Predictors of the Extent of Carotid Atherosclerosis in Patients Treated with Radiotherapy for Nasopharyngeal Carcinoma

OBJECTIVE To determine the predictors of the extent of carotid atherosclerosis in patients treated with radiotherapy (RT) for nasopharyngeal carcinoma (NPC). METHODS The present study investigated 129 post-RT NPC patients. Carotid atherosclerotic parameters, such as carotid intima-media thickness, carotid arterial stiffness and carotid plaque burden (plaque score, the presence of plaque and ≥50% stenosis) were assessed using ultrasonography. The association between carotid atherosclerotic parameters and nine potential predictors, including age, gender, post-RT duration, radiation dose, chemotherapy, diabetes mellitus, hypertension, hypercholesterolemia, and smoking, were determined using multiple regression. The cutoff values of age, post-RT duration and number of cardiovascular risk factors for the presence of carotid plaque or ≥50% carotid stenosis were analyzed using receiver operating characteristic (ROC) curve analysis. Multiple testing was corrected using Benjamini-Hochberg false discovery rate. RESULTS Age, post-RT duration and number of cardiovascular risk factors were significantly associated with carotid plaque burden (corrected P value, Pcor<0.05). Age of 44.5 years (sensitivity = 99.2% and specificity = 50%, Pcor<0.01) and post-RT duration of 8.5 years (sensitivity = 75.7% and specificity = 64.3%, Pcor<0.001) were the cutoff values for detecting carotid plaque, while post-RT duration of 13.5 years (sensitivity = 66.7% and specificity = 71.6%, Pcor<0.001) and 1.5 cardiovascular risk factors (sensitivity = 40.7% and specificity = 84.3%, Pcor<0.05) were the cutoff values for screening ≥50% carotid stenosis. CONCLUSIONS Age, post-RT duration and number of cardiovascular risk factors are significant predictors of carotid atherosclerosis in post-RT NPC patients. Post-RT NPC patients, who are at least 45 years old, with post-RT duration of 9 years or above, and/or have ≥2 cardiovascular risk factors, are more susceptible to carotid atherosclerosis.