Ultrasound Evaluation of Carotid Atherosclerosis in Post-Radiotherapy Nasopharyngeal Carcinoma Patients, Type 2 Diabetics, and Healthy Controls.

 To comprehensively evaluate and compare the degree of carotid atherosclerosis in patients treated with radiotherapy (RT) for nasopharyngeal carcinoma (NPC) and in patients with type 2 diabetes mellitus (DM), and using healthy subjects as controls.  The present study recruited 69 post-RT NPC patients without conventional cardiovascular risk factors, 70 type 2 diabetic patients without previous RT, and 76 healthy controls without conventional cardiovascular risk factors and previous RT. For each participant, 5 carotid atherosclerotic parameters, namely carotid intima-media thickness (CIMT), carotid arterial stiffness (CAS), presence of carotid plaque, carotid plaque score, and presence of ≥ 50 % carotid stenosis, were assessed using ultrasonography. The differences in these carotid atherosclerotic parameters between study groups were compared using ANCOVA or logistic regression after the adjustment for age and gender. Multiple comparisons were corrected using the Benjamini-Hochberg false discovery rate.  Post-RT NPC patients and type 2 diabetics had a significantly higher CIMT, CAS and carotid plaque burden compared to the healthy subjects (corrected P-value, Pcor < 0.05). In addition, carotid atherosclerosis in post-RT NPC patients tended to be more severe with significantly higher CAS and carotid plaque burden than that in type 2 diabetics (Pcor < 0.05).  Neck RT for NPC is an independent risk factor of carotid atherosclerosis, and radiation induces more severe carotid atherosclerosis in post-RT NPC patients. Thus, assessment of carotid atherosclerosis using ultrasonography may be necessary for these patients and should be indicated in the routine follow-up of NPC.