Prospective analysis of carotid artery flow in breast cancer patients treated with supraclavicular irradiation 8 or more years previously: no increase in ipsilateral carotid stenosis after radiation noted

When Two Maladies Meet: Disease Burden and Pathophysiology of Stroke in Cancer

Stroke and cancer are disabling diseases with an enormous global burden, disproportionately affecting vulnerable populations and low- and middle-income countries. Both these diseases share common risk factors, which warrant concerted attention toward reshaping population health approaches and the conducting of fundamental studies. In this article, an overview of epidemiological trends in the prevalence and burden of cancer and stroke, underlying biological mechanisms and clinical risk factors, and various tools available for risk prediction and prognosis are provided. Finally, future recommendations for research and existing gaps in our understanding of pathophysiology. Further research must investigate the causes that predispose patients to an increased risk of stroke and/or cancer, as well as biomarkers that can be used to predict growing morbidity and mortality.

Is radiation-induced arteriopathy in long-term breast cancer survivors an underdiagnosed situation?: Critical and pragmatic review of available literature

PURPOSE

Although considered exceptional, radiation-induced arteriopathy in long-term breast cancer survivors involves three main arterial domains in the irradiated volume, namely axillary-subclavian, coronary, and carotid. Stenosis of medium-large arteries is caused by "accelerated" atherosclerosis, particularly beyond 10 years after long-forgotten radiotherapy. The present review aims at summarizing what is known about arteriopathy, as well as the state of the art in terms of diagnosis and therapeutic management.

DIAGNOSIS

Pauci-symptomatic over years, the usual clinical presentation of arteriopathy involves arm pain with coldness due to subacute or critical ischemia (arterial occlusion), wrongly attributed to an exclusive neurological disorder, and more rarely transient ischemic accident or angina. Evaluation of the supra-aortic trunks by computed tomography and/or magnetic resonance angiography visualizes artery lesions, while Doppler ultrasonography in expert hands assesses diagnosis and downstream functional impact. In severe cases, more invasive angiography directly visualizes long irregular arterial stenosis (full-field radiotherapy), allowing accurate prognosis and treatment.

MANAGEMENT

Requires early diagnosis to enable initiation of medical treatment that increases blood flow (aspirin) as soon as moderate stenosis is detected, combined with correction of vascular risk factors. In intermediate cases, these therapeutic measures are completed by revascularization strategies using transluminal angioplasty-stenting (wall thickness). Antifibrotic treatment is useful in advanced cases with combined radiation injuries.

CONCLUSION

In follow-up of long-term breast cancer survivors with node irradiation, myocardial infarction is treated even if radiotherapy is forgotten, while recognition and diagnosis of chronic arm ischemia due to subclavian artery stenosis needs to be improved for appropriate therapeutic management.

Peripheral Artery Disease and Stroke

Peripheral artery disease (PAD) and stroke can occur as vascular complication of anticancer treatment. Although the mechanisms, monitoring, and management of cardiotoxicities have received broad attention, vascular toxicities remain often underrecognized. In addition, the development of new chemotherapeutic drugs bears the risk of vasotoxicities that are yet to be identified and may not be realized with short-term follow-up periods. The propensity to develop PAD and/or stroke reflects the complex interplay between patient's baseline risk and preexisting vascular disease, particularly hypertension and diabetes, while evidence for genetic predisposition is increasing. Chemotherapeutic agents with a prominent vascular side effect profile have been identified. Interruption of vascular endothelial growth factor (VEGF) inhibitors (VEGFIs) signaling (i.e., bevacizumab) is associated with vascular toxicity and clinical sequelae such as hypertension, stroke, and thromboembolism beyond acute coronary syndromes. Cisplatin and 5-fluorouracil are the main drugs involved in the stroke risk. In addition, circulating concentrations of VEGF are reduced by cyclophosphamide administered at continuous low doses, which might underpin some of the observed vascular toxicity, such as stroke, as seen in patients treated with VEGF inhibitors. The risk of stroke is also increased after treatment with anthracyclines that can induce endothelial dysfunction and increase arterial stiffness. Proteasome inhibitors ( bortezomib and carfilzomib) and immunomodulatory agents (thalidomide, lenalidomide, and pomalidomide), approved for use in multiple myeloma, carry a black box warning for an increased risk of stroke. Finally, head-and-neck radiotherapy is associated with a doubled risk of cerebrovascular ischemic event, especially if exposure occurs in childhood. The mechanisms involved in radiation vasculopathy are represented by endothelial dysfunction, medial necrosis, fibrosis, and accelerated atherosclerosis. However, BCR-ABL tyrosine kinase inhibitor (TKI), used for the treatment of chronic myeloid leukemia (CML), is the main antineoplastic drugs involved in the development of PAD. In particular, second- and third-generation TKIs, such as nilotinib and ponatinib, while emerging as a potent arm in contrasting CML, are associated with a higher risk of PAD development rather than traditional imatinib. Factors favoring vascular complication are the presence of traditional cardiovascular risk factors (CVRF) and predisposing genetic factors, high doses of BCR-ABL TKIs, longer time of drug exposure, and sequential use of potent TKIs. Therefore, accurate cardiovascular risk stratification is strongly recommended in patient candidate to anticancer treatment associated with higher risk of vascular complication, in order to reduce the incidence of PAD and stroke through CVRF correction and selection of appropriate tailored patient strategy of treatment. Then, a clinical follow-up, eventually associated with instrumental evaluation through vascular ultrasound, should be performed.

