Risk of ischemic stroke in korean patients with Cancer: Insights from national health insurance data

Objectives: This study aimed to compare the cumulative incidence of ischemic stroke between patients with and without cancer, estimate the hazard ratio of stroke in patients with cancer compared to those without cancer, and compare our results with those of other nationwide studies. Materials and Methods: We recruited 91,424 patients diagnosed with cancer from the Korean National Health Insurance Service database between 2011 and 2015 and enrolled 182,848 controls. These participants were followed up for 5 years. We estimated the hazard ratios for ischemic stroke occurrence in the patient groups for all cancer types and nine specific cancer types during follow-up at 6 months and 1, 3, and 5 years. Results: For all cancer types, except colorectal, gallbladder, bile duct, and head and neck cancers, the slope of the cumulative increase in ischemic stroke in the early period was higher than that in longer follow-up durations. Ischemic stroke risk was elevated after the 6-month follow-up in patients with cancer compared to patients without cancer (95% confidence interval [CI]: 1.56–1.94). Over 3–5 years, Ischemic stroke risk increased in patients with lung (CI: 1.56–2.04), pancreatic (CI: 1.33–1.95), and liver cancers (CI: 1.07–1.39), compared to cancer-free individuals, whereas no significant increase was observed in patients with thyroid (CI: 0.79–1.13), stomach (CI: 0.92–1.17), colorectal (CI: 0.69–1.48), gallbladder (CI: 0.91–9.89), bile duct (CI: 0.39–3.50), and head and neck (CI: 0.26–74.30) cancers. Conclusion: Our findings regarding stomach, colorectal, and liver cancers differ from the results of Western studies. Conducting a nationwide study within each country, rather than applying findings from other countries, is preferable for predicting and preventing ischemic stroke development in patients with cancer when using insurance-based data.