The distribution of vascular endothelial growth factor-producing cells in clinical radiation necrosis of the brain: pathological consideration of their potential roles

Expression and distribution of hypoxia-inducible factor-1α and vascular endothelial growth factor in comparison between radiation necrosis and tumor tissue in metastatic brain tumor: A case report

We report the case of a 70-year-old woman with metastatic brain tumors who underwent surgical removal of the tumor and radiation necrosis. The patient had a history of colon cancer and had undergone surgical removal of a left occipital tumor. Histopathological evaluation revealed a metastatic brain tumor. The tumor recurred six months after surgical removal, followed by whole-brain radiotherapy, and the patient underwent stereotactic radiosurgery. Six months later, the perifocal edema had increased, and the patient became symptomatic. The diagnosis was radiation necrosis and corticosteroids were initially effective. However, radiation necrosis became uncontrollable, and the patient underwent removal of necrotic tissue two years after stereotactic radiosurgery. Pathological findings predominantly showed necrotic tissue with some tumor cells. Since the vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1α (HIF-1α) were expressed around the necrotic tissue, the main cause of the edema was determined as radiation necrosis. Differences in the expression levels and distribution of HIF-1α and VEGF were observed between treatment-naïve and recurrent tumor tissue and radiation necrosis. This difference suggests the possibility of different mechanisms for edema formation due to the tumor itself and radiation necrosis. Although distinguishing radiation necrosis from recurrent tumors using MRI remains challenging, the pathophysiological mechanism of perifocal edema might be crucial for differentiating radiation necrosis from recurrent tumors.

Reduction of acute radiation-induced brain injury in rats by anlotinib

OBJECTIVES

Radiation therapy in the treatment of brain tumors also leads to the occurrence of radiation brain injury (RBI). Anlotinib is a small-molecule inhibitor of multi-receptor tyrosine kinase with high selectivity for vascular endothelial growth factor receptor-2. In this study, we constructed a rat model of RBI and investigated the effect of anlotinib on RBI and its mechanism of action through drug intervention during the acute phase of RBI.

METHODS

Six-week-old male (Sprague-Dawley) rats were used to construct an animal model of RBI to evaluate the protective effect of anlotinib on acute RBI by histopathological staining, brain edema determination, blood-brain barrier integrity evaluation and quick real time-polymerase chain reaction , ELISA detection of inflammation-related indexes, and western-blot detection of related gene protein expression.

RESULTS

Anlotinib reduced the degree of edema in the hippocampal region of rats, improved the pathological morphology of neural cells and vascular endothelial cells, and decreased blood-brain barrier permeability. Anlotinib reduced glial fibrillary acidic protein protein expression in the hippocampal region of rat brain tissue and inhibited astrocyte activation. It inhibited the release of inflammatory factors (interleukin [IL]-6, IL-8 and vascular endothelial growth factor) and down-regulated the expression of janus kinase-2/signal transducer and activator of transcription-3 (JAK2/STAT3) signaling pathway-related proteins.

CONCLUSION

This study found that anlotinib has a protective effect against RBI in rats and anlotinib may be a new candidate for the treatment of RBI.

Can low-dose intravenous bevacizumab be as effective as high-dose bevacizumab for cerebral radiation necrosis?

Although intravenous bevacizumab (IVBEV) is the most promising treatment for cerebral radiation necrosis (CRN), there is no conclusion on the optimal dosage. Our retrospective study aimed to compare the efficacy and safety of high-dose with low-dose IVBEV in treating CRN associated with radiotherapy for brain metastases (BMs). This paper describes 75 patients who were diagnosed with CRN secondary to radiotherapy for BMs, treated with low-dose or high-dose IVBEV and followed up for a minimum of 6 months. The clinical data collected for this study include changes in brain MRI, clinical symptoms, and corticosteroid usage before, during, and after IVBEV treatment. At the 3-month mark following administration of IVBEV, a comparison of two groups revealed that the median percentage decreases in CRN volume on T2-weighted fluid-attenuated inversion recovery and T1-weighted gadolinium contrast-enhanced image (T1CE), as well as the signal ratio reduction on T1CE, were 65.8% versus 64.8% (p = 0.860), 41.2% versus 51.9% (p = 0.396), and 37.4% versus 35.1% (p = 0.271), respectively. Similarly, at 6 months post-IVBEV, the median percentage reductions of the aforementioned parameters were 59.5% versus 62.0% (p = 0.757), 39.1% versus 31.3% (p = 0.851), and 35.4% versus 28.2% (p = 0.083), respectively. Notably, the incidence of grade ≥3 adverse events was higher in the high-dose group (n = 4, 9.8%) than in the low-dose group (n = 0). Among patients with CRN secondary to radiotherapy for BMs, the administration of high-dose IVBEV did not demonstrate superiority over low-dose IVBEV. Moreover, the use of high-dose IVBEV was associated with a higher incidence of grade ≥3 adverse events compared with low-dose IVBEV.

Bevacizumab in the Treatment of Refractory Brain Edema in High-grade Glioma

We report the case of a 14-year-old boy with a steroid-dependent refractory tumor whose longstanding dexamethasone treatment was successfully discontinued after a course of bevacizumab. The use of bevacizumab despite the absence of clear evidence of radionecrosis allowed a significant decrease in the amount of the brain edema.

Whole brain radiation therapy resulting in radionecrosis: a possible link with radiosensitising chemoimmunotherapy

Radionecrosis describes a rare but serious complication of radiation therapy. In clinical practice, stereotactic radiosurgery (SRS) is increasingly used in combination with systemic therapy, including chemotherapy, immune checkpoint inhibitor and targeted therapy, either concurrently or sequentially. There is a paucity of literature regarding radionecrosis in patients receiving whole brain radiation therapy (WBRT) alone (without additional SRS) in combination with immunotherapy or targeted therapies. It is observed that certain combinations increase the overall radiosensitivity of the tumorous lesions. We present a rare case of symptomatic radionecrosis almost 1 year after WBRT in a patient with non-squamous non-small cell lung cancer on third-line chemoimmunotherapy. We discuss available research regarding factors that may lead to radionecrosis in these patients, including molecular and genetic profiles, specific drug therapy combinations and their timing or increased overall survival.

Bevacizumab reduces peritumoral brain edema in lung cancer brain metastases after radiotherapy

BACKGROUND

The aim of this study was to investigate the efficacy of bevacizumab (Bev) in reducing peritumoral brain edema (PTBE) after stereotactic radiotherapy (SRT) for lung cancer brain metastases.

METHODS

A retrospective analysis was conducted on 44 patients with lung cancer brain metastases (70 lesions) who were admitted to our oncology and Gamma Knife center from January 2020 to May 2022. All patients received intracranial SRT and had PTBE. Based on treatment with Bev, patients were categorized as SRT + Bev and SRT groups. Follow-up head magnetic resonance imaging was performed to calculate PTBE and tumor volume changes. The edema index (EI) was used to assess the severity of PTBE. Additionally, the extent of tumor reduction and intracranial progression-free survival (PFS) were compared between the two groups.

RESULTS

The SRT + Bev group showed a statistically significant difference in EI values before and after radiotherapy (p = 0.0115), with lower values observed after treatment, but there was no difference in the SRT group (p = 0.4008). There was a difference in the distribution of EI grades in the SRT + Bev group (p = 0.0186), with an increased proportion of patients at grades 1-2 after radiotherapy, while there was no difference in the SRT group (p > 0.9999). Both groups demonstrated a significant reduction in tumor volume after radiotherapy (p < 0.05), but there was no difference in tumor volume changes between the two groups (p = 0.4089). There was no difference in intracranial PFS between the two groups (p = 0.1541).

CONCLUSION

Bevacizumab significantly reduces the severity of PTBE after radiotherapy for lung cancer. However, its impact on tumor volume reduction and intracranial PFS does not reach statistical significance.

