Leukemia is the most common form of cancer diagnosed in children and acute lymphoblastic leukemia, or ALL as it’s commonly called, is the most common type of leukemia. ALL is a cancer of the blood and bone marrow, and it affects the body's white blood cells (WBCs). Normally, these cells help fight infection and protect the body against disease. But in leukemia, these cells turn cancerous and multiply when they shouldn't, resulting in too many abnormal WBCs.
Bone marrow is a blood-like substance found inside our bones. It’s important because of its role in making all kinds of blood cells: red blood cells that carry oxygen, white blood cells that fight infections and platelets that help blood clot.