Abstract 4366111: Neck Adiposity Measured on Pre-therapy Oncologic Computed Tomography Scans Predicts the Development of Radiation Therapy-induced Carotid Artery Disease in Patients with Head and Neck Cancer

Background: Bidirectional signaling between arteries and adjacent adipose tissue has been implicated in atherosclerosis progression. Adipose tissue characterization by CT imaging techniques has emerged as a novel risk-predicting tool for future cardiovascular events. This study aimed to evaluate whether neck adiposity at the time of cancer diagnosis is associated with the subsequent development of radiation therapy (RT) induced carotid artery disease (RICAD) in patients with head and neck cancer (HNC). Methods: Patients with HNC treated with RT at a tertiary center between 2005 and 2010 were identified. Oncologic CT scans of the neck performed for RT planning purposes were used to quantify adipose tissue and skeletal muscle mass at the C3 spinal level by SliceOmatic, version 5.0 Tomovision (Figure 1). Adipose tissue and skeletal muscle volumes were indexed to account for height. Fine-Gray competing risk regression models with stepwise forward selection were used to evaluate the association between baseline clinical and imaging characteristics with subsequent development of the composite event of new or worsened carotid atherosclerosis, carotid artery stenosis >50%, transient ischemic attack (TIA) or stroke. Results: Of 231 patients, 91% were male and 97% white, with a mean age of 74 ± 9 years. Prior to RT, 42% had hypertension, 28% dyslipidemia, 12% diabetes, and 3.5% prior stroke/TIA. At a median follow-up of 9.8 years (IQR 10.5), 42% developed new or worsened carotid atherosclerosis, 12% carotid stenosis >50%, and 6% stroke/TIA, while 39% expired. In the multivariable Fine-Gray analysis, neck adipose tissue index was significantly associated with the development of the composite event (HR 1.04 per unit increase, 95% CI 1.01–1.06, p = 0.0015). Baseline use of antiplatelet agents was also associated with the composite event (HR 2.18, 95% CI 1.41–3.36, p = 0.0004) while no significant association was noted with other characteristics such as age, traditional cardiovascular risk factors, prior atherosclerotic disease, statin use, RT dose and skeletal muscle mass. Conclusion: Neck adiposity was associated with RICAD in our cohort of HNC patients with long follow up, supporting the hypothesis of an interplay between inflamed perivascular adiposity and development of carotid artery disease post RT in survivors of HNC. Adipose tissue quantification using SOC oncologic CT scans may assist with patient risk stratification and guide surveillance.