(HealthDay News) — Exposure to 4 or more computed tomography (CT) scans before age 18 years is associated with increased risk of subsequent intracranial tumors, leukemia, and lymphoma, according to a study published online in CMAJ, the journal of the Canadian Medical Association.

Wei-Hao Wang, MD, from Taipei Medical University in Taiwan, and colleagues conducted a nested, population-based, case-control study to examine the risk of intracranial tumors, leukemia, or lymphoma among children, adolescents, and young adults (<25 years) after radiation exposure from CT at or before 18 years of age. A total of 7807 cases of newly diagnosed intracranial tumors, leukemia, and lymphoma were included and matched with 78,057 noncancer controls.

The researchers found that exposure to a single pediatric CT scan did not increase the risk of intracranial tumors, leukemia, or lymphoma compared with no exposure. However, incidence of one of the cancer outcomes of interest was increased for participants exposed to four or more CT scans (incidence rate ratio, 2.30). The highest risks of cancer were seen with receiving 4 or more CT scans at or before 6 years or age, followed by ages 7 to 12 and 13 to 18 years.

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“Younger children appeared vulnerable to cancer risks associated with repeated CT exposure,” the authors write. “Although these tumors are uncommon, these results indicate that judicious CT usage and radiation-reducing techniques should be advocated.”

Abstract/Full Text