High prevalence of small vessel disease long after cranial irradiation

Late-onset vascular complications of radiotherapy for primary brain tumors: a case-control and cross-sectional analysis

PURPOSE

Radiotherapy (RT) is a recognized risk factor for cerebrovascular (CV) disease in children and in adults with head and neck cancer. We aimed to investigate whether cerebral RT increases the risk of CV disease in adults with primary brain tumors (PBT).

METHODS

We retrospectively identified adults with a supratentorial PBT diagnosed between 1975 and 2006 and with at least 10 years follow-up after treatment. We analyzed demographic, clinical, and radiological features with special attention to CV events. We also described CV events, vascular risk factors, and intracranial artery modifications in a cross-sectional study of irradiated patients alive at the time of the study.

RESULTS

A total of 116 patients, treated with RT (exposed group), and 85 non-irradiated patients (unexposed group) were enrolled. Stroke was more frequent in irradiated PBT patients than in the unexposed group (42/116 (36%) vs 7/85 (8%); p < 0.001), with higher prevalence of both ischemic (27/116 (23%) vs 6/85 (7%); p = 0.004) and hemorrhagic (12/116 (10%) vs 1/85 (1%); p = 0.02) stroke. In the irradiated group, patients with tumors near the Willis Polygon were more likely to experience stroke (p < 0.016). Fourty-four alive irradiated patients were included in the cross-sectional study. In this subgroup, intracranial arterial stenosis was more prevalent (11/45, 24%) compared to general population (9%).

CONCLUSIONS

Stroke prevalence is increased in long-surviving PBT patients treated with cranial RT.

IMPLICATIONS FOR CANCER SURVIVORS

CV events are frequent in long survivors of PBT treated with cerebral RT. We propose a check list to guide management of late CV complications in adults treated with RT for PBT.

Complications of Cancer Therapy in Children: A Comprehensive Review of Neuroimaging Findings

ABSTRACT

Complications of cancer therapy in children can result in a spectrum of neurologic toxicities that may occur at the initiation of therapy or months to years after treatment. Although childhood cancer remains rare, increasing survival rates mean that more children will be living longer after cancer treatment. Therefore, complications of cancer therapy will most likely occur with increasing frequency.At times, it is very difficult to differentiate between therapeutic complications and other entities such as tumor recurrence, development of secondary malignancy, and infection (among other conditions). Radiologists often play a key role in the diagnosis and evaluation of pediatric patients with malignancies, and thus, awareness of imaging findings of cancer complications and alternative diagnoses is essential in guiding management and avoiding misdiagnosis. The aim of this review article is to illustrate the typical neuroimaging findings of cancer therapy-related toxicities, including both early and late treatment effects, highlighting pearls that may aid in making the appropriate diagnosis.

Spatial distribution of cerebral microbleeds and FLAIR hyperintensities on follow-up MRI after radiotherapy for lower grade glioma

Background and purpose

Cerebral microbleeds (CMBs) and fluid-attenuated-inversion recovery (FLAIR) hyperintensities on brain MRI scans after radiotherapy (RT) are considered markers for microvascular damage and related cognitive changes. However, the spatial distribution using existing scoring systems as well as colocation of these imaging biomarkers remain unclear, hampering clinical interpretation. This study aims to elucidate the distribution and colocation of these markers in patients with lower grade glioma (LGG).

Materials and methods

CMBs were spatially classified on retrospective 1.5 T susceptibility weighted MRI scans according to the existing Microbleed Anatomical Rating Scale (MARS) and were additionally scored for being located in hippocampus, amygdala, cortex, white matter (WM), grey matter (GM), WM/GM junction and for their spatial relation to FLAIR hyperintensities. Scoring was performed for whole, ipsilateral and contralateral cerebrum (with respect to tumour bulk).

Results

Fifty-one scans were included of which 28 had at least one CMB. The majority of CMBs were localized in the lobar area and in deep and periventricular white matter (DPWM) - generally in WM. Only few CMBs were found in GM. In scans obtained up to 7 years after RT completion the majority of CMBs were not colocalized with FLAIR hyperintensities.

Conclusion

CMBs and FLAIR hyperintensities appear to be separate imaging biomarkers for radiation therapy induced microvascular damage, as they are not colocalized in patients with LGG, especially not early on after completion of RT.

