Atypical Meningioma Research Articles

PATH-15. DIGITAL PCR ANALYSIS FOR DETECTINGTERT PROMOTOR MUTATION IN MENINGIOMAS

Abstract The WHO Classification of Brain Tumors 5th edition requires the evaluation of TERT promoter mutations and CDKN2A/B homozygous deletions for the diagnosis of malignant meningiomas. Digital PCR (dPCR) is an emerging method for highly sensitive quantitative analysis. In this study, we performed TERT promoter mutation analysis using Pyrosequencing and dPCR in specimens with atypical and anaplastic meningiomas to investigate its utility and clinical significance. Adult patients diagnosed with atypical or anaplastic meningiomas after tumor resection between January 2009 and June 2023 were included. Genomic DNA was extracted from the excised specimens. TERT promoter mutations was analyzed by using the Pyrosequence and dPCR methods and compared with the clinical course. A total of 37 meningioma cases (13 males and 24 females) with 64 specimens were included. Atypical meningioma, grade II (WHO 2016) at diagnosis was 53 specimens (83%) and anaplastic meningioma, grade III (WHO 2016) was 11 specimens (17%). Of these, 7 (10%) were diagnosed with TERT promoter mutations by pyrosequencing, and one case with a low frequency (15%) of mutations by dPCR that tested negative by pyrosequencing had repeated recurrences in a short period of time. The dPCR method is highly sensitive in detecting low frequency TERT promoter mutations in tumor cell subpopulations and may contribute to the determination of treatment by predicting the malignant course of the disease. The results suggest that dPCR could contribute to therapeutic decision-making by detecting low-frequency TERT promoter mutations in tumor cell subpopulations.

NCOG-21. ADJUVANT RADIATION THERAPY IN ATYPICAL MENINGIOMA TREATMENT DOES NOT IMPROVE PROGRESSION FREE SURVIVAL OR OVERALL SURVIVAL: A RETROSPECTIVE COHORT STUDY

Abstract Treatment of atypical meningiomas (AMs) presents a challenge due to their aggressive nature and tendency to recur. While there is clear evidence for the role of surgical resection of AMs, the use of adjuvant radiation therapy (ART) is a topic of ongoing debate. The aim of this study is to explore the impact of ART following surgical resection of AMs. The primary outcomes of interest are progression free survival (PFS) and overall survival (OS). Records were reviewed for all patients treated for Ams at our institution between January 1, 2014 and January 1, 2024. Patients were grouped into two cohorts, those who were initially treated with surgical resection only and those who also received adjuvant RT. PFS and OS were compared between the two groups using Kaplan Meier curves and Log Rank test. Additionally, multivariable cox proportional hazard models were used to adjust for age, MIB, and resection Simpson grading. There were 76 patients who were initially treated with surgery only and 23 patients who had surgery and ART. No significant difference in PFS or OS was observed between the groups (p=0.3522 and p=0.3636, respectively); including after adjusting for age, MIB, and Simpson grading (HR= 1.55 [0.64-3.76], p= 0.330; and HR = 0.95 [0.31-2.93] p= 0.934, respectively). On multivariate analysis, MIB >10 was associated with a significant difference in PFS (HR=2.76 [1.15-6.59], p=0.023). With ART, PFS was 91% at 12 and 60% at 36 months (versus 89% and 57%, respectively, with surgery only). OS was 95% at 12 and 88% at 36 months (versus 91% and 85%, respectively, with surgery only). In this series, ART was not observed to significantly improve PFS or OS compared to surgery alone. Larger series are needed to determine if there is a subset of patients who benefit from ART.

