Leukaemia is the most common form of blood cancer in children. Leukaemia is a blood cancer that affects the white blood cells, a really important part of our immune system that fights infection. 

When a child has leukaemia, control of blood cell production breaks down. The bone marrow - the soft tissue in the mdidle of our bones where all our blood cells are made - makes lots of abnormal white blood, or leukaemia cells. These never mature into proper white blood cells, vital to a healthy immune system, and so children with leukaemia are at more risk of infection.