Curbing CT Scans In Kids Could Cut Cancer Risk

By: CBS News (Posted by Melissa Brunner)
By: CBS News (Posted by Melissa Brunner)

(CBS News) Computerized tomography, or CT scans, are being given to children and adolescents in increasing rates, according to new research, potentially putting cancer in their futures.

The researchers estimate that nearly 5,000 future cancer cases could be caused by the roughly 4 million pediatric CT scans performed each year.

"The increased use of CT in pediatrics, combined with the wide variability in radiation doses, has resulted in many children receiving a high-dose examination," the study authors wrote.

Published Jun 10 in JAMA Pediatrics, the new study tracked CT scan rates among children younger than 15 from 1996 to 2005.

A CT scan uses x-rays to create pictures of cross-sections of the body, including the brain, chest, spine and abdomen.

Previous research has shown children with a history of frequent CT scans or X-rays may be at an increased risk for cancer due to radiation exposure.

A June 2012 study in The Lancet found kids who get two or three CT scans before they turn 15 face three times more risk for brain cancer, and those who get five to 10 scans in the same time frame face triple the risk for leukemia. The overall rates, however, were still low, the researchers pointed out: The risk of leukemia in children is already about 1 in 2,000, so having multiple CT scans might increase that risk to about 1 in 600 cases.

CT scans expose people to more radiation than a typical X-ray. Children are more sensitive to radiation-induced cancer than older adults because they have more years for the cancer to develop, according to the researchers, who were led by Dr. Diana L. Miglioretti, a senior investigator at the Group Health Research Institute and the University of California, Davis.

Miglioretti's team looked at a decade's worth of pediatric CT scans from databases of seven U.S. health care systems that included up to 371,000 children. They also measured radiation exposure from 744 pediatric CT scans of the head, chest, abdomen/pelvis and spine -- these tests make up about 95 percent of pediatric CT scans, according to the researchers.

The researchers found the number of CT scans given to kids during the study period doubled among children ages 5 and younger and tripled for those between 5 and 14 years old. The rates stabilized between 2006 and 2007, before starting to decline.

The risks were higher for patients who underwent abdomen or spine CT scans than those who underwent other types, the researchers discovered.

Specifically for girls, who were found to be at a higher radiation risk than boys, the researchers predicted that a radiation-induced cancer might result from every 300 to 390 abdomen/pelvis scans, 330 to 480 chest CTs, and 270 to 800 spine scans, depending on age. Younger patients faced higher risk than older children.

Leukemia risk was highest from head CTs for children younger than 5 years of age at a rate of almost two cases per 10,000 CT scans.

Reducing the highest 25 percent of doses to the midpoint dose may prevent 43 percent of the cancers, they estimated. They called for more research into whether other imaging methods or no imaging at all could be as effective for kids.

In an accompanying editorial published in the same journal issue, Dr. Alan R. Schroeder, a pediatrician at the Santa Clara Valley Medical Center in San Jose, Calif. and JAMA Internal Medicine editor Dr. Rita F. Redberg wrote that eliminating unnecessary medical scans and using the minimal dose necessary is a "high priority" for public health.

"This will require a shift in our culture to become more tolerant of clinical diagnoses without confirmatory imaging, more accepting of 'watch and wait' approaches and less accepting of the 'another test can't hurt' mentality," they stated.

Top medical societies have teamed up in recent years for a Choosing Wisely campaign that identifies tests or treatments that are commonly overused within their therapeutic areas.

For example, the American Academy of Pediatrics says CT scans immediately after minor head injuries -- which are given to 50 percent of children who visit hospital emergency rooms with head woes -- are not necessary, and doctors should conduct a thorough exam first. The academy added that CT scans should also not be used in simple seizure cases or to routinely figure out what's causing children's abdominal pain.

The American College of Radiology, which was not involved in the research, said in an emailed statement to CBSNews.com that parents shouldn't delay or skip a needed medical imaging test based solely on this study. The organization added that the absolute risk of cancer is very small compared with the clear benefits of a medically-justifiable scan. Modern CT scanners use radiation doses that are up to 90 percent lower than those used even 10 years ago, the group added.

"Parents should certainly discuss such potential risk with their physician, but this appropriate concern should not translate into refusal of necessary and potentially life-saving care," Dr. Marta Hernanz-Schulman, chair of the American College of Radiology Pediatric Imaging Commission, said in the statement.

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