Velocity of tumor spontaneous expansion predicts long-term outcomes for diffuse low-grade gliomas

Anatomical and subcortical invasiveness in diffuse low-grade astrocytomas differ between IDH status and provide prognostic information

Background

Diffuse astrocytomas preferentially infiltrate eloquent areas affecting the outcome. A preoperative understanding of isocitrate dehydrogenase (IDH) status may offer opportunities for specific targeted therapies impacting treatment management. The aim of this study was to analyze clinical, topographical, radiological in WHO 2 astrocytomas with different IDH status and the long-term patient's outcome.

Methods

A series of confirmed WHO 2 astrocytoma patients (between 2005 and 2015) were retrospectively analyzed. MRI sequences (FLAIR) were used for tumor volume segmentation and to create a frequency map of their locations into the Montreal Neurological Institute (MNI) space. The Brain-Grid (BG) system (standardized radiological tool of intersected lines according to anatomical landmarks) was used as an overlay for infiltration analysis of each tumor. Long-term follow-up was used to perform a survival analysis.

Results

Forty patients with confirmed IDH status (26 IDH-mutant, IDHm/14 IDH-wild type, IDHwt) according to WHO 2021 classification were included with a mean follow-up of 7.8 years. IDHm astrocytomas displayed a lower number of BG-voxels (P < 0.05) and were preferentially located in the anterior insular region. IDHwt group displayed a posterior insular and peritrigonal location. IDHwt group displayed a shorter OS compared with IDHm (P < 0.05), with the infiltration of 7 or more BG-voxels as an independent factor predicting a shorter OS.

Conclusions

IDHm and IDHwt astrocytomas differed in preferential location, number of BG-voxels and OS at long follow-up time. The number of BG-voxels affected the OS in IDHwt was possibly reflecting higher tumor invasiveness. We encourage the systematic use of alternative observational tools, such as gradient maps and the Brain-Grid analysis, to better detect differences of tumor invasiveness in diffuse low-grade gliomas subtypes.

A disulfidptosis-associated long noncoding RNA signature to predict low-grade glioma classification, prognosis, tumor microenvironment, and therapy regimens: Observational study

This study aimed to investigate the function of disulfidptosis-associated long noncoding RNAs (DAlncRNAs) in low-grade gliomas (LGG) through bioinformatics analysis and construct a signature to predict the classification, prognosis, tumor microenvironment, and selection of immunotherapy and chemotherapy in LGG. Genomic, clinical, and mutational information of 526 patients with LGG was retrieved from The Cancer Genome Atlas repository. A nonnegative matrix factorization algorithm was applied to classify patients with LGG. Univariate, LASSO regression, and multivariate Cox regression analyses were performed to determine prognostic DAlncRNAs. Following the median risk score, we defined the sample as a high-risk (HR) or low-risk group. Finally, survival, receiver operating characteristic curve, risk curve, principal component, independent prognosis, risk difference, functional enrichment, tumor microenvironment, immune cell infiltration, mutation, and drug sensitivity analyses were performed. Patients were classified into C1 and C2 subtypes associated with disulfidptosis. Eight prognostic DAlncRNAs (AC003035.2, AC010157.2, AC010273.3, AC011444.3, AC092667.1, AL450270.1, AL645608.2, and LINC01571) were identified, and a prognostic signature of LGG was developed. The DAlncRNA-based signature was found to be an independent prognostic factor in patients with LGG, thereby constructing a nomogram. In addition, in the HR group, immune function was more active and the tumor mutation burden was higher. The patients were mainly composed of subtype C2, and their prognosis was worse. Immunotherapy and chemotherapy were predicted in the HR and low-risk groups, respectively. Our study, based on DAlncRNAs, highlights 2 disulfidptosis-associated LGG subtypes with different prognostic and immune characteristics and creates a novel disulfidptosis-associated prognostic signature, which may inform the classification, prognosis, molecular pathogenesis, and therapeutic strategies for patients with LGG.

