Pathophysiology, diagnosis, and treatment of radiation necrosis in the brain

Stereotactic radiotherapy for metastatic brain tumors: A comparative analysis of dose distributions among VMAT, Helical TomoTherapy, CyberKnife, Gamma Knife, and ZAP-X

This study evaluates various radiotherapy techniques for treating metastatic brain tumor (BT), focusing on non-coplanar volumetric modulated arc radiotherapy (NC-VMAT), coplanar VMAT (C-VMAT), Helical TomoTherapy (HT), CyberKnife (CK), Gamma Knife (GK), and ZAP-X. CT images and structures of 12 patients who underwent CK for a single BT were utilized. Twelve treatment plans were created for each planning device. All plans adopted the approach of prescription doses to planning target volume D99.5%. They were divided into stereotactic radiosurgery (SRS) (prescription dose; 21-23 Gy) and stereotactic radiotherapy (SRT) (prescription dose; 30-36.5 Gy) groups and the same parameters evaluated included Gradient Index (GI), Paddick Conformity Index (CI), and treatment time (t-time). In the SRS group, mean values of GI and CI values were: NC-VMAT (4.28, 0.60), C-VMAT (5.61, 0.44), HT (4.68, 0.42), CK (4.31, 0.61), GK (2.81, 0.82), and ZAP-X (2.99, 0.80). In the SRT group: NC-VMAT (3.27, 0.84), C-VMAT (3.81, 0.82), HT (3.76, 0.65), CK (2.98, 0.77), GK (2.61, 0.90), and ZAP-X (2.80, 0.84). There were no significant differences in the mean values of CI and GI between ZAP-X and GK in both groups (p > 0.05). NC-VMAT and C-VMAT had shorter t-time than other techniques in both groups. ZAP-X is relatively superior in CI and GI for small tumors, similar to GK, while differences with NC-VMAT and CK diminish as tumor volume increases. ZAP-X, CK, and GK have longer t-time than other treatment techniques, regardless of volume.

Development of a recursive partitioning analysis for prediction of radiation necrosis following single-fraction stereotactic radiosurgery for intact brain metastases

PURPOSE/OBJECTIVE

Radiation necrosis (RN) is a potential complication after stereotactic radiosurgery (SRS) for brain metastases. This study develops a recursive partitioning analysis (RPA) to identify patients at risk for RN following SRS.

METHODS

Patients who underwent single-fraction SRS for intact brain metastases at a single institution from 2017 to 2021 were identified. Cox regression identified factors associated with RN, and variables with p < 0.1 were included in the RPA. Patients with staged SRS, incomplete records, or less than 3 months of follow-up were excluded.

RESULTS

The study included 170 patients with 919 lesions, with median follow-up of 9 months. Primary disease sites were non-small cell lung cancer (NSCLC, 49%), breast cancer (12%), melanoma (11%), renal cancer (6%), and others (22%). Median prescription dose was 24 Gy, and median maximum lesion dimension (MLD) was 0.7 cm. RN occurred in 110 (12.2%) lesions, of which 32 (3.5%) were symptomatic, at median of 4.9 months after SRS. Variables for RPA included primary disease site, tumor location, MLD, prior SRS, number of SRS targets, dosimetry, prior hemorrhage, and concurrent systemic therapy. RPA identified four groups: Group 1 (MLD ≤ 0.8 cm, non-breast/NSCLC/renal), Group 2 (MLD ≤ 0.8 cm, breast/NSCLC/renal), Group 3 (MLD > 0.8 cm, no post-SRS hemorrhage), and Group 4 (MLD > 0.8 cm, post-SRS hemorrhage). Two-year RN free survival was 99% (Group 1), 89% (Group 2), 70% (Group 3), and 52% (Group 4).

CONCLUSION

This is the first RPA model for RN after single-fraction SRS, which may aid in risk assessment and distinguishing RN from tumor progression.

Chronic expanding hematoma following Gamma Knife irradiation for primary central nervous system lymphoma: illustrative case

BACKGROUND

Chronic expanding hematoma (CEH) is a rare disease characterized by slow expansion, especially reported after Gamma Knife radiosurgery (GKRS) for cerebral arteriovenous malformations. No cases have been reported following treatment for primary central nervous system lymphoma (PCNSL). Vascular endothelial growth factor and vascular endothelial growth factor receptor-1 (VEGFR-1) have been reported to be responsible for CEH induction.

OBSERVATIONS

A 56-year-old woman underwent partial tumor removal for PCNSL in the left temporo-occipital lobe at another hospital. One and a half months later, a new lesion was observed, and she underwent GKRS, including the residual lesion. She was treated with multiple chemotherapy regimens including R-MPV (rituximab, methotrexate, procarbazine, vincristine) but relapsed repeatedly and was administered tirabrutinib. Four years after GKRS, the gadolinium-enhanced lesion slowly grew. Tumor recurrence or radiation necrosis was suspected, and surgical removal was performed. The tissue was composed of nonmalignant brain tissue and fibrinized hematoma, which demonstrated strong expression of VEGFR-1 on immunostaining, and the pathological diagnosis was CEH.

LESSONS

In this patient, CEH could have resulted from VEGFR-1 expression due to GKRS. For a patient with slow lesion growth following GKRS for PCNSL, surgical removal should be considered, taking into account the possibility of CEH along with recurrence and radiation necrosis. https://thejns.org/doi/10.3171/CASE258.

Recent advances in laser interstitial thermal therapy in the treatment of brain metastases and radiation necrosis

PURPOSE

This manuscript reviews advancements in Laser Interstitial Thermal Therapy (LITT) for treating brain metastases and radiation necrosis, emphasizing its minimally invasive nature and precision in targeting deep-seated or eloquent area lesions. It analyzes studies from 2011 to 2024 to evaluate LITT's efficacy, safety, and complications while highlighting the need for standardized clinical endpoints. Despite its potential, LITT remains a secondary treatment due to limited high-level evidence, requiring further research and multidisciplinary collaboration.

METHODS

A systematic PubMed search identified 2,004 articles on LITT for brain metastases and radiation necrosis. Filtering for studies from 2011 to 2024 resulted in 60 selected articles: 4 clinical trials, 22 observational studies, 3 case reports, 2 case series, and the rest review articles. Relevant data were extracted, analyzed, and compiled for this review.

RESULTS

LITT is primarily used for lesions unsuitable for open craniotomy, such as deep-seated or eloquent-area tumors. Literature supports its increasing neuro-oncological applications, particularly in brain metastases, gliomas, meningiomas, and radiation necrosis.

CONCLUSION

The evolving landscape of brain metastasis treatment underscores the importance of a multidisciplinary approach incorporating standardized reporting, advanced imaging, and molecular diagnostics. Further innovation and collaboration are needed to optimize LITT's role in neuro-oncology and address treatment challenges in the era of personalized medicine.

Evolving Role of PET Imaging in Assessing Vascular and Central Nervous System Complications of Radiation Therapy in Head and Neck Cancer

Radiation therapy for head and neck cancer is a cornerstone of treatment but can come with significant and lasting complications. Reduced vascularity and fibrosis heighten the risks of stroke, infection, and diminished quality of life. Advances in imaging technologies, such as fluorodeoxyglucose PET and sodium fluoride-PET, have emerged as critical tools for diagnosing and monitoring vascular inflammation and calcification, enabling earlier interventions and improved patient management. This review examines the pathophysiology of RT-induced damage, with a focus on vascular and connective tissue complications, and highlights the evolving role of PET imaging in early detection and management of these effects.