Pathophysiology and probable etiology of cerebral small vessel disease in vascular dementia and Alzheimer's disease

Vascular cognitive impairment and dementia (VCID) is commonly caused by vascular injuries in cerebral large and small vessels and is a key driver of age-related cognitive decline. Severe VCID includes post-stroke dementia, subcortical ischemic vascular dementia, multi-infarct dementia, and mixed dementia. While VCID is acknowledged as the second most common form of dementia after Alzheimer's disease (AD) accounting for 20% of dementia cases, VCID and AD frequently coexist. In VCID, cerebral small vessel disease (cSVD) often affects arterioles, capillaries, and venules, where arteriolosclerosis and cerebral amyloid angiopathy (CAA) are major pathologies. White matter hyperintensities, recent small subcortical infarcts, lacunes of presumed vascular origin, enlarged perivascular space, microbleeds, and brain atrophy are neuroimaging hallmarks of cSVD. The current primary approach to cSVD treatment is to control vascular risk factors such as hypertension, dyslipidemia, diabetes, and smoking. However, causal therapeutic strategies have not been established partly due to the heterogeneous pathogenesis of cSVD. In this review, we summarize the pathophysiology of cSVD and discuss the probable etiological pathways by focusing on hypoperfusion/hypoxia, blood-brain barriers (BBB) dysregulation, brain fluid drainage disturbances, and vascular inflammation to define potential diagnostic and therapeutic targets for cSVD.

Radiotherapy-Related Neurologic Complications in Patients with Nasopharyngeal Carcinoma: A Multicenter Epidemiologic Study in Southern China

BACKGROUND

We aim at describing the incidence, potential predisposing factors, and progression of major radiotherapy-related neurologic complications (RRNC) in nasopharyngeal carcinoma (NPC)-endemic regions, especially southern China.

METHODS

We performed a multicenter longitudinal retrospective study with clinical follow-ups in 22,302 patients with post-radiotherapy NPC between January 2003 and June 2017 covering three major residential areas. Epidemiology, potential predisposing/protective factors, clinicopathologic progression, and survival conditions of each RRNC were separately recorded and analyzed on the basis of their related clinical, radiologic, and laboratory parameters.

RESULTS

949 new cases of RRNCs occurred among the 22,302 patients with post-radiotherapy NPC during 101,714 person years' follow-up, which is equal to an incidence density rate of 9.3 new cases per 1000 person year. Radiation-induced cranial nerve palsy showed the highest incidence (2.68%, 597/22,302) with the earliest onset (median latency, 4.45 years) as well. Patients benefited from intensity-modulated radiotherapy (IMRT) over conventional radiotherapy (CRT) in both overall survival (median survival 13.2 years for IMRT vs. 8.3 years for CRT) and RRNC-free survival (except for epilepsy and cranial nerve palsy). Causes of death varied substantially between patients with or without RRNCs.

CONCLUSIONS

Our study indicates a non-negligible incidence of RRNC spectrum in southern China in the past ten years. IMRT is one of the most significant protectors against development and progression of RRNCs.

IMPACT

Our findings support the hypothesis that patients with NPC with preexisting predispositions would receive long-term benefits from IMRT and other dose-related modulations (like hyperfractionation and dose conformation).

White matter hyperintensities relate to executive dysfunction, apathy, but not disinhibition in long-term adult survivors of pediatric cerebellar tumor

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Pediatric brain tumor survivors have more executive dysfunction than controls.

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White matter hyperintensities are positively associated with executive dysfunction.

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White matter hyperintensities are positively associated with apathy.

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Multivariate regression supports white matter hyperintensity associations.

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Survivors appear to drive white matter hyperintensities associations.

