title: Clinical implication of an insufficient number of examined lymph nodes after curative resection for gastric cancer.
abstract: BACKGROUND
  The seventh edition of the tumor, lymph node (LN), metastasis (TNM) staging system increased the required number of examined LNs in gastric cancer from 15 to 16. However, the same staging system defines lymph node-negative gastric cancer regardless of the number of examined LNs. In this study, the authors evaluated whether gastric cancer can be staged properly with fewer than 15 examined LNs.
  
  
  METHODS
  The survival rates of 10,010 patients who underwent curative gastrectomy from 1987 to 2007 were analyzed. The patients were divided into 2 groups according to the number of examined LNs, termed the "insufficient" group (≤15 examined LNs) and the "sufficient" group (≥16 examined LNs). The survival curves of patients from both groups were compared according to the seventh edition of the TNM classification.
  
  
  RESULTS
  Three hundred sixteen patients (3.2%) had ≤15 examined LNs for staging after they underwent standard, curative lymphadenectomy. Patients who had T1 tumor classification, N0 lymph node status, and stage I disease with an insufficient number of examined LNs after curative gastrectomy had a significantly worse prognosis than patients who had ≥16 examined LNs. Moreover, having an insufficient number of examined LNs was an independent prognostic factor for patients who had T1, N0, and stage I disease.
  
  
  CONCLUSIONS
  Lymph node-negative cancers in which ≤15 LNs were examined, classified as N0 in the new TNM staging system, could not adequately predict patient survival after curative gastrectomy, especially in patients with early stage gastric cancer.
authors.affiliation: Department of Surgery, Yonsei University Health System, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Taeil
authors.initials: T
authors.lastname: Son
authors.forename: Woo Jin
authors.initials: WJ
authors.lastname: Hyung
authors.forename: Joong Ho
authors.initials: JH
authors.lastname: Lee
authors.forename: Yoo Min
authors.initials: YM
authors.lastname: Kim
authors.forename: Hyoung-Il
authors.initials: HI
authors.lastname: Kim
authors.forename: Ji Yeong
authors.initials: JY
authors.lastname: An
authors.forename: Jae-Ho
authors.initials: JH
authors.lastname: Cheong
authors.forename: Sung Hoon
authors.initials: SH
authors.lastname: Noh
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005743:Gastrectomy; D006801:Humans; D016015:Logistic Models; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D016019:Survival Analysis; D016896:Treatment Outcome