RADIATION-INDUCED INJURY TO THE CAROTID-ARTERY - A LONGITUDINAL-STUDY

Therapeutic radiation can lead to damage of arterial walls. In the present investigation, we studied prospectively 16 patients without pre-existing vascular disease (13 males, three females; mean age = 59.75 +/- 11.9 years) who had undergone surgery and post-operative radiation therapy (cumulative dose = 56.2 +/- 10.2 Gy) for the treatment of carcinoma of the head and neck. The carotid arteries were examined every 3 months for 19.9 +/- 8.7 months using Doppler ultrasound and B-mode sonography. The thickness of the arterial walls was determined using an index (outer:inner mean arterial wall), and it was compared to a group of age-matched control subjects (n = 16) with healthy arteries. The index of the common carotid artery (CCA) was initially 1.14 +/- 0.04 in both the right and left CCA in the radiation-treated subjects. By the end of the study, this index had increased significantly to 1.37 +/- 0.14 in both right and left CCA in the radiation-treated subjects (p < 0.01). There was a significant difference in arterial wall thickness between the radiation-treated and control subjects (p < 0.001). Frequent and extensive smooth-surfaced plaques indicative of arterial thickening in the area of the common carotid and internal carotid arteries were seen in the irradiated patients. Four patients developed > 50% atherosclerotic stenosis of the internal carotid artery. These data suggest that arterial damage may occur following radiation treatment of the head and neck area. Modification of radiation therapy for the post-surgical treatment of head tumors coupled with the continuous monitoring of the carotid arteries using B-mode sonography could minimize this arterial damage.