CT Scans May Increase Risk of Brain Cancer

A new study suggests that computerized tomography (CT) related radiation exposure can increase brain tumor risk in children.

Researchers at the Netherlands Cancer Institute (NKI; Amsterdam), Academic Medical Center (AMC; Amsterdam, The Netherlands), and other institutions reviewed a Dutch nationwide retrospective cohort of 168,394 children who received one or more CT scans between 1979 and 2012 so as to evaluate leukemia and brain tumor risk following exposure to low-dose ionizing radiation from CT scans in childhood. Cancer incidence, vital status, and confounder information were obtained by record linkage with external registries, and standardized incidence ratios were calculated for the general population.

The results revealed that the overall cancer incidence rate was 1.5 times higher than expected. For all brain tumors combined, and for malignant and nonmalignant brain tumors separately, dose-response relationships were observed with radiation dose to the brain, with relative risk (RR) increasing between two and four times for the highest dose category. The researchers observed no such association for leukemia, probably because radiation doses to the bone marrow, where leukemia originates, were low. The study was published on July 18, 2018, in Journal of the National Cancer Institute.

“Computed tomography, a strong diagnostic tool, delivers higher radiation doses than most imaging modalities. As CT use has increased rapidly, radiation protection is important, particularly among children,” concluded senior author Michael Hauptmann, PhD, of NKI, and colleagues. “Incidence of brain tumors was higher in the cohort of children with CT scans. Careful justification of pediatric CT scans and dose optimization, as done in many hospitals, are essential to minimize risks.”

Several studies indicate that brain tumor incidence increases with number of pediatric head CTs in a dose-dependent manner, with measurable excess incidence even after a single scan. However, as CT remains an invaluable technology, its use remains mandated as long as there is a clinical indication for the CT scan, and the radiation dose is as small as reasonably achievable.

Related Links:
Netherlands Cancer Institute
Academic Medical Center