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.

Radiation-induced carotid artery atherosclerosis

PURPOSE

Carotid arteries frequently receive significant doses of radiation as collateral structures in the treatment of malignant diseases. Vascular injury following treatment may result in carotid artery stenosis (CAS) and increased risk of stroke and transient ischaemic attack (TIA). This systematic review examines the effect of radiotherapy (RT) on the carotid arteries, looking at the incidence of stroke in patients receiving neck radiotherapy. In addition, we consider possible surrogate endpoints such as CAS and carotid intima-medial thickness (CIMT) and summarise the evidence for radiation-induced carotid atherosclerosis.

MATERIALS AND METHODS

From 853 references, 34 articles met the criteria for inclusion in this systematic review. These papers described 9 studies investigating the incidence of stroke/TIA in irradiated patients, 11 looking at CAS, and 14 examining CIMT.

RESULTS

The majority of studies utilised suboptimally-matched controls for each endpoint. The relative risk of stroke in irradiated patients ranged from 1.12 in patients with breast cancer to 5.6 in patients treated for head and neck cancer. The prevalence of CAS was increased by 16-55%, with the more modest increase seen in a study using matched controls. CIMT was increased in irradiated carotid arteries by 18-40%. Only two matched-control studies demonstrated a significant increase in CIMT of 36% and 22% (p=0.003 and <0.001, respectively). Early prospective data demonstrated a significant increase in CIMT in irradiated arteries at 1 and 2 years after RT (p<0.001 and <0.01, respectively).

CONCLUSIONS

The incidence of stroke was significantly increased in patients receiving RT to the neck. There was a consistent difference in CAS and CIMT between irradiated and unirradiated carotid arteries. Future studies should optimise control groups.

Ischemic stroke and transient ischemic attack after head and neck radiotherapy: a review

BACKGROUND AND PURPOSE

Cerebrovascular disease can complicate head and neck radiotherapy and result in transient ischemic attack and ischemic stroke. Although the incidence of radiation vasculopathy is predicted to rise with improvements in median cancer survival, the pathogenesis, natural history, and management of the disease are ill defined.

METHODS

We examined studies on the epidemiology, imaging, pathogenesis, and management of medium- and large-artery intra- and extra-cranial disease after head and neck radiotherapy. Controlled prospective trials and larger retrospective trials from the last 30 years were prioritized.

RESULTS

The relative risk of transient ischemic attack or ischemic stroke is at least doubled by head and neck radiotherapy. Chronic radiation vasculopathy affecting medium and large intra- and extra-cranial arteries is characterized by increasing rates of hemodynamically significant stenosis with time from radiotherapy. Disease expression is the likely consequence of the combined radiation insult to the intima-media (accelerating atherosclerosis) and to the adventitia (injuring the vasa vasorum). Optimal medical treatment is not established. Carotid endarterectomy is confounded by the need to operate across scarred tissue planes, whereas carotid stenting procedures have resulted in high restenosis rates.

