Hematologic Cancer Risks in Children Associated With Medical Imaging

Source: Smith-Bindman R, Alber SA, Kwan ML, et al. Medical imaging and pediatric and adolescent hematologic cancer risk. N Engl J Med. 2025; 10.1056/NEJMoa2502098; doi: 10.1056/NEJMoa2502098.Investigators from multiple institutions conducted a retrospective cohort study to evaluate the association of medical imaging and hematologic cancers in children. Study participants were patients who were born between 1996 and 2016 and attended at least 1 visit in the first 3 months of life at 1 of 5 large integrated health care systems in the US or Ontario, Canada. These children were followed until the age of 21 years, their first hematologic cancer diagnosis, death, or until they left their health care system. Procedural and diagnostic codes were used to identify medical imaging in study participants. The absorbed dose of radiation to active bone marrow was estimated for each imaging study, and the cumulative dose in each participant during their study period was calculated. Hematologic cancer diagnoses were obtained by reviewing health care system and population-based registries. Hematologic cancers were categorized as lymphoid (including acute lymphoblastic leukemia), myeloid (including non-lymphoid leukemias), and histiocytic- or dendritic-cell cancers. Cox proportional hazards models were used to assess the relative risk of hematologic cancers in children with exposure to imaging studies, after stratifying on sex, birth year, presence of Down syndrome, and site.Data were analyzed on 3,724,623 children, with a mean of 10.1 years of follow-up. A total of 2,961 hematologic cancers were diagnosed in study children, including 2,349 (79.3%) lymphoid cancers, 460 (15.5%) with myeloid cancers or acute leukemia, and 129 (4.4%) with histiocytic- or dendritic-cell cancers. Overall, 1,506 (50.9%) hematologic cancers were diagnosed in children 1.0 mGy. Compared to those with no exposure, the relative risk (RR) of hematologic cancer increased significantly in those with radiation exposure and increased with higher doses: RR=1.16 for 0 to