title: The Ratio-Based N Staging System Can More Accurately Reflect the Prognosis of T4 Gastric Cancer Patients with D2 Lymphadenectomy Compared with the 7th American Joint Committee on Cancer/Union for International Cancer Control Staging System.
abstract: OBJECTIVE
  The utility of N classification has been questioned after the 7th edition of the American Joint Committee on Cancer (AJCC)/Union for International Cancer Control (UICC) was published. We evaluated the correlation between ratio-based N (rN) classification with the overall survival of pathological T4 gastric cancer patients who underwent D2 lymphadenectomy.
  
  
  METHODS
  We reviewed 222 cases of advanced gastric cancer patients who underwent curative gastrectomy between January 2006 and December 2015. The T4 gastric cancer patents were classified into four groups according to the lymph node ratio (the number of metastatic lymph nodes divided by the retrieved lymph nodes): rN0, 0%; rN1, ≤13.3%; rN2, ≤40.0%; and rN3, >40.0%.
  
  
  RESULTS
  The rN stage showed a large down stage migration compared with pathological T4N3 (AJCC/UICC). There was a significant difference in overall survival between rN2 and rN3 groups in patients with pT4N3 (P=0.013). In contrast, the difference in metastatic lymph nodes was not significant in these patients (≥16 vs. <15; P=0.177). In addition, the rN staging system showed a more distinct difference in overall survival than the pN staging system for pathological T4 gastric cancer patients.
  
  
  CONCLUSIONS
  Our results confirm that rN staging could be a good alternative for pathological T4 gastric cancer patients who undergo D2 lymphadenectomy. However, before applying this system to gastric cancer patients who undergo D2 lymphadenectomy, a larger sample size is required to further evaluate the usefulness of the rN staging system for all stages, including less advanced stages.
authors.affiliation: Department of Surgery, Hanyang University Guri Hospital, Guri, Korea.
authors.forename: Sung Hwan
authors.initials: SH
authors.lastname: Hwang
authors.affiliation: Department of Surgery, Hanyang University Guri Hospital, Guri, Korea.
authors.forename: Hyun Il
authors.initials: HI
authors.lastname: Kim
authors.affiliation: Department of Surgery, Hanyang University Guri Hospital, Guri, Korea.
authors.forename: Jun Seong
authors.initials: JS
authors.lastname: Song
authors.affiliation: Department of Surgery, Hanyang University Guri Hospital, Guri, Korea.
authors.forename: Min Hong
authors.initials: MH
authors.lastname: Lee
authors.affiliation: Department of Surgery, Hanyang University Seoul Hospital, Seoul, Hanyang University College of Medicine, Korea.
authors.forename: Sung Joon
authors.initials: SJ
authors.lastname: Kwon
authors.affiliation: Department of Surgery, Hanyang University Guri Hospital, Guri, Korea.
authors.forename: Min Gyu
authors.initials: MG
authors.lastname: Kim
keywords: Prognosis; Stomach neoplasms; TNM staging