Pentoxifylline and Vitamin E Can Restrict Radiation Necrosis via Vascular Pathways, Experimental Study in an Animal Model

OBJECTIVE

Radiation necrosis (RN) is a long-term side effect of Gamma Knife stereotactic radiosurgery that may require surgical intervention. Pentoxifylline and vitamin E have previously been shown to be effective in the treatment of RN in the published literature, but there are no data on the prophylactic use of these molecules or, more importantly, whether prophylaxis is required.

METHODS

The iatrogenic RN model included 50 Sprague-Dawley rats of both sexes. There were 7 treatment subgroups established. Gamma-Plan 8.32 was used to plan after magnetic resonance scans were performed in a specially designed frame. The injection doses used in the treatment groups were vitamin E (30 mg/kg/day in a single dose) and pentoxifylline (50 mg/kg/day in 2 doses). Control magnetic resonance scans were performed at the end of a 16-week treatment, and the subjects were decapitated for pathological evaluations.

RESULTS

The intensity of hypoxia - inducible factor 1α immunoreactivity is statistically significantly lower in the therapeutic vitamin E, prophylactic pentoxifylline and vitamin E, and therapeutic pentoxifylline and vitamin E groups than in the other groups. Similarly, the intensity of vascular endothelial growth factor immunoreactivity was reduced in the therapeutic vitamin E and prophylactic pentoxifylline and vitamin E treatment modality groups. When compared with other groups, the therapeutic pentoxifylline group had significantly fewer vascular endothelial growth factor-immunoreactive cells in the perinecrotic area, with an accompanying decreased contrast enhancement pattern.

CONCLUSIONS

Both vitamin E and pentoxifylline are effective for the treatment and/or restriction of RN, either alone or in combination. The use of these molecules as a preventive measure did not outperform the therapeutic treatment.

Effect of Bevacizumab Treatment in Cerebral Radiation Necrosis : Investigation of Response Predictors in a Single-Center Experience

OBJECTIVE

Bevacizumab is a feasible option for treating cerebral radiation necrosis (RN). We investigated the clinical outcome of RN after treatment with bevacizumab and factors related to the initial response and the sustained effect.

METHODS

Clinical data of 45 patients treated for symptomatic RN between September 2019 and February 2021 were retrospectively collected. Bevacizumab (7.5 mg/kg) was administered at 3-week intervals with a maximum four-cycle schedule. Changes in the lesions magnetic resonance image (MRI) scans were examined for the response evaluation. The subgroup analysis was performed based on the initial response and the long-term maintenance of the effect.

RESULTS

Of the 45 patients, 36 patients (80.0%) showed an initial response, and eight patients (17.8%) showed delayed worsening of the corresponding lesion. The non-responders showed a significantly higher incidence of diffusion restriction on MRI than the responders (100.0% vs. 25.0%, p<0.001). The delayed worsening group showed a significantly higher proportion of glioma pathology than the maintenance group (87.5% vs. 28.6%, p=0.005). Cumulative survival rates with sustained effect were significantly higher in the groups with non-glioma pathology (p=0.019) and the absence of diffusion restriction (p<0.001). Pathology of glioma and diffusion restriction in MRI were the independent risk factors for non-response or delayed worsening after initial response.

CONCLUSION

The initial response of RN to bevacizumab was favorable, with improvement in four-fifths of the patients. However, a certain proportion of patients showed non-responsiveness or delayed exacerbations. Bevacizumab may be more effective in treating RN in patients with non-glioma pathology and without diffusion restriction in the MRI.

Radionecrosis mimicking pseudo‑progression in a patient with lung cancer and brain metastasis following the combination of anti‑PD‑1 therapy and stereotactic radiosurgery: A case report

Brain metastases (BMs) usually develop in patients with non-small cell lung cancer. In addition to systemic therapy, radiation therapy and surgery, anti-programmed cell death-ligand 1 (PD-L1) therapy is another promising clinical anticancer treatment modality. However, the optimal timing and drug-drug interactions of anti-PD-L1 therapy with other combined treatments remain to be elucidated. Treatment with anti-PD-L1 therapy is associated with an increased risk of radionecrosis (RN) regardless of tumor histology. The present study described a case of RN in a patient with lung adenocarcinoma and with BM who received anti-PD-L1 therapy. Before anti-PD-L1 treatment, the patient received whole brain radiotherapy. During durvalumab treatment, the intracranial metastases regressed. The progression of intracranial lesions 9 months later prompted a second-line of therapy with PD-L1 inhibitor durvalumab and stereotactic radiotherapy (SRT). Despite stereotactic irradiation, the lesions progressed further, leading to surgical resection. On examination, RN was detected, but there was no evidence of metastatic lung cancer. The aim of the present study was to present the longitudinal change in magnetic resonance imaging in RN following STR and anti-PD-L1 combined therapy. The atypical image of RN is conditionally important for making an accurate preoperative diagnosis.

Mechanistic approach of the therapeutic potential of mesenchymal stem cells on brain damage in irradiated mice: emphasis on anti-inflammatory and anti-apoptotic effects

BACKGROUND AND OBJECTIVES

Brain damage which has been induced by radiation generally occurs in radiotherapeutics patients. Stem cell transplantation represents a vital applicant for alleviating neurodegenerative disorders. This work aims at exploring the potential of bone marrow-derived mesenchymal stem cells (BM-MSCs) on brain injury induced by γ radiation in mice and the possible underlying mechanisms were elucidated.

MATERIALS AND METHODS

Mice were allocated into three groups; Group I (Control), Group II (Irradiated control) where mice submitted to 5 Gy of whole-body γ radiation, Group III (Irradiated + BM-MSCs) where mice were intravenously injected of BM-MSCs at a dose of 106 cells/mice 24 h following irradiation. Animals were sacrificed 28 d following exposure to γ radiation.

RESULTS

It was observed that BM-MSCs therapy provided a valuable tissue repair as evidenced by a reduction in inflammatory mediators including tumor necrosis factor alpha (TNF-α), interleukin-1β (IL-1β), nuclear factor kappa (NF-κβ), phosphorylated NF-κβ-p65 (P-NF-κβ-p65), interferon-gamma (IFNγ) and monocyte chemoattractant protein-1 (MCP-1) associated with decreased levels of transforming growth factor-β (TGF-β) and vascular endothelial growth factor (VEGF) in brain tissues of irradiated mice. Furthermore, neuronal apoptosis was declined in brain tissues of the BM-MSCs group as remarkable inhibition of caspase-3 and Bax accompanied by elevation of Bcl-2 proteins expression. These results were supported by histopathological investigation.

CONCLUSIONS

In conclusion, BM-MSCs could display a vital rule in alleviating brain injury in radio-therapeutic patients.

A Multi-Disciplinary Approach to Diagnosis and Treatment of Radionecrosis in Malignant Gliomas and Cerebral Metastases

Radiation necrosis represents a potentially devastating complication after radiation therapy in brain tumors. The establishment of the diagnosis and especially the differentiation from progression and pseudoprogression with its therapeutic implications requires interdisciplinary consent and monitoring. Herein, we want to provide an overview of the diagnostic modalities, therapeutic possibilities and an outlook on future developments to tackle this challenging topic. The aim of this report is to provide an overview of the current morphological, functional, metabolic and evolving imaging tools described in the literature in order to (I) identify the best criteria to distinguish radionecrosis from tumor recurrence after the radio-oncological treatment of malignant gliomas and cerebral metastases, (II) analyze the therapeutic possibilities and (III) give an outlook on future developments to tackle this challenging topic. Additionally, we provide the experience of a tertiary tumor center with this important issue in neuro-oncology and provide an institutional pathway dealing with this problem.

Susceptibility-weighted imaging cannot distinguish radionecrosis from recurrence in brain metastases after radiotherapy: a comparison with high-grade gliomas

AIM

To explore the efficiency of susceptibility-weighted imaging (SWI) in the differential diagnosis of recurrence from radionecrosis in brain metastases (BM) and in high-grade gliomas (HGG).