Trends in Efficacy Endpoints in Phase II Glioblastoma Trials: A Regulatory Science Analysis (FY2020-FY2022)

Background/Objectives: In glioblastoma trials, efficacy evaluation often deviates from the standard Response Evaluation Criteria in Solid Tumors (RECIST), an objective response rate (ORR) method, because of the unique nature of brain tumors. In phase II trials from the fiscal years (FYs) 2017-2019, primary endpoints (PEs) were overall survival (OS) at 29%, ORR at 20%, progression-free survival (PFS) at 17%, and OS rate at 10%. Clinical trial methodologies have likely evolved in recent years. This study analyzed trends in efficacy endpoint settings for phase II trials from FY2020 to FY2022 compared with FY2017-2019. Methods: Using Clarivate's Cortellis™ Clinical Trial Intelligence database, 116 phase II glioblastoma trials initiated between April 2020 and March 2023 were identified. After exclusions, 88 trials were analyzed. Trial characteristics, PEs, secondary endpoints (SEs), and designs were summarized and compared to prior data. Results: Of 101 PEs in the 88 trials, approximately half targeted newly diagnosed patients, and most tested pharmaceutical products. The most common PEs were FS (22%), OS (20%), and PFS rate (17%), while among 299 SEs, OS (15%), PFS (15%), and quality of life (14%) were most frequent. Time-to-event outcomes were employed in 74 (73%) trials, whereas ORR was used as a PE in only 7 trials (8%). ORR as a PE was significantly lower than in FY2017-2019 (p = 0.022). Conclusions: Recent glioblastoma trials show increased diversity in efficacy endpoints with less reliance on ORR compared to earlier periods, reflecting evolving strategies to address the unique challenges of glioblastoma treatment and evaluation.

Study Protocol of a Prospective Phase 2 Study of Chlorophyllin for the Management of Brain Radionecrosis in Patients With Diffuse Glioma (CHROME)

INTRODUCTION

Chlorophyllin (CHL) effectively decreases the side effects of radiotherapy (RT) by scavenging radiation-induced free radicals and reactive oxygen species in preclinical trials. This study aims to assess the efficacy of oral CHL for the treatment of brain radionecrosis in patients with diffuse glioma.

METHODS

This is a phase 2 trial prospective, interventional study. Adults (> 18 years) with a histological diagnosis of diffuse glioma developing radionecrosis will be eligible for the study. Radionecrosis will be identified using standard imaging protocols with magnetic resonance imaging (MRI) with or without positron emission tomography (PET). Patients will be accrued in two strata: symptomatic (stratum A) and asymptomatic (stratum B). Chlorophyllin will be prescribed to all patients using a morning oral dose of 750 mg before breakfast for 3 months. In addition, participants in stratum A will be given a tapering dose of dexamethasone for 1 month, while stratum B will not be receiving any steroids. Imaging with an MRI brain protocol and PET scan will be planned at 1 month and MRI at 3 months after starting CHL. The primary endpoint is the clinical-radiological response at 1 month. Secondary endpoints include response at 3 months, biological responses, survival analysis, and quality-of-life scores. The total sample size is 118 (60 and 58 in stratum A and B, respectively), with one interim analysis planned.

DISCUSSION

Radionecrosis leads to significant morbidity and is usually treated with corticosteroids, which can lead to several side effects from both acute and long-term use. Refractory radionecrosis requires treatment with bevacizumab or surgical resection. Chlorophyllin is a cheap, safe, and readily available phytopharmaceutical drug, which is being investigated in the phase 2 study and, if proven effective, can be considered an alternative for treating radionecrosis.

TRIAL REGISTRATION

Clinical Trial Registry India (CTRI): CTRI/2023/08/056166; ClinicalTrials.gov: NCT06016452.

Fractionated stereotactic radiotherapy of brainstem metastases - Clinical outcome and prognostic factors

Introduction

Brain metastases (BM) are the most common malignancy in the central nervous system (CNS) and observed in approximately 30% of cancer patients. Brainstem metastases (BSM) are challenging because of their location and the associated neurological risks. There are still no general therapeutic recommendations in this setting. Stereotactic radiosurgery (SRS) is one of few possible local therapy options but limited due to the tolerance dose of the brainstem. There is still no standard regarding the optimal dose und fractionation.

Methods

We retrospectively analyzed 65 patients with fractionated stereotactic radiotherapy (fSRT) for 69 BSM. FSRT was delivered at a dose of 30 Gy in six fractions prescribed to the 70 % isodose performed with Cyberknife. Overall survival (OS), local control (LC) and total intracranial brain control (TIBC) were analyzed via Kaplan-Meier method. Cox proportional hazards models were used to identify prognostic factors.

Results

Median follow-up was 27.3 months. One-year TIBC was 35.0 % and one-year LC was 84.1 %. Median OS was 8.9 months. In total, local progression occurred in 7.7 % and in 8.2 % symptomatic radiation-induced contrast enhancements (RICE) were diagnosed. In univariate analysis the Karnofsky performance scale index (KPI) (p = 0,001) was an independent prognostic factor for longer OS. Acute CTCAE grade 3 toxicities occurred in 18.4 %.

Conclusion

FSRT for BSM is as an effective and safe treatment approach with high LC rates and reasonable neurological toxicity despite the poor prognosis in this patient cohort is still very poor. Clinical and imaging follow-up is necessary to identify cerebral progression and adverse toxicity including RICE.

Treatment of cerebral radiation necrosis using hyperbaric oxygen therapy in a child: illustrative case

BACKGROUND

Cerebral radiation necrosis (RN) is an uncommon sequela that occurs in up to 25% of irradiated patients. This can occur 6 months to several years after therapy and create symptoms of headaches, focal neurological deficits, seizures, or behavioral changes. Management can involve corticosteroids, antiplatelet drugs, surgery, and hyperbaric oxygen therapy (HBOT). Currently, there is a paucity of literature investigating these therapies for routine use in the pediatric population.

OBSERVATIONS

A 5-year-old male with a right frontal atypical teratoid rhabdoid tumor previously underwent craniotomy for tumor resection, followed by chemotherapy, radiation, and autologous stem cell transplant therapy. Progressive radiographic changes surrounding the resection cavity were noted on routine surveillance imaging 20 months after the initial craniotomy and 11 months after the completion of radiation therapy. A biopsy ultimately confirmed RN. Due to the patient's previous complications with steroid use, the patient underwent HBOT. This achieved a significant improvement in clinical and radiographic sequelae of RN.

LESSONS

HBOT was utilized successfully for the management of this patient's RN. HBOT should be considered for pediatric patients with cerebral RN as a potential treatment strategy. https://thejns.org/doi/10.3171/CASE24460.

Proton Radiation Therapy: A Systematic Review of Treatment-Related Side Effects and Toxicities

Cancer is the second leading cause of death worldwide. Around half of all cancer patients undergo some type of radiation therapy throughout the course of their treatment. Photon radiation remains (RT) the most widely utilized modality of radiotherapy despite recent advancements in proton radiation therapy (PBT). PBT makes use of the particle's biological property known as the Bragg peak to better spare healthy tissue from radiation damage, with data to support that this treatment modality is less toxic than photon RT. Hence, proton radiation dosimetry looks better compared to photon dosimetry; however, due to proton-specific uncertainties, unexpected acute, subacute, and long-term toxicities can be encountered. Reported neurotoxicity resulting from proton radiation treatments include radiation necrosis, moyamoya syndrome, neurosensory toxicities, brain edema, neuromuscular toxicities, and neurocognitive toxicities. Pulmonary toxicities include pneumonitis and fibrosis, pleural effusions, and bronchial toxicities. Pericarditis, pericardial effusions, and atrial fibrillations are among the cardiac toxicities related to proton therapy. Gastrointestinal and hematological toxicities are also found in the literature. Genitourinary toxicities include urinary and reproductive-related toxicities. Osteological, oral, endocrine, and skin toxicities have also been reported. The side effects will be comparable to the ones following photon RT, nonetheless at an expected lower incidence. The toxicities collected mainly from case reports and clinical trials are described based on the organs affected and functions altered.

Determinants of cerebral radionecrosis in animal models: A systematic review

BACKGROUND

Radionecrosis is a common complication in radiation oncology, while mechanisms and risk factors have yet to be fully explored. We therefore conducted a systematic review to understand the pathogenesis and identify factors that significantly affect the development.

