CT Scans Linked to Increased Risk of Hematologic Malignancies

Undergoing computed tomography (CT) scans in childhood, adolescence, or young adulthood can increase a person’s risk of developing a hematologic malignancy later in life, according to research published in Nature Medicine.

Based on this study, researchers estimate that, for every 10,000 children who undergo a CT scan today, 1.4 will develop a hematologic malignancy attributable to radiation exposure in the 12 years after the CT scan.

For this study, researchers analyzed a large cohort of patients from 9 European countries who had undergone a CT scan before the age of 22 years. The cohort included 876,771 patients who underwent more than 1.3 million CT scans and were followed for at least 2 years after their first scan.

At a mean follow-up of 7.8 years, 790 hematologic malignancies had been identified, including 578 lymphoid malignancies and 203 myeloid malignancies and acute leukemias.

The researchers observed an increased relative risk (RR) of hematologic malignancies for ionizing radiation doses to the active bone marrow (ABM) of 10 mGy or higher, as seen in the table below. The researchers estimated radiation doses to the ABM based on the body part scanned, patient characteristics, the time period, and inferred CT technical parameters.

Risk of Hematologic Malignancies by Radiation Dose
ABM Dose Range	All Hematologic Malignancies, RR (95% CI)	Lymphoid Malignancies, RR (95% CI)	Myeloid Malignancies and Acute Leukemia, RR (95% CI)
0-5 mGy	Reference	Reference	Reference
5-10 mGy	1.10 (0.87-1.39)	1.07 (0.81-1.42)	1.08 (0.69-1.71)
10-15 mGy	1.53 (1.20-1.97)	1.65 (1.24-2.20)	1.16 (0.70-1.92)
15-25 mGy	1.40 (1.09-1.80)	1.41 (1.05-1.90)	1.31 (0.80-2.15)
25-50 mGy	1.87 (1.42-2.45)	1.81 (1.32-2.49)	1.96 (1.17-3.29)
50 mGy or higher	2.66 (1.92-3.70)	2.64 (1.80-3.89)	2.75 (1.47-5.14)

The estimated excess relative risk per 100 mGy was 1.96 (95% CI, 1.10-3.12) for all hematologic malignancies combined, 2.01 (95% CI, 1.02-3.42) for lymphoid malignancies, and 2.02 (95% CI, 0.47-4.77) for myeloid malignancies and acute leukemia.

“Our results strengthen the body of evidence of increased cancer risk at low radiation doses and highlight the need for continued justification of pediatric CT examinations and optimization of doses,” the researchers wrote.

Reference

Bosch de Basea Gomez M, Thierry-Chef I, Harbron R, et al. Risk of hematological malignancies from CT radiation exposure in children, adolescents and young adults. Nat Med. Published online November 9, 2023. doi:10.1038/s41591-023-02620-0

This article originally appeared on Cancer Therapy Advisor