NCOG-20. RADIATION-RELATED MORBIDITY OUTCOMES IN ATYPICAL MENINGIOMA PATIENTS: A RETROSPECTIVE COHORT STUDY

Abstract Atypical meningiomas present with unique challenges in management and prognosis. Given their tendency to recur, adjuvant radiation therapy (ART) is frequently utilized, however there are few reports on radiation-related morbidity in this patient population. The study aims to investigate the radiation-related complications in atypical meningioma patients treated with or without ART. The primary outcomes were the incidence and severity of RT-related morbidity. All patients treated for atypical meningiomas at our institution between January 1, 2014 and January 1, 2024 were retrospectively analyzed. Patients were grouped into two cohorts, those who were initially treated with surgical resection only and those who also received adjuvant RT. Radiation morbidity grading was assigned for all patients that received radiation treatments during their clinical course based on established grading systems. Fisher’s Exact and Kruskal-Wallis tests were used to determine associations between the two groups. There were 76 patients who were initially treated with surgery only and 23 patients who had surgery and ART. Mean length of follow-up among all patients was 55.6 months. Significantly lower rates of RT-related morbidity in the surgery only group were observed compared to the surgery and RT cohort (15.8% vs. 60.9%, p < 0.0001). Among patients in the surgery only cohort, 23 patients received RT at recurrence or progression. When comparing this subgroup to those who underwent ART, there was no significant difference in the severity of RT-related morbidity (p=0.2724). In this series, patients receiving ART experienced a higher incidence of radiation-related morbidity. When comparing only those who received RT, there was no difference in the incidence or severity of radiation-related morbidity between the two cohorts.

SURG-13. PATHOLOGICAL EXAMINATION OF MENINGIOMA RECURRENCE AFTER ABSORBABLE ARTIFICIAL DURA MATER RECONSTRUCTION

Abstract INTRODUCTION In meningioma surgery, the removal of the tumor and tumor-attached dura mater is essential. Due to its high affinity, absorbable artificial dura mater is used for the reconstruction of dural defects. In this study, we report a pathological examination of dural-like tissue in a case of meningioma that recurred at the same site after the use of absorbable artificial dura mater during initial surgery. METHOD We investigated two cases in which absorbable artificial dura mater was used for dural reconstruction during meningioma resection, and subsequently, a recurrent lesion was identified at the site of the dural reconstruction. We examined MRI images and surgical and pathological findings at the time of recurrence in these cases. RESULT All patients underwent total resection, and the pathological diagnosis was atypical meningioma. MRI images at the time of recurrence revealed multiple meningiomas along the artificial dura site. Gross findings during recurrent surgery indicated that the absorbable dura had been replaced by dura-like tissue, with the tumor also attached to the same site. Pathological findings showed bundles of fibrous tissue within the dura-like tissue, albeit with a sparser density compared to autologous dura mater. Meningioma cell invasion and angiogenesis were also observed in the dural-like tissue. DISCUSSION In all cases, multiple meningiomas were found along the dural-like tissue. This suggests that meningioma cells invading the dural-like tissue may have used it as a scaffold for meningioma recurrence. Future studies are necessary to determine the appropriateness of absorbable artificial dura mater for dural defect sites during malignant meningioma surgery.

RADT-20. POSTOPERATIVE RADIOTHERAPY PROVIDES ADDITIVE PROGRESSION-FREE SURVIVAL BENEFIT IN ATYPICAL MENINGIOMAS REGARDLESS OF EXTENT OF RESECTION

Abstract WHO Grade II meningiomas represent a minority of all meningiomas. The creation of treatment algorithms has remained challenging, with the need to add postoperative radiotherapy (RT) following satisfactory gross total resection being oftentimes debated. Thus, the goal of this study was to understand which factors, if any, predispose to recurrence of atypical meningiomas following resection. Therefore, we retrospectively review a 90-patient cohort of WHO grade II meningiomas who underwent surgical resection. Patients were clustered based on tumor location, (convexity or non-convexity) and whether they had received postoperative RT. Following extraction of biographic characteristics, the extent of tumor resection and tumor recurrence were measured. A detailed uni- and multivariate analysis was carried out to determine which factors, if any, predisposed to recurrence. The cohort consisted of 90 patients with a WHO Grade II meningiomas. A gross total resection was achieved in 66.7% of patients. Patients who had a gross total resection and received postoperative RT had longer progression-free survival (p = 0.031) than patients with subtotal resections (STR), regardless of radiation status, and patients with a GTR who did not receive radiation. On uni- and multivariate analysis, receiving postoperative RT was the only factor associated with no recurrence of disease (p = 0.023); no association was found for extent of resection (p = 0.63) or location (p = 0.18). In conclusion, the treatment of WHO grade II meningiomas remains challenging. In this study, we showed how the addition of radiotherapy remains beneficial even in cases of gross total resection, regardless of location. We postulate how microscopic disease not observed on MRI may be responsible for these findings.