METHODS

We performed a systematic literature search based on the PRISMA guidelines using PubMed, Ovid, and Web of Science databases. The complete search strategy can be found as a preregistered protocol on PROSPERO (CRD42023361662).

RESULTS

We included 83 studies, most involving healthy animals (n = 72, 86.75 %). High doses of hemispherical irradiation of 30 Gy in rats and 50 Gy in mice led repeatedly to radionecrosis among different studies and set-ups. Higher dose and larger irradiated volume were associated with earlier onset. Fractionated schedules showed limited effectiveness in the prevention of radionecrosis. Distinct anatomical brain structures respond to irradiation in various ways. White matter appears to be more vulnerable than gray matter. Younger age, more evolved animal species, and genetic background were also significant factors, whereas sex was irrelevant. Only 13.25 % of the studies were performed on primary brain tumor bearing animals, no studies on brain metastases are currently available.

CONCLUSION

This systematic review identified various factors that significantly affect the induction of radionecrosis. The current state of research neglects the utilization of animal models of brain tumors, even though patients with brain malignancies constitute the largest group receiving brain irradiation. This latter aspect should be primarily addressed when developing an experimental radionecrosis model for translational implementation.

Radiomic Analysis of Treatment Effect for Patients with Radiation Necrosis Treated with Pentoxifylline and Vitamin E

BACKGROUND

The combination of oral pentoxifylline (Ptx) and vitamin E (VitE) has been used to treat radiation-induced fibrosis and soft tissue injury. Here, we review outcomes and perform a radiomic analysis of treatment effects in patients prescribed Ptx + VitE at our institution for the treatment of radiation necrosis (RN).

METHODS

A total of 48 patients treated with stereotactic radiosurgery (SRS) had evidence of RN and had MRI before and after starting Ptx + VitE. The radiation oncologist's impression of the imaging in the electronic medical record was used to score response to treatment. Support Vector Machine (SVM) was used to train a model of radiomics features derived from radiation necrosis on pre- and 1st post-treatment T1 post-contrast MRIs that can classify the ultimate response to treatment with Ptx + VitE.

RESULTS

A total of 43.8% of patients showed evidence of improvement, 18.8% showed no change, and 25% showed worsening RN upon imaging after starting Ptx + VitE. The median time-to-response assessment was 3.17 months. Nine patients progressed significantly and required Bevacizumab, hyperbaric oxygen therapy, or surgery. Patients who had multiple lesions treated with SRS were less likely to show improvement (p = 0.037). A total of 34 patients were also prescribed dexamethasone, either before (7), with (16), or after starting (11) treatment. The use of dexamethasone was not associated with an improved response to Ptx + VitE (p = 0.471). Three patients stopped treatment due to side effects. Finally, we were able to develop a machine learning (SVM) model of radiomic features derived from pre- and 1st post-treatment MRIs that was able to predict the ultimate treatment response to Ptx + VitE with receiver operating characteristic (ROC) area under curve (AUC) of 0.69.

CONCLUSIONS

Ptx + VitE appears safe for the treatment of RN, but randomized data are needed to assess efficacy and validate radiomic models, which may assist with prognostication.

Recent Status of Phase I Clinical Trials for Brain Tumors: A Regulatory Science Study of Exploratory Efficacy Endpoints

BACKGROUND

Appropriate exploratory efficacy data from Phase I trials are vital for subsequent phases. Owing to the uniqueness of brain tumors (BTs), use of different strategies to evaluate efficacy is warranted. We studied exploratory efficacy evaluation in Phase I trials involving BTs.

METHODS

Using Clarivate's Cortellis™, 42 Phase I trials of BT interventions conducted from 2020 to 2022 were analyzed for efficacy endpoints, which were set as primary endpoints (PEs) or secondary endpoints (SEs). Additionally, these metrics were compared in two subgroups: trials including only BTs (Group-A) and those including BTs among mixed solid tumors (Group-B).

RESULTS

Selected studies included a median of 1.5 PEs (range, 1-6) and 5 SEs (range, 0-19). Efficacy endpoints were included as PEs and SEs in 2 (5%) and 31 (78%) trials, respectively. Among the latter 31 trials that included 94 efficacy endpoints, 24, 22, 20, 9, and 8 reflected overall response rate (ORR), progression-free survival (PFS), overall survival (OS), duration of response (DOR), and disease control rate (DCR), respectively. ORR for BT was determined using various methods; however, the Response Evaluation Criteria in Solid Tumors (RECIST) was used less frequently in Group-A than in Group-B (p = 0.0039).

CONCLUSIONS

Recent Phase I trials included efficacy endpoints as SEs, with ORR, PFS, or OS included in ~ 50% trials and DOR or DCR in ~ 25%. No established criteria exist for imaging evaluation of BTs. Phase I trials involving mixed solid tumor cohorts revealed challenges in designing methods to assess the exploratory efficacy of BTs.

Mathematical modeling of brain metastases growth and response to therapies: A review

Brain metastases (BMs) are the most common intracranial tumor type and a significant health concern, affecting approximately 10% to 30% of all oncological patients. Although significant progress is being made, many aspects of the metastatic process to the brain and the growth of the resulting lesions are still not well understood. There is a need for an improved understanding of the growth dynamics and the response to treatment of these tumors. Mathematical models have been proven valuable for drawing inferences and making predictions in different fields of cancer research, but few mathematical works have considered BMs. This comprehensive review aims to establish a unified platform and contribute to fostering emerging efforts dedicated to enhancing our mathematical understanding of this intricate and challenging disease. We focus on the progress made in the initial stages of mathematical modeling research regarding BMs and the significant insights gained from such studies. We also explore the vital role of mathematical modeling in predicting treatment outcomes and enhancing the quality of clinical decision-making for patients facing BMs.

Dynamic monitoring of radiation-induced white matter microstructure injury in nasopharyngeal carcinoma via high-angular resolution diffusion imaging

PURPOSE

To investigate white matter microstructural abnormalities caused by radiotherapy in nasopharyngeal carcinoma (NPC) patients using MRI high-angular resolution diffusion imaging (HARDI).

METHODS

We included 127 patients with pathologically confirmed NPC: 36 in the pre-radiotherapy group, 29 in the acute response period (post-RT-AP), 23 in the early delayed period (post-RT-ED) group, and 39 in the late-delayed period (post-RT-LD) group. HARDI data were acquired for each patient, and dispersion parameters were calculated to compare the differences in specific fibre bundles among the groups. The Montreal Neurocognitive Assessment (MoCA) was used to evaluate neurocognitive function, and the correlations between dispersion parameters and MoCA were analysed.

RESULTS

In the right cingulum frontal parietal bundles, the fractional anisotropy value decreased to the lowest level post-RT-AP and then reversed and increased post-RT-ED and post-RT-LD. The mean, axial, and radial diffusivity were significantly increased in the post-RT-AP (p < 0.05) and decreased in the post-RT-ED and post-RT-LD groups to varying degrees. MoCA scores were decreased post-radiotherapy than those before radiotherapy (p = 0.005). MoCA and mean diffusivity exhibited a mild correlation in the left cingulum frontal parahippocampal bundle.

CONCLUSIONS

White matter tract changes detected by HARDI are potential biomarkers for monitoring radiotherapy-related brain damage in NPC patients.

Prognostic Factors for Recurrent Glioma: A Population-Based Analysis

Background

The overall survival (OS) for patients with recurrent glioma is meager. Also, the effect of radionecrosis and prognostic factors for recurrent glioma remains controversial. In this regard, developing effective predictive models and guiding clinical care is crucial for these patients.

Methods

We screened patients with recurrent glioma after radiotherapy and those who received surgery between August 1, 2013, and December 31, 2020. Univariate and multivariate Cox regression analyses determined the independent prognostic factors affecting the prognosis of recurrent glioma. Moreover, nomograms were constructed to predict recurrent glioma risk and prognosis. Statistical methods were used to determine the prediction accuracy and discriminability of the nomogram prediction model based on the area under the curve (AUC), the C-index, the decision curve analysis (DCA), and the calibration curve. In order to distinguish high-risk and low-risk groups for OS, the X-Tile and Kaplan-Meier (K-M) survival curves were employed, and the nomogram prediction model was further validated by the X-Tile and K-M survival curves.

