CT scan may increase brain tumor risk

A new study shows that CT Scans, commonly used in medical imaging, may increase the risk of brain tumors.

The use of computed tomography (CT) scans has dramatically increased over the last two decades.

While CT scans have greatly improved diagnostic capabilities, they also deliver higher radiation doses than any other test. Therefore, radiation protection is a concern. Especially among children, who may receive higher radiation doses, are more open to radiation-related malignancies than adults. Children also have more time to show effects.

Leukemia and brain tumors are the most common malignancies caused by radioactivity among children and young adults. Researchers have therefore evaluated brain tumor and leukemia risks following exposure to radiation from CT scans in children.

From a nationwide group of 168,394 Dutch children who received one or more CT scans between the year 1979 and 2012, researchers found cancer incidents and vital status by recording linkage.

The study found that cancer incidents 1.5 times higher than expected. For all kinds of brain tumors combined and for malignant and nonmalignant brain tumors separately, dose-response relationships were seen with radiation dose to the brain.

Relative risks have increased to between two to four for highest dose category. The radiation doses to the bone marrow, where leukemia originates, were found to be low.

The study also shows that this pattern of excess cancer risk may be partially due to confounding by indication, as the incidence of brain tumor was higher in the cohort than in the general population.

CT scans are sometimes also used to identify conditions related to an increase tumor risk.

"Epidemiological studies of cancer risks from low doses of medical radiation are challenging, nevertheless, our careful evaluation of the data and evidence from other studies indicates that CT-related radiation exposure increases brain tumor risk. Careful justification of pediatric CT scans and dose optimization, as done in many hospitals, are essential to minimize risks." said the study's principal investigator, Michael Hauptmann.

The findings appeared in the journal, Journal of National Cancer Institute.