title: Number of Lymph Nodes Removed and Survival after Gastric Cancer Resection: An Analysis from the US Gastric Cancer Collaborative.
abstract: BACKGROUND
  Examination of at least 16 lymph nodes (LNs) has been traditionally recommended during gastric adenocarcinoma resection to optimize staging, but the impact of this strategy on survival is uncertain. Because recent randomized trials have demonstrated a therapeutic benefit from extended lymphadenectomy, we sought to investigate the impact of the number of LNs removed on prognosis after gastric adenocarcinoma resection.
  
  
  METHODS
  We analyzed patients who underwent gastrectomy for gastric adenocarcinoma from 2000 to 2012, at 7 US academic institutions. Patients with M1 disease or R2 resections were excluded. Disease-specific survival (DSS) was calculated using the Kaplan-Meier method and compared using log-rank and Cox regression analyses.
  
  
  RESULTS
  Of 742 patients, 257 (35%) had 7 to 15 LNs removed and 485 (65%) had ≥16 LNs removed. Disease-specific survival was not significantly longer after removal of ≥16 vs 7 to 15 LNs (10-year survival, 55% vs 47%, respectively; p = 0.53) for the entire cohort, but was significantly improved in the subset of patients with stage IA to IIIA (10-year survival, 74% vs 57%, respectively; p = 0.018) or N0-2 disease (72% vs 55%, respectively; p = 0.023). Similarly, for patients who were classified to more likely be "true N0-2," based on frequentist analysis incorporating both the number of positive and of total LNs removed, the hazard ratio for disease-related death (adjusted for T stage, R status, grade, receipt of neoadjuvant and adjuvant therapy, and institution) significantly decreased as the number of LNs removed increased.
  
  
  CONCLUSIONS
  The number of LNs removed during gastrectomy for adenocarcinoma appears itself to have prognostic implications for long-term survival.
authors.affiliation: Department of Surgery, Stanford Cancer Institute, Stanford University, Stanford, CA.
authors.forename: Sepideh
authors.initials: S
authors.lastname: Gholami
authors.affiliation: Department of Statistics, Stanford University, Stanford, CA.
authors.forename: Lucas
authors.initials: L
authors.lastname: Janson
authors.affiliation: Department of Surgery, Stanford Cancer Institute, Stanford University, Stanford, CA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Worhunsky
authors.affiliation: Department of Surgery, Stanford Cancer Institute, Stanford University, Stanford, CA.
authors.forename: Thuy B
authors.initials: TB
authors.lastname: Tran
authors.affiliation: Department of Surgery, Emory University, Winship Cancer Institute, Atlanta, GA.
authors.forename: Malcolm Hart
authors.initials: MH
authors.lastname: Squires
authors.affiliation: Department of Surgery, Barnes Jewish Hospital and the Alvin J Siteman Cancer Center, Washington University, St. Louis, MO.
authors.forename: Linda X
authors.initials: LX
authors.lastname: Jin
authors.affiliation: Department of Surgery, The Johns Hopkins University, Baltimore, MD.
authors.forename: Gaya
authors.initials: G
authors.lastname: Spolverato
authors.affiliation: Department of Surgery, Wake Forest University, Winston-Salem, NC.
authors.forename: Konstantinos I
authors.initials: KI
authors.lastname: Votanopoulos
authors.affiliation: Department of Surgery, The Ohio State University, Columbus, OH.
authors.forename: Carl
authors.initials: C
authors.lastname: Schmidt
authors.affiliation: Department of Surgery, University of Wisconsin, Madison, WI.
authors.forename: Sharon M
authors.initials: SM
authors.lastname: Weber
authors.affiliation: Department of Surgery, The Ohio State University, Columbus, OH.
authors.forename: Mark
authors.initials: M
authors.lastname: Bloomston
authors.affiliation: Department of Surgery, University of Wisconsin, Madison, WI.
authors.forename: Clifford S
authors.initials: CS
authors.lastname: Cho
authors.affiliation: Department of Surgery, Wake Forest University, Winston-Salem, NC.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Levine
authors.affiliation: Department of Surgery, Barnes Jewish Hospital and the Alvin J Siteman Cancer Center, Washington University, St. Louis, MO.
authors.forename: Ryan C
authors.initials: RC
authors.lastname: Fields
authors.affiliation: Department of Surgery, The Johns Hopkins University, Baltimore, MD.
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Pawlik
authors.affiliation: Department of Surgery, Emory University, Winship Cancer Institute, Atlanta, GA.
authors.forename: Shishir K
authors.initials: SK
authors.lastname: Maithel
authors.affiliation: Department of Statistics, Stanford University, Stanford, CA.
authors.forename: Bradley
authors.initials: B
authors.lastname: Efron
authors.affiliation: Department of Surgery, Stanford Cancer Institute, Stanford University, Stanford, CA.
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Norton
authors.affiliation: Department of Surgery, Stanford Cancer Institute, Stanford University, Stanford, CA. Electronic address: gpoultsides@stanford.edu.
authors.forename: George A
authors.initials: GA
authors.lastname: Poultsides
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D000328:Adult; D000368:Aged; D005260:Female; D005743:Gastrectomy; D006801:Humans; D008197:Lymph Node Excision / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D016019:Survival Analysis; D016896:Treatment Outcome; D014481:United States