Acute lymphoblastic leukemia (ALL) is a "liquid" tumor or cancer of the blood that starts in the bone marrow and spreads to the bloodstream (the term leukemia comes from Greek words for white and blood). ALL is the most common pediatric cancer, accounting for 35% of all cancers in children. There are about 7,000 new cases in children and adolescents (birth to 21 years of age) in the United States each year.
What is leukemia?
Leukemia starts in the bone marrow, the spongy internal part of bones where new blood is made. Leukemia starts when a single, young white blood cell called a "blast" develops a series of mistakes or mutations that allow it to multiply uncontrollably. Eventually, blasts take over the bone marrow and crowd out normal blood cells. One blast soon becomes 10 billion cells. This is the number of leukemia cells that is typically present in the body at the time of diagnosis.
What are the normal blood cells in the bone marrow?
There are 3 types of cells that are made by the bone marrow:
- Red blood cells: carry oxygen
- White blood cells: help fight infections.
- Platelets: help blood clot
What are the symptoms of leukemia?
Leukemia cells "crowd out" these normal blood cells. It is the decrease in normal cells that produces the symptoms of leukemia:
- Fatigue and being pale results from a decreased number of red blood cells, known as anemia.
- Fever due to the disease itself or from infection because there are a decreased number of healthy white blood cells, known as neutropenia.
- Bruising or bleeding from decreased platelets, known as thrombocytopenia.
- Bone pain that is sometimes associated with swelling of the joints.
The signs and symptoms of leukemia are the same as more common childhood illnesses and many children are treated for those other illnesses before leukemia is diagnosed.
-William Carroll, MD, New York University Medical Center
Reviewed and edited by
CureSearch.org Medical Editorial Board
May 2008