Evaluation of a nnU-Net type automated clinical volumetric tumor segmentation tool for diffuse low-grade glioma follow-up

BACKGROUND AND PURPOSE

Diffuse low-grade gliomas (DLGG) are characterized by a slow and continuous growth and always evolve towards an aggressive grade. Accurate prediction of the malignant transformation is essential as it requires immediate therapeutic intervention. One of its most precise predictors is the velocity of diameter expansion (VDE). Currently, the VDE is estimated either by linear measurements or by manual delineation of the DLGG on T2 FLAIR acquisitions. However, because of the DLGG's infiltrative nature and its blurred contours, manual measures are challenging and variable, even for experts. Therefore we propose an automated segmentation algorithm using a 2D nnU-Net, to 1) gain time and 2) standardize VDE assessment.

MATERIALS AND METHODS

The 2D nnU-Net was trained on 318 acquisitions (T2 FLAIR & 3DT1 longitudinal follow-up of 30 patients, including pre- & post-surgery acquisitions, different scanners, vendors, imaging parameters…). Automated vs. manual segmentation performance was evaluated on 167 acquisitions, and its clinical interest was validated by quantifying the amount of manual correction required after automated segmentation of 98 novel acquisitions.

RESULTS

Automated segmentation showed a good performance with a mean Dice Similarity Coefficient (DSC) of 0.82±0.13 with manual segmentation and a substantial concordance between VDE calculations. Major manual corrections (i.e., DSC<0.7) were necessary only in 3/98 cases and 81% of the cases had a DSC>0.9.

CONCLUSION

The proposed automated segmentation algorithm can successfully segment DLGG on highly variable MRI data. Although manual corrections are sometimes necessary, it provides a reliable, standardized and time-winning support for VDE extraction to asses DLGG growth.

Integrated analysis of necroptosis related gene signature to predict clinical outcomes, immune status and drug sensitivity in lower grade Glioma

Background

The treatment of lower grade gliomas (LGG) is currently the most challenging dilemma in the management of intracranial tumors. Necroptosis is a type of programmed cell death that is closely associated with tumor progression, However, the role of necroptosis related genes in LGG is not yet well elucidated.

Methods

Online databases were used to obtain gene expression and clinical information. After gene differential expression analysis, a risk score model based on prognostic differentially expressed necroptosis-related genes (DENGs) were constructed to predict prognosis for LGG patients. The validity of the risk score model was then assessed with Kaplan-Meier survival curve. The prognostic DENGs included in the risk score model were then subjected to gene expression analysis, functional enrichment analysis, consensus clustering analysis, and single cell sequencing analysis. Finally, we investigated the correlation of the risk score and immune infiltration in LGG tumor microenvironment and drug sensitivity for LGG patients in different risk groups.

Results

A survival risk score model was constructed based on seven prognostic DENGs, which demonstrated satisfactory performance in predicting the prognosis of LGG patients. According to functional enrichment analyses, these seven DENGs may play a regulatory role in LGG tumorigenesis through several immune and metabolic pathways. LGG patients could be categorized into two clusters with distinct prognosis and clinicopathologic characteristics based on the expression of seven DENGs. Single-cell sequencing analysis demonstrated that the DENG signature was differentially expressed in various types of cells in LGG and may play a vital role in oncogenesis. Additionally, drug sensitivity analysis suggested that the seven-gene signature could guide clinical medication for LGG patients.

Conclusion

Our study developed a reliable necroptosis-related signature to predict the prognosis of LGG patients. This gene signature may also help estimate immune status and anti-cancer drug sensitivity in LGG patients. Our findings may pave the way to enhance our understanding of necroptosis in LGG.

Tumor Volume Growth Rates and Doubling Times during Active Surveillance of IDH-mutant Low-Grade Glioma

PURPOSE

Isocitrate dehydrogenase-mutant (IDH-mt) gliomas are incurable primary brain tumors characterized by a slow-growing phase over several years followed by a rapid-growing malignant phase. We hypothesized that tumor volume growth rate (TVGR) on MRI may act as an earlier measure of clinical benefit during the active surveillance period.

EXPERIMENTAL DESIGN

We integrated three-dimensional volumetric measurements with clinical, radiologic, and molecular data in a retrospective cohort of IDH-mt gliomas that were observed after surgical resection in order to understand tumor growth kinetics and the impact of molecular genetics.

