Radiation-Induced Edema After Single-Fraction or Multifraction Stereotactic Radiosurgery for Meningioma: A Critical Review

Imaging Findings Post-Stereotactic Radiosurgery for Vestibular Schwannoma: A Primer for the Radiologist

Noninvasive tumor control of vestibular schwannomas through stereotactic radiosurgery allows high rates of long-term tumor control and has been used primarily for small- and medium-sized vestibular schwannomas. The posttreatment imaging appearance of the tumor, temporal patterns of growth and treatment response, as well as extratumoral complications can often be both subtle or confusing and should be appropriately recognized. Herein, the authors present an imaging-based review of expected changes as well as associated complications related to radiosurgery for vestibular schwannomas.

Enhanced VEGF secretion and blood-brain barrier disruption: Radiation-mediated inhibition of astrocyte autophagy via PI3K-AKT pathway activation

Radiation-induced damage to the blood-brain barrier (BBB) is the recognized pathological basis of radiation-induced brain injury (RBI), a side effect of head and neck cancer treatments. There is currently a lack of therapeutic approaches for RBI due to the ambiguity of its underlying mechanisms. Therefore, it is essential to identify these mechanisms in order to prevent RBI or provide early interventions. One crucial factor contributing to BBB disruption is the radiation-induced activation of astrocytes and oversecretion of vascular endothelial growth factor (VEGF). Mechanistically, the PI3K-AKT pathway can inhibit cellular autophagy, leading to pathological cell aggregation. Moreover, it acts as an upstream pathway of VEGF. In this study, we observed the upregulation of the PI3K-AKT pathway in irradiated cultured astrocytes through bioinformatics analysis, we then validated these findings in animal brains and in vitro astrocytes following radiation exposure. Additionally, we also found the inhibition of autophagy and the oversecretion of VEGF in irradiated astrocytes. By inhibiting the PI3K-AKT pathway or promoting cellular autophagy, we observed a significant amelioration of the inhibitory effect on autophagy, leading to reductions in VEGF oversecretion and BBB disruption. In conclusion, our study suggests that radiation can inhibit autophagy and promote VEGF oversecretion by upregulating the PI3K-AKT pathway in astrocytes. Blocking the PI3K pathway can alleviate both of these effects, thereby mitigating damage to the BBB in patients undergoing radiation treatment.

Predicting peritumoral edema development after gamma knife radiosurgery of meningiomas using machine learning methods: a multicenter study

OBJECTIVES

Edema is a complication of gamma knife radiosurgery (GKS) in meningioma patients that leads to a variety of consequences. The aim of this study is to construct radiomics-based machine learning models to predict post-GKS edema development.

METHODS

In total, 445 meningioma patients who underwent GKS in our institution were enrolled and partitioned into training and internal validation datasets (8:2). A total of 150 cases from multicenter data were included as the external validation dataset. In each case, 1132 radiomics features were extracted from each pre-treatment MRI sequence (contrast-enhanced T1WI, T2WI, and ADC maps). Nine clinical features and eight semantic features were also generated. Nineteen random survival forest (RSF) and nineteen neural network (DeepSurv) models with different combinations of radiomics, clinical, and semantic features were developed with the training dataset, and evaluated with internal and external validation. A nomogram was derived from the model achieving the highest C-index in external validation.

RESULTS

All the models were successfully validated on both validation datasets. The RSF model incorporating clinical, semantic, and ADC radiomics features achieved the best performance with a C-index of 0.861 (95% CI: 0.748-0.975) in internal validation, and 0.780 (95% CI: 0.673-0.887) in external validation. It stratifies high-risk and low-risk cases effectively. The nomogram based on the predicted risks provided personalized prediction with a C-index of 0.962 (95%CI: 0.951-0.973) and satisfactory calibration.

CONCLUSION

This RSF model with a nomogram could represent a non-invasive and cost-effective tool to predict post-GKS edema risk, thus facilitating personalized decision-making in meningioma treatment.

CLINICAL RELEVANCE STATEMENT

The RSF model with a nomogram built in this study represents a handy, non-invasive, and cost-effective tool for meningioma patients to assist in better counselling on the risks, appropriate individual treatment decisions, and customized follow-up plans.

KEY POINTS

• Machine learning models were built to predict post-GKS edema in meningioma. The random survival forest model with clinical, semantic, and ADC radiomics features achieved excellent performance. • The nomogram based on the predicted risks provides personalized prediction with a C-index of 0.962 (95%CI: 0.951-0.973) and satisfactory calibration and shows the potential to assist in better counselling, appropriate treatment decisions, and customized follow-up plans. • Given the excellent performance and convenient acquisition of the conventional sequence, we envision that this non-invasive and cost-effective tool will facilitate personalized medicine in meningioma treatment.

