Smoking behavior changes and risk of cardiovascular diseases after cancer diagnosis: a nationwide cohort study

Purpose: D ue to advances in cancer detection and treatment and decreasing cancer-specific mortality rates, cancer survivors are increasing. However, they are at increased risk of cardiovascular diseases (CVDs). We investigated the association between changes in smoking behavior and specific CVD outcomes in cancer survivors. Methods: This retrospective cohort study included patients diagnosed with cancer between 2010 and 2016 who received health examinations before and after cancer diagnosis. Smoking behavior changes were defined as sustained non-smokers, quitters, initiators/relapsers, and sustained smokers. Cancer survivors were followed until 2019 for incident myocardial infarction (MI), ischemic stroke (IS), heart failure (HF), and atrial fibrillation (AF). Results: Among 269,917 cancer survivors (45.6% male; mean age [SD], 56.3 [12.1] years) followed for a mean 4.1 years, 2699 MI, 3089 IS, 9326 HF, and 2444 AF events occurred. The adjusted hazard ratios (aHRs) and 95% CIs of MI, IS, HF, and AF were 1.64 (1.44–1.88), 1.61 (1.43–1.83), 1.55 (1.44–1.67), and 1.22 (1.05–1.41) in sustained smokers compared with sustained non-smokers and were higher than quitters (aHR [95% CI], 1.22 [1.07–1.38], 1.22 [1.09–1.37], 1.26 [1.18–1.34], 1.05 [0.92–1.20], respectively) and initiators/relapsers (aHR [95% CI], 1.53 [1.14–2.05], 1.29 [0.97–1.73], 1.28 [1.07–1.52], 1.04 [0.73–1.47], respectively). Conclusion: Smoking cessation after cancer diagnosis was associated with lower risk of MI, IS, HF, and AF compared to sustained smokers. Smoking cessation should be emphasized throughout the cancer care trajectory, especially at the period of cancer diagnosis to reduce risk of adverse cardiovascular events.