Leukemia is a cancer of the white blood cells, the soldiers in the body's immune system responsible for detecting and destroying disease-causing agents. According to the American Cancer Society, it is the most common childhood cancer, accounting for nearly a third of all cancers among children younger than 15 years old.
Nearly all cases of childhood leukemia are acute, with 80 percent being acute lymphoid leukemia (ALL), characterized by the overproduction of abnormal B- or T-cell lymphocytes, and 20 percent being acute myeloid leukemia (AML), in which granulocytes are overproduced.
The study included 827 children up to age 15 diagnosed with either ALL or AML. The children with leukemia were each compared with other children randomly selected from the California birth registry who were matched by factors such as age, gender, ethnicity and maternal race.
Interviews were conducted with mothers within four months of the diagnosis of leukemia, and the mothers were asked to report on the number of X-rays received by the child at least 12 months or more before the leukemia diagnosis. Mothers were also asked about their exposures to X-rays during pregnancy and the year prior to pregnancy.
The researchers noted that dental X-rays were not considered because they are so common and deliver such a low dose of radiation that exposure to those radiographs would not discriminate between individuals with high and low levels of radiation exposure.
The study found an increased risk from X-rays for ALL, but not for AML or T-cell leukemia, and there was no association with age at first exposure. Furthermore, there was no increased risk associated with
|Contact: Sarah Yang|
University of California -- Berkeley