RESULTS

Using log-linear mixed modeling, the entire cohort (n = 128) had a continuous %TVGR per 6 months of 10.46% [95% confidence interval (CI), 9.11%-11.83%] and a doubling time of 3.5 years (95% CI, 3.10-3.98). High molecular grade IDH-mt gliomas, defined by the presence of homozygous deletion of CDKN2A/B, had %TVGR per 6 months of 19.17% (95% CI, 15.57%-22.89%) which was significantly different from low molecular grade IDH-mt gliomas with a growth rate per 6 months of 9.54% (95% CI, 7.32%-11.80%; P < 0.0001). Using joint modeling to comodel the longitudinal course of TVGR and overall survival, we found each one natural logarithm tumor volume increase resulted in more than a 3-fold increase in risk of death (HR = 3.83; 95% CI, 2.32-6.30; P < 0.0001).

CONCLUSIONS

TVGR may be used as an earlier measure of clinical benefit and correlates well with the WHO 2021 molecular classification of gliomas and survival. Incorporation of TVGR as a surrogate endpoint into future prospective studies of IDH-mt gliomas may accelerate drug development.

Brain Plasticity Profiling as a Key Support to Therapeutic Decision-Making in Low-Grade Glioma Oncological Strategies

The ability of neural circuits to compensate for damage to the central nervous system is called postlesional plasticity. In diffuse low-grade gliomas (LGGs), a crosstalk between the brain and the tumor activates modulations of plasticity, as well as tumor proliferation and migration, by means of paracrine and electrical intercommunications. Such adaptative mechanisms have a major impact on the benefits and risks of oncological treatments but are still disregarded by current neuro-oncological guidelines. In this review, the authors first aimed to highlight clinical, radiological, and oncological markers that robustly reflect the plasticity potentials and limitations in LGG patients, including the location of the tumor and the degree of critical white matter tract infiltration, the velocity of tumor expansion, and the reactional changes of neuropsychological performances over time. Second, the interactions between the potential/limitations of cerebral plasticity and the efficacy/tolerance of treatment options (i.e., surgery, chemotherapy, and radiotherapy) are reviewed. Finally, a longitudinal and multimodal treatment approach accounting for the evolutive profiles of brain plasticity is proposed. Such an approach integrates personalized predictive models of plasticity potentials with a step-by-step therapeutic decision making and supports onco-functional balanced strategies in patients with LGG, with the ultimate aim of optimizing overall survival and quality of life.

Advances in molecular and imaging biomarkers in lower-grade gliomas

INTRODUCTION

Lower-grade (grade 2-3) gliomas (LGGs) constitutes a group of primary brain tumors with variable clinical behaviors and treatment responses. Recent advancements in molecular biology have redefined their classification, and novel imaging modalities emerged for the noninvasive diagnosis and follow-up.

AREAS COVERED

This review comprehensively analyses the current knowledge on molecular and imaging biomarkers in LGGs. Key molecular alterations, such as IDH mutations and 1p/19q codeletion, are discussed for their prognostic and predictive implications in guiding treatment decisions. Moreover, the authors explore theranostic biomarkers for the potential of tailored therapies. Additionally, they also describe the utility of advanced imaging modalities, including widely available techniques, as dynamic susceptibility contrast perfusion-weighted imaging and less validated, emerging approaches, for the noninvasive LGGs characterization and follow-up.

EXPERT OPINION

The integration of molecular markers enhanced the stratification of LGGs, leading to the new concept of integrated histomolecular classification. While the IDH mutation is an established key prognostic and predictive marker, recent results from IDH inhibitors trials showed its potential value as a theranostic marker. In this setting, advanced MRI techniques such as 2-D-hydroxyglutarate spectroscopy are very promising for the noninvasive diagnosis and monitoring of LGGs. This progress offers exciting prospects for personalized medicine and improved treatment outcomes in LGGs.

