title: Comparison of differentiated thyroid cancer in children and adolescents (≤20 years) with young adults.
abstract: BACKGROUND
  Age is a major prognostic factor in differentiated thyroid cancer (DTC). It is not clear if paediatric DTC has a different histopathological profile and outcome than DTC in adult patients <45 years of age.
  
  
  OBJECTIVE
  To assess whether DTC in children and adolescents differs from young age group by comparing paediatric DTC (age ≤ 20) with DTC in patients >20 to <45 years of age.
  
  
  METHODS
  We studied all cases of paediatric DTC seen during the period 1998-2011. We compared this group with a large sample of 213 consecutive adult patients in the age group >20 to <45 years seen during the period 1998-1999 in terms of their pathological features, extent of the disease and long-term outcome. Both groups were managed by the same team at a single institution.
  
  
  RESULTS
  A total of 310 DTC were studied including 97 paediatric patients [median age 17 years (range, 8-20)] and 213 young adult patients [median age 33 years (range, 20·5-44·9)]. There was no difference in gender distribution, tumour subtypes, size and tumour multifocality, but there was a significantly higher rate of extrathyroidal extension [40/75 (53·3%) vs 81/213 (38·0%), P = 0·03], lymph node [57/73 (78%) vs 102/183 (55·7%), P < 0·0001] and distant metastases [16/97 (16·5%) vs 8/213 (3·8%), P < 0·0001] in the paediatric than the adult groups. Kaplan-Meier analysis showed a higher risk of persistent/recurrent disease in the paediatric group than adults (log-rank test 0·03). However, there was no mortality secondary to DTC in both groups.
  
  
  CONCLUSIONS
  Paediatric DTC is distinct from DTC in the young adults (age >20 to <45 years). It is characterized by a higher rate of extrathyroidal extension, lymph node and distant metastases and a higher risk of persistent/recurrent DTC.
authors.affiliation: Department of Medicine, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia.|Department of Molecular Oncology, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia.|Research Center-Jeddah, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia.
authors.forename: Ali S
authors.initials: AS
authors.lastname: Alzahrani
authors.affiliation: Department of Medicine, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia.
authors.forename: Dania
authors.initials: D
authors.lastname: Alkhafaji
authors.affiliation: Department of Medical Imaging, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia.
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Tuli
authors.affiliation: Department of Pathology, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia.
authors.forename: Hindi
authors.initials: H
authors.lastname: Al-Hindi
authors.affiliation: Research Center-Jeddah, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia.
authors.forename: Bakr Bin
authors.initials: BB
authors.lastname: Sadiq
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D002648:Child; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local; D017063:Outcome Assessment, Health Care / Q000379:methods* / Q000706:statistics & numerical data*; D016016:Proportional Hazards Models; D012307:Risk Factors; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000628:therapy*; D047368:Tumor Burden; D055815:Young Adult