title: Increased Lymph Node Yield Is Associated With Improved Survival in Rectal Cancer Irrespective of Neoadjuvant Treatment: Results From a National Cohort Study.
abstract: BACKGROUND
  It has been proposed that the lymph node yield achieved during rectal cancer resection is associated with survival. It is debated whether a high lymph node yield improves survival, per se, or whether it does so by diminishing the International Union Against Cancer stage drifting effect.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the prognostic implications of the lymph node yield in curative resected rectal cancer.
  
  
  METHODS
  This study was based on data from a prospectively maintained colorectal cancer database.
  
  
  METHODS
  This was a national cohort study.
  
  
  METHODS
  All 6793 patients in Denmark who were diagnosed with International Union Against Cancer stage I to III adenocarcinoma of the rectum and so treated in the period from 2003 to 2011 were included in the analysis.
  
  
  METHODS
  The primary outcome measure was overall survival.
  
  
  RESULTS
  The observed percentages of patients with International Union Against Cancer stage III disease with a lymph node yield less than 12 or 12 or more were 28.1 % and 40.7% (p < 0.0001) in the non-neoadjuvant treatment group and 26.9% and 38.3% (p < 0.0001) in the neoadjuvant treatment group. The 5-year overall survival rates for patients with a lymph node yield <12 or 12 or more were 73.1% and 80.6% in International Union Against Cancer stages I to II (p < 0.0001) and 57.4% and 53.3% in stage III (p < 0.142) in the neoadjuvant treatment group and 70.4% and 79.2% in stages I to II (p < 0.0001) and 46.6% and 59.1% in International Union Against Cancer stage III (p < 0.0001) in the non-neoadjuvant treatment group. In multivariate analysis, the lymph node yield turned out to be an independent prognostic factor, irrespective of neoadjuvant treatment.
  
  
  CONCLUSIONS
  It is not possible in an observational study to tell whether the findings are associations rather than causal relationships.
  
  
  CONCLUSIONS
  Increased lymph node yield was associated with better overall survival in rectal cancer, irrespective of neoadjuvant treatment. Stage migration was observed.
authors.affiliation: 1 Department of Surgery, Herlev Hospital, University of Copenhagen, Herlev, Denmark 2 Department of Surgery, Roskilde Hospital, University of Copenhagen, Roskilde, Denmark.
authors.forename: Jakob
authors.initials: J
authors.lastname: Lykke
authors.forename: Per
authors.initials: P
authors.lastname: Jess
authors.forename: Ole
authors.initials: O
authors.lastname: Roikjaer
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003718:Denmark; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology / Q000601:surgery*; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D012007:Rectum / Q000473:pathology / Q000601:surgery*; D015996:Survival Rate; D016896:Treatment Outcome