Clinical Features of Radiation-induced Carotid Atherosclerosis

Prevalence of Cerebral Small-Vessel Disease in Long-Term Breast Cancer Survivors Exposed to Both Adjuvant Radiotherapy and Chemotherapy

Purpose

Adjuvant radiotherapy and chemotherapy for breast cancer have been related to transient ischemic attacks and stroke. To date, no studies have investigated the relationship between these adjuvant therapies and subclinical cerebral small-vessel disease in survivors of breast cancer. We compared white matter lesion (WML) volume and prevalence of brain infarctions and cerebral microbleeds (CMBs) between breast cancer survivors exposed to adjuvant radiotherapy and chemotherapy (aRCeBCSs) for primary disease and a population-based reference group.

Patients and Methods

Multimodal magnetic resonance imaging (1.5 T) was performed in 187 aRCeBCSs who received primary breast cancer treatment on average more than 20 years before this study and 374 age-matched reference women without a history of cancer. WML volume was segmented using fully automated software. Experienced raters reviewed all scans for cortical infarctions, lacunar infarctions, strictly lobar CMBs, and deep/infratentorial CMBs with or without lobar CMBs. Within the aRCeBCS group, we also analyzed the association between relative radiotherapy exposure to the carotid artery and prevalence of WML volume and CMBs.

Results

The aRCeBCS group had a higher prevalence of both total CMBs and CMBs in a deep/infratentorial region than the reference group. No between-group differences were observed in the prevalence of infarctions or WML volume. Exposure of the carotid artery to radiation was not associated with WML volume or CMBs.

Conclusion

More CMBs were found in the aRCeBCS group than in the population-based controls. These vascular lesions potentially mark cerebrovascular frailty that could partially explain the well-documented association between chemotherapy and cognitive dysfunction. No support was found for a radiotherapy-related origin of CMBs.

NEMO modulates radiation-induced endothelial senescence of human umbilical veins through NF-κB signal pathway

Recently several laboratories have reported that radiation induces senescence in endothelial cells. Senescent cells can secrete multiple growth-regulatory proteins, some of which affect tumor growth, survival, invasion or angiogenesis. The purpose of this study was to explore the mechanisms of radiation-induced senescence and its effects on angiogenesis in human umbilical vein endothelial cells (HUVECs). HUVECs were either pretreated with or without PS1145 prior to irradiation with 0-8 Gy. PS1145 is a novel, highly specific small-molecule inhibitor of nuclear factor kappa B essential modulator (NEMO). MTT assays showed that in HUVECs untreated with PS1145, there was an increase in the number of radiation-induced senescence-like endothelial cells 5 days after 8 Gy irradiation, while pretreatment with PS1145 significantly ameliorated the induction in senescence of HUVECs compared to the control group. Electrophoretic mobility shift assay (EMSA) showed that pretreatment with PS1145 inhibited the radiation-induced NF-κB activation, which regulates cell fate in response to genotoxic stress. In addition, Western blotting demonstrated less translocation of p65 from cytoplasm to nucleus. Furthermore, real-time polymerase chain reaction (PCR) showed that pretreatment with PS1145 inhibited the increase of mRNA expressions of interleukin-6 (IL-6) and p53-induced death domain (PIDD) protein, which have been show to play crucial roles in both senescence and apoptosis (P < 0.05). TUNEL staining revealed an increase in apoptotic HUVECs in the group pretreated with PS1145 after irradiation. The series of functional assays further showed that radiation-induced senescence-like HUVECs had malfunctions in migration, invasion and formation of capillary-like structures, compared with the sham-irradiated and untreated, irradiated groups. Taken together, these findings indicate that the angiogenic capacity of radiation-induced senescence-like HUVECs decreased, and that irradiation caused vascular endothelial cells to gain a senescence-like phenotype through the DSB/NEMO/NF-κB signal pathway. The data suggests that NEMO may be a critical switch that regulates cellular senescence and apoptosis caused by exposure to radiation, and provides new clues for the clinical potential of the combination of radiotherapy and angiogenesis inhibitors.