Spontaneous resolution of intracranial hypertension following radiotherapy for posterior parasagittal meningioma: About two cases and review of the literature

We report the cases of two patients who underwent normofractionated radiotherapy for evolutive asymptomatic parasagittal meningiomas. After completion of radiotherapy, both patients presented severe headache and vomiting episodes without papillar edema. We then decided a "wait-and-scan" strategy because of the slit-ventricles, and symptoms regressed spontaneously. MRI showed significant tumor regression a year after radiotherapy with a newly developed collateral venous drainage system in the first patient and a left, unusually large, superior anastomotic vein in the second. These clinical presentation and radiological evolution are compatible with venous stenosis caused by radiation-induced symptomatic edema, fading after the development of a collateral venous drainage system. The relation between pressure-related headaches and venous anatomy remains unclear in parasagittal meningiomas. These observations underline the importance of the study of venous anatomy when pressure-related headaches are suspected. Further clinical descriptions might help the clinicians to treat these patients' symptoms.

Stereotactic Radiosurgery for Intracranial Meningiomas

Meningiomas are thought to originate from the meningothelial cells of the arachnoid mater and are the most common primary brain tumor in adults. Histologically confirmed meningiomas occur with an incidence of 9.12/100,000 population and account for 39% of all primary brain tumors and 54.5% of all non-malignant brain tumors. Risk factors for meningioma include age 65 years and older, female gender, African-American race, history of exposure to head and neck ionizing radiation, and certain genetic disorders such as neurofibromatosis II. Intracranial meningiomas are the most commonly benign, WHO Grade I neoplasms. Atypical and anaplastic are considered malignant lesions.

Factors associated with radiation toxicity and long-term tumor control more than 10 years after Gamma Knife surgery for non-skull base, nonperioptic benign supratentorial meningiomas

OBJECTIVE

Gamma Knife surgery (GKS) is a well-established treatment for benign intracranial meningiomas; however, the dosimetric factors associated with long-term GKS efficacy and safety remain to be elucidated. Using data obtained with at least 10 years of follow-up, the authors aimed 1) to analyze GKS efficacy and safety for the treatment of benign meningiomas confined to non-skull base, nonperioptic supratentorial locations and 2) to determine the radiation dose window that allows for long-term efficacy and safety, namely the minimum dose to achieve long-term local control (LC) and the maximum safe dose to avoid adverse radiation effects (AREs).

METHODS

A retrospective analysis was performed on patients who underwent GKS for benign meningiomas in the abovementioned location at the authors' institution between 1998 and 2010 and who received follow-up for more than 10 years. The authors meticulously extracted the values of various dosimetric factors by using a dose-volume histogram. Cox proportional hazard regression analyses were performed to investigate the dosimetric factors associated with LC and ARE.

RESULTS

Fifty-five patients (male/female ratio 1:4.2) with 68 tumors were enrolled. The median (range) gross target volume and marginal dose were 4.2 (0.2-31.7) cm3 and 14.3 (9-20) Gy, respectively. In total, 23.5% of tumors progressed at an average of 72 months, with 10- and 15-year progression-free survival rates of 80.9% and 73.5%, respectively. In univariate analysis, higher marginal dose, coverage (%), Dmin, D98%, Dmean, D2%, Dmax, and Paddick conformity index were significantly associated with LC. In multivariate analysis, D98% was the significant factor, with a cutoff value of 11 Gy (HR 0.754, p < 0.001). Symptomatic AREs occurred in 7 patients at an average of 7 months after GKS. AREs were significantly associated with the volume of normal tissue irradiated with more than 14 Gy (nV14Gy), with a cutoff value of 0.66 cm3 (HR 2.459, p = 0.002).

CONCLUSIONS

D98% was a barometer of the minimum required dose associated with long-term LC, and nV14Gy was related to symptomatic AREs. The authors recommend a marginal dose ranging from 11 to 14 Gy to achieve long-term efficacy and safety in patients with non-skull base, nonperioptic benign supratentorial meningiomas, with the assumption of thorough tumor coverage.

Radiotherapy and radiosurgery for meningiomas

Meningiomas comprise a histologically and clinically diverse set of tumors arising from the meningothelial lining of the central nervous system. In the past decade, remarkable progress has been made in deciphering the biology of these common neoplasms. Nevertheless, effective systemic or molecular therapies for meningiomas remain elusive and are active areas of preclinical and clinical investigation. Thus, standard treatment modalities for meningiomas are limited to maximal safe resection, radiotherapy, or radiosurgery. This review examines the history, clinical rationale, and future directions of radiotherapy and radiosurgery as integral and effective treatments for meningiomas.