MATERIALS AND METHODS

From September 2016 to November 2018, 56 patients with BM and 42 patients with HGG were included in this retrospective study. BM and HGG were assigned to the recurrence and radionecrosis groups according to their histopathology or follow-up results. The proportion of dark signal intensity (proDSI), which was defined as the area of dark signal on SWI or the enhancing area on contrast-enhanced T1-weighted imaging (T1WI), was calculated for each patient. Analysis of variance (ANOVA) with Tukey's honestly significant difference test was used for the repeat multiple comparisons. Receiver operating characteristic curve analysis was performed to validate the diagnostic performance.

RESULTS

For HGG, the proDSI in the recurrence group was significantly lower than that in the radionecrosis group (0.13 ± 0.05 versus 0.43 ± 0.11, p<0.001); however, for BM, no statistical difference was found between groups (0.49 ± 0.09 versus 0.46 ± 0.08, p=0.26). proDSI had the best diagnostic performance (AUC = 0.87, 95% CI: 0.76-0.98; sensitivity = 0.87; specificity = 0.88) for HGG, when a cut-off value of 0.21 was selected.

CONCLUSIONS

Semi-quantitative analysis using SWI is feasible for the differential diagnosis between recurrence and radionecrosis in HGG, but is not feasible in BM. Semi-quantitative assessment based on SWI should interpreted with caution in BM after radiotherapy in clinical practice.

Systemic Therapy Type and Timing Effects on Radiation Necrosis Risk in HER2+ Breast Cancer Brain Metastases Patients Treated With Stereotactic Radiosurgery

Background

There is a concern that HER2-directed systemic therapies, when administered concurrently with stereotactic radiosurgery (SRS), may increase the risk of radiation necrosis (RN). This study explores the impact of timing and type of systemic therapies on the development of RN in patients treated with SRS for HER2+ breast cancer brain metastasis (BCBrM).

Methods

This was a single-institution, retrospective study including patients >18 years of age with HER2+ BCBrM who received SRS between 2013 and 2018 and with at least 12-month post-SRS follow-up. Presence of RN was determined via imaging at one-year post-SRS, with confirmation by biopsy in some patients. Demographics, radiotherapy parameters, and timing (“during” defined as four weeks pre- to four weeks post-SRS) and type of systemic therapy (e.g., chemotherapy, HER2-directed) were evaluated.

Results

Among 46 patients with HER2+ BCBrM who received SRS, 28 (60.9%) developed RN and 18 (39.1%) did not based on imaging criteria. Of the 11 patients who underwent biopsy, 10/10 (100%) who were diagnosed with RN on imaging were confirmed to be RN positive on biopsy and 1/1 (100%) who was not diagnosed with RN was confirmed to be RN negative on biopsy. Age (mean 53.3 vs 50.4 years, respectively), radiotherapy parameters (including total dose, fractionation, CTV and size target volume, all p>0.05), and receipt of any type of systemic therapy during SRS (60.7% vs 55.6%, p=0.97) did not differ between patients who did or did not develop RN. However, there was a trend for patients who developed RN to have received more than one agent of HER2-directed therapy independent of SRS timing compared to those who did not develop RN (75.0% vs 44.4%, p=0.08). Moreover, a significantly higher proportion of those who developed RN received more than one agent of HER2-directed therapy during SRS treatment compared to those who did not develop RN (35.7% vs 5.6%, p=0.047).

Conclusions

Patients with HER2 BCBrM who receive multiple HER2-directed therapies during SRS for BCBrM may be at higher risk of RN. Collectively, these data suggest that, in the eight-week window around SRS administration, if HER2-directed therapy is medically necessary, it is preferable that patients receive a single agent.

Bevacizumab is an effective treatment for symptomatic cerebral necrosis after carbon ion therapy for recurrent intracranial malignant tumours: A case report

Carbon ion therapy (CIT) is a form of particle therapy, which not only spares normal tissues but may also improve local control of recurrent intracranial tumours. Cerebral radiation necrosis (RN) is one of the most serious adverse reactions of recurrent brain tumours following reirradiation, which may lead to neurological decline or even death. Bevacizumab is an anti-vascular endothelial growth factor antibody, which has been used to treat symptomatic RN. However, studies on bevacizumab for the treatment of CIT-induced RN are sparse. The present study described two cases that were successfully treated with bevacizumab for symptomatic RN following CIT for recurrent intracranial malignant tumours. The two recurrent intracranial malignant tumours, a chondrosarcoma in the right cavernous sinus and an anaplastic meningioma in the right frontal lobe, were enrolled in a clinical trial of CIT. Both cases were treated intravenously with bevacizumab when deterioration that appeared to be symptomatic brain RN was observed. Just before CIT, enhanced magnetic resonance imaging (MRI) was performed in each case to confirm tumour recurrence. Both cases exhibited a deterioration in symptoms, as well as on MRI, at 12-month intervals following CIT. The first case underwent positron emission tomography/computed tomography to confirm no increase in fluorodeoxyglucose uptake in lesion areas. Both cases were diagnosed as having symptomatic brain RN and began intravenous administration of four cycles of 5 mg/kg bevacizumab biweekly. The patients responded well, with rapid and marked improvements on MRI, and in clinical symptoms. No tumour progression was observed 24 months after CIT. In conclusion, bevacizumab was revealed to exert marked effects on symptomatic brain RN following CIT. Notably, cycles of bevacizumab should be administered specifically based on the aim of treating brain necrosis, and long-term or prophylactic applications are not recommended.

Single low-dose targeted bevacizumab infusion in adult patients with steroid-refractory radiation necrosis of the brain: a phase II open-label prospective clinical trial

OBJECTIVE

There is an unmet need for safe and rapidly effective therapies for refractory brain radiation necrosis (RN). The aim of this prospective single-arm phase II trial was to evaluate the safety and efficacy of a single low-dose targeted bevacizumab infusion after blood-brain barrier disruption (BBBD) in adult patients with steroid-refractory brain RN.

METHODS

Ten adults with steroid-refractory, imaging-confirmed brain RN were enrolled between November 2016 and January 2018 and followed for 12 months after treatment. Bevacizumab 2.5 mg/kg was administered as a one-time targeted intra-arterial infusion immediately after BBBD. Primary outcomes included safety and > 25% decrease in lesion volume. Images were analyzed by a board-certified neuroradiologist blinded to pretrial diagnosis and treatment status. Secondary outcomes included changes in headache, steroid use, and functional status and absence of neurocognitive sequelae. Comparisons were analyzed using the Fisher exact test, Mann-Whitney U-test, linear mixed models, Wilcoxon signed-rank test, and repeated-measures 1-way ANOVA.

RESULTS

Ten adults (mean ± SD [range] age 35 ± 15 [22–62] years) participated in this study. No patients died or exhibited serious adverse effects of systemic bevacizumab. At 3 months, 80% (95% CI 44%–98%) and 90% (95% CI 56%–100%) of patients demonstrated > 25% decrease in RN and vasogenic edema volume, respectively. At 12 months, RN volume decreased by 74% (median [range] 76% [53%–96%], p = 0.012), edema volume decreased by 50% (median [range] 70% [−11% to 83%], p = 0.086), and headache decreased by 84% (median [range] 92% [58%–100%], p = 0.022) among the 8 patients without RN recurrence. Only 1 (10%) patient was steroid dependent at the end of the trial. Scores on 12 of 16 (75%) neurocognitive indices increased, thereby supporting a pattern of cerebral white matter recovery. Two (20%) patients exhibited RN recurrence that required further treatment at 10 and 11 months, respectively, after bevacizumab infusion.

CONCLUSIONS

For the first time, to the authors’ knowledge, the authors demonstrated that a single low-dose targeted bevacizumab infusion resulted in durable clinical and imaging improvements in 80% of patients at 12 months after treatment without adverse events attributed to bevacizumab alone. These findings highlight that targeted bevacizumab may be an efficient one-time treatment for adults with brain RN. Further confirmation with a randomized controlled trial is needed to compare the intra-arterial approach with the conventional multicycle intravenous regimen.

