ESTRO 2023 - Abstract Book

S303

Sunday 14 May 2023

ESTRO 2023

Conclusion A significant difference in baseline and one-year follow-up cognitive scores was found between brain and HN patients. The mean brain dose, treatment location, sex and age were associated with cognitive performance after RT. Future research includes adding baseline WHO performance status, tumor type and more dose parameters on this dataset. PD-0402 TOAST Classification of Ischemic Stroke in NPC Post-Radiotherapy: A Nationwide Cohort Study T. Lin 1,3 , C. Lin 2,4,5 , Y. Lai 1 1 China Medical University Hospital, Department of Radiation Oncology, Taichung, Taiwan; 2 China Medical University Hospital, Department of Neurology, Taichung, Taiwan; 3 China Medical University, Graduate Institute of Biomedical Sciences, Taichung, Taiwan; 4 China Medical University Hospital, Management Office for Health Data, Taichung, Taiwan; 5 China Medical University, College of Medicine, Taichung, Taiwan Purpose or Objective The standard treatment of nasopharyngeal carcinoma (NPC) is definitive radiotherapy (RT) with or without chemotherapy. Radiotherapy to the neck is known to cause ischemic stroke, and the underlying cause of RT-induced stroke is generally accepted as post-irradiation vasculopathy, leading to arterial stenosis and plaque formation. Although the associated risk factors of ischemic stroke in head and neck cancer have been frequently discussed in multiple studies, the pattern and type of post-RT stroke is rarely examined. The prognosis and outcome of ischemic stroke is strongly linked to its etiology, and patients receive treatment based on their individual ischemic stroke mechanism. According to Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification, ischemic stroke can be classified into five categories based on its etiology: large-artery atherosclerosis, small vessel occlusion, cardioembolism, stroke of other determined etiology, and stroke of undetermined etiology. In this study, we report the TOAST classification of ischemic stroke in NPC patients by combining the multicenter cancer registry database and the stroke registry database in Taiwan. By analyzing the nationwide databases, we provide the real- world data of stroke characteristics in post-RT NPC patients. Materials and Methods We included patients with stroke from the Taiwan Stroke Registry (TSR) from 2006 to 2018. Patients with a previous diagnosis of NPC (ICD-9-CM 147; ICD-10-CM C11) were identified from the National Health Insurance Research Database (NHIRD). The NHIRD and TSR databases were linked by encrypted and unique personal identification numbers. We therefore identified stroke patients with a history of NPC as our study cohort and further established a comparison cohort comprising stroke patients without NPC. Figure 1. Flow diagram of study cohort design