Septal radioablation therapy for patients with hypertrophic obstructive cardiomyopathy: first-in-human study

Aims

There is still no non-invasive septal reduction therapy for patients with hypertrophic obstructive cardiomyopathy (HOCM). This study aimed to investigate the feasibility, safety, and efficacy of stereotactic body radiotherapy (SBRT) in patients with drug-refractory symptomatic HOCM.

Methods and results

The radiation target of ventricular septum was determined by multiple anatomical imaging. Stereotactic body radiotherapy was performed with standard techniques. Patients were treated with a single fraction of 25 Gy, followed up at 1, 3, 6, and 12 months by clinical visit. Five patients were enrolled and completed the 12 months follow-up. The mean radioablation time was 21.6 min, and the mean target volume was 10.5 cm³. All five patients survived and showed improvements in symptoms after SBRT. At 12 months post-SBRT, the echocardiography-derived left ventricular outflow tract gradient decreased from 88 mmHg (range, 63-105) to 52 mmHg (range, 36-66) at rest and from 101 mmHg (range, 72-121) to 74 mmHg (range, 65-100) after Valsalva. The end-diastolic thickness of the targeted septum reduced from 23.7 mm (range, 20.3-29) to 22.4 mm (range, 19.7-26.5); 6 min walking distance increased from 190.4 m (range, 50-370) to 412.0 m (range, 320-480). All patients presented with new fibrosis in the irradiated septum area. No radiation-related complications were observed during SBRT and up to 12 months post procedure.

Conclusion

The current study suggests that SBRT might be a feasible radioablation therapeutic option for patients with drug-refractory symptomatic HOCM.

Trial registration

ClinicalTrials.gov Identifier: NCT04686487.

Primary Stereotactic Radiosurgery Provides Favorable Tumor Control for Intraventricular Meningioma: A Retrospective Analysis

The surgical resection of intraventricular meningiomas (IVMs) remains challenging because of their anatomically deep locations and proximity to vital structures, resulting in non-negligible morbidity and mortality rates. Stereotactic radiosurgery (SRS) is a safe and effective treatment option, providing durable tumor control for benign brain tumors, but its outcomes for IVMs have rarely been reported. Therefore, the goal of the present study was to evaluate the SRS outcomes for IVMs at our institution. This retrospective observational study included 11 patients with 12 IVMs with a median follow-up period of 52 months (range, 3-353 months) treated with SRS using the Leksell Gamma Knife. Nine (75%) tumors were located in the trigone of the lateral ventricle, two (17%) in the body of the lateral ventricle, and one (8%) in the third ventricle. Tumor control was achieved in all cases, and seven (55%) decreased in size. Post-SRS perifocal edema was observed in four (37%; three asymptomatic and one symptomatic but transient) patients, all of which were resolved by the last follow-up. SRS appears to provide safe and excellent tumor control for IVMs. A longer follow-up with a larger number of cases is desired for a more solid conclusion.

Neurocognitive considerations in the treatment of meningioma with radiation therapy: applications for quantitative neuroimaging and precision radiation medicine

This article focuses on the role of radiotherapy in the management of meningioma, in the definitive and adjuvant setting and across the spectrum of meningioma grade. Treatment paradigms, informed by clinical evidence, are discussed. Notably, we focus on the impact of radiotherapy on normal brain tissues and neurocognitive function, particularly the dose-dependent changes in white matter and cerebral cortex thickness. Novel imaging techniques have allowed the identification of microstructural changes to eloquent white matter, cortex, and subcortical regions as biomarkers for understanding RT-induced changes in cognitive functioning. Deficits in multiple domains including attention, memory, language and executive function can become more pronounced following radiation. Longitudinal assessment with imaging and neurocognitive testing pre- and post-radiation have allowed correlation between dose to specific regions of the brain and decline in associated domains of neurocognitive function. These findings suggest incorporation of areas at higher risk for neurocognitive sequelae into precision radiation planning. Volumetric arc therapy, advanced planning with cortical sparing, proton therapy and stereotactic radiosurgery are reviewed as options for delivering therapeutic dose to target volumes while minimizing risk to adjacent sensitive regions. The treatment of meningioma is an evolving area, with improving outcomes for higher grade disease in modern trials, where care must be taken to maximize both disease control as well as quality of life for patients.

