Upgrading your best chances. Postdiagnosis smoking cessation boosts life expectancy of patients with cancer. A systematic review and meta-analysis

Background: Tobacco use is linked to increased cancer risk, and people who smoke represent a large proportion of newly diagnosed patients with cancer. The fact that smoking cessation at the time of diagnosis can improve the patient's life expectancy is still not broadly understood. We conducted a systematic review and meta-analysis to quantify the survival benefits obtainable by quitting smoking on diagnosis. We included articles found in MEDLINE and EMBASE until 2 January 2024. We conducted a random effects meta-analysis, studying correlates of between-studies heterogeneity and exploring the presence of publication bias. There were 36 eligible studies published in 1980-2023, totalling over 17 000 actively smoking patients with cancer. The most studied cancer sites were the lung (n=17) and head and neck (n=14). The median proportion of patients who quit on diagnosis was 42.5%. Postdiagnosis cessation was associated with longer overall survival (summary HR (sHR) 0.71, 95% CI 0.65 to 0.78), progression-free survival (sHR 0.64, 95% CI 0.41 to 0.98), disease-free/recurrence-free survival (sHR 0.59, 95% CI 0.43 to 0.81) and improved local/locoregional control (sHR 0.69, 95% CI 0.50 to 0.94). Heterogeneity was generally large; for overall survival, study results were stronger when properly adjusted but did not vary across cancer sites. There was evidence for publication bias, but the results were only marginally altered on imputation of potentially missing studies. Postdiagnosis smoking cessation is effective in improving the chances of survival for patients with cancer. Cessation support programmes should be integrated into the routine management of patients with cancer as they may favourably affect survival.