title: Optimal colorectal cancer staging criteria in TNM classification.
abstract: OBJECTIVE
  Histologic components of the TNM classification system have been repeatedly revised since the fifth edition (TNM5). TNM classification revisions provide different criteria for categorizing tumor nodules without residual lymph node structure (ND). However, there are few systematic evaluations regarding the effectiveness of these revisions.
  
  
  METHODS
  A multicenter pathologic review for ND in colorectal cancer (CRC) was performed. Tumor staging defined by TNM5, sixth edition (TNM6), and seventh edition (TNM7) were compared on the basis of Akaike information criterion (AIC) and Harrell's concordance index (c-index). Moreover, TNM7's prognostic value was compared between the original ND and modified criteria, which considered all regional NDs as lymph node metastasis (LNM) irrespective of the original structure.
  
  
  RESULTS
  In 1,716 treated patients with CRC (1994 to 1998), tumor stages (I/II/III) exhibited better prognoses in TNM7 (AIC, 3055.1; c-index, 0.7215) than in TNM6 (AIC, 3063.7; c-index, 0.7149), but not better than in TNM5 (AIC, 3051.6; c-index, 0.7240). Comparing the original TNM7 and modified criteria, 4.2% of patients were classified in different N stages (N0/N1/N2a/N2b); both AIC and the c-index were superior in the modified criteria (AIC, 3029.40; c-index, 0.7271) compared with the original criteria (AIC, 3040.58; c-index, 0.7230). Modified criteria were also associated with improved prognostic power of tumor stages (I/IIA/IIB/IIC/IIIA/IIIB/IIIC). These results were similar in another cohort of 2,242 treated patients with CRC (1999 to 2003).
  
  
  CONCLUSIONS
  The prognostic value of TNM7 is better than that of TNM6; however, improvement over TNM5 is insignificant. By considering all regional NDs as LNM irrespective of their morphology, TNM classification can be simplified and its prognostic value improved.
authors.affiliation: National Defense Medical College, Tokorozawa, Japan. ueno@ndmc.ac.jp
authors.forename: Hideki
authors.initials: H
authors.lastname: Ueno
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Mochizuki
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Akagi
authors.forename: Takaya
authors.initials: T
authors.lastname: Kusumi
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Yamada
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ikegami
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawachi
authors.forename: Shingo
authors.initials: S
authors.lastname: Kameoka
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ohkura
authors.forename: Tadahiko
authors.initials: T
authors.lastname: Masaki
authors.forename: Ryoji
authors.initials: R
authors.lastname: Kushima
authors.forename: Keiichi
authors.initials: K
authors.lastname: Takahashi
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Ajioka
authors.forename: Kazuo
authors.initials: K
authors.lastname: Hase
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ochiai
authors.forename: Ryo
authors.initials: R
authors.lastname: Wada
authors.forename: Keiichi
authors.initials: K
authors.lastname: Iwaya
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Shimazaki
authors.forename: Takahiro
authors.initials: T
authors.lastname: Nakamura
authors.forename: Kenichi
authors.initials: K
authors.lastname: Sugihara
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000145:classification / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D005260:Female; D006801:Humans; D007564:Japan; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D015588:Observer Variation; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D012044:Regression Analysis; D015203:Reproducibility of Results; D016019:Survival Analysis; D013997:Time Factors; D055815:Young Adult