The term leukemia refers to cancers of the white blood cells (also called leukocytes or WBCs). Leukemias, as a group, make up about a quarter of all pediatric cancers. Luckily, with treatment, most children with leukemia will be free of the disease without it coming back.
Leukemias start in the bone marrow — the soft tissue found inside bones that produces blood cells. When a child is diagnosed with leukemia, it’s because the white blood cells in the body are producing abnormally. These cells (also known as blasts) start to crowd out the healthy cells in the bone marrow. Eventually, the healthy cells have no place to go, so they stop producing. When a child's body no longer produces enough healthy white blood cells it can cause anemia, swollen lymph nodes, and other symptoms of leukemia in children.
Leukemia is classified as being either acute (meaning it’s rapidly developing) or chronic (meaning it’s slowly developing). About 98% of pediatric leukemias are acute.