Radiotherapy for Meningioma

Meningiomas are the most common primary intracranial brain tumor, and have a heterogeneous biology and an unmet need for targeted treatment options. Existing treatments for meningiomas are limited to surgery, radiotherapy, or a combination of these depending on clinical and histopathological features. Treatment recommendations for meningioma patients take into consideration radiologic features, tumor size and location, and medical comorbidities, all of which may influence the ability to undergo complete resection. Ultimately, outcomes for meningioma patients are dictated by extent of resection and histopathologic factors, such as World Health Organization (WHO) grade and proliferation index. Radiotherapy is a critical component of meningioma treatment as either a definitive intervention using stereotactic radiosurgery or external beam radiotherapy, or in the adjuvant setting for residual disease or for adverse pathologic factors, such as high WHO grade. In this chapter, we provide a comprehensive review of radiotherapy treatment modalities, therapeutic considerations, radiation planning, and clinical outcomes for meningioma patients.

Dual-Energy Computed Tomography-Based Iodine Concentration Estimation for Evaluating Choroidal Malignant Melanoma Response to Treatment: Optimization and Primary Validation

Contrast-enhanced imaging for choroidal malignant melanoma (CMM) is mostly limited to detecting metastatic tumors, possibly due to difficulties in fixing the eye position. We aimed to (1) validate the appropriateness of estimating iodine concentration based on dual-energy computed tomography (DECT) for CMM and optimize the calculation parameters for estimation, and (2) perform a primary clinical validation by assessing the ability of this technique to show changes in CMM after charged-particle radiation therapy. The accuracy of the optimized estimate (eIC_optimized) was compared to an estimate obtained by commercial software (eIC_commercial) by determining the difference from the ground truth. Then, eIC_optimized, tumor volume, and CT values (80 kVp, 140 kVp, and synthesized 120 kVp) were measured at pre-treatment and 3 months and 1.5−2 years after treatment. The difference from the ground truth was significantly smaller in eIC_optimized than in eIC_commercial (p < 0.01). Tumor volume, CT values, and eIC_optimized all decreased significantly at 1.5−2 years after treatment, but only eIC_commercial showed a significant reduction at 3 months after treatment (p < 0.01). eIC_optimized can quantify contrast enhancement in primary CMM lesions and has high sensitivity for detecting the response to charged-particle radiation therapy, making it potentially useful for treatment monitoring.

Radiation of meningioma dural tail may not improve tumor control rates

Introduction

Dural tails are thickened contrast-enhancing portions of dura associated with some meningiomas. Prior studies have demonstrated the presence of tumor cells within the dural tail, however their inclusion in radiation treatment fields remains controversial. We evaluated the role of including the dural tail when treating a meningioma with stereotactic radiation and the impact on tumor recurrence.

Methods

This is a retrospective, single-institution, cohort study of patients with intracranial World Health Organization (WHO) grade 1 meningioma and identified dural tail who were treated with stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT) from January 2012 to December 2018. SRS and FSRT subgroups were categorized based on coverage or non-coverage of the dural tail by the radiation fields, as determined independently by a radiation oncologist and a neurosurgeon. Demographics, tumor characteristics, radiation plans, and outcomes were evaluated. High grade tumors were analyzed separately.

Results

A total of 187 WHO grade 1 tumors from 177 patients were included in the study (median age: 62 years, median follow-up: 40 months, 78.1% female) with 104 receiving SRS and 83 receiving FSRT. The dural tail was covered in 141 (75.4%) of treatment plans. There was no difference in recurrence rates (RR) or time to recurrence (TTR) between non-coverage or coverage of dural tails (RR: 2.2% vs 3.5%, P = 1.0; TTR: 34 vs 36 months, P = 1.00). There was no difference in the rate of radiation side effects between dural tail coverage or non-coverage groups. These associations remained stable when SRS and FSRT subgroups were considered separately, as well as in a high grade cohort of 16 tumors.

Conclusion

Inclusion of the dural tail in the SRS or FSRT volumes for meningioma treatment does not seem to reduce recurrence rate. Improved understanding of dural tail pathophysiology, tumor grade, tumor spread, and radiation response is needed to better predict the response of meningiomas to radiotherapy.

Effect of osteoporotic conditions on the development of peritumoral brain edema after LINAC-based radiation treatment in patients with intracranial meningioma

PURPOSE

Disruption of the tumor-brain barrier in meningioma is a crucial factor in peritumoral brain edema (PTBE). We previously reported the possible effect of osteoporosis on the integrity of the arachnoid trabeculae because both the bone and the arachnoid trabeculae are composed of type 1 collagen. We hypothesized that osteoporotic conditions may be associated with PTBE occurrence after radiation treatment in patients with meningioma.

