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, P(cor)<0.05). Age of 44.5 years (sensitivity = 99.2% and specificity = 50%, P(cor)<0.01) and post-RT duration of 8.5 years (sensitivity = 75.7% and specificity = 64.3%, P(cor)<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%, P(cor)<0.001) and 1.5 cardiovascular risk factors (sensitivity = 40.7% and specificity = 84.3%, P(cor)<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.