Exposure to single CT scan in children tied to low cancers risk, but four or more CTs double risk

Taiwan: A recent study in CMAJ (Canadian Medical Association Journal) has highlighted the importance of the prudent use of computed tomography (CT) in the pediatric population. 

The study showed that among children under the age of 18 years, exposure to a single CT scan was not associated with increased risks of subsequent brain tumours, lymphoma, or leukaemia. However, the researchers observed increased cancer risks among those with four or more CT scans; the risk was doubled, particularly among young children. 

The researchers found that for 1 CT scan, there was no increased risk of any of the cancers compared with no exposure. Children who received 2 to 3 CT scans had an increased risk of intracranial tumours; those who received four or more CT scans had a more than twofold risk of intracranial tumours, leukaemia and non-Hodgkin lymphoma.

Computed tomography in children has increased worldwide in recent decades, but there is conflicting evidence about cancer risks from these scans in this cohort. Computed tomography scans use low-dose radiation that can damage cells.

To understand if there is a link between CT scans and certain types of cancer and tumours, researchers looked at data on 7807 children in Taiwan diagnosed with intracranial tumours, leukemia or lymphoma between 2000 and 2013 matched with 78 057 controls within the Taiwanese national health system. They compared tumour rates for those who had had CT scans versus those who had not.

"Our work reinforces the importance of radiation protection strategies, addressed by the International Atomic Energy Agency," writes Dr. Yu-Hsuan Joni Shao, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan, with coauthors. "Unnecessary CT scans should be avoided, and special attention should be paid to patients who require repeated CT scans."

Younger children appeared to be more at risk of developing cancer from repeated CT scans.

"Parents and pediatric patients should be well informed on risks and benefits before radiological procedures and encouraged to participate in decision-making around imaging."

Even though these tumours and cancers are rare, the authors urge careful use of this technology and suggest that healthcare providers consider using radiation-reducing techniques.

Reference:

Wei-Hao Wang, Chia-Yu Sung, Shih-Chung Wang and Yu-Hsuan Joni Shao, CMAJ April 24, 2023 195 (16) E575-E583; DOI: https://doi.org/10.1503/cmaj.221303.