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Risks and causes

Chronic lymphocytic leukaemia is the most common type of chronic leukaemia. Read about the risk factors and causes.

Risk factors

We don't know the cause of most cases of leukaemia but there are some risk factors that may increase your risk of developing chronic leukaemia.

A risk factor is something that may make you more likely to develop a particular condition or disease.

Family history

We know that there is some kind of inherited genetic change in some people who develop CLL. Studies show that people with a parent or sibling with CLL have a 6 to 9 times increased risk of developing it themselves. So far, we don't know of any specific gene changes that are linked to CLL. 

CLL is most common in Australia, the USA and Europe. It is very uncommon in people from China, Japan, or Southeast Asian countries.

It is more common in white people than black people. The reasons for these differences are not known.

Electromagnetic fields

Electromagnetic fields are often talked about as a possible risk factor for developing leukaemia. We are all exposed to electromagnetic radiation.

No increase in the risk has ever been found in adults who are exposed to the normal background levels people generally have in their own homes.

Low immunity

An overview of published evidence has shown that people with low immunity due to HIV or AIDS are three times more likely than the general population to develop leukaemia. 

People treated with medicines to lower their immunity after an organ transplant have a risk that is double that of the general population.

Chemical exposure and radiation

Radiation is known to increase the risk of other types of leukaemia but has not generally been linked to an increased risk of CLL. 

There have been some studies that suggest certain hair dyes might increase the risk of developing CLL. In one of these studies, they found that only women who had used permanent black hair dye had an increased risk of CLL. The other study showed an increase in risk only for women who used hair dyes before 1980. We need more research to clarify if hair dye use today increases the risk of CLL.

Last reviewed: 
09 Nov 2017
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    B Eichorst and others. Annals of Oncology, 2015, Vol. 26 (Supplement 5): 78-84

  • Elevated risk of chronic lymphocytic leukemia and other indolent non-Hodgkin's lymphomas among relatives of patients with chronic lymphocytic leukemia
    LR Goldin, M Bjorkholm, SY Kristinsson, (and others)
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  • Incidence of cancers in people with HIV/AIDS compared with immunosuppressed transplant recipients: a meta-analysis
    AE Grulich, MT van Leeuwen, MO,Falster (and others)
    Lancet, 2007; Vol: 370:59-67

  • Personal use of hair dye and the risk of certain subtypes of non-Hodgkin lymphoma
    Y Zhang, SD Sanjose, PM Bracci (and others)
    American Journal of Epidemiology  2008, Vol: 167:1321-31

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    SC Larsson and  A Wolk
    International Journal of Cancer 2008; Vol:122:1418-21

  • 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 with details of the particular issue you are interested in.

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