Results

According to a Cox regression analysis, independent prognostic factors of recurrent glioma after radiotherapy with radionecrosis were World Health Organization (WHO) grade and gliosis percentage. We utilized a nomogram prediction model to analyze results visually. The C-index was 0.682 (95% CI: 0.616-0.748). According to receiver operating characteristic (ROC) analysis, calibration plots, and DCA, the nomogram prediction model was found to have a high-performance ability, and all patients were divided into low-risk and high-risk groups based on OS (P < .001).

Conclusion

WHO grade and gliosis percentage are prognostic factors for recurrent glioma with radionecrosis, and a nomogram prediction model was established based on these two variables. Patients could be divided into high- and low-risk groups with different OS by this model, and it will provide individualized clinical decisions for future treatment.

Neurocognitive Effects and Necrosis in Childhood Cancer Survivors Treated With Radiation Therapy: A PENTEC Comprehensive Review

PURPOSE

A PENTEC review of childhood cancer survivors who received brain radiation therapy (RT) was performed to develop models that aid in developing dose constraints for RT-associated central nervous system (CNS) morbidities.

METHODS AND MATERIALS

A comprehensive literature search, through the PENTEC initiative, was performed to identify published data pertaining to 6 specific CNS toxicities in children treated with brain RT. Treatment and outcome data on survivors were extracted and used to generate normal tissue complication probability (NTCP) models.

RESULTS

The search identified investigations pertaining to 2 of the 6 predefined CNS outcomes: neurocognition and brain necrosis. For neurocognition, models for 2 post-RT outcomes were developed to (1) calculate the risk for a below-average intelligence quotient (IQ) (IQ <85) and (2) estimate the expected IQ value. The models suggest that there is a 5% risk of a subsequent IQ <85 when 10%, 20%, 50%, or 100% of the brain is irradiated to 35.7, 29.1, 22.2, or 18.1 Gy, respectively (all at 2 Gy/fraction and without methotrexate). Methotrexate (MTX) increased the risk for an IQ <85 similar to a generalized uniform brain dose of 5.9 Gy. The model for predicting expected IQ also includes the effect of dose, age, and MTX. Each of these factors has an independent, but probably cumulative effect on IQ. The necrosis model estimates a 5% risk of necrosis for children after 59.8 Gy or 63.6 Gy (2 Gy/fraction) to any part of the brain if delivered as primary RT or reirradiation, respectively.

CONCLUSIONS

This PENTEC comprehensive review establishes objective relationships between patient age, RT dose, RT volume, and MTX to subsequent risks of neurocognitive injury and necrosis. A lack of consistent RT data and outcome reporting in the published literature hindered investigation of the other predefined CNS morbidity endpoints.

Brain and Brain Stem Necrosis After Reirradiation for Recurrent Childhood Primary Central Nervous System Tumors: A PENTEC Comprehensive Review

PURPOSE

Reirradiation is increasingly used in children and adolescents/young adults (AYA) with recurrent primary central nervous system tumors. The Pediatric Normal Tissue Effects in the Clinic (PENTEC) reirradiation task force aimed to quantify risks of brain and brain stem necrosis after reirradiation.

METHODS AND MATERIALS

A systematic literature search using the PubMed and Cochrane databases for peer-reviewed articles from 1975 to 2021 identified 92 studies on reirradiation for recurrent tumors in children/AYA. Seventeen studies representing 449 patients who reported brain and brain stem necrosis after reirradiation contained sufficient data for analysis. While all 17 studies described techniques and doses used for reirradiation, they lacked essential details on clinically significant dose-volume metrics necessary for dose-response modeling on late effects. We, therefore, estimated incidences of necrosis with an exact 95% CI and qualitatively described data. Results from multiple studies were pooled by taking the weighted average of the reported crude rates from individual studies.

RESULTS

Treated cancers included ependymoma (n = 279 patients; 7 studies), medulloblastoma (n = 98 patients; 6 studies), any CNS tumors (n = 62 patients; 3 studies), and supratentorial high-grade gliomas (n = 10 patients; 1 study). The median interval between initial and reirradiation was 2.3 years (range, 1.2-4.75 years). The median cumulative prescription dose in equivalent dose in 2-Gy fractions (EQD22; assuming α/β value = 2 Gy) was 103.8 Gy (range, 55.8-141.3 Gy). Among 449 reirradiated children/AYA, 22 (4.9%; 95% CI, 3.1%-7.3%) developed brain necrosis and 14 (3.1%; 95% CI, 1.7%-5.2%) developed brain stem necrosis with a weighted median follow-up of 1.6 years (range, 0.5-7.4 years). The median cumulative prescription EQD22 was 111.4 Gy (range, 55.8-141.3 Gy) for development of any necrosis, 107.7 Gy (range, 55.8-141.3 Gy) for brain necrosis, and 112.1 Gy (range, 100.2-117 Gy) for brain stem necrosis. The median latent period between reirradiation and the development of necrosis was 5.7 months (range, 4.3-24 months). Though there were more events among children/AYA undergoing hypofractionated versus conventionally fractionated reirradiation, the differences were not statistically significant (P = .46).

CONCLUSIONS

Existing reports suggest that in children/AYA with recurrent brain tumors, reirradiation with a total EQD22 of about 112 Gy is associated with an approximate 5% to 7% incidence of brain/brain stem necrosis after a median follow-up of 1.6 years (with the initial course of radiation therapy being given with conventional prescription doses of ≤2 Gy per fraction and the second course with variable fractionations). We recommend a uniform approach for reporting dosimetric endpoints to derive robust predictive models of late toxicities following reirradiation.

Simultaneous evaluation of brain metastasis and thoracic cancer using semiconductor 11C-methionine PET/CT imaging

OBJECTIVE

To investigate the potential of whole-body digital 11C-methionine (MET) PET/CT imaging for simultaneous evaluation of thoracic cancer patients suspected of local recurrence (LR) after stereotactic radiosurgery (SRS) for brain metastasis.

METHODS

A total of 45 lung or breast cancer patients suspected of LR after SRS were investigated using brain and whole-body MET-PET/CT scans. We compared the tumor-to-normal ratio (TNR) and maximum standardized uptake values (SUVmax) between patients with LR and radiation necrosis (RN) and performed receiver operating characteristic (ROC) analyses. We also investigated associations among extracranial recurrence, intracranial recurrence, primary site, and initial treatment type.

RESULTS

A total of 44 LR and 14 RN lesions were analyzed. In the ROC analyses for differentiating LR from RN, TNR showed higher area under the curve (AUC) (0.82) than SUVmax (0.79), and the cutoff TNR value (2.12) was higher than current cutoff values of conventional PET systems. The whole-body scans detected extracranial recurrences in 31.1% of the patients. Recurrence rates were not significantly correlated with existence of intracranial recurrence or primary site, but patients who underwent non-surgical treatment (consisting of stage III/ IV patients according to the Union for International Cancer Control TNM classification or small-cell lung cancer patients) showed significantly higher recurrence than the surgically treated patients (68.8% vs. 10.3%, p = 0.0001).

CONCLUSION

In digital MET-PET/CT imaging, TNR was a more useful parameter to differentiate LR from RN than SUVmax, and the cutoff value was higher than those with conventional PET systems. Additional whole-body scans could detect extracranial recurrence and would be especially useful for advanced thoracic cancer patients who underwent non-surgical treatment.

Somatic Versus Germline: A Case Series of Three Children With ATM-Mutated Medulloblastoma

Somatic versus Germline-A Case Series of Three Children with ATM- mutated Medulloblastoma.

