Occupational radiation exposure and thyroid cancer incidence in a cohort of U.S. radiologic technologists, 1983–2013

Cari M. Kitahara, Dale L. Preston, Gila Neta, Mark P. Little, Michele M. Doody, Steven L. Simon, Alice J. Sigurdson, Bruce H. Alexander, Martha S. Linet

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25 Scopus citations


Although childhood exposure to ionizing radiation is a well-established risk factor for thyroid cancer, the risk associated with adulthood exposure remains unclear. We prospectively examined the association between cumulative, low-to-moderate dose occupational radiation exposure to the thyroid and thyroid cancer incidence in the U.S. Radiologic Technologists cohort. The study included 89,897 members who completed at least two of four mailed questionnaires and were cancer-free at the time of the first questionnaire. Cumulative occupational thyroid radiation dose (mean = 57 mGy, range = 0–1,600 mGy) was estimated based on self-reported work histories, historical data and, during the years 1960–1997, 783,000 individual film badge measurements. During follow-up, we identified 476 thyroid cancer cases. We used Poisson regression to estimate excess relative risk of thyroid cancer per 100 milliGray (ERR/100 mGy) absorbed dose to the thyroid gland. After adjusting for attained age, sex, birth year, body mass index and pack-years smoked, we found no association between thyroid dose and thyroid cancer risk (ERR/100 mGy = −0.05, 95% CI <–0.10, 0.34). In this large cohort study of radiologic technologists, protracted, low-to-moderate dose ionizing radiation exposure to the thyroid gland in adulthood was not associated with an increased risk of thyroid cancer.

Original languageEnglish (US)
Pages (from-to)2145-2149
Number of pages5
JournalInternational Journal of Cancer
Issue number9
StatePublished - Nov 1 2018

Bibliographical note

Funding Information:
Key words: thyroid cancer, ionizing radiation, occupational exposure, cohort study, radiologic technologists Conflicts of interest: None Grant sponsor: The Intramural Research Program of the National Cancer Institute, NIH DOI: 10.1002/ijc.31270 History: Received 1 Sep 2017; Accepted 9 Jan 2018; Online 22 Jan 2018 Correspondence to: Cari M. Kitahara, PhD, MHS, National Cancer Institute, 9609 Medical Center Drive, Rm 7E-536, Bethesda, MD 20892, USA, Tel.: [2402767406], Fax: 1[240-276-7840], E-mail: kita-harac@mail.nih.gov

Funding Information:
1Division of Cancer Epidemiology and Genetics, Radiation Epidemiology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 2Hirosoft International, Eureka, CA 3Division of Cancer Control and Population Sciences, Implementation Science, National Cancer Institute, National Institutes of Health, Bethesda, MD 4Division of Environmental Health Sciences, School of Public Health, University of Minnesota, Minneapolis, MN

Publisher Copyright:
© 2018 UICC


  • cohort study
  • ionizing radiation
  • occupational exposure
  • radiologic technologists
  • thyroid cancer


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