Association of Exposure to Diagnostic Low-Dose Ionizing Radiation with Risk of Cancer among Youths in South Korea

Abstract

Importance: Diagnostic low-dose ionizing radiation has great medical benefits; however, its increasing use has raised concerns about possible cancer risks. Objective: To examine the risk of cancer after diagnostic low-dose radiation exposure. Design, Setting, and Participants: This population-based cohort study included youths aged 0 to 19 years at baseline from South Korean National Health Insurance System claim records from January 1, 2006, to December 31, 2015. Exposure to diagnostic low-dose ionizing radiation was classified as any that occurred on or after the entry date, when the participant was aged 0 to 19 years, on or before the exit date, and at least 2 years before any cancer diagnosis. Cancer diagnoses were based on International Statistical Classification of Diseases and Related Health Problems, Tenth Revision codes. Data were analyzed from March 2018 to September 2018. Main Outcomes and Measures: The primary analysis assessed the incidence rate ratios (IRRs) for exposed vs nonexposed individuals using the number of person-years as an offset. Results: The cohort included a total of 12068821 individuals (6339782 [52.5%] boys). There were 2309841 individuals (19.1%) aged 0 to 4 years, 2951679 individuals (24.5%) aged 5 to 9 years, 3489709 individuals (28.9%) aged 10 to 14 years, and 3317593 individuals (27.5%) aged 15 to 19 years. Of these, 1275829 individuals (10.6%) were exposed to diagnostic low-dose ionizing radiation between 2006 and 2015, and 10792992 individuals (89.4%) were not exposed. By December 31, 2015, 21912 cancers were recorded. Among individuals who had been exposed, 1444 individuals (0.1%) received a cancer diagnosis. The overall cancer incidence was greater among exposed individuals than among nonexposed individuals after adjusting for age and sex (IRR, 1.64 [95% CI, 1.56-1.73]; P