Radiation necrosis after radiation therapy treatment of brain metastases: A computational approach

Metastasis is the process through which cancer cells break away from a primary tumor, travel through the blood or lymph system, and form new tumors in distant tissues. One of the preferred sites for metastatic dissemination is the brain, affecting more than 20% of all cancer patients. This figure is increasing steadily due to improvements in treatments of primary tumors. Stereotactic radiosurgery (SRS) is one of the main treatment options for patients with a small or moderate number of brain metastases (BMs). A frequent adverse event of SRS is radiation necrosis (RN), an inflammatory condition caused by late normal tissue cell death. A major diagnostic problem is that RNs are difficult to distinguish from BM recurrences, due to their similarities on standard magnetic resonance images (MRIs). However, this distinction is key to choosing the best therapeutic approach since RNs resolve often without further interventions, while relapsing BMs may require open brain surgery. Recent research has shown that RNs have a faster growth dynamics than recurrent BMs, providing a way to differentiate the two entities, but no mechanistic explanation has been provided for those observations. In this study, computational frameworks were developed based on mathematical models of increasing complexity, providing mechanistic explanations for the differential growth dynamics of BMs relapse versus RN events and explaining the observed clinical phenomenology. Simulated tumor relapses were found to have growth exponents substantially smaller than the group in which there was inflammation due to damage induced by SRS to normal brain tissue adjacent to the BMs, thus leading to RN. ROC curves with the synthetic data had an optimal threshold that maximized the sensitivity and specificity values for a growth exponent β* = 1.05, very close to that observed in patient datasets.

Histopathologically confirmed radiation-induced damage of the brain - an in-depth analysis of radiation parameters and spatio-temporal occurrence

BACKGROUND

Radiation-induced damage (RID) after radiotherapy (RT) of primary brain tumors and metastases can be challenging to clinico-radiographically distinguish from tumor progression. RID includes pseudoprogression and radiation necrosis; the latter being irreversible and often associated with severe symptoms. While histopathology constitutes the diagnostic gold standard, biopsy-controlled clinical studies investigating RID remain limited. Whether certain brain areas are potentially more vulnerable to RID remains an area of active investigation. Here, we analyze histopathologically confirmed cases of RID in relation to the temporal and spatial dose distribution.

METHODS

Histopathologically confirmed cases of RID after photon-based RT for primary or secondary central nervous system malignancies were included. Demographic, clinical, and dosimetric data were collected from patient records and treatment planning systems. We calculated the equivalent dose in 2 Gy fractions (EQD22) and the biologically effective dose (BED2) for normal brain tissue (α/β ratio of 2 Gy) and analyzed the spatial and temporal distribution using frequency maps.

RESULTS

Thirty-three patients were identified. High-grade glioma patients (n = 18) mostly received one normofractionated RT series (median cumulative EQD22 60 Gy) to a large planning target volume (PTV) (median 203.9 ccm) before diagnosis of RID. Despite the low EQD22 and BED2, three patients with an accelerated hyperfractionated RT developed RID. In contrast, brain metastases patients (n = 15; 16 RID lesions) were often treated with two or more RT courses and with radiosurgery or fractionated stereotactic RT, resulting in a higher cumulative EQD22 (median 162.4 Gy), to a small PTV (median 6.7 ccm). All (n = 34) RID lesions occurred within the PTV of at least one of the preceding RT courses. RID in the high-grade glioma group showed a frontotemporal distribution pattern, whereas, in metastatic patients, RID was observed throughout the brain with highest density in the parietal lobe. The cumulative EQD22 was significantly lower in RID lesions that involved the subventricular zone (SVZ) than in lesions without SVZ involvement (median 60 Gy vs. 141 Gy, p = 0.01).

CONCLUSIONS

Accelerated hyperfractionated RT can lead to RID despite computationally low EQD22 and BED2 in high-grade glioma patients. The anatomical location of RID corresponded to the general tumor distribution of gliomas and metastases. The SVZ might be a particularly vulnerable area.

Perfusion MRI in the evaluation of brain metastases: current practice review and rationale for study of baseline MR perfusion imaging prior to stereotactic radiosurgery (STARBEAM-X)

Stereotactic radiosurgery is an established focal treatment for brain metastases with high local control rates. An important side-effect of stereotactic radiosurgery is the development of radionecrosis. On conventional MR imaging, radionecrosis and tumour progression often have similar appearances, but have contrasting management approaches. Perfusion MR imaging is often used in the post-treatment setting in order to help distinguish between the two, but image interpretation can be fraught with challenges.Perfusion MR plays an established role in the baseline and post-treatment evaluation of primary brain tumours and a number of studies have concentrated on the value of perfusion imaging in brain metastases. Of the parameters generated, relative cerebral blood volume is the most widely used variable in terms of its clinical value in differentiating between radionecrosis and tumour progression. Although it has been suggested that the relative cerebral blood volume tends to be elevated in active metastatic disease following treatment with radiosurgery, but not with treatment-related changes, the literature available on interpretation of the ratios provided in the context of defining tumour progression is not consistent.This article aims to provide an overview of the role perfusion MRI plays in the assessment of brain metastases and introduces the rationale for the STARBEAM-X study (Study of assessment of radionecrosis in brain metastases using MR perfusion extra imaging), which will prospectively evaluate baseline perfusion imaging in brain metastases. We hope this will allow insight into the vascular appearance of metastases from different primary sites, and aid in the interpretation of post-treatment perfusion imaging.

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.

Neurocognitive function following (chemo)radiotherapy for nasopharyngeal cancer and other head and neck cancers: A systematic review

When radiotherapy is used in the treatment of head and neck cancers, the brain commonly receives incidental doses of radiotherapy with potential for neurocognitive changes and subsequent impact on quality of life. This has not been widely investigated to date. A systematic search of MEDLINE, EMBASE, Psycinfo Info and the Cochrane Central Register of Controlled Trials (CENTRAL) electronic databases was conducted. Of 2077 records screened, 20 were eligible comprising 1308 patients. There were no randomised studies and 73.3% of included patients were from single center studies. IMRT was delivered in 72.6% of patients, and chemotherapy used in 61%. There was considerable heterogeneity in methods. Narrative synthesis was therefore carried out. Most studies demonstrated inferior neurocognitive outcomes when compared to control groups at 12 months and beyond radiotherapy. Commonly affected neurocognitive domains were memory and language which appeared related to radiation dose to hippocampus, temporal lobe, and cerebellum. Magnetic Resonance Imaging could be valuable in the detection of early microstructural and functional changes, which could be indicative of future neurocognitive changes. In studies investigating quality of life, the presence of neurocognitive impairment was associated with inferior quality of life outcomes. (Chemo)radiotherapy for head and neck cancer appears to be associated with a risk of long-term neurocognitive impairment. Few studies were identified, with substantial variation in methodology, thus limiting conclusions. High quality large prospective head and neck cancer studies using standardised, sensitive, and reliable neurocognitive tests are needed.

Increased risk for ex-vacuo ventriculomegaly with leukoencephalopathy (EVL) in whole brain radiation therapy and repeat radiosurgery treated brain metastasis patients

INTRODUCTION

Cerebral atrophy with leukoencephalopathy is a known morbidity after whole brain radiation therapy (WBRT), resulting in ex-vacuo ventriculomegaly with leukoencephalopathy (EVL). Here we studied the correlation between WBRT, stereotactic radiosurgery (SRS), and risk for EVL in brain metastases patients.

METHODS

In a retrospective study, we identified 195 patients (with 1,018 BM) who underwent SRS for BM (2007-2017) and had > 3 months of MRI follow-up. All patients who underwent ventriculoperitoneal shunting were excluded. Cerebral atrophy was measured by ex-vacuo-ventriculomegaly, defined based on Evans' criteria. Demographic and clinical variables were analyzed using logistic regression models.