METHODS

A receiver operating characteristic curve analysis was used to identify the optimal cut-off values of mean skull Hounsfield unit for predicting osteopenia and osteoporosis in patients from our registry. Multivariate Cox regression analysis was used to determine whether possible osteoporosis independently predicted PTBE development in patients with meningioma after radiation.

RESULTS

A total of 106 intracranial meningiomas were included for the study. All patients received linear accelerator-based radiation therapy in our hospital over an approximate 6-year period. Multivariate Cox regression analysis identified that hypothetical osteoporosis was an independent predictive factor for the development of PTBE in patients with meningioma after linear accelerator-based radiation treatment (hazard ratio 5.20; 95% confidence interval 1.11-24.46; p = 0.037).

CONCLUSIONS

Our study suggests that possible osteoporotic conditions may affect PTBE development after linear accelerator-based radiation treatment for intracranial meningioma. However, due to the study's small number of patients, these findings need to be validated in future studies with larger cohorts, before firm recommendations can be made.

Magnetic Resonance Imaging (MRI) Differential Diagnosis of Meningiomas Using ANOVA

This work explored the diagnostic value of different subtypes of meningiomas under T2WI low signal based on analysis of variance (ANOVA), and the expression differences of Ki67, VEGF, and P73 in different subtypes were analyzed. 67 patients with meningioma confirmed surgically and pathologically in hospital were selected as the research subjects, whose pathological classification occurs with obvious low signal on T2WI. First, the age distribution of the subjects and the distribution of different subtypes were counted. Then, ANOVA was adopted to analyze the MRI imaging signs of patients with different subtypes of meningioma. Finally, the differences of Ki67, VEGF, and P73 proteins and mRNA expression levels in different subtypes were detected via immunohistochemical assay and qPCR. The results showed that the proportion of patients with transitional meningioma was the most, which was 43.28%, while the proportion of patients with meningeal melanoma was the least, which was 7.46%. In patients with transitional meningioma, the MRI images showed mixed signals in different layers. Fibrous MRI images showed hyalinosis and calcification of collagen fibers in the tumor, with low T2WI signal. Sand-shape MRI images showed double low signals. MRI images of meningeal melanoma showed high signal on T1-weighted Imaging (T1WI) and low signal on T2WI. The protein expression and mRNA levels of Ki67 and P73 in transitional meningioma were evidently higher in contrast to those in fibrous meningioma (P < 0.05). The expression level of VEGF protein and mRNA in meningeal melanoma were notably higher in contrast to those in fibro meningioma (P < 0.05). It was revealed that the MRI images of the four subtypes of meningiomas under ANOVA-based T2WI low signal were quite different, and the expressions of Ki67, P73, and VEGF in different subtypes had significant differences. This work provided a reference basis for the preoperative diagnosis, treatment, and prognosis of meningiomas.

Advances in Multidisciplinary Management of Skull Base Meningiomas

The surgical management of Skull Base Meningiomas (SBMs) has radically changed over the last two decades. Extensive surgery for patients with SBMs represents the mainstream treatment; however, it is often challenging due to narrow surgical corridors and proximity to critical neurovascular structures. Novel surgical technologies, including three-dimensional (3D) preoperative imaging, neuromonitoring, and surgical instruments, have gradually facilitated the surgical resectability of SBMs, reducing postoperative morbidity. Total removal is not always feasible considering a risky tumor location and invasion of surrounding structures and brain parenchyma. In recent years, the use of primary or adjuvant stereotactic radiosurgery (SRS) has progressively increased due to its safety and efficacy in the control of grade I and II meningiomas, especially for small to moderate size lesions. Patients with WHO grade SBMs receiving subtotal surgery can be monitored over time with surveillance imaging. Postoperative management remains highly controversial for grade II meningiomas, and depends on the presence of residual disease, with optional upfront adjuvant radiation therapy or close surveillance imaging in cases with total resection. Adjuvant radiation is strongly recommended in patients with grade III tumors. Although the currently available chemotherapy or targeted therapies available have a low efficacy, the molecular profiling of SBMs has shown genetic alterations that could be potentially targeted with novel tailored treatments. This multidisciplinary review provides an update on the advances in surgical technology, postoperative management and molecular profile of SBMs.

