Chronic lymphocytic leukaemia (CLL) risks and causes
This page tells you about chronic lymphocytic leukaemia and its risk factors. There are sections about
How common is CLL?
CLL is the most common type of chronic (slowly developing) leukaemia but it is still relatively rare. It mostly occurs in people over the age of 60 and is very rare in people under 40. Men are twice as likely to develop CLL as women. We don't know why that is.
People who have a parent or sibling with CLL have an increased risk of developing it themselves. But so far, we have not found any specific gene changes that increase a person's risk of CLL. Most people with CLL do not have other family members with the condition. 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.
Other medical conditions
People who have low immunity due to HIV or AIDS or taking medicines after an organ transplant also have an increased risk of CLL.
Other medical conditions that may slightly increase the risk of developing CLL include diabetes in men, chest infections, sinusitis, shingles, chronic osteoarthritis and having an inflamed prostate gland.
Some people who have relatives with particular blood disorders or other medical conditions are slightly more likely to develop CLL than the general population. The conditions include Hodgkin lymphoma, monoclonal gammopathy of undetermined significance (MGUS) and Waldenström's macroglobulinaemia.
You can view and print the quick guides for all the pages in the About CLL section.
In total, counting all types, there are around 8,300 cases of leukaemia diagnosed in the UK each year. About 2,800 of these are chronic lymphocytic leukaemia. CLL is by far the most common type of chronic (slowly developing) leukaemia.
It is much more common to get CLL if you are older. It is more common in people over 60 and is very rare under 40. Men are more likely to develop CLL than women. We don't know why that is.
Although leukaemia is the most common type of childhood cancer, leukaemia in children is nearly always acute leukaemia – either acute myeloid leukaemia or acute lymphoblastic leukaemia. Chronic leukaemia is very rare in children.
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.
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. But 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.
Results of a large European study showed that men with diabetes had double the risk of B cell chronic lymphocytic leukaemia. But women with diabetes did not have an increased risk. We need more research to find out why this is.
Some studies have shown that people who have had certain medical conditions have a slightly increased risk of developing CLL. The conditions include the following.
- Pneumonia (chest infection)
- Shingles infection
- Auto immune haemolytic anaemia
- Chronic osteoarthritis
- Inflamed prostate (prostatitis)
It is possible that some of these conditions are due to reduced immunity in the early stages of CLL, rather than the cause.
One study has shown that first degree relatives of people diagnosed with Hodgkin lymphoma have double the risk of CLL. Although there is some evidence of CLL running in families, it is important to remember that most cases of CLL do not have a family link.
One study has shown a doubled risk of CLL in people who have a first degree relative diagnosed with a blood disorder called monoclonal gammopathy of undetermined significance. Having a first degree relative with lymphoplasmacytic lymphoma (also called Waldenström's macroglobulinaemia) has been shown in one study to triple the risk of CLL.
Electromagnetic fields are often talked about as a possible risk factor for developing leukaemia. We are all exposed to electromagnetic radiation. It is all around us. Some research has suggested that electromagnetic fields might be a risk factor for leukaemia. But no increase in the risk of CLL has ever been found in adults who are exposed to the normal background levels people generally have in their own homes.
An overview of published evidence has shown that people with low immunity due to HIV or AIDS are 3 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.
Two studies have shown an increased risk of CLL in women who have used hair dye. In one of these studies, only women who had used permanent black hair dye had an increased risk, while the other study showed an increase in risk only for women who used hair dyes before 1980. More studies are needed to clarify if hair dye use today increases risk of CLL.
One study that combined the results of 4 previous studies showed that people who are very overweight (obese) have a slightly increased risk of CLL. We need more research to be sure that being overweight really increases the risk of CLL.
Radiation is known to increase the risk of other types of leukaemia but has not generally been linked to an increased risk of CLL. But one study has showed an increased risk of CLL in Czech uranium miners who had high exposure to radon (a radioactive gas).
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