title: Smoking and prognostic factors in an observational setting in patients with advanced non-small cell lung carcinoma.
abstract: BACKGROUND
  This prospective observational study estimated the effect of prognostic factors, particularly continued smoking during therapy, on survival in advanced non-small cell lung cancer (NSCLC) patients receiving gemcitabine-platinum. Further, prognostic factors were used to build a survival model to improve prognosis prediction in naturalistic clinical settings.
  
  
  METHODS
  Eligibility criteria included: Stage IIIB/IV NSCLC, no prior chemotherapy, and Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1. A Cox regression model was constructed and validated by randomizing patients into two datasets (Construction [C]:Validation [V]; 3:1 ratio). Country, disease stage, hypercalcemia, "N" factor, weight reduction, performance status, and superior vena cava obstruction were pre-defined variables forced into the model. Continued smoking was tested with adjustment for these variables.
  
  
  RESULTS
  One thousand two hundred and fourteen patients (C=891 and V=323) were enrolled. The final predictive model, established in the Construction dataset, identified four significant (p≤0.05) and independent predictors of survival, which were disease stage, performance status, gemcitabine-platinum regimen, and T-stage. Smoking during therapy was not significantly associated with survival (Hazard Ratio [95% CI]: 0.955 [0.572, 1.596], p=0.8618; versus never smokers).
  
  
  CONCLUSIONS
  Although continued smoking during therapy was not significantly associated with shorter survival, the model developed in this study forms an evidence-based approach to assessing prognosis in advanced stage NSCLC.
authors.affiliation: 1. Chest Department, Changhua Christian Hospital, Changhua City, and the Institute of Medical and Molecular Toxicology, Chung Shan Medical University, Taichung City, Taiwan.
authors.forename: Chien-Te
authors.initials: CT
authors.lastname: Li
authors.forename: Magdalena
authors.initials: M
authors.lastname: Marek
authors.forename: Salih Z
authors.initials: SZ
authors.lastname: Guclu
authors.forename: Younseup
authors.initials: Y
authors.lastname: Kim
authors.forename: Mohamed
authors.initials: M
authors.lastname: Meshref
authors.forename: Shukui
authors.initials: S
authors.lastname: Qin
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Kadziola
authors.forename: Kurt
authors.initials: K
authors.lastname: Krejcy
authors.forename: Sedat
authors.initials: S
authors.lastname: Altug