Leukemia is a cancer of the blood or bone marrow. Bone marrow produces blood cells. Leukemia can happen when there is a problem with the production of blood cells. It usually affects the leukocytes, or white blood cells.It is most likely to affect people over the age of 55 years, but it is also the most common cancer in those aged under 15 years. Elliott has finally beaten his leukemia, after 3 years of a harsh battle! #cancer #kids #young #disease #sad #sims #victory #fightcancer