Causes and risk factors of CML

It is not clear why people get CML. It is not linked to smoking, diet, exposure to chemicals or infections. And it does not run in families.

There are some factors that might increase the risk of developing CML.


CML can happen at any age. But it is more common as people get older. Over half of the people diagnosed with CML in the UK are over 65.


CML is slightly more common in men than women.

Radiation exposure

Exposure to very high radiation levels increases the risk of developing CML. For example, these might be the high levels of radiation following a nuclear accident. Very few people in the UK will be exposed to radiation levels high enough to increase their risk.

Research has found no link between the risk of developing CML and:

  • living near nuclear power stations
  • exposure to electro-magnetic fields
  • living near high-voltage electricity cables
  • household radon (naturally occurring gas).

Like other cancers, CML is not infectious and it cannot be passed on to other people.

Back to Diagnosing

Being diagnosed with CML

If your GP thinks you may have CML, they will refer you to a haematologist who will arrange more tests.