Case Report: Diagnostic Dilemma between Atypical Meningioma and Glioblastoma-our Observation

Both meningioma and glioblastoma are very common intra-cranial neoplasm. Typically both have distinguishing clinical and radiological features which aid in diagnosis and thus pre-operative preparation, planning, counseling the patient etc. But dilemma may often arise in case of non-grade-I meningioma making confusion in favor of higher grade astrocytoma (glioblastoma). In that case total per-operative picture, surgical approach, post- operative managements, and disease prognosis will be altered. We faced such kind of confusion in a case so reported here. Bang. J Neurosurgery 2024; 13(2): 157-161

Safety of 177Lu-DOTATATE administration in a patient with recurrent meningioma complicated by radiation necrosis: a case report

Radiation-associated meningiomas are characterized by high rates of recurrence. 177Lu-DOTATATE may represent a treatment option for these tumors, but safety of this agent for patients with a history of radiation necrosis is unknown. In this case report, we describe the preliminary safety of 177Lu-DOTATATE administration for a patient with prior history of radiation necrosis. The patient was diagnosed with central nervous system (CNS) germinoma at age 17, managed with chemoradiation. Twenty years later, a left-parietal extra-axial mass was identified within the prior radiation field, with diagnosis of atypical meningioma established on subtotal resection. He received additional radiation therapy (RT, 60 Gy, 30 fractions). Seventeen months later, tumor progression was treated with gamma knife radiosurgery (GKRS, 15 Gy, single fraction). Seven months after GKRS, seizures recurred, with imaging consistent with radiation necrosis. The patient was treated with bevacizumab (7.5 mg/kg, every 3 weeks, 4 doses). One year later, magnetic resonance imaging (MRI) brain revealed tumor progression within the treatment field. 68 Ga-DOTATATE positron emission tomography demonstrated that the meningioma was DOTATATE-avid with no evidence of metastasis. The patient was treated with 177Lu-DOTATATE (two infusions, two months apart), which was well tolerated with no significant toxicities and no recurrence of radiation necrosis. Two months after the second infusion, the patient experienced disease progression and was transitioned to bevacizumab. In this patient with three prior courses of intracranial radiation and subsequent radiation necrosis, 177Lu-DOTATATE was well-tolerated. 177Lu-DOTATATE administration may be feasible for patients with a history of radiation necrosis.

Metastatic Intracranial Choriocarcinoma in the Absence of a Primary Lesion: A Case Report

AbstractIntracranial choriocarcinoma is a rare and aggressive neoplasm characterized by the proliferation of trophoblastic tissue. Although choriocarcinoma most commonly arises in the uterus as a component of gestational trophoblastic neoplasia, instances of intracranial choriocarcinoma are exceptionally uncommon. We report a case of intracranial choriocarcinoma without any evidence of a tumor elsewhere. A 25-year-old woman presented with a history of 1 month of evolution with right frontal hemicranial headache, followed by visual disturbances, otalgia, and diplopia. On neurological examination, she was conscious, cooperative, and well-oriented; a grade 1 bilateral papilledema, left homonymous hemianopsia, and sixth cranial nerve paresis, with diplopia, were detected. Neuroimaging showed a right parieto-occipital lesion with features mimicking an atypical meningioma. After surgical resection, a diagnosis of choriocarcinoma was issued. Primary intracranial choriocarcinomas are typically located in the sellar and pineal regions. The occurrence of this tumor within the occipital lobe suggested metastasis; however, a primary tumor in the thoracic or abdominal organs was not observed and a delayed metastasis was considered. This case highlights the diagnostic challenges associated with intracranial choriocarcinoma.

Impact on natural history of atypical meningioma after changes in 2016 edition of the world health organization (WHO) classification of central nervous system tumors: a literature review.

