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Research Article

Increasing risks of ischemic stroke in oral cancer patients treated with radiotherapy or chemotherapy: a nationwide cohort study

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Pages 808-816 | Received 15 Jun 2014, Accepted 15 Sep 2014, Published online: 22 Oct 2014
 

Abstract

Background: Several studies have identified correlations between cancer and increased risks of ischemic stroke (IS), particularly following radiotherapy (RT) or chemotherapy (CT). However, data regarding relative risks of IS in oral cancer are limited. The aim of this study was to compare hazard ratios (HR) of IS among oral cancer patients treated with and without RT, CT, or both (CCRT). Methods: We analyzed data collected by the Taiwan National Health Insurance Research Database (NHIRD) from 1996 to 2009, which covered approximately 99.5% of the medical claims submitted nationally. A total of 21,853 patients diagnosed with oral cancer from 2000 to 2008 were included. The Cox proportional hazard model was used to estimate the HRs of IS among different treatment modalities and a matched cohort. Results: The overall risk of IS was1.24-fold greater in patients treated with RT/CT/CCRT than those treated with surgery alone and 1.08-fold greater for surgery with adjuvant therapy (radiotherapy or chemotherapy after surgery) after adjusting for confounding factors. The incidence of IS was 0.23-fold lower in matched control group than in the oral cancer cohort. In subgroup analysis, patients who received RT/CT/CCRT and aged <40 years old were at a 2.77-fold greater risk for IS than age-matched patients who underwent surgery alone, although this difference decreased with patient age. Conclusions: Oral cancer patients, particularly those aged <40 years, who underwent RT or CT are at increased risks for IS. Other significant risk factors for IS included Charlson comorbidity index (CCI) >1, hypertension, coronary artery disease, and atrial fibrillation.

Acknowledgements/ Disclosure of interests

This study is based in part on data from the National Health insurance Research Database provided by the Bureau of National Health Insurance, Department of Health, Taiwan, and managed by the National Health Research Institutes. The authors thank the help from the Statistical Analysis Laboratory, Department of Internal Medicine, Kaohsiung Medical University Hospital. The authors would like to thank Enago (www.enago.tw) for the English language review.

Declaration of Interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this paper. This study was supported by a grant from the Kaohsiung Medical University Hospital (KMUH102-M222).

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