title: A new pN staging system based on both the number and anatomic location of metastatic lymph nodes in gastric cancer.
abstract: BACKGROUND
  Our aim was to establish a new pN staging system for gastric cancer based on the number and location of metastatic lymph nodes (MLNs) and to compare it with other systems.
  
  
  METHODS
  We retrospectively analyzed the prognostic data of 521 gastric cancer patients who underwent curative resection. Survival analyses were used to establish a pN staging system that considers both the number and location of MLNs and to compare discriminatory ability and monotonicity of gradients (linear trend χ (2) score), homogeneity ability (likelihood ratio test), and prognostic stratification ability (Akaike information criterion) between Japanese Gastric Cancer Association (JGCA) and Union for International Cancer Control (UICC) systems.
  
  
  RESULTS
  Cut-point survival analysis divided pN(+) patients into two groups: Nxn1~6 and Nxn≥7. N0, N1, N2, and N3 (the previous classifications) were replaced by N0, N1n1~6, N2n1~6, and N1n≥7 + N2n≥7 + N3n1~6 + N3n≥7, respectively. Compared with two widely used staging systems, the new system had the highest likelihood ratio test [106.06 (new) vs 95.09 (JGCA) vs 94.33 (UICC)] and linear trend χ (2) scores [102.30 (new) vs 89.12 (JGCA) vs 86.97(UICC)] and the lowest Akaike information criterion (AIC) score [2,283.88 (new) vs 2,285.31 (JGCA) vs 2,299.88 (UICC)].
  
  
  CONCLUSIONS
  A new pN staging system based on the number and location of MLNs is an efficient prognostic indicator of the survival of patients with gastric cancer following radical surgery.
authors.affiliation: Gastric Cancer Center, Sun Yat-Sen University, Guangzhou, 510080, People's Republic of China.
authors.forename: Jianhui
authors.initials: J
authors.lastname: Chen
authors.forename: Chuangqi
authors.initials: C
authors.lastname: Chen
authors.forename: Yulong
authors.initials: Y
authors.lastname: He
authors.forename: KaiMing
authors.initials: K
authors.lastname: Wu
authors.forename: Hui
authors.initials: H
authors.lastname: Wu
authors.forename: Shirong
authors.initials: S
authors.lastname: Cai
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000401:mortality / Q000556:secondary*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002681:China / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000401:mortality / Q000473:pathology*; D015996:Survival Rate / Q000639:trends; D013997:Time Factors