The Value of Anlotinib in the Treatment of Intractable Brain Edema: Two Case Reports

About 20-30 percent of patients with cancer, such as non-small cell lung cancer, breast cancer, melanoma and renal cell carcinoma, will develop brain metastases (BM). Primary and secondary brain tumors are often accompanied by peritumoral edema. Due to the limited intracranial space, peritumoral edema will further increase the intracranial pressure and aggravate clinical symptoms. Radiotherapy, as a basic component of the treatment of intracranial tumors, induces blood vessel damage and aggravates brain edema. The combination of edema caused by the tumor itself and radiotherapy is collectively referred to as intractable brain edema. Edema can increase intracranial pressure and cause associated neurologic symptoms, which seriously affects the quality of life of patients. Steroids, specifically dexamethasone, have become the gold standard for the management of tumor-associated edema. However, steroids can lead to variety of adverse effects, including moon face, high blood pressure, high blood sugar, increased risk of infection, bone thinning (osteoporosis), and fractures, especially with prolonged use. The investigation of other types of drugs is urgently needed to address this problem.Compared to other anti-angiogenic agents, anlotinib acts on vascular endothelial growth factor receptors (VEGFR1, VEGFR2/KDR, and VEGFR3), fibroblast growth factor receptors (FGFR1, FGFR2, FGFR3 and FGFR4), platelet derived growth factor receptor (PDGFR) and stem cell factor receptor (c-kit) simultaneously. However, according to the literature retrieval, there are no studies on anlotinib for the treatment of intractable brain edema. We describe here two cases of brain edema and review the literature available and hope to discover new agents that are safer and more effective.

Stereotactic radiosurgery of benign brain tumors in elderly patients: evaluation of outcome and toxicity

BACKGROUND

Stereotactic radiosurgery (SRS) is widely accepted as a therapeutic option for meningiomas (M) and vestibular schwannomas (VS). However, data on outcome and toxicity in the elderly population have rarely been reported in detail.

METHODS

All patients aged ≥ 65 years with M or VS who underwent single fraction SRS were included. Patient data were analyzed in terms of clinical tumor control and incidence of early and late treatment related complications, which were graded according to the Common Terminology Criteria for Adverse Events (CTCAE), RESULTS: We identified 245 patients with benign brain tumors (129 M and 116 VS, median tumor volume 2.9 ml, range 0.1-28). The median age was 71 years (range 65-86) and the mean follow-up times were 42 months (range 2-181). Tumors were irradiated with a median dose of 12.4 Gy. Actuarial clinical and radiological tumor control rates at 2, 5, and 10 years after SRS were 98%, 93%, and 88%, respectively. Recurrent tumors after previous treatment had a higher probability of post-radiosurgical progression (p < 0.001). Permanent toxicity (CTCAE I/II) were noted in 5.7%. No severe adverse events were observed during early and late follow up, although patients > 70 years had a slightly higher risk for toxicity (p = 0.027). The presence and extent of co-morbidities had no significant influence on local tumor control or toxicity.

CONCLUSION

SRS provides favorable tumor control with low risk for treatment-related severe complications. Thus, SRS should always be considered as treatment option for benign intracranial tumors (meningiomas, schwannomas), especially in the group of elderly patients.

Single- and Multifraction Stereotactic Radiosurgery Dose/Volume Tolerances of the Brain

PURPOSE

As part of the American Association of Physicists in Medicine Working Group on Stereotactic Body Radiotherapy investigating normal tissue complication probability (NTCP) after hypofractionated radiation therapy, data from published reports (PubMed indexed 1995-2018) were pooled to identify dosimetric and clinical predictors of radiation-induced brain toxicity after single-fraction stereotactic radiosurgery (SRS) or fractionated stereotactic radiosurgery (fSRS).

METHODS AND MATERIALS

Eligible studies provided NTCPs for the endpoints of radionecrosis, edema, or symptoms after cranial SRS/fSRS and quantitative dose-volume metrics. Studies of patients with only glioma, meningioma, vestibular schwannoma, or brainstem targets were excluded. The data summary and analyses focused on arteriovenous malformations (AVM) and brain metastases.

RESULTS

Data from 51 reports are summarized. There was wide variability in reported rates of radionecrosis. Available data for SRS/fSRS for brain metastases were more amenable to NTCP modeling than AVM data. In the setting of brain metastases, SRS/fSRS-associated radionecrosis can be difficult to differentiate from tumor progression. For single-fraction SRS to brain metastases, tissue volumes (including target volumes) receiving 12 Gy (V12) of 5 cm³, 10 cm³, or >15 cm³ were associated with risks of symptomatic radionecrosis of approximately 10%, 15%, and 20%, respectively. SRS for AVM was associated with modestly lower rates of symptomatic radionecrosis for equivalent V12. For brain metastases, brain plus target volume V20 (3-fractions) or V24 (5-fractions) <20 cm³ was associated with <10% risk of any necrosis or edema, and <4% risk of radionecrosis requiring resection.