RESULTS

Ex-vacuo ventriculomegaly was observed on pre-radiosurgery imaging in 29.7% (58/195) of the study cohort. On multivariate analysis, older age was the only variable associated with pre-radiosurgery ventriculomegaly. Of the 137 patients with normal ventricular size before radiosurgery, 27 (19.7 %) developed ex-vacuo ventriculomegaly and leukoencephalopathy (EVL) post-SRS. In univariate analysis, previous whole brain radiation therapy was the main factor associated with increased risk for developing EVL (OR = 5.08, p < 0.001). In bivariate models that included prior receipt of WBRT, both the number of SRS treatments (OR = 1.499, p = 0.025) and WBRT (OR = 11.321, p = 0.003 were independently associated with increased EVL risk.

CONCLUSIONS

While repeat radiosurgery contributes to the risk of EVL in BM patients, this risk is ∼20-fold lower than that associated with WBRT.

High-dose bevacizumab for radiation-induced brain necrosis: a case report

Radiation-induced brain necrosis (RIBN) is a common adverse event from radiation therapy. We present a case of a 56-year-old man, diagnosed with non-small-cell lung cancer with brain metastases 2 years prior, for which he had received whole brain radiotherapy and brain stereotactic radiosurgery, who presented to the oncology unit with headache, dizziness and abnormal gait. MRI of the brain revealed radiological worsening of a cerebellar mass, including edema and mass effect. After a multidisciplinary tumor board meeting, the patient was diagnosed with RIBN and received 4 cycles of high-dose bevacizumab, with complete symptom resolution and significant radiological response. We report the successful use of a high-dose, shorter-duration treatment protocol of bevacizumab for RIBN.

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.

Stereotactic radiotherapy for brain metastases: predictive factors of radionecrosis

PURPOSE

Stereotactic radiotherapy (SRT) is a highly effective approach and represents the current standard of treatment for patients with limited number of brain metastasis (BM). SRT is generally well tolerated but can sometimes lead to radionecrosis (RN). The aim of this study was to identify predictive factors of radionecrosis related to SRT for brain metastasis.

METHODS

This retrospective observational cohort study included patients who underwent SRT in the Institut Sainte Catherine between January 1st, 2017 and December 31st, 2020 for the treatment of brain metastasis from any cancer. Individual data and particularly signs of radionecrosis (clinical, imaging, anatomopathological) were collected from electronic medical records. Radionecrosis was defined as the occurrence on MRI of contrast-enhancing necrotic lesions, surrounded by edema, occurring at least 6 months after SRT and localized within fields of irradiation.

RESULTS

123 patients were included; median age was 66 years. 17 patients (11.8%) developed radionecrosis after a median follow up of 418.5 days [63;1498]. Predictive factors of radionecrosis in multivariate analysis were age under 66 years with a sensitivity of 77% and a specificity of 56%. No other factor as the presence of comorbidities, the number of irradiated metastases, the PTV volume or the volume of irradiated healthy brain were predictive of radionecrosis.

CONCLUSION

Age at treatment initiation and tumor location seems to be correlated with radionecrosis in patients with brain metastasis treated with SRT. These elements could be useful to adapted radiation therapy.

Re-irradiation for recurrent/progressive pediatric brain tumors: from radiobiology to clinical outcomes

INTRODUCTION

Brain tumors are the most common solid tumors in children. Neurosurgical excision, radiotherapy, and/or chemotherapy represent the standard of care in most histopathological types of pediatric central nervous system (CNS) tumors. Even though the successful cure rate is reasonable, some patients may develop recurrence locally or within the neuroaxis.

AREA COVERED

The management of these recurrences is not easy; however, significant advances in neurosurgery, radiation techniques, radiobiology, and the introduction of newer biological therapies, have improved the results of their salvage treatment. In many cases, salvage re-irradiation is feasible and has achieved encouraging results. The results of re-irradiation depend upon several factors. These factors include tumor type, extent of the second surgery, tumor volume, location of the recurrence, time that elapses between the initial treatment, the combination with other treatment agents, relapse, and the initial response to radiotherapy.

EXPERT OPINION

Reviewing the radiobiological basis and clinical outcome of pediatric brain re-irradiation revealed that re-irradiation is safe, feasible, and indicated for recurrent/progressive different tumor types such as; ependymoma, medulloblastoma, diffuse intrinsic pontine glioma (DIPG) and glioblastoma. It is now considered part of the treatment armamentarium for these patients. The challenges and clinical results in treating recurrent pediatric brain tumors were highly documented.

Functional Impairment in Pediatric Cancer Survivorship

Care for pediatric cancer survivors must include scheduled, thorough evaluations of potential chronic and late effects resulting from multidimensional cancer treatments. Assessment of functional independence with activities and participation is critical in assuring that survivors can optimally access their environments and pursue educational, occupational, and leisure activities appropriate to their interests and capabilities. Owing to their expertise in both rehabilitation and habilitation, pediatric physiatrists are of great benefit in the care of survivors of pediatric cancer.

Low-Dose Bevacizumab for the Treatment of Focal Radiation Necrosis of the Brain (fRNB): A Single-Center Case Series

Focal radiation necrosis of the brain (fRNB) is a late adverse event that can occur following the treatment of benign or malignant brain lesions with stereotactic radiation therapy (SRT) or stereotactic radiosurgery (SRS). Recent studies have shown that the incidence of fRNB is higher in cancer patients who received immune checkpoint inhibitors. The use of bevacizumab (BEV), a monoclonal antibody that targets the vascular endothelial growth factor (VEGF), is an effective treatment for fRNB when given at a dose of 5-7.5 mg/kg every two weeks. In this single-center retrospective case series, we investigated the effectiveness of a low-dose regimen of BEV (400 mg loading dose followed by 100 mg every 4 weeks) in patients diagnosed with fRNB. A total of 13 patients were included in the study; twelve of them experienced improvement in their existing clinical symptoms, and all patients had a decrease in the volume of edema on MRI scans. No clinically significant treatment-related adverse effects were observed. Our preliminary findings suggest that this fixed low-dose regimen of BEV can be a well-tolerated and cost-effective alternative treatment option for patients diagnosed with fRNB, and it is deserving of further investigation.

The complementary role of MRI and FET PET in high-grade gliomas to differentiate recurrence from radionecrosis

Introduction

Conventional magnetic resonance imaging (MRI) has limitations in differentiating tumor recurrence (TR) from radionecrosis (RN) in high-grade gliomas (HGG), which can present with morphologically similar appearances. Multiparametric advanced MR sequences and Positron Emission Tomography (PET) with amino acid tracers can aid in diagnosing tumor metabolism. The role of both modalities on an individual basis and combined performances were investigated in the current study.

Materials and Methods

Patients with HGG with MRI and PET within three weeks were included in the retrospective analysis. The multiparametric MRI included T1-contrast, T2-weighted sequences, perfusion, diffusion, and spectroscopy. MRI was interpreted by a neuroradiologist without using information from PET imaging. 18F-Fluoroethyl-Tyrosine (FET) uptake was calculated from the areas of maximum enhancement/suspicion, which was assessed by a nuclear medicine physician (having access to MRI to determine tumor-to-white matter ratio over a specific region). A definitive diagnosis of TR or RN was made based on the combination of multidisciplinary joint clinic decisions, histopathological examination, and clinic-radiological follow-up as applicable.

Results

62 patients were included in the study between July 2018 and August 2021. The histology during initial diagnosis was glioblastoma, oligodendroglioma, and astrocytoma in 43, 7, and 6 patients, respectively, while in 6, no definitive histological characterization was available. The median time from radiation (RT) was 23 months. 46 and 16 patients had TR and RN recurrence, respectively. Sensitivity, specificity, and accuracy using MRI were 98, 77, and 94%, respectively. Using PET imaging with T/W cut-off of 2.65, sensitivity, specificity, and accuracy were 79, 84, and 80%, respectively. The best results were obtained using both imaging combined with sensitivity, specificity, and accuracy of 98, 100, and 98%, respectively.

Conclusion

Combined imaging with MRI and FET-PET offers multiparametric assessment of glioma recurrence that is correlative and complimentary, with higher accuracy and clinical value.