Clinical trial registration no.: NCT02819479 (ClinicalTrials.gov)

Impact of Gut Microbiota on Radiation-Associated Cognitive Dysfunction and Neuroinflammation in Mice

Radiation-induced brain injury is a common complication of brain irradiation that eventually leads to irreversible cognitive impairment. Evidence has shown that the gut microbiome may play an important role in radiation-induced cognitive function. However, the effects of gut microbiota on radiation-induced brain injury (RIBI) remain poorly understood. Here we studied the link between intestinal microbes and radiation-induced brain injury to further investigate the effects of intestinal bacteria on neuroinflammation and cognitive function. We first verified the differences in gut microbes between male and female mice and administered antibiotics to C57BL/6 male mice to deplete the gut flora and then expose mice to radiation. We found that depletion of intestinal flora after irradiation may act as a protective modulator against radiation-induced brain injury. Moreover, we found that pretreatment with depleted gut microbes in RIBI mice suppressed brain pro-inflammatory factor production, and high-throughput sequencing analysis of mouse feces at 1-month postirradiation revealed microbial differences. Interestingly, a proportion of Verrucomicrobia Akkermansia showed partial recovery. Additionally, short-chain fatty acid treatments increased neuroinflammation in the radiation-induced brain injury model. Although a further increase in cognitive function was not observed, brain injury was aggravated in whole-brain irradiated mice to some extent. The protective effects of depleted intestinal flora and the utilization of the brain-gut axis open new avenues for development of innovative therapeutic strategies for radiation-induced brain injury.

The Tumor Control According to Radiation Dose of Gamma Knife Radiosurgery for Small and Medium-Sized Brain Metastases from Non-Small Cell Lung Cancer

Objective

The effectiveness of gamma knife radiosurgery (GKR) in the treatment of brain metastases is well established. The aim of this study was to evaluate the efficacy and safety of maximizing the radiation dose in GKR and the factors influencing tumor control in cases of small and medium-sized brain metastases from non-small cell lung cancer (NSCLC).

Methods

We analyzed 230 metastatic brain tumors less than 5 mL in volume in 146 patients with NSCLC who underwent GKR. The patients had no previous radiation therapy for brain metastases. The pathologies of the tumors were adenocarcinoma (n=207), squamous cell carcinoma (n=18), and others (n=5). The radiation doses were classified as 18, 20, 22, and 24 Gy, and based on the tumor volume, the tumors were categorized as follows : small-sized (less than 1 mL) and medium-sized (1–3 and 3–5 mL). The progression-free survival (PFS) of the individual 230 tumors and 146 brain metastases was evaluated after GKR depending on the pathology, Eastern Cooperative Oncology Group (ECOG) performance score (PS), tumor volume, radiation dose, and anti-cancer regimens. The radiotoxicity after GKR was also evaluated.

Results

After GKR, the restricted mean PFS of individual 230 tumors at 24 months was 15.6 months (14.0–17.1). In small-sized tumors, as the dose of radiation increased, the tumor control rates tended to increase (p=0.072). In medium-sized tumors, there was no statistically difference in PFS with an increase of radiation dose (p=0.783). On univariate analyses, a statistically significant increase in PFS was associated with adenocarcinomas (p=0.001), tumors with ECOG PS 0 (p=0.005), small-sized tumors (p=0.003), radiation dose of 24 Gy (p=0.014), synchronous lesions (p=0.002), and targeted therapy (p=0.004). On multivariate analyses, an improved PFS was seen with targeted therapy (hazard ratio, 0.356; 95% confidence interval, 0.150–0.842; p=0.019). After GKR, the restricted mean PFS of brain at 24 months was 9.8 months (8.5–11.1) in 146 patients, and the pattern of recurrence was mostly distant within the brain (66.4%). The small and medium-sized tumors treated with GKR showed radiotoxicitiy in five out of 230 tumors (2.2%), which were controlled with medical treatment.

Conclusion

The small-sized tumors were effectively controlled without symptomatic radiation necrosis as the radiation dose was increased up to 24 Gy. The medium-sized tumors showed potential for symptomatic radiation necrosis without signifcant tumor control rate, when greater than 18 Gy. GKR combined targeted therapy improved the tumor control of GKR-treated tumors.

Radiation therapy-associated toxicity: Etiology, management, and prevention

Radiation therapy (RT) is a curative treatment for many malignancies and provides effective palliation in patients with tumor-related symptoms. However, the biophysical effects of RT are not specific to tumor cells and may produce toxicity due to exposure of surrounding organs and tissues. In this article, the authors review the clinical context, pathophysiology, risk factors, presentation, and management of RT side effects in each human organ system. Ionizing radiation works by producing DNA damage leading to tumor death, but effects on normal tissue may result in acute and/or late toxicity. The manifestation of toxicity depends on both cellular characteristics and affected organs' anatomy and physiology. There is usually a direct relationship between the radiation dose and volume to normal tissues and the risk of toxicity, which has led to guidelines and recommended dose limits for most tissues. Side effects are multifactorial, with contributions from baseline patient characteristics and other oncologic treatments. Technological advances in recent decades have decreased RT toxicity by dramatically improving the ability to deliver RT that maximizes tumor dose and minimizes organ dose. Thus the study of RT-associated toxicity is a complex, core component of radiation oncology training that continues to evolve alongside advances in cancer management. Because RT is used in up to one-half of all patients with cancer, an understanding of its acute and late effects in different organ systems is clinically pertinent to both oncologists and nononcologists.

Research progress on mechanism and imaging of temporal lobe injury induced by radiotherapy for head and neck cancer

Radiotherapy (RT) is an effective treatment for head and neck cancer (HNC). Radiation-induced temporal lobe injury (TLI) is a serious complication of RT. Late symptoms of radiation-induced TLI are irreversible and manifest as memory loss, cognitive impairment, and even temporal lobe necrosis (TLN). It is currently believed that the mechanism of radiation-induced TLI involves microvascular injury, neuron and neural stem cell injury, glial cell damage, inflammation, and the production of free radicals. Significant RT-related structural changes and dose-dependent changes in gray matter (GM) and white matter (WM) volume and morphology were observed through computed tomography (CT) and magnetic resonance imaging (MRI) which were common imaging assessment tools. Diffusion tensor imaging (DTI), dispersion kurtosis imaging (DKI), susceptibility-weighted imaging (SWI), resting-state functional magnetic resonance (rs-fMRI), magnetic resonance spectroscopy (MRS), and positron emission tomography (PET) can be used for early diagnosis and prognosis evaluation according to functional, molecular, and cellular processes of TLI. Early diagnosis of TLI is helpful to reduce the incidence of TLN and its related complications. This review summarizes the clinical features, mechanisms, and imaging of radiation-induced TLI in HNC patients. KEY POINTS: • Radiation-induced temporal lobe injury (TLI) is a clinical complication and its symptoms mainly include memory impairment, headache, and cognitive impairment. • The mechanisms of TLI include microvascular injury, cell injury, and inflammatory and free radical injury. Significant RT-related structural changes and dose-dependent changes in TL volume and morphology were observed through CT and MRI. • SWI, MRS, DTI, and DKI and other imaging examinations can detect anatomical and functional, molecular, and cellular changes of TLI.

Under-recognized toxicities of cranial irradiation

Cranial irradiation of primary or metastatic lesions is frequent, historically with 3D-conformal radiation therapy and now with stereotactic radiosurgery and intensity modulation. Evolution of radiotherapy technique is concomitant to systemic treatment evolution permitting long time survival. Thus, physicians have to face underestimated toxicities on long-survivor patients and unknown toxicities from combination of cranial radiotherapy to new therapeutics as targeted therapies and immunotherapies. This article proposes to develop these toxicities, without being exhaustive, to allow a better apprehension of cranial irradiation in current context.

Bevacizumab for stereotactic radiosurgery-induced radiation necrosis in patients with non-small cell lung cancer treated with immune check-point inhibitors

BACKGROUND

Bevacizumab was shown to be effective in the treatment of brain radiation necrosis (RN) attributed to the use of stereotactic radiosurgery (SRS). Data on its efficacy and safety in non-small cell lung cancer (NSCLC) patients treated with immune check-point inhibitors (ICI) is lacking.

