Acute lymphocytic leukemia (ALL) is the most common type of leukemia that children get. A cancer of the blood, ALL begins in the bone marrow, where blood cells are produced. Bone marrow is found in the soft, spongy center of the long bones of the arms and legs. These bones make the three major types of blood cells. White blood cells fight infection. Red blood cells carry oxygen. Platelets make the blood clot and stop bleeding.
In ALL, there are too many lymphoblasts (immature white blood cells) in the blood and bone marrow. These crowd out normal, healthy blood cells that the body needs. Red blood cells don’t have room to grow, nor do other white blood cells or plateletes.
There are four subtypes of ALL, depending on the cell that is affected:
- T cell ALL
- Philadelphia chromosome
- ALL diagnosed in infants
- ALL diagnosed in children over 10 years of age
Doctors do not know what causes leukemia in children. There are several factors that may increase a child’s risk, but not definitively.
The National Cancer Institute states that family history or exposure to radiation may increase the risk for childhood ALL.