CONCLUSIONS

Head and neck radiotherapy significantly increases the risk of transient ischemic attack and ischemic stroke. Evidence-based guidelines for the management of asymptomatic and symptomatic (medium- and large-artery) radiation vasculopathy are lacking. Long-term prospective studies remain a priority, as the incidence of the problem is anticipated to rise with improvements in postradiotherapy patient survival.

Stenting in the remnant of the third aortic arch in a case of post-irradiation occluded internal carotid artery

Collateral networks between the external carotid artery and internal carotid arteries become crucial for cerebral perfusion after occlusion of internal carotid arteries. We report the first case of a patient who received percutaneous transluminal angioplasty and stenting in a collateral vessel between the external and internal carotid artery for treatment of radiation induced severe stenosis of the internal carotid artery in the context of a contralateral internal carotid artery occlusion.

Effects of external irradiation of the neck region on intima media thickness of the common carotid artery

BACKGROUND

Several studies have shown that common carotid intima-media thickness (IMT) is increased after radiotherapy (RT) to the head and neck. However, further studies are needed to define the exact mechanism of radiation-induced injury in large vessels, investigate the relationship between radiation dose and large vessel injury and evaluate the rate of progress of atherosclerosis in irradiated vessels.

OBJECTIVES

To investigate whether external irradiation to the carotid area has any effect on IMT of the common carotid artery in a group of patients who received RT vs control group matched for age, gender and race.

METHODS

We studied 19 patients (10 male; 47.8 +/- 17.4 years) during a 5-month period (January 2009-July 2009); they had completed RT with a mean of 2.9 years before (range: 1 month-6 years) The mean radiation dose to the neck in the irradiated patients was 41.2 +/- 15.6 Gy (range: 25-70 Gy). Common carotid IMT was measured with echo-color Doppler. Nineteen healthy adult patients (10 male; 47.8 +/- 17.6) were recruited as a control group.

RESULTS

IMT was not significantly higher in patients when compared to the control group (0.59 +/- 0.16 vs 0.56 +/- 0.16 mm, p = 0.4). There was no significant difference between the two groups in relation to the absence (p = 0.7) or presence (p = 0.6) of vascular risk factors. Although the difference did not reach statistical significance (p = 0.1), the irradiated young patients (age < or = 52 years) had IMT measurements higher (0.54 +/- 0.08 mm) than the non-irradiated young patients (0.49 +/- 0.14 mm). The mean carotid IMT increased with increasing doses of radiation to the neck (p = 0.04).

CONCLUSION

This study shows that increased IMT of the common carotid artery after RT is radiation-dose-related. Therefore it is important to monitor IMT, which can be used as an imaging biomarker for early diagnosis of cerebrovascular disease in patients who have had radiotherapy for treatment of cancer of the head and neck and who are at increased risk for accelerated atherosclerosis in carotid arteries.

Radiation to supraclavicular and internal mammary lymph nodes in breast cancer increases the risk of stroke

The aim of this study was to assess whether adjuvant treatment of breast cancer (BC) affects the risk of stroke, and to explore radiation targets and fraction doses regarding risk and location of stroke. In a Swedish BC cohort diagnosed during 1970-2003, we carried out a nested case-control study of stroke after BC, with relevant details extracted from medical records. The odds ratio (OR) for radiotherapy (RT) vs that of no RT did not differ between cases and controls (OR=0.85; confidence interval, CI=0.6-1.3). Radiotherapy to internal mammary chain (IMC) and supraclavicular (SCL) lymph nodes vs that of no RT was associated with a higher, although not statistically significant, risk of stroke (OR=1.3; CI=0.8-2.2). In a pooled analysis, RT to IMC and SCL vs the pooled group of no RT and RT to breast/chest wall/axilla (but not IMC and SCL), showed a significant increase of stroke (OR=1.8; CI=1.1-2.8). There were no associations between cancer laterality, targets of RT, and location of stroke. The radiation targets, IMC and SCL, showed a statistically significant trend for an increased risk of stroke with daily fraction dose. Our finding of a target-specific increased risk of stroke and a dose-response relationship for daily fraction dose, indicate that there may be a causal link between RT to the IMC and SCL and risk of stroke.