METHODS

A multi-center retrospective analysis of all consecutive patients with NSCLC treated with ICI, who received bevacizumab for post-SRS RN between April 2017 and June 2020. Improvement in RN-associated symptoms, RN radiological improvement, and decrease in corticosteroid dose following bevacizumab initiation were assessed.

RESULTS

Thirteen patients were identified. The median time from diagnosis of RN to initiation of bevacizumab was 3 months (range 1.1-7.8 months), and the median number of bevacizumab cycles before assessment was 2 (range, 1-5). Patients continued ICI during treatment with bevacizumab. Improvement in RN-associated symptoms was observed in 11 patients (85%). In ten patients (77%) the daily dose of dexamethasone was decreased. Radiological improvement of RN occurred in all 11 cases available for radiological assessment (100%). Treatment was withheld in two patients for grade 3-4 toxicity. At a median follow up of 11.9 months (range 2.0-35.4 months), one patient experienced a recurrent episode of RN; the estimated median survival since RN diagnosis was 21.9 months (95% CI 3.8-40.2 months).

CONCLUSION

Treatment with bevacizumab appears to be safe and effective for the treatment of SRS-induced RN in patients with NSCLC treated with ICI. This is the first series to report on the use of bevacizumab in this clinical scenario.

Radiation Necrosis from Stereotactic Radiosurgery-How Do We Mitigate?

OPINION STATEMENT

Intracranial stereotactic radiosurgery (SRS) is an effective and convenient treatment for many brain conditions. Data regarding safety come mostly from retrospective single institutional studies and a small number of prospective studies. Variations in target delineation, treatment delivery, imaging follow-up protocols and dose prescription limit the interpretation of this data. There has been much clinical focus on radiation necrosis (RN) in particular, as it is being increasingly recognized on follow-up imaging. Symptomatic RN may be treated with medical therapy (such as corticosteroids and bevacizumab) with surgical resection being reserved for refractory patients. Nevertheless, RN remains a challenging condition to manage, and therefore upfront patient selection for SRS remains critical to provide complication-free control. Mitigation strategies need to be considered in situations where the baseline risk of RN is expected to be high-such as large target volume or re-irradiation. These may involve reduction in the prescribed dose or hypofractionated stereotactic radiation therapy (HSRT). Recently published guidelines and international meta-analysis report the benefit of HSRT in larger lesions, without compromising control rates. However, careful attention to planning parameters and SRS techniques still need to be adhered, even with HSRT. In cases where the risk is deemed to be high despite mitigation, a combination approach of surgery with or without post-operative radiation should be considered.

Iatrogenic cerebral radiation necrosis

Cerebral radiation necrosis is the most serious late reaction to high doses of ionising radiation to the brain, and its treatment is generally unsatisfactory. We present a patient who developed cerebral radiation necrosis after protracted fluoroscopy during repeated embolisations of an extracranial arteriovenous malformation. Treatment with bevacizumab (a humanised murine monoclonal antibody against vascular endothelial growth factor) was followed by neurological and radiological improvements.

Accelerator-based BNCT for patients with recurrent glioblastoma: a multicenter phase II study

Background

Boron neutron capture therapy (BNCT) utilizes tumor-selective particle radiation. This study aimed to assess the safety and efficacy of accelerator-based BNCT (AB-BNCT) using a cyclotron-based neutron generator (BNCT 30) and ¹⁰B-boronophenylalanine (SPM-011) in patients with recurrent malignant glioma (MG) (primarily glioblastoma [GB]).

Methods

This multi-institutional, open-label, phase II clinical trial involved 27 recurrent MG cases, including 24 GB cases, who were enrolled from February 2016 to June 2018. The study was conducted using the abovementioned AB-BNCT system, with 500 mg/kg SPM-011 (study code: JG002). The patients were bevacizumab-naïve and had recurrent MG after standard treatment. The primary endpoint was the 1-year survival rate, and the secondary endpoints were overall survival (OS) and progression-free survival (PFS). Results were compared to those of a previous Japanese domestic bevacizumab trial for recurrent GB (JO22506).

Results

The 1-year survival rate and median OS of the recurrent GB cases in this trial were 79.2% (95% CI: 57.0–90.8) and 18.9 months (95% CI: 12.9–not estimable), respectively, whereas those of JO22506 were 34.5% (90% CI: 20.0–49.0) and 10.5 months (95% CI: 8.2–12.4), respectively. The median PFS was 0.9 months (95% CI: 0.8–1.0) by the RANO criteria. The most prominent adverse event was brain edema. Twenty-one of 27 cases were treated with bevacizumab following progressive disease.

Conclusions

AB-BNCT demonstrated acceptable safety and prolonged survival for recurrent MG. AB-BNCT may increase the risk of brain edema due to re-irradiation for recurrent MG; however, this appears to be controlled well with bevacizumab.

A retrospective analysis of GSE84010: Cell adhesion molecules might contribute to bevacizumab resistance in glioblastoma

Bevacizumab (BEV) is an anti-angiogenesis antibody which has shown favorable therapeutic effects on some solid tumors. However, many clinical trials showed that BEV could only improve PFS instead of OS in glioblastoma (GBM) patients. However, some studies indicate that specific molecular subtypes of GBM could still benefit from combination treatment of BEV and Stupp protocol. Through the subgroup analysis of GSE84010 dataset, we found the neural and proneural subgroup can benefit from the administration of BEV in terms of OS, which is statistically significant. The further KEGG pathway enrichment analysis showed cell adhesion molecules (CAMs) pathway was enriched, and the expression of ITGAM has a predictive value for prognosis. These findings can provide some hints for future administration of BEV in newly diagnosed GBM patients.

Perspective of mesenchymal transformation in glioblastoma

Despite aggressive multimodal treatment, glioblastoma (GBM), a grade IV primary brain tumor, still portends a poor prognosis with a median overall survival of 12–16 months. The complexity of GBM treatment mainly lies in the inter- and intra-tumoral heterogeneity, which largely contributes to the treatment-refractory and recurrent nature of GBM. By paving the road towards the development of personalized medicine for GBM patients, the cancer genome atlas classification scheme of GBM into distinct transcriptional subtypes has been considered an invaluable approach to overcoming this heterogeneity. Among the identified transcriptional subtypes, the mesenchymal subtype has been found associated with more aggressive, invasive, angiogenic, hypoxic, necrotic, inflammatory, and multitherapy-resistant features than other transcriptional subtypes. Accordingly, mesenchymal GBM patients were found to exhibit worse prognosis than other subtypes when patients with high transcriptional heterogeneity were excluded. Furthermore, identification of the master mesenchymal regulators and their downstream signaling pathways has not only increased our understanding of the complex regulatory transcriptional networks of mesenchymal GBM, but also has generated a list of potent inhibitors for clinical trials. Importantly, the mesenchymal transition of GBM has been found to be tightly associated with treatment-induced phenotypic changes in recurrence. Together, these findings indicate that elucidating the governing and plastic transcriptomic natures of mesenchymal GBM is critical in order to develop novel and selective therapeutic strategies that can improve both patient care and clinical outcomes. Thus, the focus of our review will be on the recent advances in the understanding of the transcriptome of mesenchymal GBM and discuss microenvironmental, metabolic, and treatment-related factors as critical components through which the mesenchymal signature may be acquired. We also take into consideration the transcriptomic plasticity of GBM to discuss the future perspectives in employing selective therapeutic strategies against mesenchymal GBM.

