Effect of smoking on survival from non-small cell lung cancer.

Abstract

1570 Background: Although a well-established risk factor for lung cancer, the impact of smoking on the survival of non-small cell lung cancer (NSCLC) is not well-known. This study evaluated the effects of tobacco exposure on outcomes from NSCLC. Methods: We performed a retrospective analysis of Veteran’s Affairs Comprehensive Cancer Registry of NSCLC patients diagnosed between 1995 and 2009. Data abstracted included age, gender, family history, stage at diagnosis, histology, tumor grade, smoking history, other exposures, treatment received and overall survival (OS). Smoking status was categorized as never-smoker, past-smoker and current-smoker based on the self-reported history at diagnosis. Multivariate analysis was performed using SAS version 10.2. Results: The study population (n=61,440) comprised predominantly of males (98%), of which Caucasians (81%) formed the majority. The median age at diagnosis within this cohort was 68 years (range: 22-108 years) and median follow-up was 6 months (range: <1 – 161 months). Squamous cell carcinoma (35%) and adenocarcinoma (30%) were the most common histologies. The majority (71%) presented with stage III or IV disease. Positive family history was identified in one-third. Current smokers were diagnosed with NSCLC at a younger age (65 yrs) compared to never-smokers (71 yrs) and past-smokers (72 yrs) (p<0.001). After adjusting for age at diagnosis, grade, histology, family history and treatment, current-smokers (n=34613) [Hazard ratio (HR) 1.059; 95% CI, 1.012-1.108], but not past-smokers (n=23864) (HR 1.008; 95% CI, 0.962-1.056), had worse OS for Stage III and IV NSCLC, compared to never-smokers (n=2963). Smoking status was not prognostic in stage I and II NSCLC. Conclusions: Current smokers were 6 years younger than never-smokers at diagnosis of NSCLC. Although current smoking was associated with worse prognosis, especially in stages III and IV, the impact of smoking status on OS was modest, at least in males. Therefore, primary prevention of smoking cessation is more likely to be meaningful than efforts on smoking cessation after the diagnosis of NSCLC.