Meningiomas and their WHO histological diagnostic criteria is complex, especially for grade 2 tumors presenting a interobserverdiscordance as high as 12.2%. The 2016 edition of the WHO Classification of CNS tumors recommended brain invasion as a stand-alone grading criterion for diagnosing an atypical grade 2 meningioma (AM). To provide an overview of the classification of 2016 WHO impact on the natural history of atypical meningioma (AM) relative to previous classification. To achieve this goal, we selected articles from the period 2017-2024 in Medline search on atypical meningiomas and analyzed them after following the following criteria: 1) reports with confirmed histopathological diagnosis according to WHO 2016 and or 2021 criteria; 2) series and case reports; 3) detailed and individualized clinical outcomes for AM; and 4) papers written in English; after that a total of 3445 patients reported in 67 manuscripts from worldwide centers from 2017 to March 2024 were analyzed. The patient's age at the time of surgery ranged from 1month to 97years (mean 52.28 ± 18.7years). The most common tumor site was the convexity, accounting for 67.8%, followed by the skull base in 30.6%, ventricle in 1%, and spine in 0.6%; Gross total resection (GTR) was performed in 71.25% and subtotal resection (STR) in 28.75%; 1021 patients (29.63%) underwent adjuvant radiotherapy, and 22 patients (0.6%) were treated with adjuvant chemotherapy; tumor recurrence was reported in 1221 patients (35.44%) and 859 deaths (24.93%). 1) AM prevalence in females; 2) AM age distribution similar to the distribution of meningiomas in general; 3) AM recurrence rate of 35.44%, despite the high rate of GTR, which was higher than previously reported; 4) deepening knowledge in molecular mechanism of tumor progression will provide alternative therapeutic approaches for AM.

A phase II, open-label, single-arm trial of pembrolizumab for recurrent meningioma and solitary fibrous tumor.

Atypical and anaplastic meningiomas account for 20% of all meningioma cases. Solitary fibrous tumor (SFT) is a type of soft tissue sarcoma with similar attributes to meningioma. For patients with refractory or recurrent disease after previous surgery or radiotherapy, there is no effective treatment. Pembrolizumab, an anti-programmed cell death 1 (PD-1) antibody, is an effective treatment for various solid tumors. PD-1 ligand is highly expressed in aggressive meningiomas. We aimed to assess the effectiveness of pembrolizumab in treating meningioma and SFT recurrence after surgery and radiation therapy. This prospective single-arm phase II trial comprised 15 patients with recurrent meningioma and 3 with anaplastic SFT, treated at a single institution during 2018 to 2022. The study was terminated due to a lack of efficacy and slow accrual. The primary endpoint was 6-month progression-free survival (PFS-6). Median progression-free survival (PFS) was 2.6 months, and median overall survival (OS) was 40 months. The 6- and 12-month PFS were both 11.1%. The 6- and 12-month OS were 94.4% and 61.1%, respectively. According to the Response Assessment in Neuro-Oncology (RANO) criteria, the overall response rate was 11%, with 2 patients achieving stable disease and 2 with partial response. Three patients (16.7%) developed grade 3 toxicity. Our results showed that pembrolizumab failed to improve PFS-6 in patients with aggressive meningioma or anaplastic SFT. However, two patients, one with atypical meningioma and one with anaplastic SFT, achieved a partial response. More clinical studies are needed to identify which subset of patients may benefit from this treatment.

Meningiomas in Elderly Subjects: Retrospective Studies of 8 Cases and a Literature Review

Aim. Intracranial meningiomas in adults are mainly benign tumors that develop from the meninges. They are common, accounting for about 18 to 20% of primary intracranial tumors, and they are slow-growing, with a predominance in women. They can occur at any age but are most common after the age of 56. Symptoms vary depending on the location of the tumor, its size, and the anatomical structures it comes into contact with. Surgery is the main treatment modality for meningiomas. The objective of this study is to evaluate the cases of meningiomas in our series and to compare their different aspects, such as epidemiological, clinical, radiological, therapeutic, histological, evolutionary, and prognostic characteristics, with those reported in other series of the literature. We seek to highlight the similarities and differences between our series and previous studies, considering recent advances in this field. Materials and measures. In our series, the retrospective study of 8 cases of intracranial meningioma in elderly subjects diagnosed and operated on at the Neurosurgery Department of a hospital over a period of 4 years. Brain CT and MRI were the primary preoperative diagnostic means. The use of these imaging techniques was essential to establish the diagnosis and plan the surgical procedure. The histopathological study was performed to confirm the post-operative diagnosis and determine the histological type, as well as the grade of the meningiomas, referring to the WHO classification to plan an appropriate follow-up of the management. Results. Meningiomas accounted for 2.33% of intracranial meningiomas in elderly subjects, and 22.22% were in subjects under 65 years of age out of 342 tumors operated on in the Department during the same period. The female predominance was clear, at 62%, compared to 38% for men. The average age of our patients was 69.9 years, with extremes of 65 and 74 years. The main clinical symptoms observed in our patients were headache, motor deficit (hemiparesis, hemiplegia), sensory deficit, convulsions, and cranial pair involvement (optic nerve and facial nerve).On CT, the tumor mass was spontaneously hyperdense in 100% of cases. After the injection of iodine product, there was a homogeneous intense contrast intake in all cases. Only 2 patients in our series performed CT scans, of which we found perilesional edema and mass effect in 100% of cases. No calcifications or bone abnormalities were detected. MRI was performed on all our patients, allowing us to better specify the topographical diagnosis of meningiomas. Overall, surgical excision was complete (Simpson’s grade I and grade II) in 62.5% of cases. The most common histological types were meningotheliomatous meningioma (4 cases), transitional meningioma (1 case), mucoid fibrous meningioma (1 case), and atypical meningioma (2 cases). The post-operative course was favorable in most patients, and the post-operative complications consisted mainly of wound infection (1 case), CSF leakage (1 case), and hemorrhage (1 case).

