Abstract
BACKGROUND: Although evidence-based tobacco cessation treatments are recommended for all patients with cancer who smoke, they are often underutilized in routine oncology care due to time and resource constraints and limited understanding of the impact of smoking cessation on long-term outcomes in patients with advanced-stage cancer. This study aimed to evaluate the association between smoking cessation and overall survival (OS) in cancer survivors who smoke, across all disease stages. METHODS: We conducted an observational cohort study of 13,282 patients diagnosed with cancer who were evaluated in our outpatient oncology clinics between June and December 2018. Patients who smoked were prospectively followed to evaluate smoking cessation rates over the following 6 months. We assessed the impact of index-visit smoking status and smoking cessation within 6 months on 2-year OS using multivariable Cox proportional hazards models and the Kaplan-Meier method. RESULTS: Compared with patients who never smoked (n=6,568; 49.5%), those who reported currently smoking (n=1,725; 13.0%) (adjusted hazard ratio for death [aHR], 1.35; CI, 1.20-1.53) or having previously smoked (n=4,989; 37.6%) (aHR, 1.13; CI, 1.03-1.25) at their index visit had increased risk of all-cause mortality. Only 22.1% (n=381) of patients who reported currently smoking at their index visit quit smoking within 6 months. In multivariable analyses, patients who continued to smoke had a higher risk of all-cause mortality (aHR, 1.97; CI, 1.53-2.55) compared with those who had quit smoking. Subgroup analyses by cancer stage revealed an association between continued smoking and all-cause mortality in patients with advanced-stage (III or IV) cancer (aHR, 2.11; 95% CI, 1.60-2.79). CONCLUSIONS: Postdiagnosis smoking cessation is associated with improved OS in cancer survivors, including those with advanced-stage cancer. Smoking cessation support should be provided to all cancer survivors who smoke, irrespective of cancer type or stage. Promoting smoking cessation in oncology care settings via systematic implementation efforts may aid in reducing smoking and mortality rates.