CONCLUSIONS

The risk of radionecrosis after SRS and fSRS can be modeled as a function of dose and volume treated. The use of fSRS appears to reduce risks of radionecrosis for larger treatment volumes relative to SRS. More standardized dosimetric and toxicity reporting is needed to facilitate future pooled analyses that can refine predictive models of brain toxicity risks.

Gamma Knife radiosurgery for intracranial benign meningiomas: follow-up outcome in 130 patients

OBJECTIVEThe authors retrospectively analyzed the follow-up data in 130 patients with intracranial benign meningiomas after Gamma Knife radiosurgery (GKRS), evaluated the tumor progression-free survival (PFS) rate and neurological function preservation rate, and determined the predictors by univariate and multivariate survival analysis.METHODSThis cohort of 130 patients with intracranial benign meningiomas underwent GKRS between May 2012 and May 2015 at the Second Hospital of Tianjin Medical University. The median age was 54.5 years (range 25-81 years), and women outnumbered men at a ratio of 4.65:1. All clinical and radiological data were obtained for analysis. No patient had undergone prior traditional radiotherapy or chemotherapy. The median tumor volume was 3.68 cm3 (range 0.23-45.78 cm3). A median margin dose of 12.0 Gy (range 10.0-16.0 Gy) was delivered to the tumor with a median isodose line of 50% (range 50%-60%).RESULTSDuring a median follow-up of 36.5 months (range 12-80 months), tumor volume regressed in 37 patients (28.5%), was unchanged in 86 patients (66.2%), and increased in 7 patients (5.4%). The actuarial tumor progression-free survival (PFS) rate was 98%, 94%, and 87% at 1, 3, and 5 years, respectively, after GKRS. Tumor recurred in 7 patients at a median follow-up of 32 months (range 12-56 months). Tumor volume ≥ 10 cm3 (p = 0.012, hazard ratio [HR] 8.25, 95% CI 1.60-42.65) and pre-GKRS Karnofsky Performance Scale score < 90 (p = 0.006, HR 9.31, 95% CI 1.88-46.22) were independent unfavorable predictors of PFS rate after GKRS. Of the 130 patients, 101 (77.7%) presented with one or more neurological symptoms or signs before GKRS. Neurological symptoms or signs improved in 40 (30.8%) patients, remained stable in 83 (63.8%), and deteriorated in 7 (5.4%) after GKRS. Two (1.5%) patients developed new cranial nerve (CN) deficit. Tumor volume ≥ 10 cm3 (p = 0.042, HR = 4.73, 95% CI 1.06-21.17) and pre-GKRS CN deficit (p = 0.045, HR = 4.35, 95% CI 0.84-22.48) were independent unfavorable predictors for improvement in neurological symptoms or signs. Six (4.6%) patients developed new or worsening peritumoral edema with a median follow-up of 4.5 months (range 2-7 months).CONCLUSIONSGKRS provided good local tumor control and high neurological function preservation in patients with intracranial benign meningiomas. Patients with tumor volume < 10 cm3, pre-GKRS Karnofsky Performance Scale score ≥ 90, and no pre-GKRS CN deficit (I-VIII) can benefit from stereotactic radiosurgery. It can be considered as the primary or adjuvant management of intracranial benign meningiomas.

Stereotactic radiosurgery combined with anlotinib for limited brain metastases with perilesional edema in non-small cell lung cancer: Rvision-001 study protocol

INTRODUCTION

About 50% of patients with non-small cell lung cancers (NSCLC) are diagnosed with brain metastases during treatment, and stereotactic radiosurgery (SRS) is an important treatment for brain oligometastasis. Some patients with brain metastases have cerebral edema before treatment, and radiation therapy may also cause, or aggravate brain edema. Vascular endothelial growth factor (VEGF) promotes angiogenesis and increase vascular permeability, and previous studies have shown that anti-VEGF treatment can reduce brain edema. We hypothesized that anlotinib hydrochloride can reduce perilesional edema around brain metastases, create conditions for subsequent SRS, increase local control rate and improve patient prognosis.

METHODS

From one week before stereotactic radiosurgery, patients begin to receive anlotinib once a day (12 mg) from day 1-14 of a 21 day cycle, with two cycles in total. Brain magnetic resonance imaging (MRI) scan is taken before treatment, one week and one month after medication. A total of 50 patients will be included in this study. The primary endpoint is the Edema Index, and the secondary endpoints are intracranial objective response rate (iORR), intracranial progression-free survival (iPFS), objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS), overall survival (OS), safety, and the rate of SRS after anlotinib treatment.

