title: The New American Joint Committee on Cancer/International Union Against Cancer staging system for adenocarcinoma of the stomach: increased complexity without clear improvement in predictive accuracy.
abstract: OBJECTIVE
  To evaluate the changes in the 7th edition American Joint Committee on Cancer (AJCC) staging system for stomach cancer compared to the 6th edition; to compare the predictive accuracy of the two staging systems.
  
  
  METHODS
  In a combined database containing 2,196 patients who underwent an R0 resection for gastric adenocarcinoma, differences between the two staging systems were evaluated and stage-specific survival estimates compared. Concordance probability and Brier scores were estimated for both systems to examine the predictive accuracy.
  
  
  RESULTS
  Nodal status cutoff values were changed, leading to a more even distribution for the redefined N1, N2, and N3 group. AJCC 6th edition stage II reflected a highly heterogeneous population, which is now adequately subdivided in the AJCC 7th edition into stages IIA, IIB, and IIIA. The predictive accuracy of N classification improved significantly as measured by concordance. Despite increased complexity, the predictive accuracy of AJCC 7th stage grouping was significantly worse than that of the AJCC 6th edition.
  
  
  CONCLUSIONS
  The increased complexity of the 7th edition staging system is accompanied by improvements in the predictive value of nodal staging as compared to the 6th edition, but it was no better in overall stage-specific predictive accuracy. Future refinements of the tumor, node, metastasis staging system should consider whether increased complexity is balanced by improved prognostic accuracy.
authors.affiliation: Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY, USA. jdikken@gmail.com
authors.forename: Johan L
authors.initials: JL
authors.lastname: Dikken
authors.forename: Cornelis J H
authors.initials: CJ
authors.lastname: van de Velde
authors.forename: Mithat
authors.initials: M
authors.lastname: Gönen
authors.forename: Marcel
authors.initials: M
authors.lastname: Verheij
authors.forename: Murray F
authors.initials: MF
authors.lastname: Brennan
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Coit
mesh_terms: D000230:Adenocarcinoma / Q000145:classification / Q000401:mortality* / Q000556:secondary* / Q000628:therapy; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging / Q000592:standards*; D011379:Prognosis; D011446:Prospective Studies; D013274:Stomach Neoplasms / Q000145:classification / Q000401:mortality* / Q000473:pathology* / Q000628:therapy; D015996:Survival Rate; D055815:Young Adult