Genomic Profiling of Lower-Grade Gliomas Subtype with Distinct Molecular and Clinicopathologic Characteristics via Altered DNA-Damage Repair Features

Lower WHO grade II and III gliomas (LGGs) exhibit significant genetic and transcriptional heterogeneity, and the heterogeneity of DNA damage repair (DDR) and its relationship to tumor biology, transcriptome, and tumor microenvironment (TME) remains poorly understood. In this study, we conducted multi-omics data integration to investigate DDR alterations in LGG. Based on clinical parameters and molecular characteristics, LGG patients were categorized into distinct DDR subtypes, namely, DDR-activated and DDR-suppressed subtypes. We compared gene mutation, immune spectrum, and immune cell infiltration between the two subtypes. DDR scores were generated to classify LGG patients based on DDR subtype features, and the results were validated using a multi-layer data cohort. We found that DDR activation was associated with poorer overall survival and that clinicopathological features of advanced age and higher grade were more common in the DDR-activated subtype. DDR-suppressed subtypes exhibited more frequent mutations in IDH1. In addition, we observed significant upregulation of activated immune cells in the DDR-activated subgroup, which suggests that immune cell infiltration significantly influences tumor progression and immunotherapeutic responses. Furthermore, we constructed a DDR signature for LGG using six DDR genes, which allowed for the division of patients into low- and high-risk groups. Quantitative real-time PCR results showed that CDK1, CDK2, TYMS, SMC4, and WEE1 were significantly upregulated in LGG samples compared to normal brain tissue samples. Overall, our study sheds light on DDR heterogeneity in LGG and provides insight into the molecular pathways of DDR involved in LGG development.

Same but different. Incidental and symptomatic lower grade gliomas show differences in molecular features and survival

PURPOSE

Data on differences in overall survival and molecular characteristics between incidental (iLGG) and symptomatic lower grade Glioma (sLGG) are limited. The aim of this study was to investigate differences between patients with iLGG and sLGG.

METHODS

All adult patients with a histologically proven diffuse (WHO°II) or anaplastic (WHO°III) glioma who underwent their first surgery at the authors' institution between 2010 and 2019 were retrospectively included. Tumor volume on pre- and postoperative MRI scans was determined. Clinical and routine neuropathological data were gained from patients' charts. If IDH1, ATRX and EGFR were not routinely assessed, they were re-determined.

RESULTS

Out of 161 patients included, 23 (14%) were diagnosed as incidental findings. Main reasons for obtaining MRI were: headache(n = 12), trauma(n = 2), MRI indicated by other departments(n = 7), staging examination for cancer(n = 1), volunteering for MRI sequence testing(n = 1). The asymptomatic patients were significantly younger with a median age of 38 years (IqR28-48) vs. 50 years (IqR38-61), p = 0.011. Incidental LGG showed significantly lower preoperative tumor volumes in T1 CE (p = 0.008), FLAIR (p = 0.038) and DWI (p = 0.028). Incidental LGG demonstrated significantly lower incidence of anaplasia (p = 0.004) and lower expression of MIB-1 (p = 0.008) compared to sLGG. IDH1-mutation was significantly more common in iLGG (p = 0.024). Incidental LGG showed a significantly longer OS (mean 212 vs. 70 months, p = 0.005) and PFS (mean 201 vs. 61 months, p = 0.001) compared to sLGG.

CONCLUSION

Our study is the first to depict a significant difference in molecular characteristics between iLGG and sLGG. The findings of this study confirmed and extended the results of previous studies showing a better outcome and more favorable radiological, volumetric and neuropathological features of iLGG.

DNA Methylation and Histone Modification in Low-Grade Gliomas: Current Understanding and Potential Clinical Targets