White matter hyperintensities (WMHs) have been related to executive dysfunction, apathy and disinhibition in a wide range of neurological populations. However, this relationship has not been examined in survivors of pediatric brain tumor. The goal of this study was to investigate how executive dysfunction, apathy, and disinhibition relate to WMHs in 31 long-term survivors of pediatric cerebellar brain tumor and 58 controls, using informant-report data from the Frontal Systems Behavior Scale. Total WMH volume was quantified using the Lesion Growth Algorithm. Further, periventricular, and subcortical volumes were identified based on proximity to custom ventricle masks generated in FSL. A ratio of WMH volume to whole brain volume was used to obtain normalized WMH volumes. Additionally, a multivariate regression analysis was performed. On average, informant-report scores were within normal limits and only executive dysfunction was significantly higher in survivors compared to controls (t(47.9) = -2.4, p=.023). Informants reported clinically significant levels of apathy in 32.3% of survivors. Informants also reported clinically significant executive dysfunction in 19.4 % of survivors and clinically significant disinhibition in, again, 19.4 % of survivors. Increased volume of WMHs was positively correlated with executive dysfunction (r = 0.33, p = 0.02) and apathy (r = 0.23, p = .04). Similarly, multivariate regression demonstrated correlations with executive dysfunction (p=.05, FDR corrected) and apathy (p=.05, FDR corrected). Exploratory analysis demonstrated an interaction wherein the relationship between total WMHs and executive dysfunction and apathy depends on whether the participant was a survivor. The current findings indicate that increased WMH volumes are associated with higher ratings of apathy and executive dysfunction, and that these results are likely unique to cerebellar brain tumor survivors. WMH burden may serve as a useful marker to identify survivors at risk of executive dysfunction or increased apathy.

Sphingosine-1-phosphate and its mimetic FTY720 do not protect against radiation-induced ovarian fibrosis in the nonhuman primate†

Oocytes are highly radiosensitive, so agents that prevent radiation-induced ovarian follicle destruction are important fertility preservation strategies. A previous study in rhesus macaques demonstrated that ovarian treatment with antiapoptotic agents, sphingosine-1-phosphate (S1P) and FTY720, its long-acting mimetic, preserved follicles following a single dose of 15 Gy X-ray radiation, and live offspring were obtained from FTY720-treated animals. However, it is unknown whether these antiapoptotic agents also protected the ovarian stroma from late effects of radiation, including vascular damage and fibrosis. Using ovarian histological sections from this study, we evaluated the vasculature and extracellular matrix in the following cohorts: vehicle + sham irradiation, vehicle + irradiation (OXI), S1P + irradiation (S1P), and FTY720 + irradiation (FTY720). One ovary from each animal was harvested prior to radiation whereas the contralateral ovary was harvested 10 months post-treatment. We assessed vasculature by immunohistochemistry with a PECAM1 antibody, hyaluronan by a hyaluronan binding protein assay, and collagen by picrosirius red and Masson's trichrome staining. Disorganized vessels were observed in the medulla in the OXI and S1P cohorts relative to the sham, but the vasculature in the FTY720 cohort appeared intact, which may partially explain fertoprotection. There were no differences in the hyaluronan matrix among the cohorts, but there was thickening of the tunica albuginea and fibrosis in the OXI cohort relative to the sham, which was not mitigated by either S1P or FTY720 treatment. Thus, the fertoprotective properties of S1P and FTY720 may be limited given their inability to protect the ovarian stroma against the late effects of radiation-induced fibrosis.

Neuroimaging Biomarkers and Neurocognitive Outcomes in Pediatric Medulloblastoma Patients: a Systematic Review

Medulloblastoma is a malign posterior fossa brain tumor, mostly occurring in childhood. The CNS-directed chemoradiotherapy treatment can be very harmful to the developing brain and functional outcomes of these patients. However, what the underlying neurotoxic mechanisms are remain inconclusive. Hence, this review summarizes the existing literature on the association between advanced neuroimaging and neurocognitive changes in patients that were treated for pediatric medulloblastoma. The PubMed/Medline database was extensively screened for studies investigating the link between cognitive outcomes and multimodal magnetic resonance (MR) imaging in childhood medulloblastoma survivors. A behavioral meta-analysis was performed on the available IQ scores. A total of 649 studies were screened, of which 22 studies were included. Based on this literature review, we conclude medulloblastoma patients to be at risk for white matter volume loss, more frequent white matter lesions, and changes in white matter microstructure. Such microstructural alterations were associated with lower IQ, which reached the clinical cut-off in survivors across studies. Using functional MR scans, changes in activity were observed in cerebellar areas, associated with working memory and processing speed. Finally, cerebral microbleeds were encountered more often, but these were not associated with cognitive outcomes. Regarding intervention studies, computerized cognitive training was associated with changes in prefrontal and cerebellar activation and physical training might result in microstructural and cortical alterations. Hence, to better define the neural targets for interventions in pediatric medulloblastoma patients, this review suggests working towards neuroimaging-based predictions of cognitive outcomes. To reach this goal, large multimodal prospective imaging studies are highly recommended.

Brain white matter lesions are associated with reduced hypothalamic volume and cranial radiotherapy in childhood-onset craniopharyngioma

CONTEXT

White matter lesions (WML) are caused by obstruction of small cerebral vessels associated with stroke risk. Craniopharyngioma (CP) patients suffer from increased cerebrovascular mortality.

