title: Validation of the lymph node ratio as a prognostic factor in patients with N1 nonsmall cell lung cancer.
abstract: BACKGROUND
  The number of positive lymph nodes (LNs) has been proposed as a prognostic indicator in N1 nonsmall cell lung cancer (NSCLC). However, the number of positive LNs is confounded by the number of LNs resected during surgery. The lymph node ratio (LNR) (the ratio of the number of positive LNs divided by the number of LNs resected) can circumvent this limitation. The prognostic significance of the LNR has been demonstrated in elderly patients with NSCLC. The objective of the current study was to evaluate whether a higher LNR is a marker of worse survival in patients with NSCLC aged ≤65 years who have N1 disease.
  
  
  METHODS
  The Surveillance, Epidemiology, and End Results database was used to identify 4004 patients who underwent resection for N1 NSCLC. Patients were classified into 3 groups according to LNR (≤0.15, 0.16-0.5, and >0.5). Associations of the LNR with lung cancer-specific and overall mortality were evaluated using the Kaplan-Meier method. Stratified and Cox regression analyses were used to assess correlations between the LNR and survival after adjusting for other prognostic factors.
  
  
  RESULTS
  Unadjusted analysis indicated that a higher LNR was associated with worse lung cancer-specific survival (P < .0001) and overall survival (P < .0001). Stratified and multivariate analyses also indicated that the LNR was an independent predictor of survival after controlling for potential confounders.
  
  
  CONCLUSIONS
  The current results confirmed that the LNR is an independent prognostic factor for survival in patients with N1 NSCLC. This information may be used to identify patients who are at greater risk of cancer recurrence.
authors: University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, USA.
authors: Sirisha
authors: S
authors: Jonnalagadda
authors: Jacqueline
authors: J
authors: Arcinega
authors: Cardinale
authors: C
authors: Smith
authors: Juan P
authors: JP
authors: Wisnivesky
mesh_terms: D000328:Adult; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000208:ethnology / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms / Q000208:ethnology / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology* / Q000601:surgery; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D018426:SEER Program; D014481:United States / Q000453:epidemiology