Chronic leukaemia develops when damaged myeloid white blood cells grow out of control.
- These abnormal white cells are not fully developed and do not work properly, plus they live too long, so there are too many circulating in the blood, leaving little room for cells to be produced.
- It is a rare type of cancer and usually develops very slowly.
What causes chronic myeloid leukaemia?
- The cause of CML isn’t known, however most people diagnosed with it have an abnormal chromosome called the Philadelphia chromosome.
- It has also been linked to exposure to very high levels of radiation, like being a survivor of an atomic bomb.
What are the symptoms?
Many people have no symptoms, or very non-specific symptoms in the early stages of CML and it may be discovered only when a blood test is taken for a different reason.
As it advances, however, CML can result in the following symptoms:
- Frequent infections, as without enough mature, healthy white blood cells it’s a lot harder to fight off bacteria and viruses.
- Tiredness and sometimes breathlessness, caused by a lack of red blood cells (also known as anaemia). There are often not enough red blood cells because the abnormal lymphocytes are taking up too much space in the bone marrow.
- Unexplained bruising or bleeding, such as nosebleeds, caused by a lack of platelets in the blood.
- Abnormal lymphocytes may collect in lymph glands and cause swellings in the neck, armpits or groin.
- The spleen may become enlarged and cause a tender lump in the upper left-hand side of the stomach.
- Some people will have sweating or a high temperature at night.
- Some people lose weight.
How is it diagnosed?
CML is relatively easy to diagnose. A GP will perform a complete blood count (CBC) test and if it shows an unusually high level of immature white blood cells, they will refer the patient to a haematologist (blood specialist), for advice and treatment.
- The haematologist will ask about the patients full medical history and do a physical examination to check for any enlargement of the lymph nodes, spleen or liver.
- They'll also need to have more blood tests. If the tests show leukaemia cells, they may need to have a bone marrow biopsy for a clear diagnosis, and to help with planning the best treatment for them.
Ultimately, CML is diagnosed by testing for the Philedelphia chromosome. This can be detected during routine Cytogenetic tests.
CML is often divided into three phases. It typically begins in the chronic phase, and over the course of several years progresses to an accelerated phase and ultimately to a blast phase.
How is it treated?
Treatment for CML depends on the phase of the illness, but the main type of treatment is Imatinib, a drug that works by blocking signals within the leukaemia cells, which makes them die.
Imatinib can be used in all three phases of CML, as long as it hasn’t been used in the phase prior.
- Chemotherapy is also used in some cases, and high dose treatment with a stem cell transplant is also an option for some people. This can cure the leukaemia in some cases (it’s more likely to be an option for younger people who have a brother or sister whose stem cells are a close match to their own).
- In the blast phase the aim of treatment is to reduce symptoms and try to put the leukaemia back into a second chronic phase. Blast phase CML is like an acute leukaemia, so combinations of chemotherapy drugs that are used to treat acute leukaemia are often used.
- The effectiveness of any treatment can be monitored using the polymerase chain reaction (PCR) test, which shows whether the Philadelphia chromosome is present or not. This way any recurrence or change in the leukaemia can be detected.
The PCR test can show the leukaemia even when it can't be seen using standard tests, and before any symptoms happen.
Treatments may be given to deal with conditions caused by CML. For example, a very high white blood cell count can sometimes lead to a clogging-up of blood vessels which can cause some physical problems. However, it can be treated by removing the extra white cells from the blood – a process called leukopheresis.