title: Impact of extranodal extension on prognosis in lymph node-positive gastric cancer.
abstract: BACKGROUND
  The TNM classification system is used widely for tumour staging, and directs the treatment and prognosis of patients with cancer. The aim of this study was to assess the prognostic value of extranodal extension (ENE) in patients with early gastric cancer.
  
  
  METHODS
  All patients who underwent gastrectomy with lymphadenectomy for primary gastric cancer with lymph node metastases between January 2003 and June 2006 were reviewed. Histological slides of metastatic nodes were reviewed by two gastrointestinal pathologists. The association of ENE with clinicopathological characteristics was assessed. The disease-specific survival rate was calculated by the Kaplan-Meier method, and a multivariable Cox regression model was used to identify independent prognostic factors.
  
  
  RESULTS
  Some 1143 patients were included. ENE was associated with advanced pT and pN category, larger tumour size and lymphovascular/perineural invasion. In multivariable analysis, pT category, pN category, ENE, lymphovascular invasion and perineural invasion were found to be independent prognostic factors in node-positive gastric carcinoma. The 5-year survival rate of patients with ENE was 48·1 per cent, compared with 78·2 per cent for patients without ENE (P < 0·001). In the subgroup of patients with early gastric cancer, ENE was associated with a worse 5-year survival rate in patients with early (T1) gastric cancer: 75 per cent in patients with ENE versus 96·9 per cent in those without (P < 0·001).
  
  
  CONCLUSIONS
  ENE is an independent prognostic factor in patients with early and advanced gastric cancer.
authors.affiliation: Departments of Surgery, Ulsan University College of Medicine and Asan Medical Centre, Seoul, Korea.
authors.forename: I-S
authors.initials: IS
authors.lastname: Lee
authors.forename: Y-S
authors.initials: YS
authors.lastname: Park
authors.forename: M-H
authors.initials: MH
authors.lastname: Ryu
authors.forename: M J
authors.initials: MJ
authors.lastname: Song
authors.forename: J-H
authors.initials: JH
authors.lastname: Yook
authors.forename: S-T
authors.initials: ST
authors.lastname: Oh
authors.forename: B-S
authors.initials: BS
authors.lastname: Kim
mesh_terms: D000328:Adult; D000369:Aged, 80 and over; D018572:Disease-Free Survival; D005260:Female; D005743:Gastrectomy / Q000379:methods / Q000401:mortality; D006801:Humans; D008197:Lymph Node Excision / Q000379:methods / Q000401:mortality; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D055815:Young Adult