OBJECTIVE

To investigate the effect of reduced HT volume and cranial radiotherapy (CRT) on WML in childhood-onset CP patients.

DESIGN

A cross-sectional study of 41 patients (24 women) surgically treated childhood-onset CP in comparison to controls.

SETTING

The South Medical Region of Sweden (2.5 million inhabitants).

METHODS

With magnetic resonance imaging (MRI), we analysed qualitative measurement of WML based on the visual rating scale of Fazekas and quantitative automated segmentation of WML lesion. Also, measurement HT volume and of cardiovascular risk factors were analysed.

RESULTS

Patients had a significant increase in WML volume (mL) (P = .001) compared to controls. Treatment with cranial radiotherapy (CRT) vs no CRT was associated with increased WML volume (P = .02) as well as higher Fazekas score (P = .001). WML volume increased with years after CRT (r = 0.39; P = .02), even after adjustment for fat mass and age. A reduced HT volume was associated with increased WML volume (r = -0.61, P < .001) and explained 26% of the variation (r²  = 0.26). Altogether, 47% of the WML volume was explained by age at investigation, HT volume and CRT. Patients with more WML also had higher cardiovascular risk.

CONCLUSIONS

CRT may be associated directly with increased WML volume or indirectly with reduced HT volume associated with higher cardiovascular risk. Risk factors should be carefully monitored in these patients.

Modern Radiotherapy for Pediatric Brain Tumors

Cancer is a leading cause of death in children with tumors of the central nervous system, the most commonly encountered solid malignancies in this population. Radiotherapy (RT) is an integral part of managing brain tumors, with excellent long-term survival overall. The tumor histology will dictate the volume of tissue requiring treatment and the dose. However, radiation in developing children can yield functional deficits and/or cosmetic defects and carries a risk of second tumors. In particular, children receiving RT are at risk for neurocognitive effects, neuroendocrine dysfunction, hearing loss, vascular anomalies and events, and psychosocial dysfunction. The risk of these late effects is directly correlated with the volume of tissue irradiated and dose delivered and is inversely correlated with age. To limit the risk of developing these late effects, improved conformity of radiation to the target volume has come from adopting a volumetric planning process. Radiation beam characteristics have also evolved to achieve this end, as exemplified through development of intensity modulated photons and the use of protons. Understanding dose limits of critical at-risk structures for different RT modalities is evolving. In this review, we discuss the physical basis of the most common RT modalities used to treat pediatric brain tumors (intensity modulated radiation therapy and proton therapy), the RT planning process, survival outcomes for several common pediatric malignant brain tumor histologies, RT-associated toxicities, and steps taken to mitigate the risk of acute and late effects from treatment.

Radiation-induced accelerated aging of the brain vasculature in young adult survivors of childhood brain tumors

Background

Cranial radiotherapy may damage the cerebral vasculature. The aim of this study was to understand the prevalence and risk factors of cerebrovascular disease (CVD) and white matter hyperintensities (WMHs) in childhood brain tumors (CBT) survivors treated with radiotherapy.

Methods

Seventy CBT survivors who received radiotherapy were enrolled in a cross-sectional study at a median 20 years after radiotherapy cessation. The prevalence of and risk factors for CVD were investigated using MRI, MRA, and laboratory testing. Tumors, their treatment, and stroke-related data were retrieved from patients’ files.

Results

Forty-four individuals (63%) had CVD at a median age of 27 years (range, 16-43 years). The prevalence rates at 20 years for CVD, small-vessel disease, and large-vessel disease were 52%, 38%, and 16%, respectively. Ischemic infarcts were diagnosed in 6 survivors, and cerebral hemorrhage in 2. Lacunar infarcts were present in 7, periventricular or deep WMHs in 34 (49%), and mineralizing microangiopathy in 21 (30%) survivors. Multiple pathologies were detected in 44% of the participants, and most lesions were located in a high-dose radiation area. Higher blood pressure was associated with CVD and a presence of WMHs. Higher cholesterol levels increased the risk of ischemic infarcts and WMHs, and lower levels of high-density lipoprotein and higher waist circumference increased the risk of lacunar infarcts.

Conclusions

Treating CBTs with radiotherapy increases the risk of early CVD and WMHs in young adult survivors. These results suggest an urgent need for investigating CVD prevention in CBT patients.

