title: Radiation exposure does not significantly contribute to the risk of recurrence of Chernobyl thyroid cancer.
abstract: BACKGROUND
  Papillary thyroid carcinoma (PTC) in patients exposed to environmental radioiodine after the Chernobyl accident is thought to have a relatively aggressive clinical course. Long-term results of treatment are not well known, especially in comparison with sporadic PTC.
  
  
  OBJECTIVE
  The determination of risk factors for PTC recurrence in a controlled for baseline factors group of patients with radiation-related and sporadic PTC.
  
  
  METHODS
  Retrospective cohort study involving patients treated for PTC and followed-up in 1991-2008. Risk factors were assessed by stratified analysis using the proportional hazard model.
  
  
  METHODS
  Referral center-based.
  
  
  METHODS
  A total of 497 patients were enrolled. Patients exposed to radioiodine were 172 individuals with reconstructed individual radiation thyroid doses ranging 51-3170 mGy. Patients with sporadic PTC included 325 individuals matched to exposed patients for sex, age ± 5 yr and time to treatment ± 2 yr.
  
  
  METHODS
  Cancer recurrence.
  
  
  RESULTS
  Nodal disease increased the recurrence rate (HR = 5.21; 95% CI = 1.63-16.7) while the presence of tumor capsule (HR = 0.17; 95% CI = 0.06-0.45) and, particularly, treatment according to the Revised American Thyroid Association Management Guidelines for Patients with Thyroid Nodules and Differentiated Thyroid Cancer significantly reduced it (HR = 0.16; 95% CI = 0.06-0.42). None of the tested variables interacted with radiation factor.
  
  
  CONCLUSIONS
  PTC developing after internal exposure to radioiodine does not display specific risk factors for recurrence different from those in sporadic PTC. Common treatment approaches for patients with PTC should be recommended regardless of a history of radiation exposure.
authors.affiliation: Department of Radiosurgery, Medical Radiological Research Center of Russian Academy of Medical Sciences, Obninsk 249036, Russian Federation.
authors.forename: Pavel O
authors.initials: PO
authors.lastname: Rumyantsev
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Saenko
authors.forename: Alexey A
authors.initials: AA
authors.lastname: Ilyin
authors.forename: Valery F
authors.initials: VF
authors.lastname: Stepanenko
authors.forename: Ulyana V
authors.initials: UV
authors.lastname: Rumyantseva
authors.forename: Aleksandr Yu
authors.initials: AY
authors.lastname: Abrosimov
authors.forename: Evgeny F
authors.initials: EF
authors.lastname: Lushnikov
authors.forename: Tatiana I
authors.initials: TI
authors.lastname: Rogounovitch
authors.forename: Yoshisada
authors.initials: Y
authors.lastname: Shibata
authors.forename: Norisato
authors.initials: N
authors.lastname: Mitsutake
authors.forename: Anatoly F
authors.initials: AF
authors.lastname: Tsyb
authors.forename: Shunichi
authors.initials: S
authors.lastname: Yamashita
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D002291:Carcinoma, Papillary / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D047852:Chernobyl Nuclear Accident; D002648:Child; D015331:Cohort Studies; D018572:Disease-Free Survival; D023381:Endpoint Determination; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008197:Lymph Node Excision; D009364:Neoplasm Recurrence, Local; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology; D011827:Radiation; D012307:Risk Factors; D012426:Russia / Q000453:epidemiology; D013964:Thyroid Neoplasms / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D013965:Thyroidectomy; D013972:Thyrotropin / Q000037:antagonists & inhibitors; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D013972:Thyrotropin