title: Selection for adjuvant chemotherapy in completely resected stage I non-small cell lung cancer: external validation of a Chinese prognostic risk model.
abstract: BACKGROUND
  The ability to sub-stratify survival within stage I is an important consideration as it is assumed that survival is heterogeneous within this sub-group. Liang et al. recently published a nomogram to predict post-operative survival in patients undergoing lung cancer surgery. The aim of our study is external validation of their published nomogram in a British cohort focusing on stages IA and IB to determine applicability in selection of adjuvant chemotherapy within stage I.
  
  
  METHODS
  Patient variables were extracted and the score individually calculated. Receiver operative characteristics curve (ROC) was calculated and compared with the original derivation cohort and the discriminatory ability was further quantified using survival plots by splitting our (external) validation cohort into three tertiles and Kaplan Meier plots were constructed and individual curves tested using Cox regression analysis on Stata 13 and R 3.1.2 respectively.
  
  
  RESULTS
  A total of 1,238 patients were included for analysis. For all patients from stage IA to IIB the mean (SD) score was 9.95 (4.2). The ROC score comparing patients who died versus those that remained alive was 0.62 (95% CI: 0.58 to 0.67). When divided into prognostic score tertiles, survival discrimination remained evident for the entire cohort, as well as those for stage IA and IB alone. The P value comparing survival between the middle and highest score with baseline (low score) was P=0.031 and P=0.034 respectively.
  
  
  CONCLUSIONS
  Our results of external validation suggested lower survival discrimination than reported by the original group; however discrimination between survival remained evident for stage I.
authors.affiliation: Department of Thoracic Surgery, The Royal Brompton and Harefield Hospitals NHS Trust, London, UK.
authors.forename: Ulas
authors.initials: U
authors.lastname: Kumbasar
authors.affiliation: Department of Thoracic Surgery, The Royal Brompton and Harefield Hospitals NHS Trust, London, UK.
authors.forename: Hilgardt
authors.initials: H
authors.lastname: Raubenheimer
authors.affiliation: Department of Thoracic Surgery, The Royal Brompton and Harefield Hospitals NHS Trust, London, UK.
authors.forename: May
authors.initials: M
authors.lastname: Al Sahaf
authors.affiliation: Department of Thoracic Surgery, The Royal Brompton and Harefield Hospitals NHS Trust, London, UK.
authors.forename: Nizar
authors.initials: N
authors.lastname: Asadi
authors.affiliation: Department of Thoracic Surgery, The Royal Brompton and Harefield Hospitals NHS Trust, London, UK.
authors.forename: Maria Elena
authors.initials: ME
authors.lastname: Cufari
authors.affiliation: Department of Thoracic Surgery, The Royal Brompton and Harefield Hospitals NHS Trust, London, UK.
authors.forename: Chiara
authors.initials: C
authors.lastname: Proli
authors.affiliation: Department of Thoracic Surgery, The Royal Brompton and Harefield Hospitals NHS Trust, London, UK.
authors.forename: Periklis
authors.initials: P
authors.lastname: Perikleous
authors.affiliation: Department of Thoracic Surgery, The Royal Brompton and Harefield Hospitals NHS Trust, London, UK.
authors.forename: Zakiyah
authors.initials: Z
authors.lastname: Niwaz
authors.affiliation: Department of Thoracic Surgery, The Royal Brompton and Harefield Hospitals NHS Trust, London, UK.
authors.forename: Emma
authors.initials: E
authors.lastname: Beddow
authors.affiliation: Department of Thoracic Surgery, The Royal Brompton and Harefield Hospitals NHS Trust, London, UK.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Anikin
authors.affiliation: Department of Thoracic Surgery, The Royal Brompton and Harefield Hospitals NHS Trust, London, UK.
authors.forename: Niall
authors.initials: N
authors.lastname: McGonigle
authors.affiliation: Department of Thoracic Surgery, The Royal Brompton and Harefield Hospitals NHS Trust, London, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Jordan
authors.affiliation: Department of Thoracic Surgery, The Royal Brompton and Harefield Hospitals NHS Trust, London, UK.
authors.forename: George
authors.initials: G
authors.lastname: Ladas
authors.affiliation: Department of Thoracic Surgery, The Royal Brompton and Harefield Hospitals NHS Trust, London, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Dusmet
authors.affiliation: Department of Thoracic Surgery, The Royal Brompton and Harefield Hospitals NHS Trust, London, UK.
authors.forename: Eric
authors.initials: E
authors.lastname: Lim
keywords: Lung cancer; external validation; nomogram