Difference in survival and prognostic factors between smokers and never-smokers with advanced non-small-cell lung cancer

Abstract

Our aims were to investigate whether the association between smoking and survival is significant when adjusted for prognostic factors including use of epidermal growth factor tyrosine kinase inhibitors and the Glasgow Prognostic Score, an established score for inflammation, and to explore prognostic factors. We analyzed 244 patients with stage IIIB or IV non-small-cell lung cancer in a registry, including only chemotherapy-receiving outpatients with performance status zero. Of 244 patients, 170 had died and the median follow-up time for the 74 surviving patients was 12.0 months. In multivariate Cox regression, smoker (hazard ratio compared to never-smoker: 1.67, P < 0.01), stage IV (hazard ratio compared to IIIB: 1.72, P < 0.01), and elevated C-reactive protein level (hazard ratio per 1 mg/dL increase: 1.08, P < 0.01) were significantly associated with shorter survival. The association between survival and smoking was significant, even after adjustment for the Glasgow Prognostic Score and regimens of chemotherapy (hazard ratio: 1.72, P = 0.02). In never-smokers, increased neutrophils were a major determinant of shorter survival and the interaction test between smoking and neutrophils was significant (hazard ratio per 1,000/mm(3) increase for smokers: 1.01; hazard ratio per 1,000/mm(3) increase for never-smokers: 1.44, P for interaction <0.01). Known factors including treatment response or inflammatory process are not responsible for the fact that advanced non-small-cell lung cancer patients without any history of smoking have better survival than those who have smoked.