title: Histological grading of colorectal cancer: a simple and objective method.
abstract: OBJECTIVE
  Tumor grade employed for colorectal cancer has long been based on the degree of differentiation, which is difficult to judge objectively. The aim of this study was to determine whether the extent of the poorly differentiated component (POR) could be a valuable criterion for a grading system.
  
  
  METHODS
  A total of 1075 patients with advanced colorectal cancer were pathologically reviewed. POR was newly defined as a region in which a cancer has no glandular formation, irrespective of a mucin-producing or invasive pattern, and we quantitatively classified the POR into 6 degrees using the microscopic field of an objective lens as a standard.
  
  
  RESULTS
  Survival analyses of the extent of POR demonstrated that a 3-category grading system provides the most efficient survival stratification. Grade III was applied to tumors (n = 339) for which the POR fully occupied the microscopic field of a 40x objective lens. For tumors having a smaller POR, cancer clusters without a gland structure composed of > or = 5 cancer cells ("clusters") were counted in the microscopic field of a 4x objective lens, where "clusters" were observed most intensively. Tumors with < 10 "clusters" were classified as grade I (n = 161), and those with > or = 10 "clusters" as grade II (n = 575). Patients classified as grade I demonstrated a very favorable prognosis, with a 99.3% cancer-related 5-year survival rate, whereas the survival was 86.0% for grade II and 68.9% for grade III (P < 0.0001 in each group). Multivariate analysis demonstrated that the grades of POR function as an independent prognosticator, as do T-stage and N-stage.
  
  
  CONCLUSIONS
  The grading system utilizing POR is distinctive in terms of the simplicity of judgment based on its quantification and the ability to determine which patients will likely be cured by surgery alone. It will aid in selecting postoperative treatment strategies.
authors.affiliation: Department of Surgery, National Defense Medical College, Tokorozawa, Saitama 359-8513, 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: Yojiro
authors.initials: Y
authors.lastname: Hashiguchi
authors.forename: Megumi
authors.initials: M
authors.lastname: Ishiguro
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Kajiwara
authors.forename: Taichi
authors.initials: T
authors.lastname: Sato
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Shimazaki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Hase
authors.forename: Ian C
authors.initials: IC
authors.lastname: Talbot
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002471:Cell Transformation, Neoplastic; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D015996:Survival Rate; D016896:Treatment Outcome