A Study Of Radiation-induced Cervical Artery Injury In Nasopharyngeal Cancer And The Correlation With The Radiation-induced Temporal Lobe Necrosis

BACKGROUND&OBJECTIVEAs the extension of survival time,more nasopharyngeal carcinoma patients after radiotherapy are exposed to the risk of long-term cerebral ischemic events,which is associated with radiation damage after cervical vascular exposure.This study aimed to investigate the occurrence time and predilection sites of cervical artery injury after radiotherapy,the factors affecting cervical artery injury,and the correlation between cervical artery injury and temporal lobe necrosis.METHODSA total of 181 patients with nasopharyngeal carcinoma previously treated with radiotherapy were enrolled as the study group,and 66 newly diagnosed patients with nasopharyngeal carcinoma as control group.In order to analyze the damage occurrence time and predilection sites of cervical artery injury,the study components were divided into 4 groups according to the interval after radiotherapy(group 1:within 12 months after radiotherapy;group 2:12-24 months after radiotherapy;group 3:24-36 months after radiotherapy;group 4:37 months and above after radiotherapy).All patients underwent bilateral carotid artery ultrasound to detect the location and extent of cervical artery injury.Magnetic resonance imaging(MRI)was required for patients after radiotherapy 15 months and above to evaluate the radiation induced temporal lobe necrosis(TLN).The general clinical data and treatment situation of the cases were counted.CCA/ICA:CCA+BIF+ICA.Vascular abnormalities:arterial intima thickening,plaque formation,and luminal stenosis are collectively referred to as vascular abnormalities.Significant vascular abnormalities:plaque formation and stenosis are called significant abnormalities.RESULTS1.In the study group,there was no difference in vascular injury in group 1 and group 2 compared with the control group.The incidence of cervical artery abnormalities and the number of plaques in group 3 patients were significantly higher than those in the control group.The incidence of abnormalities and significant abnormalities of cervical artery in group 4 patients were higher than those in the control group,the number of plaques and the number of vessels involved in injury were also significantly higher than those in the control group.2.Individual vessels:CCA:The incidence of vascular abnormalities and the number of plaques in group 3 patients were significantly higher than those in the control group,in group 4 patients,abnormalities rate(45.5%v.s 22.7%)and obvious abnormalities rate(33.8%v.s 10.6%)were significantly increased compared with the control,and the number of plaques were also significantly increased;ICA:only in group 4,the incidence of vascular abnormalities was higher than in the control group(19.5%v.s 6.1%);CCA/ICA:in group 3,the incidence of abnormalities of CCA/ICA was significantly higher than that in the control group(76.9 v.s 53.0),in group 4,the incidence of CCA/ICA abnormalities and obvious abnormalities was significantly higher than that of the control group(77.9%v.s 53.0%,61.0%v.s 39.4%),and the number of plaques increased(P=0.004).3.Independent risk factors for carotid artery abnormalities after radiotherapy are age>55 years,interval from irradiation? 30 months,high blood pressure,large amount of smoking;these four factors are also independent risk factors for obvious abnormality and independent risk factors affecting the severity of radiotherapy induced carotid artery injury.The number of traditional cardiovascular risk factors(male,age? 55 years,smoking,hypertension,hyperlipidemia,hyperglycemia)was also an independent risk factor for vascular abnormalities and vascular obvious abnormalities,with OR of 1.96(95%CI 1.47-2.56)and 2.23(95%CI 1.66-2.97)respectively.4.Univariate analysis of occurrence of TLN in 260 temporal lobe showed that the time interval after radiotherapy?61 months and the obvious abnormalities of ipsilateral CCA/ICA were associated with TLN.In patients with>61 months after radiotherapy,ipsilateral CCA/ICA obvious abnormalities were risk factors for TLN in this temporal lobe,with an OR value of 13.57(95%CI was 2.86-64.40,P<0.001).CONCLUSIONS1.The incidence of cervical artery injury in patients with nasopharyngeal carcinoma within 24 months after radiotherapy did not increase.24 to 36 months after radiotherapy,the incidence of cervical artery abnormalities and the number of plaques increased.The incidence of cervical artery injury was significantly increased in patients 37 months and above after radiotherapy,meanwhile,the extent of injury also significantly increased.2.The predilection site of radiation vascular injury is similar to spontaneous atherosclerosis,which occurs earlier in CCA/ICA,ICA only increased the incidence of vascular abnormalities 37 months and above after radiotherapy;BIF and SA did not show the increase in the incidence of injury and the number of plaques.3.Age>55 years,interval from radiotherapy? 30 months,high blood pressure,large amount of smoking were the independent risk factors for cervical artery abnormality and obvious abnormality in patients after radiotherapy,and the independent risk factors for the severity of radiation induced cervical artery injury.The number of traditional cardiovascular risk factors was also an independent risk factor for carotid injury.4.The interval from radiotherapy?61 months and the ipsilateral CCA/ICA obvious abnormalities were related to the occurrence of TLN.In patients with>61 months after radiotherapy,ipsilateral CCA/ICA obvious abnormalities was a risk factors for TLN.