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Leukemia is a cancer of the blood that affects white blood cells which are produced in the bone marrow. When someone has leukemia, large numbers of abnormal white blood cells are released into the blood stream. Because the cells are abnormal, they cannot work as they should to protect the body from disease.
Occurrence, risk factors and symptoms
Leukemia occurs in both children and adults. Chronic leukemia, which is slow growing, is more common in adults. Acute leukemia, which develops rapidly, is more common in children. The risk of a child developing leukemia is about 1 in 2000.
It accounts for approximately 75% of all diagnosed leukemias and 25% of all childhood cancers in the United States, with children aged 3-5 years most often diagnosed.
In most cases it is not known exactly what causes leukemia to develop but experts believe there are certain conditions that put a child at an increased risk for developing leukemia. These conditions include:
- Having an identical twin diagnosed at an early age
- Certain inherited genetic or immune system disorders
- Exposures to high levels of radiation or chemotherapy due to treatment for a previous cancer
- Having a history of taking, or currently taking drugs to suppress the immune system after an organ transplant
Symptoms children experience with leukemia are due to the large number of abnormal cells in the blood stream and to interference with the production of other important blood cells in the bone marrow. Two important cells that are affected are the red blood cells and platelets. Red blood cells carry oxygen and iron to all tissues of the body.
The anemia can cause them to look pale, feel more tired than usual and in severe cases, be short of breath while playing or exercising. Platelet cells are important for clotting. Impaired platelet function results in easy bruising and prolonged bleeding from even simple cuts. Because cells of the immune system are also affected, children with leukemia are more often sick with colds and flu symptoms. Other symptoms of leukemia include:
- Joint pain
- Swollen lymph nodes
- Poor appetite
- Abdominal pain
Genetic abnormalities lead to childhood leukemia
It is well documented that childhood leukemia is a disease caused by a number of genetic chromosomal abnormalities. These abnormalities define the different types of leukemia and their prognosis for cure or remission. There is now evidence that chromosomal abnormalities are the first step in the development of leukemia and that this begins in the prenatal period during fetal development. Evidence to this effect comes from studies of twin infants diagnosed with ALL, children with similar types of ALL and the studies of newborn blood samples on archived Guthrie cards. Identifying the same abnormal gene on the Guthrie card as in the leukemia patient’s blood cells is very strong evidence that childhood leukemia is initiated during fetal development.