CT Scans in Children Raise Risk of CancerJun 7, 2012
Computed tomography (CT) scans in children have been linked to a small increased risk for later developing leukemia and brain cancer, according to a newly published study by international researchers. They write that the benefit of performing a scan often outweighs the increased risk, but that the radiation dose should be kept as low as possible, and each scan should be done only when medically necessary.
The study, published online June 7, 2012 in the Lancet, is the first to directly assess cancer risk in patients who have had CT scans.
CT scans are performed on children for a number of reasons, such as to evaluate after injury, look for the cause of neurological disorders or pain, or look for infection. They deliver a dose of ionizing radiation that is larger than an X-ray, but that varies depending on the scan. Children are more susceptible than adults to the risks of brain tumors and leukemia from radiation.
The researchers reviewed the records of almost 180,000 patients under age 22 who had a CT scan in British hospitals between 1985 and 2002, and followed them until 2008. They found that 74 of them were eventually diagnosed with leukemia and 135 developed brain tumors. The researchers’ analysis showed that the amount of radiation exposure from an estimated 2 to 3 head CT scans given to a child can triple the risk of brain cancer, and an estimated 5 to 10 head scans can triple the risk of leukemia. While the increase was large, the risk was so small to begin with that it remained small even with the large increase. For example, researchers predict 1 excess case of leukemia and 1 excess case of brain cancer would occur for every 10,000 head CT scans in children younger than 10.
The use of CT scanning has increased rapidly in the United States in the past decade. However, since 2002, radiation doses in CTs for children have become about 2 or 3 times lower. The researchers call for even further reductions. And they suggest that alternative tests that do not involve radiation, such as ultrasound and MRI, be considered in some cases.
Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Published online June 7, 2012 in the Lancet. First author: Mark S. Pearce, PhD, New Castle University, United Kingdom.