Impact of Quitting Smoking at Diagnosis on Overall Survival in Lung Cancer Patients: A Comprehensive Meta-Analysis

Abstract

Background: Smoking cessation has been associated with reduced lung cancer mortality. This study aimed to synthesize current evidence on the impact of quitting smoking at or around the time of diagnosis of lung cancer on survival, considering factors such as histological subtype, cancer stage, and cessation intervention. Methods: A systematic search was conducted in the Ovid-MEDLINE, Ovid-EMBASE, Cochrane Central Register of Controlled Trials, and KoreaMed databases up to September 2024. Randomized controlled trials and cohort studies enrolling adult current smokers with pathologically confirmed lung cancer and comparing smoking cessation at or around diagnosis with continued smoking, were included. The primary outcome was overall survival (minimum follow-up of 3 months). The included studies were critically appraised using the revised Risk of Bias for Nonrandomized Studies (RoBANS 2) tool and meta-analyzed. Results: A total of 25 cohort studies comprising 17,584 patients were reviewed. Quitting smoking at diagnosis was associated with a 26% reduction in mortality risk (adjusted HR [aHR] 0.74, 95% CI 0.68-0.81). In subgroup analyses, quitting smoking was associated with improved survival in both non-small cell lung cancer (aHR 0.73, 95% CI 0.64-0.83) and small cell lung cancer (aHR 0.61, 95% CI 0.51-0.72), with a more pronounced benefit among patients with early-stage disease (stage I-III or limited stage; aHR 0.64, 95% CI 0.56-0.74). Furthermore, active smoking cessation interventions were significantly associated with improved survival (aHR 0.55, 95% CI 0.35-0.88). Conclusions: The findings underscore the importance of encouraging smoking cessation at the time of lung cancer diagnosis as an integral part of patient management to improve survival outcomes.