DISCUSSION

This study is a multicenter, prospective, single-arm, phase II clinical study, and explores the efficacy and tolerability of SRS with anlotinib in NSCLC patients with limited brain metastases. The aim of the study is to provide new treatment options for NSCLC patients with brain metastases.

Significance of skull osteoporosis to the development of peritumoral brain edema after LINAC-based radiation treatment in patients with intracranial meningioma

Background and purpose

Disruption of the tumor-brain barrier in meningioma plays a critical role in the development of peritumoral brain edema (PTBE). We hypothesized that osteoporotic conditions may be associated with PTBE occurrence after radiation in patients with intracranial meningioma.

Methods

We measured Hounsfield units (HU) of the frontal skull on simulation brain CT in patients who underwent linear accelerator (LINAC)-based radiation treatment for intracranial meningioma. Receiver operating characteristic curve analysis was performed to determine the optimal cut-off values for several predictive factors. The cumulative hazard for PTBE was estimated and classified according to these factors. Hazard ratios were then estimated to identify independent predictive factors associated with the development of PTBE after radiation in intracranial meningioma patients.

Results

A total of 83 intracranial meningiomas in 76 patients who received LINAC-based radiation treatment in our hospital over an approximate 5-year period were included for the study. We found mean frontal skull HU ≤630.625 and gross tumor volume >7.194 cc to be independent predictors of PTBE after radiation treatment in patients with meningioma (hazard ratio, 8.41; P = 0.019; hazard ratio, 5.92; P = 0.032, respectively). In addition, patients who were ≥65 years showed a marginally significant association with PTBE.

Conclusions

Our study suggests that possible osteoporotic conditions, large tumor volume, and older age may be associated with PTBE occurrence after LINAC-based radiation treatment for intracranial meningioma. In the future we anticipate that these findings may enhance the understanding of the underlying mechanisms of PTBE after radiation in meningioma patients.

Laser Interstitial Thermotherapy for Treatment of Symptomatic Peritumoral Edema After Radiosurgery for Meningioma

BACKGROUND

Symptomatic peritumoral edema (PTE) is a known complication after radiosurgical treatment of meningiomas. Although the edema in most patients can be successfully managed conservatively with corticosteroid therapy or bevacizumab, some medically refractory cases may require surgical resection of the underlying lesion when feasible. Laser interstitial thermotherapy (LITT) continues to gain traction as an effective therapeutic modality for the treatment of radiation necrosis where its biggest impact is through the control of peritumoral edema.

CASE DESCRIPTION

A 56-year-old woman with neurofibromatosis 2 presented with a symptomatic, regrowing left frontotemporal lesion that had previously been radiated, then resected with confirmed recurrence of grade I meningioma, and subsequently radiated again for lesion recurrence. Given her history of 2 prior same-side craniotomies, including a complication of wound infection, she was not a candidate for further open surgical resection. Having failed conservative management, she underwent LITT with intraoperative biopsy demonstrating viable grade I meningioma. Postoperatively, she demonstrated radiographic marked, serial reduction of PTE and experienced resolution of her symptoms.

CONCLUSIONS

This case demonstrates that LITT may be a viable alternative treatment for patients with meningioma with symptomatic PTE who have failed medical therapy and require surgical intervention.

Stereotactic Radiotherapy for Parasagittal and Parafalcine Meningiomas: Patient Selection and Special Considerations

Treatment options for intracranial meningiomas are surgical resection alone, surgery followed by adjuvant radiation therapy (RT), or exclusive RT. Parasagittal and parafalcine meningiomas are a subgroup of meningeal disease located close to the vascular structures. Considering the frequent venous invasion, a complete resection is not possible in the majority of cases, and even if a Simpson Grade I resection can be performed, the risk of recurrence is relevant. To date, few studies are focused on parasagittal and parafalcine meningiomas. Because of their specific related issues, particular considerations on decision-making process, outcome, and toxicity follow-up are mandatory. In fact, parasagittal and parafalcine meningiomas require a clear-cut radiological assessment, as well as a tailored toxicity risk evaluation. Moreover, similarly to other meningioma sites, also for parasagittal and parafalcine ones, a standardization of local control, toxicity, and quality of life evaluation is needed in order to lead to a pooled analysis of the results. In this context, our aim was to review the literature data regarding the role of both single-session and multisession radiosurgery (RS), and stereotactic radiotherapy (SRT) for parasagittal and parafalcine meningioma management, summarizing available data on safety and efficacy. It was also discussed how RS and SRT can be performed in a setting of evolving views concerning the treatment paradigm of the parasagittal and parafalcine meningiomas.