title: Validation of the prognostic value of lymph node ratio in patients with cutaneous melanoma: a population-based study of 8,177 cases.
abstract: BACKGROUND
  The proportion of positive among examined lymph nodes (lymph node ratio [LNR]) has been recently proposed as an useful and easy-to-calculate prognostic factor for patients with cutaneous melanoma. However, its independence from the standard prognostic system TNM has not been formally proven in a large series of patients.
  
  
  METHODS
  Patients with histologically proven cutaneous melanoma were identified from the Surveillance Epidemiology End Results database. Disease-specific survival was the clinical outcome of interest. The prognostic ability of conventional factors and LNR was assessed by multivariable survival analysis using the Cox regression model.
  
  
  RESULTS
  Eligible patients (n = 8,177) were diagnosed with melanoma between 1998 and 2006. Among lymph node-positive cases (n = 3,872), most LNR values ranged from 1% to 10% (n = 2,187). In the whole series (≥5 lymph nodes examined) LNR significantly contributed to the Cox model independently of the TNM effect on survival (hazard ratio, 1.28; 95% confidence interval, 1.23-1.32; P < .0001). On subgroup analysis, the significant and independent prognostic value of LNR was confirmed both in patients with ≥10 lymph nodes examined (n = 4,381) and in those with TNM stage III disease (n = 3,658). In all cases, LNR increased the prognostic accuracy of the survival model.
  
  
  CONCLUSIONS
  In this large series of patients, the LNR independently predicted disease-specific survival, improving the prognostic accuracy of the TNM system. Accordingly, the LNR should be taken into account for the stratification of patients' risk, both in clinical and research settings.
authors.affiliation: Clinica Chirurgica Generale, Department of Oncological and Surgical Sciences, University of Padova, Padova, Italy. simone.mocellin@unipd.it
authors.forename: Simone
authors.initials: S
authors.lastname: Mocellin
authors.forename: Sandro
authors.initials: S
authors.lastname: Pasquali
authors.forename: Carlo Riccardo
authors.initials: CR
authors.lastname: Rossi
authors.forename: Donato
authors.initials: D
authors.lastname: Nitti
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis / Q000473:pathology*; D008297:Male; D008545:Melanoma / Q000473:pathology* / Q000556:secondary* / Q000601:surgery; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods / Q000706:statistics & numerical data; D011379:Prognosis; D016016:Proportional Hazards Models; D018426:SEER Program / Q000706:statistics & numerical data; D012878:Skin Neoplasms / Q000473:pathology* / Q000601:surgery