title: Reassessing the NTCTCS Staging Systems for Differentiated Thyroid Cancer, Including Age at Diagnosis.
abstract: BACKGROUND
  Thyroid cancer is unique for having age as a staging variable. Recently, the commonly used age cut-point of 45 years has been questioned.
  
  
  OBJECTIVE
  This study assessed alternate staging systems on the outcome of overall survival, and compared these with current National Thyroid Cancer Treatment Cooperative Study (NTCTCS) staging systems for papillary and follicular thyroid cancer.
  
  
  METHODS
  A total of 4721 patients with differentiated thyroid cancer were assessed. Five potential alternate staging systems were generated at age cut-points in five-year increments from 35 to 70 years, and tested for model discrimination (Harrell's C-statistic) and calibration (R(2)). The best five models for papillary and follicular cancer were further tested with bootstrap resampling and significance testing for discrimination.
  
  
  RESULTS
  The best five alternate papillary cancer systems had age cut-points of 45-50 years, with the highest scoring model using 50 years. No significant difference in C-statistic was found between the best alternate and current NTCTCS systems (p = 0.200). The best five alternate follicular cancer systems had age cut-points of 50-55 years, with the highest scoring model using 50 years. All five best alternate staging systems performed better compared with the current system (p = 0.003-0.035). There was no significant difference in discrimination between the best alternate system (cut-point age 50 years) and the best system of cut-point age 45 years (p = 0.197).
  
  
  CONCLUSIONS
  No alternate papillary cancer systems assessed were significantly better than the current system. New alternate staging systems for follicular cancer appear to be better than the current NTCTCS system, although they require external validation.
authors.affiliation: 1 Department of Endocrinology and Diabetes, Royal Brisbane and Women's Hospital , Herston, Australia .|2 Population Health Department, QIMR Berghofer Medical Research Institute , Herston, Australia .|3 School of Medicine, University of Queensland , Herston, Australia .
authors.forename: Donald S A
authors.initials: DS
authors.lastname: McLeod
authors.affiliation: 4 Division of Endocrinology, Department of Medicine, Georgetown University Medical Center , Washington, District of Columbia.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Jonklaas
authors.affiliation: 5 Department of Radiation Oncology, Princess Margaret Hospital , Toronto, Canada .
authors.forename: James D
authors.initials: JD
authors.lastname: Brierley
authors.affiliation: 6 Department of Internal Medicine, Veterans Affairs Medical Center and University of Kentucky , Lexington, Kentucky.
authors.forename: Kenneth B
authors.initials: KB
authors.lastname: Ain
authors.affiliation: 7 Division of Endocrinology, Diabetes, and Metabolism, The Johns Hopkins University School of Medicine , Baltimore, Maryland.
authors.forename: David S
authors.initials: DS
authors.lastname: Cooper
authors.affiliation: 8 Division of Endocrinology and Metabolism, Sinai Hospital , Baltimore, Maryland.
authors.forename: Henry G
authors.initials: HG
authors.lastname: Fein
authors.affiliation: 9 Division of Endocrinology, Metabolism, and Diabetes, University of Colorado School of Medicine , Aurora, Colorado.
authors.forename: Bryan R
authors.initials: BR
authors.lastname: Haugen
authors.affiliation: 7 Division of Endocrinology, Diabetes, and Metabolism, The Johns Hopkins University School of Medicine , Baltimore, Maryland.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Ladenson
authors.affiliation: 10 Genzyme, a Sanofi Company , Cambridge, Massachusetts.
authors.forename: James
authors.initials: J
authors.lastname: Magner
authors.affiliation: 11 Thyroid Unit, Massachusetts General Hospital , Boston, Massachusetts.
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Ross
authors.affiliation: 12 Diabetes, Endocrinology, Obesity Branch, National Institutes of Health , Bethesda, Maryland.
authors.forename: Monica C
authors.initials: MC
authors.lastname: Skarulis
authors.affiliation: 13 Department of Head and Neck Surgery, University of Cincinnati Medical Center , Cincinnati, Ohio.
authors.forename: David L
authors.initials: DL
authors.lastname: Steward
authors.affiliation: 7 Division of Endocrinology, Diabetes, and Metabolism, The Johns Hopkins University School of Medicine , Baltimore, Maryland.
authors.forename: Mingzhao
authors.initials: M
authors.lastname: Xing
authors.affiliation: 14 Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center , Houston, Texas.
authors.forename: Danielle R
authors.initials: DR
authors.lastname: Litofsky
authors.affiliation: 15 Department of Nuclear Medicine, University of Cincinnati Medical Center , Cincinnati, Ohio.
authors.forename: Harry R
authors.initials: HR
authors.lastname: Maxon
authors.affiliation: 14 Department of Endocrine Neoplasia and Hormonal Disorders, The University of Texas MD Anderson Cancer Center , Houston, Texas.
authors.forename: Steven I
authors.initials: SI
authors.lastname: Sherman
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000473:pathology*; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D000368:Aged; D002291:Carcinoma, Papillary / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D013961:Thyroid Gland / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000473:pathology*