Quitting Smoking At or Around Diagnosis Improves the Overall Survival of Lung Cancer Patients: A Systematic Review and Meta-Analysis

Abstract

Introduction: Lung cancer (LC) remains a disease with poor prognosis despite recent advances in treatments. Here, we aimed at summarizing the current scientific evidence on whether quitting smoking at or around diagnosis has a beneficial effect on the survival of LC patients.

Methods: We searched MEDLINE and EMBASE for articles published until 31^st October, 2021, that quantified the impact on LC patients' survival of quitting smoking at or around diagnosis or during treatment. Study-specific data were pooled into summary relative risk (SRR) and corresponding 95% confidence intervals (CI) using random effect meta-analysis models.

Results: Twenty-one articles published between 1980 and 2021 were included, which encompassed a total of over 10,000 LC patients. There was substantial variability across studies in terms of design, patients' characteristics, treatments received, criteria used to define smoking status (quitters or continued), and duration of follow-up. Quitting smoking at or around diagnosis was significantly associated with improved overall survival (SRR 0.71, 95% CI 0.64-0.80), consistently among patients with non-small cell LC (SRR 0.77, 95% CI 0.66-0.90, n studies = 8), small cell LC (SRR 0.75, 95% CI 0.57-0.99, n studies = 4), or LC of both or unspecified histological type (SRR 0.81, 95% CI 0.68-0.96, n studies = 6).

Conclusions: Quitting smoking at or around diagnosis is associated with a beneficial effect on the survival of LC patients. Treating physicians should educate LC patients about the benefits of quitting smoking even after diagnosis and provide them with the necessary smoking cessation support.

Keywords: Lung cancer; Meta-analysis; Smoking cessation; Survival; Systematic review.