What is leukaemia?

Leukaemia is the name given to a group of cancers that develop in the bone marrow. Under normal conditions the bone marrow contains a small number of healthy immature blood cells, sometimes called blast cells. These immature blood cells mature and develop into red cells, white cells and platelets, which are eventually released into the blood stream.

Leukaemia originates in developing blood cells, which have undergone a malignant (cancerous) change. Instead of maturing properly, these cells grow and multiply in an uncontrolled fashion and interfere with normal blood cell production in the bone marrow. Most cases of leukaemia originate in developing white cells. In a small number of cases leukaemia develops in other blood-forming cells, for example in developing red cells or developing platelets.

There are several different types and subtypes of leukaemia.


Leukaemia can be either acute or chronic. The terms ‘acute’ and ‘chronic’ refer to how quickly the disease develops and progresses.

Acute leukaemia develops and progresses quickly and therefore needs to be treated as soon as it is diagnosed. It affects very immature blood cells, preventing them from maturing properly.

Chronic leukaemia results in an accumulation of more mature but abnormal white cells. It can occur at any age, but is more common in older adults and is rarely seen in children.


Leukaemia can also be either myeloid or lymphoid. The terms myeloid and lymphoid refer to the types of cell lineage in which the leukaemia first started.

When leukaemia starts somewhere in the myeloid cell line, it is called myeloid (myelocytic, myelogenous or granulocytic) leukaemia.

When leukaemia starts somewhere in the lymphoid cell line it is called lymphoblastic, lymphocytic, or lymphatic leukaemia.

The four main types of leukaemia are:

Both adults and children can develop leukaemia but certain types are more common in different age groups. We have a separate information booklet about the most common form of leukaemia in children acute lymphoblastic leukaemia (ALL).


Treatment for leukaemia may involve one or more of the following

  • Active Monitoring
  • Corticosteroids
  • Chemotherapy
  • Targeted therapy
  • Radiotherapy
  • Stem cell transplant

Please see our Treatments section for more detail on treatment for Leukaemia.


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