(HealthDay News) — Exposure to 4 or more CT scans before the age of 18 is associated with an increased risk of subsequent intracranial tumors, leukemia, and lymphoma, according to a study published in CMAJ.
Researchers examined the risk of these cancers in patients younger than 25 years of age who had CT scans performed at or before 18 years of age. The study cohort included 7807 patients with newly diagnosed intracranial tumors, leukemia, or lymphoma who were matched to 78,057 cancer-free control individuals.
The researchers found that patients who underwent a single pediatric CT scan did not have an increased risk of the cancers studied. Patients who underwent 2-3 CT scans had an increased risk of intracranial tumors (adjusted odds ratio [aOR], 2.36; 95% CI, 1.40–3.97) but not leukemia or lymphoma.
Patients who underwent 4 or more CT scans had a higher risk of intracranial tumors (aOR, 9.01; 95% CI, 2.89–28.11), leukemia (aOR, 4.80; 95% CI, 1.79–12.84), and non-Hodgkin lymphoma (aOR, 6.76; 95% CI, 1.91–23.96) but not Hodgkin lymphoma.
A higher radiation dose was associated with an increased risk of intracranial tumors but not leukemia or lymphoma. Patients in the top quintile of cumulative brain radiation dose had a significantly higher risk of intracranial tumors (aOR, 3.61, 95% CI, 1.93–6.75).
Patients who had 4 or more CT scans at or before 6 years of age had the highest risk of cancer, followed by patients who were 7-12 years of age and those who were 13-18 years of age.
“Younger children appeared vulnerable to cancer risks associated with repeated CT exposure,” the researchers wrote. “Although these tumors are uncommon, these results indicate that judicious CT usage and radiation-reducing techniques should be advocated.”