Observations on Carotid Artery Stenosis Following Neck Irradiation

Purpose/Objective(s) Carotid artery stenosis (CAS) is a known potential late effect of neck radiation. There are varying estimates of its incidence and mixed consensus on whether screening for this late effect standard practice should be. As treatment techniques have evolved and the presence of HPV has increased, the impact on the future trajectory of this problem is unclear. Materials/Methods A sample of head and neck cancer (HNC) patients treated from 1997 through 2022 who underwent carotid ultrasound (US) at any time after receiving radiation therapy to the neck were identified from an IRB-approved, single institution database. Patient treatment characteristics including radiation laterality, co-morbidities at consult, and smoking history were coded in addition to carotid US dates and results. CAS was defined as >40% stenosis of either side of the vessel, which prompted a vascular surgery consult. Results A total of 308 patients were included in this study with an average follow up of 70 months (range: 3.3-255.9 months). All included patients received bilateral neck radiation and had no evidence of disease at their last follow up. Most patients received definitive, concurrent chemoradiation (96.4%), were male (85.1%) and had a primary oropharyngeal tumor (64%). The most common co-morbidity at time of consult was hypertension (HTN, 45.8%). Median time to CAS was 10.7 years. The five- and ten-year rates of CAS were 15.4% and 39.6%, respectively. On Cox regression univariate analysis age at consult (HR=1.054, 95% CI= 0.649-1.941, p<0.001), having known HTN (HR=2.551, 95% CI=1.610-4.032, p<0.0001), hyperlipidemia (HR=1.658, 95% CI= 1.066-2.584, p=0.0248), diabetes (HR=2.398, 95% CI=1.397-4.115, p=0.0015), or cardiac disease (HR=2.283, 95% CI=1.333-3.922, p=0.0026) at time of consult, and being an ever smoker (HR=2.336, 95% CI=1.403-3.891, p=0.0011) were statistically predictive of CAS. On multivariate analysis, patients who were older (HR=1.037, 95% CI=1.008-1.068, p=0.0122), were an ever smoker (HR=2.375, 95% CI=1.425-3.968, p=0.0009), and having known hypertension (HR=2.037, 95% CI=1.235-3.356, 0.0053) at consult were at highest risk for CAS. Conclusion CAS was frequently detected five and ten years after head and neck radiation. Carotid artery US screening should be strongly considered in these patients, especially older patients with a history of smoking and/or HTN. Future prospective studies are warranted to verify this finding.