Leukemia is a cancer of the blood cells which begins in the bone marrow, the soft tissue inside the bones. All cells are produced in the bone marrow. They start as stem cells and then self-generate into more specialised cells such as white blood cells, red blood cells and platelets. Patients with leukemia produce lots of abnormal white blood cells called leukemia cells. Autologus stem cell therapy is when the patients own stem cells are used to treat the condition. Alternatively, the stem cells originate from the bone marrow or peripheral blood of a donor, this is the allongenic approach.