Quitting smoking improves two-year survival after a diagnosis of non-small cell lung cancer

Background: Smoking at diagnosis is associated with worse survival in lung cancer but the effects of quitting smoking on survival remain unclear. Methods: In a UK multi-centre study (NCT01192256) we followed all 2751 patients with newly diagnosed non-small cell lung cancer (NSCLC) for up to 2 years or until death as part of the observational trial. Patients were offered smoking cessation advice and treatments according to national guidelines and local services. Smoking status was verified by exhaled carbon monoxide levels. Kaplan-Meier survival analysis and Cox Proportional Hazards Modelling examined the effects of quitting smoking on survival at 2 years.Findings: 646 were current smokers at the time of diagnosis. The unadjusted two-year Kaplan-Meier survivor functions for quitters (0.45, 95 %CI 0.37 to 0.53) and continuers (0.32, 0.28 to 0.36) were significantly different (log-rank test p < 0.01). Median survival times were 659 days for quitters and 348 days for continuers. After adjusting for age, sex, stage, performance status, curative intent surgery, radical radiotherapy and comorbidity, the hazard ratio for quitting at diagnosis (0.75, 95 % CI 0.58 to 0.98) indicated a statistically significant reduction in the risk of death across the two-year study period.Interpretation: Quitting smoking is independently and significantly associated with improved survival regardless of stage in NSCLC. We recommend that smoking cessation advice and treatments should be offered to smokers with lung cancer.