Objectives: We sought to examine changes over time in the proportion of never smokers among surgical lung cancer patients and to determine whether smoking history affected survival.
Methods: We performed a retrospective review of a prospective database. Among never smokers and smokers, demographic and pathological data were compared. Disease-free survival (DFS) and cancer-specific survival (CSS) were analysed. Propensity matching was performed for further comparison of survival in a matched cohort.
Results: Among 3232 patients, we identified 718 never smokers (22%), 993 smokers with <30 pack history (31%) and 1521 smokers with ≥30 pack history (47%). The proportion of never smokers increased over time, comprising 26.6% of the cohort after 2007 compared with 16.1% prior thereto (P ≤ 0.001). Never smokers were younger, more likely to be women and Asian, more frequently had adenocarcinoma and lower lobe tumours and were more likely to have pStage I disease. In pStage-matched cohorts, there were no differences in DFS or CSS. Similarly, in propensity-matched groups (498 patients each), there was no difference in 5-year DFS (66% vs 67%, P = 0.661) or in CSS (84% vs 81%, P = 0.350). On univariate analysis of the matched cohort, never smoking status had no effect on DFS (hazard ratio 1.05, P = 0.661) or CSS (hazard ratio 1.16, P = 0.350).
Conclusions: The proportion of never smokers undergoing resections for lung cancer is increasing. Never smokers have distinct demographic patterns and tend to be younger women with adenocarcinoma. Despite these differences, stage and propensity-matched never smokers have the same survival as smokers and remain at equal risk for recurrence and death.