History of Ablation Therapies in Neurosurgery

Laser interstitial thermal therapy (LITT) and high-intensity focused ultrasound thermal ablation are treatment options with great potential to treat glioblastoma, metastasis, epilepsy, essential tremor, and chronic pain. Results from recent studies show that LITT is a viable alternative to conventional surgical techniques in select patient populations. Although many of the bases for these treatments have existed since the 1930s, the most important advancement in these techniques has occurred in the last 15 years and the coming years hold much promise for these treatments.

Impressive reduction of brain metastasis radionecrosis after cabozantinib therapy in metastatic renal carcinoma: A case report and review of the literature

Introduction

Radionecrosis is a consequence of SRS (stereotactic radiosurgery) for brain metastases in 34% of cases, and if symptomatic (8%-16%), it requires therapy with corticosteroids and bevacizumab and, less frequently, surgery. Oncological indications are increasing and appropriate stereotactic adapted LINACs (linear accelerators) are becoming more widely available worldwide. Efforts are being made to treat brain radionecrosis in order to relieve symptoms and spare the use of active therapies.

Case presentation

Herein, we describe a 65-year-old female patient presenting with brain radionecrosis 6 months after stereotactic radiotherapy for two brain metastatic lesions. Being symptomatic with headache and slow cognitive-motor function, the patient received corticosteroids. Because of later lung progression, the patient took cabozantinib. An impressive reduction of the two brain radionecrosis areas was seen at the brain MRI 2 months after the initiation of the angiogenic drug.

Discussion

The high incidence of radionecrosis (2/2 treated lesions) can be interpreted by the combination of SRS and previous ipilimumab that is associated with increased risk of radionecrosis. The molecular mechanisms of brain radionecrosis, and its exact duration in time, are poorly understood. We hypothesize that the antiangiogenic effect of cabozantinib may have had a strong effect in reducing brain radionecrosis areas.

Conclusion

In this clinical case, cabozantinib is associated with a fast and significant volume reduction of brain radionecrosis appearing after SRS and concomitant immunotherapy. This drug seems to show, like bevacizumab, clinical implications not only for its efficacy in systemic disease control but also in reducing brain radionecrosis. More research is needed to evaluate all molecular mechanisms of brain radionecrosis and their interaction with systemic therapies like third-generation TKIs.

Microglia drive transient insult-induced brain injury by chemotactic recruitment of CD8+ T lymphocytes

The crosstalk between the nervous and immune systems has gained increasing attention for its emerging role in neurological diseases. Radiation-induced brain injury (RIBI) remains the most common medical complication of cranial radiotherapy, and its pathological mechanisms have yet to be elucidated. Here, using single-cell RNA and T cell receptor sequencing, we found infiltration and clonal expansion of CD8⁺ T lymphocytes in the lesioned brain tissues of RIBI patients. Furthermore, by strategies of genetic or pharmacologic interruption, we identified a chemotactic action of microglia-derived CCL2/CCL8 chemokines in mediating the infiltration of CCR2⁺/CCR5⁺ CD8⁺ T cells and tissue damage in RIBI mice. Such a chemotactic axis also participated in the progression of cerebral infarction in the mouse model of ischemic injury. Our findings therefore highlight the critical role of microglia in mediating the dysregulation of adaptive immune responses and reveal a potential therapeutic strategy for non-infectious brain diseases.

Differentiating radiation necrosis from tumor recurrence: a systematic review and diagnostic meta-analysis comparing imaging modalities

PURPSOSE

Cerebral radiation necrosis (RN) is often a delayed phenomenon occurring several months to years after the completion of radiation treatment. Differentiating RN from tumor recurrence presents a diagnostic challenge on standard MRI. To date, no evidence-based guidelines exist regarding imaging modalities best suited for this purpose. We aim to review the current literature and perform a diagnostic meta-analysis comparing various imaging modalities that have been studied to differentiate tumor recurrence and RN.

METHODS

A systematic search adherent to PRISMA guidelines was performed using Scopus, PubMed/MEDLINE, and Embase. Pooled sensitivities and specificities were determined using a random-effects or fixed-effects proportional meta-analysis based on heterogeneity. Using diagnostic odds ratios, a diagnostic frequentist random-effects network meta-analysis was performed, and studies were ranked using P-score hierarchical ranking.

RESULTS

The analysis included 127 studies with a total of 220 imaging datasets, including the following imaging modalities: MRI (n = 10), MR Spectroscopy (MRS) (n = 28), dynamic contrast-enhanced MRI (n = 7), dynamic susceptibility contrast MRI (n = 36), MR arterial spin labeling (n = 5), diffusion-weighted imaging (n = 13), diffusion tensor imaging (DTI) (n = 2), PET (n = 89), and single photon emission computed tomography (SPECT) (n = 30). MRS had the highest pooled sensitivity (90.7%). DTI had the highest pooled specificity (90.5%). Our hierarchical ranking ranked SPECT and MRS as most preferable, and MRI was ranked as least preferable.

CONCLUSION

These findings suggest SPECT and MRS carry greater utility than standard MRI in distinguishing RN from tumor recurrence.

Upfront and Repeated Stereotactic Radiosurgery in Patients With Brain Metastases From NSCLC

INTRODUCTION

Approximately 40% of non-small-cell lung cancer (NSCLC) patients develop brain metastases (BM). Stereotactic radiosurgery (SRS) instead of whole-brain radiotherapy (WBRT) is increasingly administered as an upfront treatment to patients with a limited number of BM. We present outcomes and validation of prognostic scores for these patients treated with upfront SRS.

METHODS

We retrospectively analyzed 199 patients with a total of 268 SRS courses for 539 brain metastases. Median patient age was 63 years. For larger BM, dose reduction to 18 Gy or hypofractionated SRS in 6 fractions was applied. We analyzed the BMV-, the RPA-, the GPA- and the lung-mol GPA score. Cox proportional hazards models with univariate and multivariate analyses were fitted for overall survival (OS) and intracranial progression-free survival (icPFS).

RESULTS

Sixty-four patients died, 7 of them of neurological causes. Thirty eight patients (19,3%) required a salvage WBRT. Median OS was 38, 8 months (IQR: 6-NA). In univariate analysis as well as multivariate analysis, the Karnofsky performance scale index (KPI) ≥90% (P = 0, 012 and P = 0, 041) remained as independent prognostic factor for longer OS. All 4 prognostic scoring indices could be validated for OS assessment (BMV P = 0, 007; RPA P = 0, 026; GPA P = 0, 003; lung-mol GPA P = 0, 05).

CONCLUSION

In this large cohort of NSCLC patients with BM treated with upfront and repeated SRS, OS was markedly favourable, in comparison to literature. Upfront SRS is an effective treatment approach in those patients and can decidedly reduce the impact of BM on overall prognosis. Furthermore, the analysed scores are useful prognostic tools for OS prediction.

Recurrent Brain Metastasis Versus Radiation-Induced Necrosis: A Case Report and Literature Review

Radiotherapy is the cornerstone of brain metastasis management. With the advancement of therapies, patients are living longer, exposing them to the long-term effects of radiotherapy. Using concurrent or sequential chemotherapy, targeted agents, and immune checkpoint inhibitors may increase the incidence and severity of radiation-induced toxicity. Recurrent metastasis and radiation necrosis (RN) appear indistinguishable on neuroimaging, making it a diagnostic dilemma for clinicians. Here, we present a case of RN in a 65-year-old male patient who previously had brain metastasis (BM) from primary lung cancer, misdiagnosed initially as recurrent BM.

The Role of Apparent Diffusion Coefficient Values in Glioblastoma: Differentiating Tumor Progression Versus Treatment-Related Changes

OBJECTIVE

Glioblastoma represents the most common primary brain malignancy with a median survival of 15 months. Follow-up examinations are crucial to establish the presence of tumor recurrence, as well as treatment-associated changes such as ischemic infarction and radiation effects. Even though magnetic resonance imaging is a valuable tool, a histopathological diagnosis is often required because of imaging overlap between tumor recurrence and treatment associated changes. We set out to measure the apparent diffusion coefficient (ADC) values of the lesions in magnetic resonance imaging scans of treated glioblastoma patients to investigate if ADC values could accurately differentiate between tumor progression, radiation-related changes, and ischemic infarctions.

