Chronic myeloid leukaemia [CML] is divided up into 3 phases. Most people are diagnosed in 'chronic phase' where the blood count is easy to control with treatment and they feel well and are able to live a normal life. This lasts for an average of 4 - 5 years then the disease starts to change.

This change can be very subtle: the treatment may be less effective at controlling the blood count despite increasing the drug dose or the bone marrow may start to work less effectively causing anaemia or a low platelet count. At this time the blood and bone marrow may show an increase in the number of primitive cells that have not matured into normal white cells. At this stage response to treatment becomes less good. Finally increasing spleen size or fever, sweats or bone pains may become troublesome. This mixed bag of problems is called 'accelerated phase'. Most people will progress to 'blast crisis' which in two thirds will look like acute myeloid leukaemia [AML] and in one third will look like acute lymphoblastic leukaemia [ALL]. Death is usually 3 - 6 months after the start of blast crisis.

Treatment becomes less effective as the disease changes from chronic phase to accelerated phase to blast crisis. A bone marrow transplant is still the only treatment that offers the chance of a cure. The new drug Glivec has shown some good results in returning people from accelerated phase back to chronic phase. Blood counts are improved in about two thirds of people.

Once someone is in a blast crisis they will need chemotherapy similar to that used for ALL, or AML. Some people do return back to chronic phase but this usually doesn't last for long.

The accelerated and blast stages of CML are complicated and treatment is often tailored to the needs of the individual, depending on how old they are, their general health and the possibility of a bone marrow donor. Your consultant should take time to discuss these issues with you and to answer your questions as this is a difficult area and the treatments are not straightforward.