Blood cancer has many types which are based on the origin of cancer. Leukemia is also the form of blood cancer that begins in the bone marrow & results in the abnormal production of white blood cells. Bone marrow is mainly responsible for the production of Red blood cells, white blood cells and platelets but in the case of leukemia it starts producing abnormal or cancerous white blood cells. The uncontrolled production or multiplication of abnormal white cells affect the functioning of normal cells in the body.