Gliomas, the most common type of malignant primary brain tumor, were conventionally classified through WHO Grades I-IV (now 1-4), with low-grade gliomas being entities belonging to Grades 1 or 2. While the focus of the WHO Classification for Central Nervous System (CNS) tumors had historically been on histopathological attributes, the recently released fifth edition of the classification (WHO CNS5) characterizes brain tumors, including gliomas, using an integration of histological and molecular features, including their epigenetic changes such as histone methylation, DNA methylation, and histone acetylation, which are increasingly being used for the classification of low-grade gliomas. This review describes the current understanding of the role of DNA methylation, demethylation, and histone modification in pathogenesis, clinical behavior, and outcomes of brain tumors, in particular of low-grade gliomas. The review also highlights potential diagnostic and/or therapeutic targets in associated cellular biomolecules, structures, and processes. Targeting of MGMT promoter methylation, TET-hTDG-BER pathway, association of G-CIMP with key gene mutations, PARP inhibition, IDH and 2-HG-associated processes, TERT mutation and ARL9-associated pathways, DNA Methyltransferase (DNMT) inhibition, Histone Deacetylase (HDAC) inhibition, BET inhibition, CpG site DNA methylation signatures, along with others, present exciting avenues for translational research. This review also summarizes the current clinical trial landscape associated with the therapeutic utility of epigenetics in low-grade gliomas. Much of the evidence currently remains restricted to preclinical studies, warranting further investigation to demonstrate true clinical utility.

Maximal safe resection of diffuse lower grade gliomas primarily within central lobe using cortical/subcortical direct electrical stimulation under awake craniotomy

Background

Diffuse lower-grade glioma (DLGG) in the central lobe is a challenge for safe resection procedures. To improve the extent of resection and reduce the risk of postoperative neurological deficits, we performed an awake craniotomy with cortical-subcortical direct electrical stimulation (DES) mapping for patients with DLGG located primarily within the central lobe. We investigated the outcomes of cortical-subcortical brain mapping using DES in an awake craniotomy for central lobe DLGG resection.

Methods

We performed a retrospective analysis of clinical data of a cohort of consecutively treated patients from February 2017 to August 2021 with diffuse lower-grade gliomas located primarily within the central lobe. All patients underwent awake craniotomy with DES for cortical and subcortical mapping of eloquent brain areas, neuronavigation, and/or ultrasound to identify tumor location. Tumors were removed according to functional boundaries. Maximum safe tumor resection was the surgical objective for all patients.

Results

Thirteen patients underwent 15 awake craniotomies with intraoperative mapping of eloquent cortices and subcortical fibers using DES. Maximum safe tumor resection was achieved according to functional boundaries in all patients. The pre-operative tumor volumes ranged from 4.3 cm³ to 137.3 cm³ (median 19.2 cm³). The mean extent of tumor resection was 94.6%, with eight cases (53.3%) achieving total resection, four (26.7%) subtotal and three (20.0%) partial. The mean tumor residue was 1.2 cm³. All patients experienced early postoperative neurological deficits or worsening conditions. Three patients (20.0%) experienced late postoperative neurological deficits at the 3-month follow-up, including one moderate and two mild neurological deficits. None of the patients experienced late onset severe neurological impairments post-operatively. Ten patients with 12 tumor resections (80.0%) had resumed activities of daily living at the 3-month follow-up. Among 14 patients with pre-operative epilepsy, 12 (85.7%) were seizure-free after treatment with antiepileptic drugs 7 days after surgery up to the last follow-up.

Conclusions

DLGG located primarily in the central lobe deemed inoperable can be safely resected using awake craniotomy with intraoperative DES without severe permanent neurological sequelae. Patients experienced an improved quality of life in terms of seizure control.

The impact of resection in IDH-mutant WHO grade 2 gliomas: a retrospective population-based parallel cohort study

OBJECTIVE

IDH-mutant diffuse low-grade gliomas (dLGGs; WHO grade 2) are often considered to have a more indolent course. In particular, in patients with 1p19q codeleted oligodendrogliomas, survival can be very long. Therefore, extended follow-up in clinical studies of IDH-mutant dLGG is needed. The authors' primary aim was to determine results after a minimum 10-year follow-up in two hospitals advocating different surgical policies. In one center early resection was favored; in the other center an early biopsy and wait-and-scan approach was the dominant management. In addition, the authors present survival and health-related quality of life (HRQOL) in stratified groups of patients with IDH-mutant astrocytoma and oligodendroglioma.

