title: Outcomes of patients with differentiated thyroid cancer risk-stratified according to the American thyroid association and Latin American thyroid society risk of recurrence classification systems.
abstract: OBJECTIVE
  The aims of this study were to validate the proposed Latin American Thyroid Society (LATS) risk of recurrence stratification system and to compare the findings with those of the American Thyroid Association (ATA) risk of recurrence stratification system.
  
  
  METHODS
  This study is a retrospective review of papillary thyroid cancer patients treated with total thyroidectomy and radioactive iodine at a single experienced thyroid cancer center and followed according to the LATS management guidelines. Each patient was risk-stratified using both the LATS and ATA staging systems. The primary endpoints were (i) the best response to initial therapy defined as either remission (stimulated thyroglobulin [Tg] <1 ng/mL, negative ultrasonography) or persistent disease (biochemical and/or structural), and (ii) clinical status at final follow-up defined as no evidence of disease (suppressed Tg <1 ng/mL, negative ultrasonography), biochemical persistent disease (suppressed Tg >1 ng/mL in the absence of structural disease), structural persistent disease (locoregional or distant metastases), or recurrence (biochemical or structural disease identified after a period of no evidence of disease).
  
  
  RESULTS
  One hundred seventy-one papillary thyroid cancer patients were included (mean age 45 ± 16 years, followed for a median of 4 years after initial treatment). Both the ATA and LATS risk stratification systems provided clinically meaningful graded estimates with regard to (i) the likelihood of achieving remission in response to initial therapy, (ii) the likelihood of having persistent structural disease in response to initial therapy and at final follow-up, (iii) the likely locations of the persistent structural disease (locoregional vs. distant metastases), (iv) the likelihood of recurrence, and (v) the likelihood of being no evidence of disease at final follow-up. The likelihood of having persistent biochemical evidence of disease was not significantly different across the staging categories.
  
  
  CONCLUSIONS
  Both the ATA and LATS risk of recurrence systems effectively risk-stratify patients with regard to multiple important clinical outcomes. When used in conjunction with a staging system that predicts disease-specific mortality, either of these systems can be used to guide risk-adapted individualized initial management recommendations.
authors.affiliation: 1 Division of Endocrinology, Hospital de Clínicas-University of Buenos Aires , Buenos Aires, Argentina .
authors.forename: Fabián
authors.initials: F
authors.lastname: Pitoia
authors.forename: Fernanda
authors.initials: F
authors.lastname: Bueno
authors.forename: Carolina
authors.initials: C
authors.lastname: Urciuoli
authors.forename: Erika
authors.initials: E
authors.lastname: Abelleira
authors.forename: Graciela
authors.initials: G
authors.lastname: Cross
authors.forename: R Michael
authors.initials: RM
authors.lastname: Tuttle
mesh_terms: D000328:Adult; D000368:Aged; D002277:Carcinoma / Q000145:classification / Q000175:diagnosis* / Q000473:pathology*; D002291:Carcinoma, Papillary; D016208:Databases, Factual; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D007843:Latin America; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000145:classification / Q000517:prevention & control*; D012074:Remission Induction; D012189:Retrospective Studies; D012306:Risk; D012955:Societies, Medical; D013954:Thyroglobulin / Q000627:therapeutic use; D000077273:Thyroid Cancer, Papillary; D013961:Thyroid Gland / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000145:classification / Q000175:diagnosis* / Q000473:pathology*; D013965:Thyroidectomy; D016896:Treatment Outcome; D014481:United States
chemical_list: D007457:Iodine Radioisotopes; D013954:Thyroglobulin