Atypical Meningioma: A Reported Case

Early studies of atypical meningiomas confirmed that total resection of meningiomas reduces recurrence compared with subtotal resection. These studies also provided the first evidence of the usefulness of radiotherapy as adjuvant treatment for subtotally resected atypical meningiomas. Radiotherapy of meningiomas is based on the principles of radiobiology, in particular the concept of biologically effective dose (BED) of radiation, the calculation of which makes it possible to compare different radiotherapy regimens. This case study aimed to demonstrate that radiation therapy is a real therapeutic alternative in the treatment of subtotally resected atypical meningiomas.

KEAP1-mutant atypical meningioma: illustrative case.

While genetic testing of tumors is commonly used to inform the selection of systemic therapies, there is limited evidence for the application of radiotherapy for brain cancer. Recent studies have shown that Kelch-like ECH-associated protein 1 (KEAP1), a key regulator of cellular responses to oxidative and electrophilic stress, is associated with radioresistance in multiple cancer types. Several studies have reported the clinical significance of KEAP1 mutation in brain metastasis; however, the effect of KEAP1 mutations on radioresponse in meningioma has never been reported. The authors present the case of a 40-year-old female with a KEAP1 mutation-positive atypical meningioma that was initially treated with resection followed by intensity-modulated radiation therapy (IMRT). Recurrence was observed at 15 months, requiring reoperation and adjuvant stereotactic radiosurgery (SRS). An excellent treatment response was observed at 7 months post-SRS with an improvement in reported symptoms, although bevacizumab was required for the resolution of radiation necrosis observed 2 months post-SRS. To the authors' knowledge, this is the first report of KEAP1-mutant meningioma, including its clinical course after comprehensive management. Notably, treatment included multimodal radiotherapy with IMRT followed by SRS. SRS led to an excellent treatment response at the 7-month follow-up. However, radiation necrosis developed after both radiotherapy treatments, suggesting that radiological modification can be beneficial in patients with KEAP1 mutations. https://thejns.org/doi/10.3171/CASE24387.

Preoperative prediction of CNS WHO grade and tumour aggressiveness in intracranial meningioma based on radiomics and structured semantics

Preoperative identification of intracranial meningiomas with aggressive behaviour may help in choosing the optimal treatment strategy. Radiomics is emerging as a powerful diagnostic tool with potential applications in patient risk stratification. In this study, we aimed to compare the predictive value of conventional, semantic based and radiomic analyses to determine CNS WHO grade and early tumour relapse in intracranial meningiomas. We performed a single-centre retrospective analysis of intracranial meningiomas operated between 2007 and 2018. Recurrence within 5 years after Simpson Grade I-III resection was considered as early. Preoperative T1 CE MRI sequences were analysed conventionally by two radiologists. Additionally a semantic feature score based on systematic analysis of morphological characteristics was developed and a radiomic analysis were performed. For the radiomic model, tumour volume was extracted manually, 791 radiomic features were extracted. Eight feature selection algorithms and eight machine learning methods were used. Models were analysed using test and training datasets. In total, 226 patients were included. There were 21% CNS WHO grade 2 tumours, no CNS WHO grade 3 tumour, and 25 (11%) tumour recurrences were detected in total. In ROC analysis the best radiomic models demonstrated superior performance for determination of CNS WHO grade (AUC 0.930) and early recurrence (AUC 0.892) in comparison to the semantic feature score (AUC 0.74 and AUC 0.65) and conventional radiological analysis (AUC 0.65 and 0.54). The combination of human classifiers, semantic score and radiomic analysis did not markedly increase the model performance. Radiomic analysis is a promising tool for preoperative identification of aggressive and atypical intracranial meningiomas and could become a useful tool in the future.