Successful Treatment of Combined Large Cell Neuroendocrine Carcinoma Harboring an EGFR Mutation with EGFR-TKIs plus Bevacizumab: A Case Report

Large cell neuroendocrine carcinoma (LCNEC) of the lung with epidermal growth factor receptor (EGFR) mutation is rare, and few cases have been treated with EGFR tyrosine kinase inhibitors (TKIs). We report the treatment of combined LCNEC with adenocarcinoma harboring an EGFR mutation with EGFR-TKIs and bevacizumab. Our patient was a 70-year-old asymptomatic woman who underwent surgical resection of the lung for combined LCNEC with adenocarcinoma harboring an activating EGFR mutation 11 months previously. Magnetic resonance imaging (MRI) and positron emission tomography revealed metastatic lesions in the brain and lung. The patient was diagnosed with recurrence of combined LCNEC with adenocarcinoma. The brain lesion was irradiated, followed by administration of afatinib. Eight months after irradiation, brain MRI revealed ringed enhancement and perilesional edema after radiotherapy without new metastatic lesions. We switched treatment to erlotinib and bevacizumab, resulting in maintenance of stable disease for 10 months. Overall, the disease was controlled for 18 months with EGFR-TKIs and bevacizumab. Combination treatment with EGFR-TKIs and bevacizumab could be a treatment option for LCNEC of the lung harboring EGFR mutations, especially with brain metastasis.

A Comparison of Ramipril and Bevacizumab to Mitigate Radiation-Induced Brain Necrosis: An Experimental Study

BACKGROUND

Bevacizumab, an anti-vascular endothelial growth factor (VEGF) antibody, is a new treatment approach for radionecrosis. In our study, we compared the prophylactic and therapeutic usage of a promising agent, ramipril (an angiotensin-converting enzyme inhibitor), with that of bevacizumab for reducing radiation-induced brain injury after high-dose stereotactic radiosurgery (SRS).

METHODS

A total of 60 Wistar rats were used. The rats were irradiated with a single dose of 50 Gy using a Leksell Gamma Knife device. Bevacizumab and ramipril were administered in the prophylactic protocol (starting the first day of SRS) and in the therapeutic protocol (starting the fourth week of SRS). Their usage was continued until 12 weeks, and the right frontal lobes of the rats were examined histologically (hematoxylin and eosin stain) and immunohistochemically (hypoxia-inducible factor [HIF]-1α, VEGF, and CD31 antibody expression).

RESULTS

The expression of VEGF, HIF-1α, and CD31 had significantly increased at 12 weeks after SRS compared with the control group. The addition of bevacizumab or ramipril to SRS significantly mitigated the histological severity of radiation injury and the expression of VEGF, HIF-1α, and CD31. However, the prophylactic use of bevacizumab and ramipril seemed to be more effective than therapeutic administration. Our results also revealed that the greatest benefit was achieved with the use of prophylactic administration of bevacizumab compared with other treatment protocols.

CONCLUSIONS

Ramipril might be a promising agent for patients with radionecrosis. Clinical studies are required to investigate the effective and safe doses of ramipril, which is an inexpensive, well-tolerated drug that can cross the blood-brain barrier.

Brain Metastasis Recurrence Versus Radiation Necrosis: Evaluation and Treatment

Radiation necrosis (RN) occurs in 5% to 25% of patients with brain metastases treated with stereotactic radiosurgery. RN must be distinguished from recurrent tumor to determine appropriate treatment. Stereotactic biopsy remains the gold standard for identifying RN. Initial treatment of RN often involves management of edema using corticosteroids, antiangiogenic therapies, and hyperbaric oxygen therapy. For refractory symptoms, surgical resection can be considered. Minimally invasive stereotactic laser ablation has the benefit of providing tissue diagnosis and treating RN or recurrent tumor with similar efficacy. Laser ablation should be considered for lesions in need of intervention where the diagnosis requires tissue confirmation.

Bevacizumab-refractory radiation necrosis with pathologic transformation of benign meningioma following adjuvant gamma knife radiosurgery: A rare case report

RATIONALE

Bevacizumab has shown good efficacy in radiation necrosis (RN) following gamma knife radiosurgery (GKRS) and associated peritumoral edema. However, few studies have reported bevacizumab failure. Moreover, the pathologic transformation of benign meningioma following GKRS has never been reported.

PATIENTS CONCERNS

A 41-year-old man was admitted with focal seizure on the right arm.

DIAGNOSES

Magnetic resonance imaging (MRI) demonstrated a 4.7 cm-sized convexity meningioma involving left motor cortex.

INTERVENTIONS

Subtotally resected tumor was confirmed as a meningothelial meningioma and subsequently treated by GKRS. During 4-year follow-up after GKRS, seizure and hemiparesis had persisted with progressively worsened peritumoral edema regardless of steroid and bevacizumab treatment. Radical debulking of tumor was achieved and immunohistopathological examination revealed angiomatous meningioma with necrotic core presenting scanty VEGF expression.

OUTCOMES

A follow-up MRI at 4 months after debulking surgery showed a marked reduction of peritumoral edema with improvement of symptoms.

LESSONS

This is the first report of pathologically confirmed angiomatous transformation following GKRS. Although the pathogenesis is not fully understood, this rare pathologic transformation may be closely related to RN. Also, if bevacizumab is resistant, debulking surgery for reducing tumor burden could be an effective treatment option to control the RN.

Laser interstitial thermal therapy (LITT) vs. bevacizumab for radiation necrosis in previously irradiated brain metastases

PURPOSE

Both laser interstitial thermal therapy (LITT) and bevacizumab have been used successfully to treat radiation necrosis (RN) after radiation for brain metastases. Our purpose is to compare pre-treatment patient characteristics and outcomes between the two treatment options.

METHODS

Single-institution retrospective chart review identified brain metastasis patients who developed RN between 2011 and 2018. Pre-treatment factors and treatment responses were compared between those treated with LITT versus bevacizumab.

RESULTS

Twenty-five patients underwent LITT and 13 patients were treated with bevacizumab. The LITT cohort had a longer overall survival (median 24.8 vs. 15.2 months for bevacizumab, p = 0.003) and trended to have a longer time to local recurrence (median 12.1 months vs. 2.0 for bevacizumab), although the latter failed to achieve statistical significance (p = 0.091). LITT resulted in an initial increase in lesional volume compared to bevacizumab (p < 0.001). However, this trend reversed in the long term follow-up, with LITT resulting in a median volume decrease at 1 year post-treatment of - 64.7% (range - 96.0% to +  > 100%), while bevacizumab patients saw a median volume increase of +  > 100% (range - 63.0% to +  > 100%), p = 0.010.

CONCLUSIONS

Our study suggests that patients undergoing LITT for RN have longer overall survival and better long-term lesional volume reduction than those treated with bevacizumab. However, it remains unclear whether our findings are due only to a difference in efficacy of the treatments or the implications of selection bias.

Laser Interstitial Thermal Therapy in the treatment of brain metastases and radiation necrosis

Stereotactic Radiosurgery has become the main treatment for patients with limited number of brain metastases (BM). Recently, with the increasing use of this modality, there is a growth in recurrence cases. Recurrence after radiation therapy can be divided in changes favoring either tumor recurrence or radiation necrosis (RN). Laser Interstitial Thermal Therapy (LITT) is minimally invasive treatment modality that has been used to treat primary and metastatic brain tumors. When associated with real-time thermometry using Magnetic Resonance Imaging, the extent of ablation can be controlled to provide maximum coverage and avoid eloquent areas. The objective of this study was to investigate the use of LITT in the treatment of BM. An extensive review of the relevant literature was conducted and the outcome results are discussed. There is an emphasis on safety and local control rate of patients treated with this modality. The findings of our study suggest that LITT is a viable safe technique to treat recurrent BM, especially in patients with deep-seated lesions where surgical resection is not an option.

The Safety and Efficacy of Bevacizumab for Radiosurgery - Induced Steroid - Resistant Brain Edema; Not the Last Part in the Ship of Theseus

Background

Radiation-induced brain edema (RIBE) is a serious complication of radiation therapy. It may result in dramatic clinico-radiological deterioration. At present, there are no definite guidelines for management of the complication. Corticosteroids are the usual first line of treatment, which frequently fails to provide long-term efficacy in view of its adverse complication profile. Bevacizumab has been reported to show improvement in cases of steroid-resistant radiation injury. The objective of this study is to evaluate the role of Bevacizumab in post-radiosurgery RIBE.

