Childhood Leukemia

Leukemia Leukemia is a disease of the blood When leukemia begins Who gets leukemia Diagnosing leukemia Best treatments for leukemia Types of leukemia

Who gets leukemia .

Acirte leukemia is the most common childhood cancer. Often thought of as strictly a childhood disease, leukemia actually afflicts many more adults than children. Each year in the United States, approximately 3,500 children are diagnosed with acute leJkemia.

Childhood leukemia is most commonly diagnosed at ages two to seven, with the highest incidence at approximately three years of age. In the United States, leukemia is more common in whites than in blacks, and boys have a slightly higher incidence than girls. Children with certain genetic diseases have a higher risk of developing leukemia than does the general population.

Leukemia is not contagious; it cannot be passed from one person to another. Although the exact cause of childhood leukemia is a mystery, certain factors are known to increase the risk of developing the disease.

Genetic factors

Persons with extra chromosomes (genetic material contained in cells) or certain chromosomal abnormalities have a greater chance of developing leukemia. Children with Down syndrome, neurofibromatosis type 1 (NFl), Shwachman syndrome, Bloom syndrome, Franconi anemia, Kostmann syndrome, and ataxia telangiectasia have a higher risk of getting leukemia than do children without these genetic disorders. However, most children with these syndromes do not develop leukemia.

In Cases where one identical twin has leukemia before the age of 6, the other twin has a 25 percent chance of developing the disease within one year. The risk for the second twin is less if the sibling with the disease is older when diagnosed, Recent data suggest that this high degree of risk is due to connection of the circulation (blood vessels) in identical twins while in the womb. In fraternal (non-identical twins), there is minimal if any increased risk of leukemia developing in both twins.

Environmental factors

Exposure to ionizing radiation and certain toxic chemicals may predispose individuals to leukemia and other problems involving the bone marrow. Many Japanese who were exposed to fallout from the atomic bomb during World War II and some of the people living near the Chernobyl accident in the Ukraine have developed leukemia. However, children exposed to irradiation from the bombs while in the mother's womb did not have an increased risk of developing leukemia.

Chronic exposure to benzene has been associated with leukemia in adults. Also, radi¬ation given for conditions such as tinea capitis (ringworm of the scalp) and thymus enlargement can increase the risk of developing leukemia. Most children, however, are not exposed to large amounts of radiation or industrial chemicals.
The data are mixed about whether exposure to electromagnetic fields increases the risk of leukemia. Most recent data suggest that if there is an increased risk, it is minimal. For information about the US government's electromagnetic field (EMF) research efforts, including public information materials developed by the EMF Research and Public Information Dissemination (EMF RAPID) program, refer to the EMF RAPID home page on the Internet: www.niehs.nih.gov/ocljactsheets/emf/emfhtm. Additional information on electromagnetic fields is available at the FCC website at WWWfcc.gov/oeU rfsafety.

Certain types of chemotherapy (drugs that inhibit the enzyme topoisomerase and alkylating agents) or radiation treatments for prior cancers can cause acute myeloid
leukemia. The greatest risk is one year after treatment with topoisomerase inhibitors and four to five years after treatment with alkylating agents and irradiation.

Viral factors

Viruses that cause leukemia in cows, cats, chickens, gibbons, and mice have been found. A T-cell virus has been identified that causes a rare type of leukemialymphoma in adults; however, no virus has been found that causes the types of leukemia com¬monly found in children.