Radiation-induced carotid artery stenosis: a comprehensive review of the literature

In recent decades, with the improvement of radiotherapy (RT) technology and comprehensive treatment, the survival rate of head and neck malignancies has gained remarkable progress. Vascular injury and subsequent carotid stenosis following RT, as the backbone of treatment, have received increasing attention. Many investigations have demonstrated that radiation can result in the increase in carotid intima-media thickness, carotid stenosis and consequently lead to a higher risk of cerebrovascular events such as transient ischemic attack and stroke. In this review, we will examine the incidence of radiation-induced carotid artery stenosis, its morphological and histological characteristics, as well as its pathogenesis. The treatment and prevention methods, including follow-up strategies, will also be discussed at the end of the present review.

Effects of neck radiation therapy on extra-cranial carotid arteries atherosclerosis disease prevalence: systematic review and a meta-analysis

Introduction

Radiation arteritis following neck irradiation as a treatment for head and neck malignancy has been well documented. The long-term sequelae of radiation exposure of the carotid arteries may take years to manifest clinically, and extra-cranial carotid artery (ECCA) stenosis is a well-recognised vascular complication. These carotid lesions should not be regarded as benign and should be treated in the same manner as standard carotid stenosis. Previous studies have noted increased cerebrovascular events such as stroke in this cohort of patients because of high-grade symptomatic carotid stenosis resulting in emboli.

Aim

To evaluate the effect of radiation therapy on ECCA atherosclerosis progression.

Methods

Online search for case-control studies and randomised clinical trials that reported on stenosis in extra-cranial carotid arteries in patients with neck malignancies who received radiation therapy (RT) comparing them to patients with neck malignancies who did not receive RT.

Results

Eight studies were included in the final analysis with total of 1070 patients – 596 received RT compared to 474 in the control group. There was statistically significant difference in overall stenosis rate (Pooled risk ratio  =  4.38 [2.98, 6.45], P  =  0.00001) and severe stenosis (Pooled risk ratio  =  7.51 [2.78, 20.32], P <0.0001), both being higher in the RT group. Pooled analysis of the five studies that reported on mild stenosis also showed significant difference (Pooled risk ratio  =  2.74 [1.75, 4.30], 95% CI, P  =  0.0001).

Conclusion

The incidence of severe ECCA stenosis is higher among patients who received RT for neck malignancies. Those patients should be closely monitored and screening programs should be considered in all patients who receive neck RT.

Cerebral hypoperfusion secondary to radiation arteritis presenting with recurrent syncope

Radiation arteritis can lead to significant extracranial carotid artery stenosis, affecting the circle of Willis. Cerebral hypoperfusion due to arterial insufficiency is often considered as a differential diagnosis in cases of syncope but rarely proven. We present a case of a 61-year-old man with repeated episodes of syncope-negative cardiac investigations. He had a history of cervical radiation therapy for tonsillar squamous cell carcinoma 15 years previously. Carotid duplex revealed bilateral carotid occlusive disease. MR angiography showed severe multilevel extracranial carotid stenosis bilaterally with occluded left vertebral artery. A diagnosis of cerebral hypoperfusion was performed following single-photon emission CT scan. The patient underwent a left subclavian to carotid bypass, which alleviated his symptoms.

Carotid dosimetry for T1 glottic cancer radiotherapy

OBJECTIVE

Radiotherapy for T1 glottic cancer is commonly delivered using a lateral parallel opposed pair of megavoltage photon fields. There is increasing reported evidence of cerebrovascular events due to radiation-induced carotid stenosis. An alternative field arrangement is to use an anterior oblique technique. This study compares the carotid dosimetry between the two techniques and reviews the evidence for the risk of radiation-induced vascular events.

METHODS

The radiotherapy plans of 10 patients with T1 glottic cancer treated with an anterior oblique technique were examined for carotid dose. Alternative plans were then created using a parallel opposed pair of fields and the dose to the carotids compared. All patients received 50 Gy in 16 fractions treating once daily, for 5 days in a week.

RESULTS

The average of the mean dose to the carotids with the anterior oblique technique was 21 Gy compared with 37 Gy using the lateral parallel opposed pair arrangement (p < 0.0001).

CONCLUSION

An anterior oblique field arrangement for the treatment of T1 glottic cancer results in a significantly lower radiation dose to the carotid arteries, which may be clinically important in terms of reducing the risk of cerebrovascular events in long-term survivors.

ADVANCES IN KNOWLEDGE

Although the anterior oblique technique for treating early glottic cancers is well described, and it is predictable that the dose received by the carotid arteries should be lower with this technique, to our knowledge this is the first study to quantify that reduction in dose with a series of patients.