Leukemia is a type of cancer that results in the body making too many abnormal white blood cells. This uncontrolled production results in an excessive amount of white blood cells that may be immature (acute leukemia) or mature (chronic leukemia). The leukemic cells may not function well to fight infection and may interfere with the production of red blood cells (which carry oxygen) and platelets (which control bleeding).
Normally, white blood cells play an important role in the body's natural defence system. They target and destroy foreign invaders like viruses and bacteria. White blood cells are made in the marrow (the spongy core) of your bones. Without healthy and functioning white blood cells, the body is at risk of developing severe and sometimes fatal infections.