PhotoCT scans can be lifesavers when a diagnosis is in doubt. But a new study suggests that their growing use in children poses an increased risk of cancer later in life, estimating that 4,870 future cancers could be caused by the 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 notes.

In an accompanying editorial, researchers said minimizing unnecessary scans and using the lowest possible dose of radiation should be high priorities. “Uncertainty can be unsettling, but it is a small price to pay for protecting ourselves and our children from thousands of preventable cancers,” the editorial concluded.

Noting that the use of CT -- or computed tomography -- scans involving children more than doubled during the years from 1996 to 2005, researchers said the radiation associated with the scans is likely to increase the risk of radiation-induced cancer in these children in the future. The study was published Online First by JAMA Pediatrics, a JAMA Network publication.

Increased risk

The radiation doses delivered by the CT scans are in ranges that have been linked to an increased risk of cancer, the researchers noted. And they said children are more sensitive to radiation-induced cancers and also have many years of life left for cancer to develop.

“[M]ore research is urgently needed to determine when CT in pediatrics can lead to improved health outcomes and whether other imaging methods (or no imaging) could be as effective. For now, it is important for both the referring physician and the radiologist to consider whether the risks of CT exceed the diagnostic value it provides over other tests, based on current evidence,” the study concludes.

Diana L. Miglioretti, Ph.D., of the Group Health Research Institute and University of California, Davis, and colleagues conducted the study, using data from seven U.S. health care systems.

CTs doubled 

The authors note the use of CT doubled for children younger than 5 years old and tripled for children 5 to 14 years of age between 1996 and 2005 before remaining stable between 2006 and 2007 and then beginning to decline.

The projected lifetime attributable risks of solid cancer were higher for younger patients and girls than for older patients and boys. The risks were also higher for patients who underwent CT scans of the abdomen/pelvis or spine than for patients who underwent other types of CT scans, according to the results. 

The estimates also suggest that for girls, a radiation-induced solid cancer is projected to potentially result from every 300 to 390 abdomen/pelvis scans, 330 to 480 chest scans, and 270 to 800 spine scans, depending on age. The potential risk of leukemia was highest from head scans for children younger than 5 years of age at a rate of 1.9 cases per 10,000 CT scans, the results show.

The Harm in Looking

In a related editorial, Alan R. Schroeder, M.D., of the Santa Clara Valley Medical Center, San Jose, and Rita F. Redberg, M.D., editor of JAMA Internal Medicine and of the University of California, San Francisco, write: “Thus, minimizing radiation exposure by eliminating unnecessary scans and by using the minimal dose necessary to achieve a satisfactory image for necessary scans is a high priority.”

“But we can still do more to decrease the use of unnecessary scans (for which the benefit does not outweigh the risk) and to decrease the level of radiation exposure from necessary scans. 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,” said.

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