Leukemia is the most common form of cancer in children, affecting approximately 4,000 youngsters each year in the U.S. and accounting for about one in three childhood cancers.
When a child has leukemia, the bone marrow – the soft, spongy center of certain bones – begins to make new blood cells (usually white blood cells) that do not mature correctly, but continue to reproduce themselves. Normal white blood cells help fight off infection, but these abnormal cells cannot. When the immature white blood cells, called blasts, begin to crowd out other healthy cells in the bone marrow, the child experiences the symptoms of leukemia (such as infections, anemia or bleeding).
What causes leukemia?
Most childhood leukemias occur by chance and are not inherited from a parent. However, having a brother or sister with leukemia carries a slight risk. Also, children with inherited immune system problems and children who have chemotherapy to treat some other types of cancer have an increased risk of developing leukemia. Some genetic conditions, such as Down syndrome or Li-Fraumeni syndrome, carry a higher risk, as well.
There are a number of types of pediatric leukemia. The type of leukemia is determined by the kind of blood cell that is affected and the stage of development when the normal cells become leukemia cells.
The three most common types of pediatric leukemia are:
- Acute lymphocytic leukemia (ALL). Also called lymphoblastic or lymphoid, it accounts for most of the childhood leukemias. With ALL, the bone marrow makes too many lymphocytes, crowding out other blood cells. The immature cells do not work properly to fight infection. ALL can occur over a short period of days to weeks.
- Acute myelogenous leukemia (AML). You may also hear this referred to as granulocytic, myelocytic, myeloblastic or myeloid. It accounts for most other childhood leukemias. There are different types of AML, but this is usually a cancer of the blood in which too many granulocytes, a type of white blood cell, are produced in the marrow. Granulocytes normally fight infection. AML can occur over a short period of days to weeks.
- Chronic myelogenous leukemia (CML). This form of cancer is less common in children and occurs, like AML, when too many granulocytes are produced in the marrow. CML is a slow growing form of leukemia and can occur over a period of months or years.
What are the symptoms of leukemia?
The following are the most common symptoms of leukemia and may come on suddenly or take place over a period of weeks. Each child may experience symptoms differently.
- Easy bleeding and bruising
- Frequent nosebleeds
- Anemia, often causing a child to become pale, tired and have rapid breathing
- Recurrent infections, which occurs when immature white blood cells do not fight infection. The child with leukemia often shows symptoms of an infection, such as fever, runny nose and cough, and can have repeated infections in a month.
- Bone and joint pain
- Fatigue and weakness
- Abdominal pain distress, sometimes with loss of appetite and weight loss
- Swollen lymph nodes
- Shortness of breath, coughing or wheezing