Kids who get multiple CT scans appear as higher risk for cancer

Children who get four or CT scans before the age of 18, face more than double the risk of cancer compared to those who don't receive this imaging, a new study has found.

Children who get four or more computerized tomography (CT) scans before the age of 18 face more than double the risk of cancer compared to those who don’t receive this imaging, a new study has found.

The study out of Taiwan, published Monday in the Canadian Medical Association Journal (CMAJ), found children who undergo a single CT scan are not at an increased risk of developing brain tumours, leukemia, or lymphoma. However, the study found that exposure to multiple scans significantly increases a child’s risk of developing these types of cancers.

“The associated risk of cancer we observed was highest among children who had received four or more CT scans at or before six years of age, followed by those aged seven to 12 years and adolescents aged 13–18 years, suggesting that younger children are more vulnerable to radiation than older children,” the researchers stated in the study.

Children are generally more sensitive to the harmful effects of radiation than adults, as their developing cells are more vulnerable to damage, according to the U.S. National Cancer Institute. As a result, the risk of developing radiation-related cancer can be several times higher for a young child than an adult.

Because CT scans are a common way to diagnose cancer or examine a head injury in children, the researchers said they wanted to evaluate whether it caused a risk of developing intracranial tumours, leukemia, non-Hodgkin lymphoma and Hodgkin lymphoma among children, adolescents and young adults.

To do this, the researchers examined national health records from more than 7,000 Taiwanese patients diagnosed with these types of cancers between 2000 and 2013. They then compared tumour rates for those who had had CT scans versus those who had not.

For one CT scan, there was no increased risk of any of the cancers compared with no exposure.

Children who received two to three CT scans had an increased risk of intracranial tumours; and those who received four or more had a more than twofold risk of intracranial tumours, leukemia and non-Hodgkin lymphoma, the study found.