Aetiological factors and imaging program for severe radiation-induced extracranial carotid stenosis in nasopharyngeal carcinoma

Over a period of 3 years, we have collected the carotid ultrasound findings of 189 post-radiotherapy (RT) nasopharyngeal carcinoma patients. The patients had duplex ultrasound examination for assessment of extracranial carotid stenosis. Factors including age, sex, hyperlipidaemia, diabetes mellitus, smoking history, time lapsed after RT, symptoms of cerebrovascular disease were recorded. Association of individual factor with development of severe stenosis was assessed. Eighty-two (43%) patients developed moderate to severe stenosis of the common carotid and/or internal carotid artery. Age and time lapsed after RT were the only factors found to be associated with development of severe stenosis. When age >57 years and >12 years post-RT were used as rules to identify patients with severe stenosis, the sensitivity was 46.7%, specificity 98.2%, PPV 77.8% and NPV 95.6%. Radiation-induced carotid stenosis is a common event. If available resources do not allow routine surveillance, age and time lapsed after RT help to identify high-risk patients.