Biphasic Progression of Radiation-Induced Carotid Stenosis: The Predictive Role of Low-Density Plaque

Radiation therapy (RT), a primary treatment for head and neck cancer (HNC), increases the risk of radiation-induced carotid stenosis (RICS). This study examines the progression of carotid artery total occlusion (CATO) in patients with HNC after RT, focusing on low-density plaque (LDP) as a predictor, an aspect underexplored in prior research.

A retrospective cohort study assessed 44 patients with HNC who underwent RT, using 2021 follow-up data. Carotid stenosis progression was quantified via CT scans before and after LDP detection. Patients with irregular follow-up or RT within 2 years, insufficient for long-term evaluation, were excluded.

CATO occurred in 11 patients (25%) and 12 vessels (14.3%), with a median onset of 12.6 years (interquartile range [IQR], 7.6-22.5) after RT. The stenosis progression rate increased significantly from 0.00%/year (IQR, 0.0%-1.0%) before LDP detection to 4.7%/year (IQR, 3.4%-8.1%) afterward (P < .001), with a marked acceleration to 14.8%/year (IQR, 9.6%-24.0%) in the CATO group. Neither calcification nor age at RT was significantly associated with CATO, reinforcing LDP as a critical high-risk marker.

This study identifies LDP as a critical predictor of accelerated RICS, proposing a novel biphasic progression model with a slow phase before LDP detection and a rapid phase thereafter. Calcification showed no significant association with RICS progression. These findings support intensified surveillance, such as annual CT scans, and timely interventions to prevent occlusion in high-risk patients.