Systemic Mastocytosis presents as a solitary skull lesion in a child

Mastocytosis arises from the abnormal growth and accumulation of mast cells within the body’s organ systems. Within the pediatric age group, systemic mastocytosis is exceptionally rare, with only a few reported cases in the medical literature. Here, we report a case detailing a solitary skull lesion in a 10-year-old child as the sole identified manifestation of systemic mastocytosis. She presented with neurologic symptoms without any allergic or systemic manifestation. The child was initially diagnosed with hemangiopericytoma, with the differential diagnosis of atypical meningioma. The patient underwent surgery and histopathological examination confirmed the diagnosis of systemic mastocytosis. Unfortunately, the patient presented with recurrence, necessitating another surgery that again confirmed the diagnosis. Multidisciplinary team collaboration integrating clinical, radiographic, and immunophenotypic correlations is vital in the diagnosis and management of this sporadic condition.

The Impact of Molecular and Genetic Analysis on the Treatment of Patients with Atypical Meningiomas.

Meningiomas represent approximately 40% of all primary tumors of the central nervous system (CNS) and, based on the latest World Health Organization (WHO) guidelines, are classified into three grades and fifteen subtypes. The optimal treatment comprises gross total tumor resection. The WHO grade and the extent of tumor resection assessed by the Simpson grading system are the most important predictors of recurrence. Atypical meningiomas, a grade 2 meningioma, which represent almost a fifth of all meningiomas, have a recurrence rate of around 50%. Currently, different histopathologic, cytogenetic, and molecular genetic alterations have been associated with different meningioma phenotypes; however, the data are insufficient to enable the development of specific treatment plans. The optimal treatment, in terms of adjuvant radiotherapy and postoperative systemic therapy in atypical meningiomas, remains controversial, with inconclusive evidence in the literature and existing studies. We review the recent literature to identify studies investigating relevant atypical meningioma biomarkers and their clinical application and effects on treatment options.

The use of adjuvant radiotherapy in resected adult intracranial atypical meningioma in United States: A SEER analysis.

27 Background: It is unclear whether adjuvant external beam radiotherapy (EBRT) in atypical meningiomas after surgical resection provided overall survival advantage. Although meta-analysis were previously reported, there is heterogeneity in the included studies. With lack of prospective trial, we rely on observational data for management. This project aims to determine if the addition of adjuvant EBRT after resection compared to resection alone in atypical meningioma is associated with better prolonged survival among patients within United States. Methods: The National Cancer Institute Surveillance, Epidemiology and End Results database was queried for list of patients diagnosed with atypical meningioma from 2000 to 2020 according to International Classification of Disease (ICD) for Oncology, third edition with morphology codes 9539/0 and 9539/1.This was limited to intracranial location. Rate of dying among those receiving adjuvant EBRT after surgery for atypical meningiomas was compared to the rate of dying of those who had resection alone without adjuvant EBRT postoperatively. Other covariates included, age at diagnosis, gender, marital status, race, tumor laterality, tumor site, tumor, extent of resection and household median income. Chi-squared test was used to test the association between institution of adjuvant EBRT and other co-variates for categorical variable. Cox-proportional analysis was used to test the association between adjuvant EBRT and death. Observed survival was estimated using Kaplan-Meyer method. Survival curves were generated for both cohorts and log rank test was performed. Results: A total of 3,328 patients were included in analysis.1,004(30.17%) patients received adjuvant EBRT and 767(23.05%) died in the entire cohort. Rate of dying in the entire cohort is 43.84 per 1,000 person-years. Death rate for patients receiving adjuvant EBRT is 44.95 per 1,000 person-years, while patients who did not receive adjuvant EBRT had a death rate of 40.95 per 1,000 person-years. Patients aged 80 years or older, divorced and separated tend not to receive adjuvant EBRT, while patients with tumor size of 51-100mm and 101-200mm are more likely to receive adjuvant RT. Crude rate ratio among those patients receiving RT compared to the rate of those who did not receive adjuvant RT is 0.91 (95% CI: 0.76-1.07). Adjusting for possible confounders did not change the rate ratio between adjuvant EBRT compared to resection alone. Extent of resection did not modify the effect of adjuvant RT to death (likelihood ratio test-0.363). Survival analysis using Kaplan Meier curve showed no difference whether a patient received adjuvant EBRT or not (log rank test-0.238). Conclusions: There is no clear evidence on the survival benefit for use of adjuvant EBRT in resected atypical meningioma compared resection alone. This is true both in incomplete and completely resected atypical meningiomas.

