SA Rosenberg
    Lippincott, Williams and Wilkins, 2019

  • BMJ Best Practice Acute lymphocytic leukaemia
    BMJ Publishing Group Ltd, last updated March 2021

  • The information on this page is based on literature searches and specialist checking. We used many references and there are too many to list here. If you need additional references for this information please contact patientinformation@cancer.org.uk with details of the particular risk or cause you are interested in. 

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