title: Implications of Lymph Node Staging on Selection of Adjuvant Therapy for Gastric Cancer in the United States: A Propensity Score-matched Analysis.
abstract: OBJECTIVE
  To compare the efficacy of adjuvant chemoradiotherapy (CRT) and chemotherapy alone (CA) in gastric adenocarcinoma patients undergoing gastrectomy in the United States (US).
  
  
  BACKGROUND
  A majority of US gastric adenocarcinoma patients are inadequately staged (<15 nodes examined). Despite this, and limited data comparing adjuvant CRT with CA in US patients, national guidelines endorse CA in selected patients undergoing D2 lymphadenectomy.
  
  
  METHODS
  Resected stage IB-III gastric adenocarcinoma patients receiving adjuvant CRT or CA (n = 3008) were identified in the National Cancer Database (1998-2006). Cox regression identified covariates associated with overall survival (OS). CRT and CA cohorts were matched (3:1) by propensity scores based on the likelihood of receiving CA. OS was compared by Kaplan-Meier estimates.
  
  
  RESULTS
  Adjuvant CA was associated with an increased risk of death (HR 1.29, P < 0.001) relative to CRT. Inadequate lymph node staging (LNS) and nodal positivity were strong predictors of risk-adjusted mortality (P < 0.001). After propensity score-matching, CRT demonstrated superior median OS compared with CA (36.1 vs 28.9 m; P < 0.0001), regardless of stage. CRT was superior to CA in inadequately staged patients (33.1 m vs 24.5 m; P < 0.001); this benefit was less pronounced with increasing nodal examination. CRT improved OS in node-positive disease (29.8 vs 22.2 m; P < 0.001), regardless of LNS adequacy. In node-negative disease, OS did not differ significantly between CRT and CA cohorts; however, node-negative patients undergoing inadequate LNS benefited from CRT.
  
  
  CONCLUSIONS
  CRT is associated with improved stage-stratified OS compared with CA. Lymph node status and adequacy of surgical staging should influence adjuvant therapy selection in the United States.
authors.affiliation: *Department of Surgery, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA †Division of Hematology/Oncology, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA ‡Department of Radiation Oncology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA.
authors.forename: Jashodeep
authors.initials: J
authors.lastname: Datta
authors.forename: Matthew T
authors.initials: MT
authors.lastname: McMillan
authors.forename: Brett L
authors.initials: BL
authors.lastname: Ecker
authors.forename: Giorgos C
authors.initials: GC
authors.lastname: Karakousis
authors.forename: Ronac
authors.initials: R
authors.lastname: Mamtani
authors.forename: John P
authors.initials: JP
authors.lastname: Plastaras
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Giantonio
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Drebin
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Dempsey
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Fraker
authors.forename: Robert E
authors.initials: RE
authors.lastname: Roses
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology / Q000601:surgery / Q000628:therapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059186:Chemoradiotherapy, Adjuvant; D017024:Chemotherapy, Adjuvant; D005260:Female; D005500:Follow-Up Studies; D005743:Gastrectomy; D006801:Humans; D008197:Lymph Node Excision; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D057216:Propensity Score; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000401:mortality / Q000473:pathology / Q000601:surgery / Q000628:therapy*; D016019:Survival Analysis; D016896:Treatment Outcome; D014481:United States