Brain Cancer Risk after CT Radiation Exposure in the Pediatric Population
Background: Computed tomography is an imaging modality that can provide valuable diagnostic information that is not easily obtained using other imaging techniques. Critically, children experience higher risks of developing radiation-induced cancers compared to adults due to faster cell division, a longer post-irradiation lifespan, and greater local radiation dose due to smaller organs. For example, target organs in an adult typically receive a radiation dose of approximately 15 millisieverts (mSv) per scan (with an average of 2-3 CT scans per study), but neonates may receive 30 mSv per scan for a similar study.7 When a certain diagnosis is suspected, some physicians utilize unnecessary CT scans for confirmation although significant symptoms are already seen to confirm the diagnosis. With respect to head and neck CT, this radiation increases the risk of developing brain tumors.7
Objective: In this review, we explore the mechanisms behind the causation of brain tumors in young adults that have been exposed to significant CT radiation as a child.
Search Methods: To identify relevant literature, searches were conducted within the PubMed database for brain cancer incidence among the pediatric population along with the keyword “radiation”.
Results: Of the studies found, one study stated that radiation-induced gliomas (RIGs) can develop in certain patients who have undergone cranial irradiation to treat primary malignancies such as acute lymphoblastic leukemia (ALL) and medulloblastoma (MB). Using RNA sequencing to compare the gene expression profiles of RIGs versus control pediatric gliomas, RIGs demonstrated frequent PDGFRA amplification and alterations in several genes, including CDKN2A/B, NF1, and TP53, suggesting that RIGs may represent a distinct molecular entity within the spectrum of pediatric gliomas.11 In another study, a significant positive association was identified between the cumulative number of head or neck CT examinations and the risk of any type of brain cancer (p<0·0001), and of gliomas specifically.2 Radiation dose also had a positive correlation with the risk of developing brain cancer approximately 5 years later.2 Given these findings and the limited number of available publications, further research is recommended to better assess the correlations between exposure to radiation as a child and the later occurrence of brain cancer, as well as the specific pathological mechanisms that lead to this risk.
Conclusions: Studies found have shown that brain cancers (radiation-induced gliomas) are typically caused by gene expression alteration of PDGFRA, CDKN2A/B, NF1, and TP53. Additionally, many studies have found positive correlation between the radiation dosage as well as the number of scans received as a child to the development of a variety of brain tumors.
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 Deng, M.Y., Sturm, D., Pfaff, E. et al. Radiation-induced gliomas represent H3-/IDH-wild type pediatric gliomas with recurrent PDGFRA amplification and loss of CDKN2A/B. Nat Commun 12, 5530 (2021). https://doi.org/10.1038/s41467-021-25708-y
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