What is it?
Leukaemia is a cancer of the white blood cells. These cells are made in the bone marrow and help to fight infection. There are two types of white blood cells which can both be affected by leukaemia: lymphoid cells and myeloid cells.
ALL is where the bone marrow makes too many immature lymphoid cells (known as lymphoblasts or blast cells) which stop the production of healthy cells.
This type of cancer usually gets worse quickly if not treated.
Symptoms are quite general but include bruising and frequent, persistent infections.
Who does it affect?
In the UK, leukaemia makes up one-third of all childhood cancers and more than half affect children under the age of 5.
Acute Lymphoblastic Leukaemia (ALL) is the most common form of leukaemia in children under the age of 14, affecting around 400 each year.
Find out more
You can read more about the types of Acute Lymphoblastic Leukaemia and it’s treatment.