Material and Methods

Since 2012, 189 out of 1241 patients who underwent radiosurgery at our institution developed post-radiosurgery RIBE, 17 of which did not respond to high-dose corticosteroids. We systematically reviewed these 17 patients of various intracranial pathologies with clinic-radiological evidence of RIBE following gamma knife radiosurgery (GKRS). All patients received protocol-based Bevacizumab therapy. The peer-reviewed literature was evaluated.

Results

82 percent of the patients showed improvement after starting Bevacizumab. The majority began to improve after the third cycle started improvement after the third cycle of Bevacizumab. Clinical improvement preceded radiological improvement by an average of eight weeks. The first dose was 5 mg/kg followed by 7.5-10 mg/kg at with two-week intervals. Bevacizumab needs to be administered for an average of seven cycles (range 5-27, median 7) for best response. Steroid therapy could be tapered in most patients by the first follow-up. One patient did not respond to Bevacizumab and needed surgical decompression for palliative care. One noncompliant patient died due to radiation injury.

Conclusion

Bevacizumab is a effective and safe for treatment of RIBE after GKRS. A protocol-based dose schedule in addition to frequent clinical and radiological evaluations are required. Bevacizumab should be considered as an early treatment option for RIBE.

Analysis of a Surgical Series of 21 Cerebral Radiation Necroses

BACKGROUND

There is no standard approach to differentiate cerebral radiation necrosis from tumor recurrence and no standard treatment pathway for symptomatic lesions. In addition, reports on histology-proven radiation necrosis and the underlying pathophysiology are scarce and highly relevant.

METHODS

Our monocentric, retrospective analysis included 21 histology-proven cerebral radiation necroses. Our study focused on 1) potential risk factors for the development of radiation necrosis, 2) radiologic and histopathologic features of individual necroses, and 3) the suitability of previously reported magnetic resonance imaging (MRI)-based methods to identify radiation necroses based on specific structural image features.

RESULTS

Average time between radiation treatment and development of necrosis was 4.68 years (95% confidence interval, 0.19-9.55 years). Matching available MRI data sets with those of patients with tumor lesions, we compared specificity and sensitivity of 3 previously reported methods to identify radionecrosis based on imaging criteria. In our hands, none of these methods reached a sensitivity ≥70%. Radionecrosis presented with large edema and showed increased levels of cell proliferation, as inferred by Ki-67 staining. Surgical removal of radiation necrosis proved to be a safe approach with low permanent morbidity (<5%) and no mortality.

CONCLUSIONS

Although the overall incidence of cerebral radiation necrosis is low, our data suggest an increasing incidence over the last 2 decades, which is likely associated with the use of stereotactic radiotherapy. There are no imaging standards to identify radiation necrosis on standard MRI with structural sequences. Surgical removal of radiation necrosis is associated with low morbidity and mortality.

[Multicystic transformation of the post-radiation necrosis zone of the brain. A case report and literature review]

Post-radiation cyst of the brain is a rare complication that often arises many years after irradiation for head and neck neoplasms. The majority of the articles devoted to this problem are small samples or case reports. Nevertheless, the overall number of these patients is steadily increasing. The feature of post-radiation cysts is gradual enlargement followed by general cerebral and focal symptoms and ineffectiveness of therapy. Some patients with clinically significant post-radiation cysts can require surgical treatment. Insertion of Ommaya reservoir may be preferred in these patients. In some cases, this method is ineffective and more complex surgeries may be required. The objectives of this report were to analyze literature data and describe the patient with multiple recurrent brain cysts after previous irradiation for frontotemporal skin melanoma. Twenty-seven publications were analyzed for the period from 1997 to 2018. According to the literature, the incidence of post-radiation cysts varies from 0.4% to 28%, timing of occurrence - from 2 months to 27 years. These values significantly depend on the underlying disease. We report a 27-year-old patient who admitted to the Burdenko Neurosurgery Center with focal and general cerebral symptoms after irradiation for skin melanoma of the right frontotemporal region. These symptoms were caused by cystic lesion of the right temporal and frontal lobes. Surgical treatment consisted in insertion of 2 Ommaya reservoirs. This approach ensured complete regression of the cyst in the right temporal lobe and mild decrease of the cyst in the right frontal lobe.

Acute and chronic hemorrhage from radiation-induced cavernous malformation associated with late-delayed radiation necrosis in long surviving glioma patients: A case report

Although radiation therapy is a standard treatment strategy for patients with glioma, its delayed complications are not clearly understood. Radiation-induced cavernous malformation (RICM) is one of the complications in the delayed phase following radiation therapy, which usually occurs in children. Herein we present three cases of RICM with radiation necrosis in long surviving adult glioma patients, 2 with oligoastrocytoma and one with anaplastic ependymoma. Two of three patients had received an obvious overdose of radiation by additional stereotactic radiation therapy. Repeated episodes of either acute or chronic hemorrhages from RICM worsened the neurological symptoms in all cases. The interval between the last irradiation and the occurrence of symptoms was 45-173 months. The presence of hypointense rim on FLAIR or T2* on magnetic resonance imaging, which resembles the appearance of sporadic cavernous malformations, could be helpful in differentiating RICM from tumor recurrence. Surgical resection was effective in alleviating the symptoms. Microscopically, RICM is a vascular lesion with vulnerable vessels, which are observed in the center of the radiation necrosis. Repeated hemorrhages from these vessels cause either gradual or sudden worsening of neurological symptoms. Therefore, radiation overdose, which results in radiation injury, should be avoided in low grade glioma patients, who could potentially survive for a long period.

Neurosurgical applications of MRI guided laser interstitial thermal therapy (LITT)

MRI-guided laser interstitial thermal therapy (LITT) is the selective ablation of a lesion or a tissue using heat emitted from a laser device. LITT is considered a less invasive technique compared to open surgery that provides a nonsurgical solution for patients who cannot tolerate surgery. Although laser ablation has been used to treat brain lesions for decades, recent advances in MRI have improved lesion targeting and enabled real-time accurate monitoring of the thermal ablation process. These advances have led to a plethora of research involving the technique, safety, and potential applications of LITT.LITT is a minimally invasive treatment modality that shows promising results and is associated with decreased morbidity. It has various applications, such as treatment of glioma, brain metastases, radiation necrosis, and epilepsy. It can provide a safer alternative treatment option for patients in whom the lesion is not accessible by surgery, who are not surgical candidates, or in whom other standard treatment options have failed. Our aim is to review the current literature on LITT and provide a descriptive review of the technique, imaging findings, and clinical applications for neurosurgery.

Effect of bevacizumab on brain radiation necrosis in anaplastic lymphoma kinase-positive lung cancer

Central nervous system (CNS) metastases from anaplastic lymphoma kinase (ALK)-positive lung cancer often results in failure of ALK-tyrosine kinase inhibitor (TKI) therapy. Patients with uncontrolled CNS metastases receive radiation therapy, which sometimes causes brain radiation necrosis. We added bevacizumab (15 mg/kg, every 3-4 weeks) to the regimen of four ALK-positive lung cancer patients with brain radiation necrosis who were receiving ALK-TKI therapy. A decrease in brain radiation necrosis was seen in all the patients, and an improvement in symptoms was seen in three patients. In one patient who was receiving corticosteroid therapy, we could taper the dose and subsequently discontinue it. While one patient discontinued bevacizumab because of adverse events, the other three continued with the treatment. Therefore, the combination of bevacizumab with ALK-TKI seems to be an effective, manageable, and tolerable treatment for brain radiation necrosis.

