What is leukemia? Leukemia is a cancer of blood-forming cells that are in the early stages of development. In most cases white blood cells, but some types of leukemia start in other types of blood cells. Blood cells are formed in the bone marrow. Any of these cells can turn into a leukemia cell, once this happens the cell does not mature as it should. The cell may start producing rapidly, and the mutated cells will likely not undergo apoptosis as they should. These cells accumulate in the bone marrow and crowd out healthy cells. Typically, leukemia cells enter the bloodstream rather quickly. From the bloodstream they can spread to places such as the lymph nodes, spleen, liver, central nervous system, or other organs where the leukemia cells can cause those other cells to function irregularly. To understand where and how leukemia occurs it is helpful to learn more about the blood and lymphatic systems. The bone marrow is the soft inner part of the bone where blood cells are formed. There are three different types of main blood cells; white blood cells, red blood cells and platelets. In newborns, active blood cells are found in almost all bones, but during adolescence they are found primarily in flat bones (skull, shoulder blades, ribs, and pelvis) and in vertebrates. Bone marrow is made up of a small number of blood stem cells, more mature blood-forming cells, fat cells, and supporting tissues to help the tissue grow. They undergo a series of changes to produce new blood cells. This process produces 1 of 3 things: red blood cells, white blood cells, or platelets. Red blood cells carry oxygen from the lungs to all other parts of the body and carry carbon dioxide back to the lungs. Platelets are cellular fragments formed from a type of bone… paper center… spinal cord or brain cells. Facts about leukemia:1. Leukemia is the most common cancer in both children and adolescents. It accounts for almost 1 in 3 childhood cancers. But overall, childhood leukemia is a rare disease.2. ALL is more common in white children than in African-American and Asian-American children. It is also more common in boys than in girls. AML occurs about equally in boys and girls of all races.3. The 5-year survival rate for children with ALL is more than 85%, children with acute myeloid leukemia have a 5-year survival rate of 60% to 70%. Reported rates for children with JMML are 50%. The 5-year survival rates in children with CML are not very helpful because some live a long time without the leukemia being cured, but reported rates range from 60% to 80%. Rates may be higher now with the new drugs, but they haven't been around long enough to be sure.