title: Validation of the seventh edition of the American Joint Committee on cancer tumor node-staging system in patients with colorectal carcinoma in comparison with sixth classification.
abstract: BACKGROUND
  The aim of this study was to compare survival rates assessed by the seventh-staging system with those by the sixth classification.
  
  
  METHODS
  This was a retrospective study of 3,377 patients who underwent surgery for colorectal adenocarcinoma from three university hospitals. The overall survival (OS) and cancer-specific survival (CSS) rates were compared between patients whose stages according to the seventh-staging system remained the same and patients whose stages migrated, and between subgroups within each new stage (homogeneity analysis).
  
  
  RESULTS
  In seventh edition, the 5-year OS and CSS rates of patients with T3n2 tumor were significantly greater in the downstaged patients (T3N2a) than in other patients (T3N2b) (OS, P = 0.010; CSS, P = 0.009). The 5-year survival rates for patients with T4a and T4b sub-classifications according to the seventh edition did not differ from those in patients with T4N0-1. Homogeneity analysis of subgroups classified using the new system showed that some subgroups of stage IIIB (T3N2a/T4aN1) had poorer survival rates compared with patients in other sub-categories in the same stage IIIB (P < 0.001).
  
  
  CONCLUSIONS
  Overall, the seventh edition provides a more detailed classification of the prognosis than the old system. However, further study would be warranted to evaluate the validity of sub-classification in seventh TNM-staging system, especially for T4a-b and T3N2a tumors.
authors.affiliation: Colorectal Cancer Center, Kyungpook National University Medical Center, School of Medicine, Kyungpook National University, Daegu, Korea.
authors.forename: Jun Seok
authors.initials: JS
authors.lastname: Park
authors.forename: Gyu-Seog
authors.initials: GS
authors.lastname: Choi
authors.forename: Suguru
authors.initials: S
authors.lastname: Hasegawa
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Sakai
authors.forename: Jung Wook
authors.initials: JW
authors.lastname: Huh
authors.forename: Hyeong Rok
authors.initials: HR
authors.lastname: Kim
authors.forename: Sang Gyu
authors.initials: SG
authors.lastname: Kwak
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D000368:Aged; D015179:Colorectal Neoplasms / Q000401:mortality / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate