A prospective study of the effects of irradiation on the carotid artery

Objectives/Hypothesis: To prospectively assess the effects of irradiation o n the carotid artery in patients with head and neck cancer, as a possibly r elevant factor in cancer treatment planning. Study Design: Prospective stud y from a tertiary care academic setting on university (22 patients) and Vet erans Affairs (14 patients) hospital patients; 1-year follow-up, including comparison of study data with age-matched and sex-matched control subjects from epidemiological studies, Methods: Thirty-six patients with head and ne ck cancer who underwent therapeutic neck irradiation were examined by high- resolution ultrasound before and 1 year after treatment. Twelve patients we re also studied at 2 years. Measurements included the intima-media thicknes s (IMT) of the carotid artery wall, the degree of stenosis as estimated fro m velocity measurements, and the presence and size of plaque. Results: The pretreatment carotid IMT at baseline was 0.68 mm and was comparable to age- matched and sex-matched control subjects. Significant increase in the IMT w as observed on both the left (0.67 vs. 0.84 mm) and the right (0.7 vs. 0.87 mm) sides (P < .001) 1 year after irradiation. In 12 patients who complete d 24 months of follow-up the carotid IMT continued to significantly increas e statistically compared with that at the first year after treatment (left side, 0.79 vs, 0.85 mm, P = .037; right side, 0.79 vs. 0,95 mm, P =, 014), Statistically significant thickening of the carotid wall developed in all 3 6 patients by 1 year. Two patients experienced post-treatment neurological events and an area of stenosis greater than 75%. Conclusions: Neck. irradia tion significantly increases the thickness of the carotid wall during the f irst year after treatment-on average, 21 times more than in epidemiological ly matched control volunteers. This phenomenon should be taken into conside ration when planning treatment for the node-negative (NO) neck.