The objectives of this study were to evaluate survival among current smokers, former smokers, and never smokers who are diagnosed with non-small cell lung cancer (NSCLC).
The study included patients who participated in the National Comprehensive Cancer Network's NSCLC Database Project. Current, former, and never smokers were compared with respect to overall survival by fitting Cox regression models.
Data from 4200 patients were examined, including 618 never smokers, 1483 current smokers, 380 former smokers who quit 1 to 12 months before diagnosis, and 1719 former smokers who quit >12 months before diagnosis. Among patients with stage I, II, and III disease, only never smokers had better survival than current smokers (hazard ratio, 0.47 [95% confidence interval, 0.26-0.85] vs 0.51 [95% confidence interval, 0.38-0.68], respectively). Among patients with stage IV disease, the impact of smoking depended on age: Among younger patients (aged ≤55 years), being a never smoker and a former smoker for ≥12 months increased survival. After age 85 years, smoking status did not have a significant impact on overall survival.
Patients who were smoking at the time of diagnosis had worse survival compared with never smokers. Among younger patients with stage IV disease, current smokers also had worse survival compared with former smokers who quit >12 months before diagnosis. It is likely that tumor biology plays a major role in the differences observed; however, to improve survival, it is prudent to encourage all smokers to quit smoking if they are diagnosed with NSCLC.