Effect of Radiotherapy on Carotid Arteries – An Observational Study

Intoduction: Survival rates of patients with head and neck cancer have recently increased with the introduction of new technologies and developments in comprehensive treatment modalities in RT. Observing late side effects, too, has become inevitable. Vascular damages and their clinicalresults are the prevalent effects of RT.

Objective: Carotid artery lesions and stenosis could develop after radiotherapy and can be detected viaintima-media thickness. Within the scope of this research, we aimed to elucidate the planning technique to minimize the radiation dose to be exposed to the carotid arteries.

Methods: This study included42 patients with stage T1-2 N0 M0 glottic cancer who applied to our institution. CA diameters of the patients were measured before and after RT. The measurements were performed 2 cm above the CA bifurcation level, and the largest diameter (cm) was recorded. All measurements were performed on CT scans. Actual treatment images (slice thickness, 2.5 cm) acquired using a computerized tomography (CT) simulator were transferred into the Hi-Art Tomotherapy treatment system. Dose-volume histograms were used for dose comparisons.

Results: A comparison of doses administered to the RCAs and LCAs revealed that the Dmean, V35-Gy, V40-Gy, and V50-Gy values of RCA were significantly higher than those of LCA. Examination of the correlation between the RCA diameters after treatment and RT doses revealed a statistically significant correlation only for the V60-Gy dose (r = 0.299, p = 0.054). The RCA diameter was reportedly significantly narrower in smokers than nonsmokers (p = 0.039).A statistically significant significance was observed between smokers' RCA diameter and V60-Gy dose (r = 0.458, p = 0.013).A statistically significant correlation was also observed between age and only the RCA diameter in smokers (p = 0.038).

Conclusion: RT performed on the head and neck region is an important risk factor for arterial stenosis and the resulting CVEs. Smoking is one of the most important factors that increase this risk. Carotid artery doses should be considered while planning RT.