Characterization of never-smoking and its association with clinical outcomes in Chinese patients with small-cell lung cancer

Objectives: Small-cell lung cancer (SCLC) has been viewed as a smoking-related disease, with only 2% to 5% patients being never-smokers. This study aimed to investigate the clinical characteristics of never-smoking and its association with treatment outcomes in Chinese SCLC patients in real world.

Methods: We performed a retrospective study of 303 patients with SCLC and grouped into smokers and never-smokers. The clinical characteristics and treatment outcomes of two groups were collected and compared.

Results: In total, 113 patients with limited-stage (LS) SCLC and 190 patients with extensive-stage (ES) SCLC were enrolled. Sixty-nine (22.8%) patients were never-smokers. Both the median progression-free survival (PFS) and overall survival (OS) were significantly longer in never-smokers than in smokers (PFS, 8.37 vs. 7.10 months, P=0.036; OS, 19.73 vs. 14.40 months, P=0.044) in all populations. Multivariate analysis suggested that never-smoking was a significant favorable prognostic factor for PFS (HR=0.753; P=0.047) instead of OS (HR=0.780; P=0.236) in patients with SCLC. The objective response rate (ORR) to first-line therapy were similar between two group (52.6% vs. 59.4%, P=0.315). Moreover, prophylactic cranial irradiation (PCI) resulted in marginally significantly longer PFS than observation in patients with ES-SCLC who obtained objective response after first-line therapy (10.57 vs. 7.73 months, P=0.075).

Conclusion: The current study indicated that never-smokers are increasingly prevalent in Chinese patients with SCLC. Never-smokers with SCLC had significantly longer PFS and OS compared with smokers, and smoking was an independent poor prognostic factor for PFS in patients with SCLC.