FRIDAY, Oct. 8 (HealthDay News) -- Researchers report that
exposure to three or more X-rays in childhood may double the odds
that a child will develop a form of leukemia, although the overall
risk remains small.
The study authors aren't calling for an end to childhood X-rays,
which can be crucial to the treatment of conditions such as
pneumonia and broken bones. And the study doesn't definitively
prove that the X-rays directly boost the risk of leukemia.
However, the researchers are recommending that doctors not order
X-rays when they aren't necessary and that they take special
precautions regarding CT scans, which deliver much more potentially
dangerous radiation to the body.
Study co-author and epidemiologist Patricia Buffler called the
findings a "very serious alert."
"Eliminating or reducing any unnecessary exposure [to radiation] is important," said Buffler, a professor at the University of California, Berkeley's School of Public Health, although she acknowledged that "some exposures are very important for making accurate diagnoses."
Leukemia, a form of cancer that strikes the bone marrow and
blood, sickens about 3,317 children from birth to age 14 in the
United States each year, according to the Leukemia & Lymphoma
Society. One type, acute lymphoid leukemia, is the most common type
of cancer among kids aged 1 to 7 years.
Doctors can usually treat this leukemia successfully, but it has
the potential to be deadly.
In the new study, the researchers looked at the medical records
of 711 children up to the age of 14 who were diagnosed with acute
lymphoid leukemia in California from 1995-2008. Researchers
compared them to similar kids who didn't have leukemia.
The findings were published in the Oct. 1 online edition of the
International Journal of Epidemiology.
The researchers excluded the X-rays in the year prior to
diagnosis and before birth. They found that kids were 1.85 times
more likely to develop that type of leukemia if they had had three
or more X-rays. In a separate part of the study, the researchers
looked at kids with acute myeloid leukemia, but found no link
between that type of leukemia and exposure to X-rays.
In the big picture, the increased risk doesn't greatly increase
the risk of leukemia in children overall. In general, about four
out of every 100,000 kids develop the specific kind of leukemia in
question, study co-author Buffler said, and if the risk doubled the
number would go to eight.
The results are surprising in light of previous assumptions
about the safety of X-rays. "We're talking about fairly routine
diagnostic X-rays," Buffler said.
Why might X-rays be so risky? Research suggests that the kind of
radiation found in X-rays can cause cells in the body to mutate and
create cancer, Buffler explained. And CT scans, which have grown in
popularity in recent years, create more radiation than traditional
X-rays, she noted. Future studies will look into the effects of CT
scans on leukemia rates, she added.
The findings make sense to Dr. Anna Meadows, an oncologist at
Children's Hospital of Philadelphia and a professor of pediatrics
at the University of Pennsylvania.
"The bottom line is that any kind of radiation X-ray can increase the risk of cancer. There is a risk here, but the risk is small," she said.
"Doctors should not be ordering X-rays without a good reason," Meadows added. "But if there is a good reason, they shouldn't hesitate."
Learn more about
leukemia from the U.S. National Library of
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