METHODS

We evaluated ADC values among 3 groups, patients with tumor progression, radiation necrosis, and ischemic infarctions. The regions of interest were placed in the areas of greatest hypointensity among solid lesions using the ADC maps, excluding areas with necrotic, cystic, or hemorrhagic changes. The ADC values of the contralateral normal appearing white matter were also measured as the reference value for each patient. The relative ADC (rADC) values were measured for all 3 groups. Comparison between lesions and normal white matter was evaluated by Wilcoxon signed test.

RESULTS

A total of 157 patients were included in the study; 49 patients classified as tumor progression, 58 patients as radiation necrosis, and 50 patients as ischemic infarctions. The mean ± SD ADC value was 752.8 ± 132.5 for tumor progression, 479.0 ± 105.2 for radiation-related changes, and 250.1 ± 57.2 for ischemic infarctions. The mean ± SD rADC value was 1.07 ± 0.22 for tumor progression, 0.66 ± 0.14 for radiation necrosis, and 0.34 ± 0.08 for ischemic infarctions. The mean rADC values were significantly higher in tumor progression, compared with both radiation necrosis and ischemic changes (P < 0.001).

CONCLUSIONS

The present study demonstrates that ADC values are a helpful tool to differentiate between tumor progression, radiation necrosis, and posttreatment ischemic changes.

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.

Rodent Model of Brain Radionecrosis using Clinical LINAC-based Stereotactic Radiosurgery

Purpose

Methods and Materials

Results

Conclusions

Advanced MRI Protocols to Discriminate Glioma From Treatment Effects: State of the Art and Future Directions

In the follow-up treatment of high-grade gliomas (HGGs), differentiating true tumor progression from treatment-related effects, such as pseudoprogression and radiation necrosis, presents an ongoing clinical challenge. Conventional MRI with and without intravenous contrast serves as the clinical benchmark for the posttreatment surveillance imaging of HGG. However, many advanced imaging techniques have shown promise in helping better delineate the findings in indeterminate scenarios, as posttreatment effects can often mimic true tumor progression on conventional imaging. These challenges are further confounded by the histologic admixture that can commonly occur between tumor growth and treatment-related effects within the posttreatment bed. This review discusses the current practices in the surveillance imaging of HGG and the role of advanced imaging techniques, including perfusion MRI and metabolic MRI.

Surgical Management of Brain Metastasis: Challenges and Nuances

Brain metastasis is the most common type of intracranial tumor. The contemporary management of brain metastasis is a challenging issue and traditionally has carried a poor prognosis as these lesions typically occur in the setting of advanced cancer. However, improvement in systemic therapy, advances in radiation techniques and multimodal therapy tailored to the individual patient, has given hope to this patient population. Surgical resection has a well-established role in the management of brain metastasis. Here we discuss the evolving role of surgery in the treatment of this diverse patient population.

Neoadjuvant fractionated stereotactic radiotherapy followed by piecemeal resection of brain metastasis: a case series of 20 patients

BACKGROUND

The safety and effectiveness of neoadjuvant fractionated stereotactic radiotherapy (FSRT) before piecemeal resection of brain metastasis (BM) remains unknown.

METHODS

We retrospectively reviewed 20 consecutive patients with BM who underwent neoadjuvant FSRT followed by piecemeal resection between July 2019 and March 2021. The prescribed dose regimens were as follows: 30 Gy (n = 11) or 35 Gy (n = 9) in five fractions.

RESULTS

The mean follow-up duration was 7.8 months (range 2.2-22.3). The median age was 67 years (range 51-79). Fourteen patients were male. All patients were symptomatic. All tumors were located in the supratentorial compartment. The median maximum diameter and volume were 3.7 cm (range 2.6-4.9) and 17.6 cm3 (range 5.6-49.7), respectively. The median time from the end of FSRT to resection was 4 days (range 1-7). Nausea (CTCAE Grade 2) occurred in one patient and simple partial seizures (Grade 2) in two patients during radiation therapy. Gross total removal was performed in seventeen patients and sub-total removal in three patients. Postoperative complications were deterioration of paresis in two patients. Local recurrence was found in one patient (5.0%) who underwent sub-total resection at 2 months after craniotomy. Distant recurrence was found in six patients (30.0%) at a median of 6.9 months. Leptomeningeal disease recurrence was found in one patient (5.0%) at 3 months. No radiation necrosis developed.

CONCLUSIONS

Neoadjuvant FSRT appears to be a safe and effective approach for patients with BM requiring piecemeal resection. A multi-institutional prospective trial is needed.

Neuroprotective agents effective against radiation damage of central nervous system

Ionizing radiation caused by medical treatments, nuclear events or even space flights can irreversibly damage structure and function of brain cells. That can result in serious brain damage, with memory and behavior disorders, or even fatal oncologic or neurodegenerative illnesses. Currently used treatments and drugs are mostly targeting biochemical processes of cell apoptosis, radiation toxicity, neuroinflammation, and conditions such as cognitive-behavioral disturbances or others that result from the radiation insult. With most drugs, the side effects and potential toxicity are also to be considered. Therefore, many agents have not been approved for clinical use yet. In this review, we focus on the latest and most effective agents that have been used in animal and also in the human research, and clinical treatments. They could have the potential therapeutical use in cases of radiation damage of central nervous system, and also in prevention considering their radioprotecting effect of nervous tissue.

Whole Brain Irradiation or Stereotactic RadioSurgery for five or more brain metastases (WHOBI-STER): A prospective comparative study of neurocognitive outcomes, level of autonomy in daily activities and quality of life

•

The main aim of MBM treatment is to palliate neurological symptoms and to maintain an adequate QoL.

•

SRT could be the “new standard” over WBI in the management of MBM patients.

•

Neurocognitive functions could deteriorate more after WBI than after SRT.

Aims

To evaluate neurocognitive performance, daily activity and quality of life (QoL), other than usual oncologic outcomes, among patients with brain metastasis ≥5 (MBM) from solid tumors treated with Stereotactic Brain Irradiation (SBI) or Whole Brain Irradiation (WBI).

Methods

This multicentric randomized controlled trial will involve the enrollment of 100 patients (50 for each arm) with MBM ≥ 5, age ≥ 18 years, Karnofsky Performance Status (KPS) ≥ 70, life expectancy > 3 months, known primary tumor, with controlled or controllable extracranial disease, baseline Montreal Cognitive Assessment (MoCA) score ≥ 20/30, Barthel Activities of Daily Living score ≥ 90/100, to be submitted to SBI by LINAC with monoisocentric technique and non-coplanar arcs (experimental arm) or to WBI (control arm). The primary endpoints are neurocognitive performance, QoL and autonomy in daily-life activities variations, the first one assessed by MoCa Score and Hopkins Verbal Learning Test-Revised, the second one through the EORTC QLQ-C15-PAL and QLQ-BN-20 questionnaires, the third one through the Barthel Index, respectively. The secondary endpoints are time to intracranial failure, overall survival, retreatment rate, acute and late toxicities, changing of KPS. It will be considered significant a statistical difference of at least 30% between the two arms (statistical power of 80% with a significance level of 95%).

Discussion

Several studies debate what is the decisive factor accountable for the development of neurocognitive decay among patients undergoing brain irradiation for MBM: radiation effect on clinically healthy brain tissue or intracranial tumor burden? The answer to this question may come from the recent technological advancement that allows, in a context of a significant time saving, improved patient comfort and minimizing radiation dose to off-target brain, a selective treatment of MBM simultaneously, otherwise attackable only by WBI. The achievement of a local control rate comparable to that obtained with WBI remains the fundamental prerequisite.

Trial registration

NCT number: NCT04891471.