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CT scans may increase risk for brain cancer among children
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Children aged younger than 18 years who underwent CT scans may be at increased risk for developing brain tumors from the high-dose radiation exposure, according to results of a retrospective cohort study.
“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 indicate that CT-related radiation exposure increases brain tumor risk,” Michael Hauptmann, PhD, senior statistician and head of the biostatistics group in the department of epidemiology and biostatistics at Netherlands Cancer Institute in Amsterdam, said in a press release. “Careful justification of pediatric CT scans and dose optimization, as done in many hospitals, are essential to minimize risks.”
The use of CT among children has increased across Western countries.
Previous research has shown that CT scans can improve diagnostics; however, radiation doses can are often higher than the average radiation procedure, which has created cause for concern.
Children may be more vulnerable to radiation-related malignancies than adults, and there exists a potential to endure late effects over a longer lifespan.
Further, epidemiological studies have demonstrated elevated cancer risk after pediatric CT scans.
Researchers sought to determine association between childhood radiation exposure from CT scans and risk for leukemia and brain tumors among Dutch children and young adults.
Hauptmann and colleagues evaluated data from 168,394 children aged younger than 18 years who received one or more CT scan at a Dutch hospital between 1979 and 2012.
Researchers determined cancer incidence in the population by linking data with the Netherlands Cancer Registry — for all malignancies diagnosed since 1989, and myelodysplastic syndrome and nonmalignant brain tumors diagnosed since 2001 — and with the Dutch Childhood Oncology Group for incidence of childhood leukemia prior to 1989.
With 454 observed cases, the overall cancer incidence — starting 5 years after the first CT scan — appeared 1.5 times higher than expected (standardized incidence ratio [SIR] = 1.47; 95% CI, 1.34-1.61), which included 37 malignant central nervous system tumors (SIR = 2.05; 95% CI, 1.48-2.83) and 93 hematolymphoproliferative cancers (SIR = 1.39; 95% CI, 1.13-1.7).
Poisson regression testing determined excess relative risks (ERRs) per 100 mGy organ dose.
Patients had received mean cumulative bone marrow doses of 9.5 mGy at the end of follow-up.
Based on 44 cases, researchers did not observe an association between risk for leukemia — excluding myelodysplastic syndrome — with cumulative bone marrow dose (ERR = 0.21, 95% CI, –0.12 to 2.4).
Researchers reported an average cumulative brain dose of 38.5 mGy, which was significantly associated with risk for malignant and nonmalignant brain tumors combined based on 84 cases (ERR = 0.86; 95% CI, 0.2-2.22). Excluding patients with tuberous sclerosis complex did not change the association.
“Compared with the general population, incidence of brain tumors was higher in the cohort of children with CT scans, requiring cautious interpretation of the findings,” the researchers wrote.
However, researchers noted their data are limited by a lack of information on reason for CT, and excess cancer risk could be a result of confounding by indication, “if the reason for conducting a CT is associated with cancer risk,” they wrote.
“Nonetheless, careful justification of pediatric CT scans and dose optimization, as are customary in many hospitals, are essential to minimize risks,” the researchers wrote. – by Melinda Stevens
Disclosures: The authors report no relevant financial disclosures.
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