The cause of chronic myeloid leukaemia is not known, but research is going on all the time to find out. Chronic myeloid leukaemia, like other cancers, is not infectious and can't be passed on to other people. It is not caused by an inherited faulty gene so other members of your family are unlikely to develop CML just because you have it.

Research has shown that exposure to electromagnetic fields, living near high-voltage electricity cables, and household radon do not increase a person’s risk of developing chronic myeloid leukaemia.

Most people with CML are found to have an abnormal chromosome called the Philadelphia chromosome. The Philadelphia chromosome is not an inherited fault that can be passed on from one generation to the next. However, it causes the production of a particular enzyme called tyrosine kinase, which leads to the development of CML.

There are a number of risk factors that might increase a person’s risk of developing CML. These are:

Radiation

Exposure to very high radiation levels (such as following a nuclear accident or an atom bomb) is known to increase the risk of developing CML. However, very few people in the UK will be exposed to radiation levels high enough to increase their risk. In recent years there has been publicity about the increase in leukaemia in people living close to nuclear power plants. Research is still under way to see if there is any definite link between these factors, but as yet there is no evidence of this.

Exposure to chemicals

People who have been exposed to a chemical called benzene for a long time – for example, in their work – have a higher risk of developing CML. Benzene is one of the chemicals in petrol and is also used in the rubber industry.