title: The clinicopathological and survival differences between never and ever smokers with non-small cell lung cancer.
abstract: OBJECTIVE
  Cigarette smoking was regarded as the most important carcinogenic factor of lung cancer, yet in recent years lung cancer in never-smokers is an increasingly prominent public health issue. The aim of this study was to assess the epidemiological and clinicopathological characteristics of never-smoker patients with non small cell lung cancer (NSCLC), focusing on clinical risk factors and survival.
  
  
  METHODS
  We retrospectively analyzed 290 NSCLC patients who presented between 2006 and 2011. Differences in clinical features and survival between never- and ever- smoker patients were analyzed. Student's t-test and Mann-Whitney U-test were used to assess the significance of the variables between the groups. Survival curves were calculated using Kaplan-Meier method. Hazard ratio (HR) for death and its 95% confidence interval (CI) were calculated by Cox regression analysis.
  
  
  RESULTS
  There were 243 (83.8%) ever-smokers and 47 (16.2%) never-smokers. In never-smokers females predominated (80.9%) as well as patients with adenocarcinomas (78.7%). At the time of analysis 143 (49.3%) patients had died. The 5-year overall survival (OS) rates were not significantly different between never- and ever-smokers (p=0.410) . The median OS of all patients was 26 months (95% CI: 16.8-35.2). The median OS was 23 months (95% CI: 11.8- 34.2) for never-smokers and 30 months ∥95% CI: 19.7-40.3) for ever-smokers (p=0.410). Never-smokers tended to present with more advanced disease than ever-smokers (p<0.004) and also with more advanced age (p<0.001). The HR for death increased with poorer Eastern Cooperative Oncology Group ( ECOG ) performance status (PS) (ECOG 2=3), advanced stage (stage 3=4) and untreated patients. Slightly lower risk for death was registered in patients with adenocarcinoma vs those with squamous cell carcinoma (SCC).
  
  
  CONCLUSIONS
  Although no difference in survival was seen, definite epidemiologic differences do exist between never- smokers and ever-smokers patients with NSCLC. Future efforts should focus on the underlying biological differences, and on identifying potential non-tobacco related risk factors in order to improve treatment strategies for these two groups of NSCLC patients.
authors: Baskent University, School of Medicine, Department of Medical Oncology, Adana, Turkey.
authors: Sadik
authors: S
authors: Muallaoglu
authors: Cemile
authors: C
authors: Karadeniz
authors: Huseyin
authors: H
authors: Mertsoylu
authors: Ali
authors: A
authors: Ayberk Besen
authors: Ahmet
authors: A
authors: Sezer
authors: Ali
authors: A
authors: Murat Sedef
authors: Fatih
authors: F
authors: Kose
authors: Ozgur
authors: O
authors: Ozyilkan
mesh_terms: D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000209:etiology* / Q000401:mortality / Q000473:pathology; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000209:etiology* / Q000401:mortality / Q000473:pathology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*