Chronic lymphocytic leukaemia (CLL) risks and causes
This page tells you about chronic lymphocytic leukaemia and its risk factors. There are sections on
How common is CLL?
CLL is the most common type of chronic leukaemia, although still relatively rare. Chronic leukaemia is very rare in children. Leukaemia in children is nearly always acute leukaemia.
Risk factors for CLL
It is much more common to get CLL if you are older. It is most common in people over 60 and very rare under 40. Men are twice as likely to develop CLL as women. We don't know why that is.
There is some evidence of CLL running in families, but most cases of CLL do not have a family link. And it is much less common in some ethnic groups. But so far, we don't know of any specific gene changes that are linked to CLL.
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 7,200 cases of leukaemia diagnosed in the UK each year. About 3,200 of these are chronic leukaemias. About 2,600 of these are chronic lymphocytic leukaemia. So CLL is the commonest type of chronic leukaemia by far. It is much more common to get CLL if you are older. It is commonest in people over 60 and is very rare under 40. Men are twice as likely to develop CLL as 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. For example, smoking is a risk factor for lung cancer and sun exposure a risk factor for skin cancer.
We know that there is some kind of inherited genetic change in some people who develop CLL. It is much less common in some ethnic groups, for example. We know that CLL can run in families. But so far, we don't know of any specific gene changes that are linked to CLL.
One Swedish study showed that people with a first degree relative with CLL have a 7 times increased risk of developing it themselves. The same study has shown that first degree relatives of people diagnosed with Hodgkin’s 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.
Electromagnetic fields are often talked about as a possible risk factor but probably do not increase the risk of 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.
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 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 three previous studies showed that people who are overweight or obese have a slightly increased risk of CLL. We need more research to be sure that being overweight really increases the risk of CLL.
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