Management for Different Glioma Subtypes: Are All Low-Grade Gliomas Created Equal?

Following the identification of key molecular alterations that provided superior prognostication and led to the updated 2016 World Health Organization (WHO) Central Nervous System (CNS) Tumor Classification, the understanding of glioma behavior has rapidly evolved. Mutations in isocitrate dehydrogenase (IDH) 1 and 2 are present in the majority of adult grade 2 and 3 gliomas, and when used in conjunction with 1p/19q codeletion for classification, the prognostic distinction between grade 2 versus grade 3 is diminished. As such, the previously often used term of "low-grade glioma," which referred to grade 2 gliomas, has now been replaced by the phrase "lower-grade glioma" to encompass both grade 2 and 3 tumors. Additional molecular characterization is ongoing to even further classify this heterogeneous group of tumors. With such a colossal shift in the understanding of lower-grade gliomas, management of disease is being redefined in the setting of emerging molecular-genetic biomarkers. In this article, we review recent progress and future directions regarding the surgical, radiotherapeutic, chemotherapeutic, and long-term management of adult lower-grade gliomas.

Contrast enhancing spots as a new pattern of late onset pseudoprogression in glioma patients

INTRODUCTION

Magnet resonance imaging (MRI) of gliomas is assessed by Response Assessment in Neuro-Oncology Criteria (RANO), which define new contrast-enhancing lesions as a sign for tumor recurrence. Pseudoprogression after radiotherapy may mimic tumor progression in MRI but is usually limited to the first months after irradiation. We noted a late onset pattern of new contrast-enhancing spots (NCES) appearing years after radiotherapy.

METHODS

We prospectively collected 23 glioma patients with 26 NCES (three patients had two separate NCES events) between 2014 and 2016 in our weekly tumor board without further selection by diagnosis, molecular markers or pretreatment.

RESULTS

Retrospective analysis revealed a homogeneous collective of young patients (median age of 49 years at NCES) with mainly IDH-mutated glioma (61%). Initial histology showed 26% glioblastoma, 52% grade III and 22% grade II glioma. NCES occurred at late follow-up with a median of 52 months after tumor diagnosis and 30 months after the last radiotherapy. The majority of NCES regressed spontaneously within a median of 10 months (n = 11) or remained stable without further therapy with a median follow-up of 26 months (n = 7). Only 4 NCES developed MRI morphologically into tumor recurrence. Two NCES were resected without any histopathological proof of tumor recurrence, and in 2 other cases NCES were defined as ischemic stroke or radionecrosis.

CONCLUSION

We hypothesize that the late onset phenomenon of NCES predominantly represents a form of radiation-induced vasculopathy that is different from early pseudoprogression and should be considered especially in younger patients with IDH-mutated glioma before initiation of new therapy.

The management of childhood cancer survivors at risk for stroke: A Delphi survey of regional experts

BACKGROUND

Evidence is not available to guide management of childhood cancer survivors (CCS) at risk for radiation-associated cerebral vascular disease (CVD) and stroke. We propose to use a consensus-based methodology to describe the collective opinion of regional experts for the care of these patients and identify areas of controversy.

PROCEDURE

Thirty physicians from the New England region who care for CCS participated in a Delphi panel querying their management approach (imaging, laboratory tests, medications, counseling, referrals) to a CCS treated with cranial radiation formatted as five clinical scenarios (asymptomatic, small- and large-vessel CVD, transient ischemia, stroke) in three rounds of anonymous questionnaires. Consensus defined as ≥90% agreement.

RESULTS

Response rate was 100% for all three rounds. Panelists reached consensus on laboratory tests to assess stroke risk factors, stroke risk and prevention counseling, brain imaging to monitor survivors with known CVD, and acute care for stroke symptoms. Only 67% panelists agreed with MRI screening asymptomatic survivors with no history of CVD, 87% endorsed aspirin as stroke prevention for large-vessel CVD and 57% for small-vessel CVD. There was no consensus on specialty referrals. Overall, panelists practicing at large institutions and neurology subspecialists were more likely to advocate for screening, interventions, and referrals.

CONCLUSIONS

Despite lack of evidence to guide stroke prevention in CCS treated with cranial radiation, a panel of regional physicians reached consensus on managing most clinical scenarios. Controversial areas requiring further study are surveillance imaging for asymptomatic survivors, aspirin for stroke prevention, and indications for specialty referral.