title: Incidence and Mortality of Solid Cancers in People Exposed In Utero to Ionizing Radiation: Pooled Analyses of Two Cohorts from the Southern Urals, Russia.
abstract: BACKGROUND
  Previous studies have shown that acute external in utero exposure to ionizing radiation can increase cancer risk. It is not known whether chronic exposure at low dose rates, including due to radionuclide intake, influences the lifetime risk of solid cancers in the offspring. The objective of this study was to investigate solid cancer risk after in utero irradiation.
  
  
  METHODS
  Cancer incidence and mortality over a 60-year period (from January 1950 to December 2009) were analyzed in the Urals Prenatally Exposed Cohort (UPEC). The cohort comprised in utero exposed offspring of Mayak Production Association female workers and of female residents of Techa River villages. Some of the offspring also received postnatal exposure, either due to becoming radiation workers themselves or due to continuing to live in the contaminated areas of the Techa River. The mortality analyses comprised 16,821 subjects (601,372 person-years), and the incidence analyses comprised 15,813 subjects (554,411 person-years). Poisson regression was used to quantify the relative risk as a function of the in utero soft tissue dose (with cumulative doses up to 944.9 mGy, mean dose of 14.1 mGy in the pooled cohort) and the postnatal stomach dose for solid cancer incidence and mortality.
  
  
  RESULTS
  When a log-linear model was used, relative risk of cancer per 10 mGy of in utero dose was 0.99 (95% confidence interval (CI) = 0.96 to 1.01) based on incidence data and 0.98 (CI = 0.94 to 1.01) based on mortality data. Postnatal exposure to ionizing radiation was positively associated with the solid cancer risk in members of the UPEC, with a relative risk of 1.02 per 10mGy CI = 1.00 to 1.04).
  
  
  CONCLUSIONS
  No strong evidence was found that chronic low-dose-rate exposure of the embryo and fetus increased the risk of solid cancers in childhood or in adulthood. For both incidence and mortality, a tendency towards a decreased relative risk was noted with increasing doses to soft tissues of the fetus. Further follow-up will provide more precise radiation risk estimates of solid cancer as cohort members are approaching their 60s and cancer becomes more common.
authors.affiliation: Urals Research Center for Radiation Medicine, Chelyabinsk, Russian Federation.|Chelyabinsk State University, Chelyabinsk, Russian Federation.
authors.forename: Alexander
authors.identifier: http://orcid.org/0000-0003-2583-5808
authors.initials: A
authors.lastname: Akleyev
authors.affiliation: Section of Environment and Radiation, International Agency for Research on Cancer (IARC), Lyon, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Deltour
authors.affiliation: Urals Research Center for Radiation Medicine, Chelyabinsk, Russian Federation.
authors.forename: Lyudmila
authors.initials: L
authors.lastname: Krestinina
authors.affiliation: Southern Urals Biophysics Institute, Ozyorsk, Russian Federation.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Sokolnikov
authors.affiliation: Southern Urals Biophysics Institute, Ozyorsk, Russian Federation.
authors.forename: Yulia
authors.initials: Y
authors.lastname: Tsareva
authors.affiliation: Urals Research Center for Radiation Medicine, Chelyabinsk, Russian Federation.
authors.forename: Evgenia
authors.initials: E
authors.lastname: Tolstykh
authors.affiliation: Section of Environment and Radiation, International Agency for Research on Cancer (IARC), Lyon, France.
authors.forename: Joachim
authors.initials: J
authors.lastname: Schüz
mesh_terms: D000368:Aged; D015331:Cohort Studies; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology* / Q000401:mortality*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology* / Q000209:etiology / Q000401:mortality*; D011839:Radiation, Ionizing; D012426:Russia / Q000453:epidemiology; D016019:Survival Analysis