title: I-131 dose response for incident thyroid cancers in Ukraine related to the Chornobyl accident.
abstract: BACKGROUND
  Current knowledge about Chornobyl-related thyroid cancer risks comes from ecological studies based on grouped doses, case-control studies, and studies of prevalent cancers.
  
  
  OBJECTIVE
  To address this limitation, we evaluated the dose-response relationship for incident thyroid cancers using measurement-based individual iodine-131 (I-131) thyroid dose estimates in a prospective analytic cohort study.
  
  
  METHODS
  The cohort consists of individuals < 18 years of age on 26 April 1986 who resided in three contaminated oblasts (states) of Ukraine and underwent up to four thyroid screening examinations between 1998 and 2007 (n = 12,514). Thyroid doses of I-131 were estimated based on individual radioactivity measurements taken within 2 months after the accident, environmental transport models, and interview data. Excess radiation risks were estimated using Poisson regression models.
  
  
  RESULTS
  Sixty-five incident thyroid cancers were diagnosed during the second through fourth screenings and 73,004 person-years (PY) of observation. The dose-response relationship was consistent with linearity on relative and absolute scales, although the excess relative risk (ERR) model described data better than did the excess absolute risk (EAR) model. The ERR per gray was 1.91 [95% confidence interval (CI), 0.43-6.34], and the EAR per 10⁴ PY/Gy was 2.21 (95% CI, 0.04-5.78). The ERR per gray varied significantly by oblast of residence but not by time since exposure, use of iodine prophylaxis, iodine status, sex, age, or tumor size.
  
  
  CONCLUSIONS
  I-131-related thyroid cancer risks persisted for two decades after exposure, with no evidence of decrease during the observation period. The radiation risks, although smaller, are compatible with those of retrospective and ecological post-Chornobyl studies.
authors.affiliation: Radiation Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892-7238, USA. brennera@mail.nih.gov
authors.forename: Alina V
authors.initials: AV
authors.lastname: Brenner
authors.forename: Mykola D
authors.initials: MD
authors.lastname: Tronko
authors.forename: Maureen
authors.initials: M
authors.lastname: Hatch
authors.forename: Tetyana I
authors.initials: TI
authors.lastname: Bogdanova
authors.forename: Valery A
authors.initials: VA
authors.lastname: Oliynik
authors.forename: Jay H
authors.initials: JH
authors.lastname: Lubin
authors.forename: Lydia B
authors.initials: LB
authors.lastname: Zablotska
authors.forename: Valery P
authors.initials: VP
authors.lastname: Tereschenko
authors.forename: Robert J
authors.initials: RJ
authors.lastname: McConnell
authors.forename: Galina A
authors.initials: GA
authors.lastname: Zamotaeva
authors.forename: Patrick
authors.initials: P
authors.lastname: O'Kane
authors.forename: Andre C
authors.initials: AC
authors.lastname: Bouville
authors.forename: Ludmila V
authors.initials: LV
authors.lastname: Chaykovskaya
authors.forename: Ellen
authors.initials: E
authors.lastname: Greenebaum
authors.forename: Ihor P
authors.initials: IP
authors.lastname: Paster
authors.forename: Victor M
authors.initials: VM
authors.lastname: Shpak
authors.forename: Elaine
authors.initials: E
authors.lastname: Ron
mesh_terms: D000293:Adolescent; D000328:Adult; D047852:Chernobyl Nuclear Accident; D015331:Cohort Studies; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D007453:Iodide Peroxidase / Q000097:blood; D007457:Iodine Radioisotopes / Q000633:toxicity* / Q000652:urine; D008297:Male; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology* / Q000601:surgery; D016012:Poisson Distribution; D011446:Prospective Studies; D018788:Radioactive Hazard Release; D013954:Thyroglobulin / Q000097:blood; D013959:Thyroid Diseases / Q000453:epidemiology* / Q000601:surgery; D013961:Thyroid Gland / Q000528:radiation effects / Q000601:surgery; D013964:Thyroid Neoplasms / Q000139:chemically induced / Q000453:epidemiology* / Q000601:surgery; D013972:Thyrotropin / Q000097:blood; D013997:Time Factors; D014455:Ukraine / Q000453:epidemiology; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D013972:Thyrotropin; D013954:Thyroglobulin; D007453:Iodide Peroxidase