title: Analysis of thyroid malignant pathologic findings identified during 3 rounds of screening (1997-2008) of a cohort of children and adolescents from belarus exposed to radioiodines after the Chernobyl accident.
abstract: BACKGROUND
  Recent studies of children and adolescents who were exposed to radioactive iodine-131 (I-131) after the 1986 Chernobyl nuclear accident in Ukraine exhibited a significant dose-related increase in the risk of thyroid cancer, but the association of radiation doses with tumor histologic and morphologic features is not clear.
  
  
  METHODS
  A cohort of 11,664 individuals in Belarus who were aged ≤18 years at the time of the accident underwent 3 cycles of thyroid screening during 1997 to 2008. I-131 thyroid doses were estimated from individual thyroid activity measurements taken within 2 months after the accident and from dosimetric questionnaire data. Demographic, clinical, and tumor pathologic characteristics of the patients with thyroid cancer were analyzed using 1-way analysis of variance, chi-square tests or Fisher exact tests, and logistic regression.
  
  
  RESULTS
  In total, 158 thyroid cancers were identified as a result of screening. The majority of patients had T1a and T1b tumors (93.7%), with many positive regional lymph nodes (N1; 60.6%) but few distant metastases (M1; <1%). Higher I-131 doses were associated with higher frequency of solid and diffuse sclerosing variants of thyroid cancer (P < .01) and histologic features of cancer aggressiveness, such as lymphatic vessel invasion, intrathyroidal infiltration, and multifocality (all P < .03). Latency was not correlated with radiation dose. Fifty-two patients with self-reported thyroid cancers which were diagnosed before 1997 were younger at the time of the accident and had a higher percentage of solid variant cancers compared with patients who had screening-detected thyroid cancers (all P < .0001).
  
  
  CONCLUSIONS
  I-131 thyroid radiation doses were associated with a significantly greater frequency of solid and diffuse sclerosing variants of thyroid cancer and various features of tumor aggressiveness.
authors.affiliation: Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California.
authors.forename: Lydia B
authors.initials: LB
authors.lastname: Zablotska
authors.forename: Eldar A
authors.initials: EA
authors.lastname: Nadyrov
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Rozhko
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Gong
authors.forename: Olga N
authors.initials: ON
authors.lastname: Polyanskaya
authors.forename: Robert J
authors.initials: RJ
authors.lastname: McConnell
authors.forename: Patrick
authors.initials: P
authors.lastname: O'Kane
authors.forename: Alina V
authors.initials: AV
authors.lastname: Brenner
authors.forename: Mark P
authors.initials: MP
authors.lastname: Little
authors.forename: Evgenia
authors.initials: E
authors.lastname: Ostroumova
authors.forename: Andre
authors.initials: A
authors.lastname: Bouville
authors.forename: Vladimir
authors.initials: V
authors.lastname: Drozdovitch
authors.forename: Viktor
authors.initials: V
authors.lastname: Minenko
authors.forename: Yuri
authors.initials: Y
authors.lastname: Demidchik
authors.forename: Alexander
authors.initials: A
authors.lastname: Nerovnya
authors.forename: Vassilina
authors.initials: V
authors.lastname: Yauseyenka
authors.forename: Irina
authors.initials: I
authors.lastname: Savasteeva
authors.forename: Sergey
authors.initials: S
authors.lastname: Nikonovich
authors.forename: Kiyohiko
authors.initials: K
authors.lastname: Mabuchi
authors.forename: Maureen
authors.initials: M
authors.lastname: Hatch
mesh_terms: D000293:Adolescent; D000328:Adult; D047852:Chernobyl Nuclear Accident; D002648:Child; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000008:administration & dosage*; D016015:Logistic Models; D008297:Male; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology* / Q000473:pathology*; D002094:Republic of Belarus / Q000453:epidemiology; D013964:Thyroid Neoplasms / Q000453:epidemiology* / Q000473:pathology*; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes
keywords: Chernobyl nuclear accident; latency; morphology; papillary carcinoma; pathology; radiation; thyroid cancer; thyroid neoplasms