404 The Efficacy and Safety of Radiotherapy on Patients with Atypical Meningioma: A Systematic Review"

404 The Efficacy and Safety of Radiotherapy on Patients with Atypical Meningioma: A Systematic Review"

Metabolic profiling of atypical meningioma and recurrent meningioma: a comparative analysis with proton magnetic resonance spectroscopy.

Meningiomas are predominantly benign, but some cases exhibit recurrent growth after surgery and undergo malignant transformation to WHO grade 2 or grade 3. Despite progress in genetic analyses, advancements in metabolomic analysis remain less established. Herein, the authors investigated metabolic activity differences between WHO grade 1 meningiomas and WHO grade 2 or 3 meningiomas by noninvasively using proton magnetic resonance spectroscopy (1H-MRS), aiming to preoperatively estimate malignancy. They also reviewed the literature to elucidate this aspect of meningioma research. At Ryukyu University Hospital, the authors focused on 93 patients diagnosed with meningioma between 2011 and 2021. The inclusion criteria encompassed prior surgery, pathological diagnoses of meningioma, and preoperative 1H-MRS. Group I included 71 patients with WHO grade 1 meningioma and group II included 22 patients, comprising 19 and 3 with WHO grade 2 and 3 meningioma, respectively. The authors retrospectively conducted a comparative analysis of patient backgrounds and tumor metabolites. Group I and II did not differ significantly in terms of patient demographic characteristics (age and sex). Group II demonstrated a significantly lower extent of tumor resection (p < 0.01), higher MIB-1 labeling index (LI) (p < 0.05), higher incidence of prior irradiation (p < 0.001), and increased rate of tumor recurrence (p = 0.005) compared to group I. According to 1H-MRS, all metabolites, except lactate, displayed significantly higher median creatine (Cr) ratios in group II than group I: glutamine/Cr was 8.46, glutamate/Cr was 9.49, lipid/Cr was 11.36, and choline/Cr was 2.77. According to the receiver operating characteristic (ROC) analysis, glutamine had the largest area under the curve of 0.765 among 10 metabolites, and the cutoff value for distinguishing between group I and II was 5.76. In cases pathologically graded as WHO grade 2 or 3 meningiomas, metabolic products such as glutamine, glutamate, lipids, and choline increased significantly. These changes were correlated with elevation of the MIB-1 LI. In group II, the mean MIB-1 LI was 8.58, significantly higher than in group I, suggesting a strong association with pathological malignancy. Therefore, 1H-MRS may help to noninvasively predict tumor metabolic activity and tumor recurrence. Furthermore, the authors concluded from the ROC analysis that glutamine may be a potential indicator of future growth of meningioma and benefits of early surgery.

Radiosurgery in Grade II and III Meningiomas: A Systematic Review and Meta-Analysis.

Meningiomas are the most prevalent benign intracranial tumors. When they are of the invasive subtypes, i.e., grades II and III, they can recur rapidly and present a real challenge for physicians. This study is focused on the use of stereotactic radiosurgery to manage high-grade meningiomas. Medline via PubMed was searched from inception to December 2022 to retrieve studies on stereotactic radiation therapy for patients with grade II-III meningiomas. This study was conducted under PRISMA guidelines. A total of 29 articles involving 1446 patients with grade II-III meningiomas treated with stereotactic radiation therapy were included in the present study. Of these studies, 11 were conducted exclusively on patients with atypical meningiomas (grade II), 1 targeted anaplastic meningiomas (grade III), and 17 articles were carried out on both grade II and III meningiomas. The pooled 1, 2, 3, 5, and 10-year overall survival (OS) of grade II meningiomas was 0.96 [p < 0.01], 0.89 [p = 0.01], 0.90 [p = 0.09], 0.81 [p < 0.01], and 0.66 [p = 0.55], respectively. The pooled 2, 5, and 10-year OS of grade III meningiomas was 0.64 [p = 0.01], 0.41 [p = 0.01], and 0.19 [p < 0.01], respectively. Although long-term prospective studies are still required, the outcomes of stereotactic radiation therapy appear promising regarding overall outcome and progression-free survival.