Purpose: 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).
Conclusion: 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.