Nearly 5K future cancers projected to result from pediatric CT volumes

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Use of CT scans in children younger than 14 years of age more than doubled from 1996 to 2005, before growth began to slow and reverse, according to a study of seven U.S. healthcare systems published in JAMA Pediatrics.

The 4 million pediatric CT scans of the head, abdomen/pelvis, chest or spine performed in the U.S. each year are projected to result in 4,870 future cancers, according to Diana Miglioretti, PhD, of the Group Health Research Institute and University of California, Davis, and colleagues.

Risks associated with CT imaging underscore the need to reduce radiation dose and unnecessary studies. “[We] found that radiation doses from pediatric CT vary widely in clinical practice, suggesting an opportunity to reduce doses through standardized protocols and other published methods. Implementation of these readily available dose reduction strategies, combined with the elimination of unnecessary imaging, could dramatically reduce future radiation-induced cancers from CT use in pediatrics,” wrote the authors.

Included in the retrospective, observational study were 4,857,736 child-years of observation. Radiation doses were calculated for 744 CT scans performed between 2001 and 2011.

Results showed that CT use doubled in children younger than five years of age and tripled for children ages five to 14 between 1996 and 2005. Usage remained stable for two years, before beginning to decline after 2007, according to Miglioretti and colleagues.

“Effective doses varied from 0.03 to 69.2 mSv per scan. An effective dose of 20 mSv or higher was delivered by 14 percent to 25 percent of abdomen/pelvis scans, 6 percent to 14 percent of spine scans, and 3 percent to 8 percent of chest scans,” wrote the authors.

In breaking down the risks of solid cancer, Miglioretti and colleagues said for girls, one cancer is projected to result from every 300 to 390 abdomen/pelvis scans, 330 to 480 chest scans and 270 to 800 spine scans. Risks were higher for younger patients, and lower for boys.

“From a patient’s perspective, the benefits of a medically necessary CT scan far exceed the small increase in radiation-induced cancer risk,” wrote the authors. “However, some studies suggest that a third of pediatric CT scans are unnecessary and that eliminating them could potentially reduce the number of CT-attributable cancers by a third.”

The authors credited the Image Gently campaign as one of the possible causes of the decline in pediatric CT, and pointed to resources provided by the campaign to further reduce administered doses. They speculated that if standardized protocols and guidelines were used, along with the elimination of unnecessary imaging, the number of radiation-related cancers could be cut by 62 percent.

In an accompanying editorial, Alan R. Schroeder, MD, of the Santa Clara Valley Medical Center, San Jose, and Rita F. Redberg, MD, editor of JAMA Internal Medicine and of the University of California, San Francisco, argued that a decrease in unnecessary imaging will require a cultural shift. More clinical diagnoses will have to be made without confirmatory imaging. “Uncertainty can be unsettling, but it is a small price to pay for protecting ourselves and our children from thousands of preventable cancers,” they wrote.

The American College of Radiology (ACR) released a statement urging parents not to delay or forego needed medical imaging for their children based on the results of the study. “Medical imaging exams are directly linked to greater life expectancy, declines in mortality rates, and are generally safer and less expensive than the invasive procedures that they replace, such as exploratory surgery,” read the statement.

Parents should, however, discuss the risks and benefits of any procedure with a physician, added the ACR, which also emphasized the efforts of the Image Wisely and Choosing Wisely campaigns to lower dose and reduce unnecessary imaging. The ACR is a partnering organization on all three campaigns.