Leukaemia is a cancer that starts in blood-forming tissue such as the bone
marrow, which makes blood cells (red blood cells that carry oxygen around the
body, white blood cells that fight disease and infection, platelets that help to
stop bleeding when it starts).
In people with leukaemia, the bone marrow produces large numbers of abnormal
white blood cells and not enough normal red blood cells.
Leukaemia cases represent less than 4% of all cancer cases in adults but are
the most common form of cancer in children.
Source: GreenFacts
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There are different types of leukaemia.
Those that develop suddenly (over days or weeks) are called acute leukaemias.
Leukaemias that develop over months or years are chronic leukaemias.
Leukaemia is also named by the type of white blood cell affected, either the
myeloid or lymphoid cells, which are distinguished by their appearance under the
microscope.
Myeloid white blood cells are the immune system's first line of defence
against infection and are found mainly in the blood. [They] engulf and kill
foreign organisms. Lymphoid white blood cells are found in the lymph nodes and
in the blood. They lie in wait to detect foreign organisms and stimulate the
body's defences to fight them.
[CLL leukemia is Chronic Lymphoid Leukaemia. Non-CLL leukemia refers to any
other type of leukemia, that is, chronic myeloid, acute myeloid or acute
lymphoid leukemia]
