title: Proposal of new classification for stage III colon cancer based on the lymph node ratio: analysis of 4,172 patients from multi-institutional database in Japan.
abstract: BACKGROUND
  We retrospectively examined the optimal lymph node ratio (LNR) cutoff value and attempted to construct a new classification using the LNR in stage III colon cancer.
  
  
  METHODS
  The clinical and pathological data of 4,172 patients with histologically proven lymph node metastasis who underwent curative surgery for primary colon cancer at multiple institutions between 1995 and 2004 were derived from the multi-institutional database of the Japanese Society for Cancer of the Colon and Rectum (JSCCR). We determined independent prognostic factors and constructed a new classification using these factors. Finally, we compared the discriminatory ability between the new classification and the TNM seventh edition (TNM 7th) classification.
  
  
  RESULTS
  The optimal LNR cutoff value was 0.18. Multivariate analysis revealed that year of surgery, age, gender, histological type, TNM 7th T category, lymphatic invasion, venous invasion, TNM 7th N category, and LNR were found to be significant independent prognostic factors. We attempted to construct a new classification based on the combination of TNM 7th T category and LNR. As a result, the cancer-specific survivals were well stratified (P < .0001). According to the Akaike's information criteria value, the new classification was judged to be superior to the TNM 7th classification with respect to both a better fit and lower complexity.
  
  
  CONCLUSIONS
  The optimal LNR cutoff value that was found using the Japanese multi-institutional database and the new classification using LNR are considered to be extremely significant. Therefore, these findings strongly support the application of LNR in the stage classification in stage III colon cancer.
authors.affiliation: Department of Coloproctological Surgery, Juntendo University Faculty of Medicine, Tokyo, Japan, ksugimo@juntendo.co.jp.
authors.forename: Kiichi
authors.initials: K
authors.lastname: Sugimoto
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Sakamoto
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Tomiki
authors.forename: Michitoshi
authors.initials: M
authors.lastname: Goto
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Kotake
authors.forename: Kenichi
authors.initials: K
authors.lastname: Sugihara
mesh_terms: D000230:Adenocarcinoma / Q000145:classification* / Q000473:pathology* / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003110:Colonic Neoplasms / Q000145:classification* / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D007564:Japan; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D055815:Young Adult