Chemoradiotherapy-related carotid artery inflammation in head and neck cancer patients quantified by [18F]FDG PET/CT

Abstract Objectives Radiotherapy (RT) is associated with an increased risk of cardiovascular disease (CVD), but little is known about the mechanism for vascular injury and methods for early detection. Materials and methods We conducted a prospective, pilot study of carotid artery inflammation using 18 F-labeled 2-fluoro-2-deoxy- d -glucose ([ 18 F]FDG) PET/CT imaging pre- and 3 months post-RT in head-and-neck cancer (HNC) patients. [ 18 F]FDG uptake by the carotid arteries was measured by the maximum and mean target to background ratio (TBR MAX , TBR MEAN ) and the mean partial volume corrected standardized uptake value (pvcSUV MEAN ). Results Of the 22 patients who completed both pre and post-RT scans, the majority (82%) had stage III or stage IV disease and received concurrent chemotherapy. TBR MAX , TBR MEAN , and pvcSUV MEAN were all significantly higher 3 months after RT versus before RT with mean difference values (95% CI; p -value) of 0.17 (0.1–0.25; 0.0001), 0.19 (0.12–0.25; 0.0001), and 0.31 g/ml (0.12–0.5; 0.002), respectively. Fifteen patients (68%) had HPV-positive tumors, which were associated with lower pre-RT [ 18 F]FDG signal, but a greater increase in TBR MAX (19% vs 5%), TBR MEAN (21% vs 11%) and pvcSUV MEAN (20% increase vs 3% decrease), compared to HPV negativity. Conclusion There is a significant increase in carotid artery inflammation in HNC patients due to CRT that amounts to a degree that has previously been associated with higher risk for future CVD events. The subset of patients with HPV-positive tumors experienced the greatest increases in vascular inflammation due to CRT. Carotid [ 18 F]FDG uptake may be an early biomarker of RT-related vascular injury.