Brain MR findings in patients treated with particle therapy for skull base tumors

Nowadays, hadrontherapy is increasingly used for the treatment of various tumors, in particular of those resistant to conventional radiotherapy. Proton and carbon ions are characterized by physical and biological features that allow a high radiation dose to tumors, minimizing irradiation to adjacent normal tissues. For this reason, radioresistant tumors and tumors located near highly radiosensitive critical organs, such as skull base tumors, represent the best target for this kind of therapy. However, also hadrontherapy can be associated with radiation adverse effects, generally referred as acute, early-delayed and late-delayed. Among late-delayed effects, the most severe form of injury is radiation necrosis. There are various underlying mechanisms involved in the development of radiation necrosis, as well as different clinical presentations requiring specific treatments. In most cases, radiation necrosis presents as a single focal lesion, but it can be multifocal and involve a single or multiple lobes simulating brain metastasis, or it can also involve both cerebral hemispheres. In every case, radiation necrosis results always related to the extension of radiation delivery field. Multiple MRI techniques, including diffusion, perfusion imaging, and spectroscopy, are important tools for the radiologist to formulate the correct diagnosis. The aim of this paper is to illustrate the possible different radiologic patterns of radiation necrosis that can be observed in different MRI techniques in patients treated with hadrontherapy for tumors involving the skull base. The images of exemplary cases of radiation necrosis are also presented.

Salvage craniotomy for treatment-refractory symptomatic cerebral radiation necrosis

Background

The incidence of symptomatic radiation necrosis (RN) has risen as radiotherapy is increasingly used to control brain tumor progression. Traditionally managed with steroids, symptomatic RN can remain refractory to medical treatment, requiring surgical intervention for control. The purpose of our study was to assess a single institution's experience with craniotomy for steroid-refractory pure RN.

Methods

The medical records of all tumor patients who underwent craniotomies at our institution from 2011 to 2016 were retrospectively reviewed for a history of preoperative radiotherapy or radiosurgery. RN was confirmed histopathologically and patients with active tumor were excluded. Preoperative, intraoperative, and outcome information was collected. Primary outcomes measured were postoperative KPS and time to steroid freedom.

Results

Twenty-four patients with symptomatic RN were identified. Gross total resection was achieved for all patients. Patients with metastases experienced an increase in KPS (80 vs 100, P < .001) and required a shortened course of dexamethasone vs patients with high-grade gliomas (3.4 vs 22.2 weeks, P = .003). RN control and neurological improvement at 13.3 months' follow-up were 100% and 66.7%, respectively. Adrenal insufficiency after rapidly tapering dexamethasone was the only morbidity (n = 1). Overall survival was 93.3% (14/15) at 1 year.

Conclusion

In cases of treatment-refractory symptomatic RN, resection can lead to an overall improvement in postoperative health status and neurological outcomes with minimal RN recurrence. Craniotomy for surgically accessible RN can safely manage symptomatic patients, and future studies assessing the efficacy of resection vs bevacizumab may be warranted.

Successful treatment of brain radiation necrosis resulting from triple-negative breast cancer with Endostar and short-term hyperbaric oxygen therapy: a case report

Radiation necrosis (RN) is one of the complications of radiotherapy. Angiogenesis is a key factor underlying the development of RN, and Endostar, a safe and well-tolerated recombinant human endostatin, has been used to treat a variety of tumors. Thus far, however, no definitive reports on the use of Endostar for RN treatment have been reported. Here, we report the successful treatment of one patient with symptomatic brain radiation necrosis (BRN) using Endostar in combination with short-term hyperbaric oxygen therapy (HBO). One triple-negative breast cancer patient with recurrent brain metastatic lesions after standard chemoradiotherapy was referred to a specialty center outside our hospital for stereotaxic radiotherapy. Two months later, the patient showed deteriorating clinical symptoms, and magnetic resonance imaging (MRI) showed radiation necrosis with significant surrounding edema. The patient had a poor response to mannitol and steroids. After diagnosing this patient with BRN, we began short-term HBO therapy and intravenously administered Endostar for 4 cycles. The patient responded well to this strategy, showing rapidly and dramatically improved MRI findings and clinical symptoms. No tumor progression was observed at 10 months after treatment. Endostar in combination with short-term HBO therapy had marked effects on symptomatic BRN. However, additional large-scale, double-blinded, controlled trials are necessary to confirm the clinical effect of Endostar in combination with a short-term HBO therapy regimen on BRN.

Astrocytes-derived VEGF exacerbates the microvascular damage of late delayed RBI

Overexpression of vascular endothelial growth factor (VEGF) is considered the most critical factor in radiation-induced brain injury (RBI). To investigate the role of VEGF and the mechanism underlying microvascular damage in RBI, wild type mice, and transgenic mice overexpressing VEGF derived from astrocytes, were separately and randomly exposed to whole-brain or sham irradiation. Pathophysiologic changes in the brain tissue were detected 90 days after irradiation. Compared with wild type mice, the secretion of VEGF and angiopoietin-2 (Ang-2) was up-regulated in transgenic mice, whether irradiated or not, while elevated expression of VEGF, Ang-2, and glial fibrillary acidic protein (GFAP) was detected after whole-brain irradiation using western blotting. Impairment of the blood-brain barrier (BBB) was demonstrated by the leakage of dyes observed using two-photon imaging and decreased expression of zonula occludens-1 (ZO-1) and Occludin. Hematoxylin-eosin (HE) staining revealed obvious structural damage in the irradiated brains. Furthermore, damage to the BBB and histopathology in the transgenic mice were worse than those of wild type mice in the irradiated groups. There was a positive correlation among VEGF and Ang-2 expression and RBI severity. These data reveal that VEGF and Ang-2 expression is closely associated with the microvascular injury in RBI. Further, overexpression of VEGF can cause up-regulation of Ang-2 and exacerbation of RBI. Therefore, Ang-2 might be the cytokine that acts as a mediator between VEGF and microvascular injury, and is likely a new intervention target for RBI.

Do Serum Vascular Endothelial Growth Factor and Endostatin Reflect Radiological Radiation-Induced Changes After Stereotactic Radiosurgery for Cerebral Arteriovenous Malformations?

OBJECTIVE

The aim of this study was to analyze serum levels of vascular endothelial growth factor (VEGF) and endostatin in patients with cerebral treated by stereotactic radiosurgery (SRS), and to assess their association with radiological radiation-induced changes (RICs).

METHODS

To measure serum biomarkers, peripheral venous blood was collected before SRS and 1 week, 1 month, 3 months, and 6 months after SRS. To evaluate RICs, clinical and neuroimaging follow-up were performed concurrently every 6 months after SRS.

RESULTS

Twenty-seven patients were enrolled (11 in the group with RIC, 16 in the group without RIC). Serum VEGF and endostatin levels were positively correlated (P = 0.036, r = 0.405). In the group with RIC, the median serum VEGF 6 months after SRS (58.98 pg/mL) was significantly higher than that of the group without RIC (15.17 pg/mL) (P = 0.001). Multivariate analysis revealed that higher VEGF 6 months after SRS (P = 0.001, hazard ratio, 1.032; 95% confidence interval, 1.012-1.052) and lower endostatin 1 month after SRS (P = 0.007, hazard ratio, 0.964; 95% confidence interval, 0.935-0.993) were significantly associated with RICs.

CONCLUSIONS

Our results show that serum levels of VEGF 6 months after SRS were higher in the group with RIC. Serum levels of VEGF 6 months and endostatin 1 month after SRS were associated with the radiological RICs. Thus, serial measurements of serum VEGF and endostatin after SRS might help predict RICs in patients with arteriovenous malformation treated by SRS.

Bevacizumab treatment for radiation brain necrosis: mechanism, efficacy and issues

Vascular damage is followed by vascular endothelial growth factor (VEGF) expression at high levels, which is an important mechanism forradiation brain necrosis development. Bevacizumab alleviates brain edema symptoms caused by radiation brain necrosis through inhibiting VEGF and acting on vascular tissue around the brain necrosis area. Many studies have confirmed that bevacizumab effectively relieves symptoms caused by brain necrosis, improves patients' Karnofsky performance status (KPS) scores and brain necrosis imaging. However, necrosis is irreversible, and hypoxia and ischemia localized in the brain necrosis area may easily lead to radiation brain necrosis recurrence after bevacizumab is discontinued. Further studies are necessary to investigate brain necrosis diagnoses, bevacizumab indications, and the optimal mode of administration, bevacizumab resistance and necrosis with a residual or recurrent tumor.