Radiotherapy for Nasopharyngeal Carcinoma as a Risk Factor for Extracranial Carotid Stenosis. Is It Also a Risk Factor for Intracranial Arteries? A Retrospective Case-control Study

Objective: Carotid duplex ultrasound has revealed that radiotherapy is associated with stenosis of the extracranial carotid arteries in patients with nasopharyngeal carcinoma (NPC). The objective of the study was to determine the relationship between intracranial and extracranial arterial stenosis and radiation therapy using computed tomographic angiography (CTA) in patients with NPC and a history of symptomatic cerebral ischaemia. Methods: This was a retrospective case-control study conducted in Pok Oi Hospital, Hong Kong. All consecutive CTA scans of the head and neck from January 2008 to December 2009 in patients with a history of transient ischaemic attack or ischaemic stroke were included. Intracranial arterial (including intracranial internal carotid artery, M1 segment of middle cerebral artery, and intracranial vertebral artery) and extracranial arterial stenosis was defined as a diameter reduction of >= 50%. Patient demographics, history of radiotherapy for NPC, smoking history, medical history of diabetes mellitus, hypertension, and hyperlipidaemia were recorded. Results: A total of 152 patients (105 men and 47 women; mean [standard deviation] age, 64.9 [11.6] years) were enroled. Of them, 19 (12.5%) had a history of NPC and treatment by radiotherapy; 133 (87.5%) patients did not receive any head and neck radiotherapy. A statistically significantly increased risk of common carotid artery stenosis (p < 0.001; adjusted odds ratio = 34.510) and extracranial arterial stenosis (p = 0.001; adjusted odds ratio = 6.607) was observed in patients with NPC treated with radiotherapy compared with those without irradiation. Radiotherapy did not increase the risk of intracranial arterial stenosis (10/19 [52.6%] vs. 75/133 [56.4%]; p = 0.710). Conclusion: Radiotherapy for NPC is associated with an increased risk for stenosis of the extracranial arteries, particularly the common carotid artery. Radiotherapy for NPC was not shown to increase the risk of intracranial artery stenosis based on CTA findings in patients with symptomatic cerebral ischaemia.