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Age effects on radiation response: summary of a recent symposium and future perspectives.

Little MP; Brenner AV; Grant EJ; Sugiyama H; Preston DL; Sakata R; Cologne J; Velazquez-Kronen R; Utada M; Mabuchi K; Ozasa K; Olson JD; Dugan GO; Pazzaglia S; Cline JM; Applegate KE
Int J Radiat Biol 2022 Nov; 98(11):1673-1683
One of the principal uncertainties when estimating population risk of late effects from epidemiological data is that few radiation-exposed cohorts have been followed up to extinction. Therefore, the relative risk model has often been used to estimate radiation-associated risk and to extrapolate risk to the end of life. Epidemiological studies provide evidence that children are generally at higher risk of cancer induction than adults for a given radiation dose. However, the strength of evidence varies by cancer site and questions remain about site-specific age at exposure patterns. For solid cancers, there is a large body of evidence that excess relative risk (ERR) diminishes with increasing age at exposure. This pattern of risk is observed in the Life Span Study (LSS) as well as in other radiation-exposed populations for overall solid cancer incidence and mortality and for most site-specific solid cancers. However, there are some disparities by endpoint in the degree of variation of ERR with exposure age, with some sites (e.g., colon, lung) in the LSS incidence data showing no variation, or even increasing ERR with increasing age at exposure. The pattern of variation of excess absolute risk (EAR) with age at exposure is often similar, with EAR for solid cancers or solid cancer mortality decreasing with increasing age at exposure in the LSS. We shall review the human data from the Japanese LSS cohort, and a variety of other epidemiological data sets, including a review of types of medical diagnostic exposures, also some radiobiological animal data, all bearing on the issue of variations of radiation late-effects risk with age at exposure and with attained age. The paper includes a summary of several oral presentations given in a Symposium on "Age effects on radiation response" as part of the 67th Annual Meeting of the Radiation Research Society, held virtually on 3-6 October 2021.
Epidemiology; Radiation exposure; Cancer rates; Risk assessment; Age factors; Cohort studies; Ionizing radiation; In vivo studies; Mortality data; Author Keywords: Ionizing radiation; age at exposure; Japanese atomic bomb survivors; in vivo radiobiological data; attained age
Mark P. Little, Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, 9609 Medical Center Drive, Bethesda, MD 20892-9778, USA
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Transportation, Warehousing and Utilities
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International Journal of Radiation Biology
Page last reviewed: May 11, 2023
Content source: National Institute for Occupational Safety and Health Education and Information Division