There are 2 main groups of leukaemia - acute and chronic leukaemia. They are then grouped by the type of white blood cell that is affected.
Whether a leukaemia is acute or chronic describes how quickly the leukaemia is likely to develop and get worse.
Acute and chronic leukaemia
Acute leukaemias tend to develop quickly and get rapidly worse if they are not treated. Chronic leukaemias develop slowly and tend to get worse slowly, over a long time.
In chronic leukaemia, the white blood cells are almost fully developed but are not completely normal. They still work, but not as well as they should do at fighting infection. Your body makes too many of these abnormal white blood cells.
Types of chronic leukaemia
CML and CLL
The two most common types of chronic leukaemia are:
- chronic myeloid leukaemia (CML)
- chronic lymphocytic leukaemia (CLL)
The difference between them is the type of white blood cell that has become cancerous. In CLL, the abnormal cells develop from early blood cells called the lymphoid blood stem cells. The cancerous white blood cells are B lymphocytes, also called B cells.
In CML, the abnormal leukaemia cells develop from early blood cells called the myeloid blood stem cells. They become myelocytes. These cells are sometimes called granulocytes. So you may hear this type of leukaemia called chronic granulocytic leukaemia or CGL.
Hairy cell leukaemia
There is a third type of chronic leukaemia called hairy cell leukaemia. It is rarer than CLL or CML. The leukaemia cells have bits that stick out of the cell surface and look like hairs. These can be seen under a microscope and give this type of leukaemia its name.