METHODS

The authors conducted a retrospective, population-based, parallel cohort study with extended long-term follow-up. The inclusion criteria were histopathological diagnosis of IDH-mutant supratentorial dLGG from 1998 through 2009 in patients aged 18 years or older. Follow-up ended January 1, 2021; therefore, all patients had primary surgery more than 10 years earlier. In region A, a biopsy and wait-and-scan approach was favored, while early resections were advocated in region B. Regional referral practice ensured population-based data, since referral to respective centers was based strictly on the patient's residential address. Previous data from EQ-5D-3L, European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30, and EORTC BN20 questionnaires were reanalyzed with respect to the current selection of IDH-mutant dLGG and to molecular subgroups. The prespecified primary endpoint was long-term regional comparison of overall survival. Secondarily, between-group differences in long-term HRQOL measures were explored.

RESULTS

Forty-eight patients from region A and 56 patients from region B were included. Early resection was performed in 17 patients (35.4%) from region A compared with 53 patients (94.6%) from region B (p < 0.001). Characteristics at baseline were otherwise similar between cohorts. Overall survival was 7.5 years (95% CI 4.1-10.8) in region A compared with 14.6 years (95% CI 11.5-17.7) in region B (p = 0.04). When stratified according to molecular subgroups, there was only a statistically significant survival benefit in favor of early resection for patients with astrocytomas. The were no apparent differences in the different HRQOL measures between cohorts.

CONCLUSIONS

In an extended follow-up of patients with IDH-mutant dLGGs, early resection was associated with a sustained and clinically relevant survival benefit. The survival benefit was not counteracted by any detectable reduction in HRQOL.

Risk factors for early progression of diffuse low-grade glioma in adults

Background

To explore the risk factors for early progression of diffuse low-grade glioma in adults.

Methods

A retrospective analysis of pathologic and clinical data of patients diagnosed with diffuse low-grade gliomas at Southwest Hospital between January 2010 and December 2014. The progression-free survival (PFS) less than 60 months was classified as the early progress group, and the PFS greater than 60 months was the control group for comparative analysis.

Results

A total of 138 patients were included in this study, including 94 cases of astrocytoma and 44 cases of oligodendroglioma. There were 63 cases with 100% resection, 56 cases with 90–100% resection degree, and 19 cases with resection degree < 90%. The average follow-up time was 60 months, of which 80 patients progressed and 58 patients did not progress. The average progression-free survival was 61 months. The median progression-free survival was 60 months. There were 68 patients with PFS≤ 60 months and 70 patients with PFS > 60 months. The two groups were compared for statistical analysis. In univariate analysis, there were significant differences in tumor subtype (p = 0.005), range (p = 0.011), volume (p = 0.005), location (p = 0.000), and extent of resection (p = 0.000). Multifactor analysis shows tumor location (HR = 4.549, 95% CI: 1.324–15.634, p = 0.016) and tumor subtype (HR = 3.347, 95% CI = 1.373–8.157, p = 0.008), and imcomplete resection is factors influencing early progression of low-grade glioma.

Conclusions

Low-grade gliomas involving deep location such as basal ganglia, inner capsule, and corpus callosum are more likely to progress early, while incomplete resection is a risk factor in early progression of astrocytoma.

A Personalized Longitudinal Strategy in Low-Grade Glioma Patients: Predicting Oncological and Neural Interindividual Variability and Its Changes over Years to Think One Step Ahead

Diffuse low-grade glioma (LGG) is a rare cerebral cancer, mostly involving young adults with an active life at diagnosis. If left untreated, LGG widely invades the brain and becomes malignant, generating neurological worsening and ultimately death. Early and repeat treatments for this incurable tumor, including maximal connectome-based surgical resection(s) in awake patients, enable postponement of malignant transformation while preserving quality of life owing to constant neural network reconfiguration. Due to considerable interindividual variability in terms of LGG course and consecutive cerebral reorganization, a multistage longitudinal strategy should be tailored accordingly in each patient. It is crucial to predict how the glioma will progress (changes in growth rate and pattern of migration, genetic mutation, etc.) and how the brain will adapt (changes in patterns of spatiotemporal redistribution, possible functional consequences such as epilepsy or cognitive decline, etc.). The goal is to anticipate therapeutic management, remaining one step ahead in order to select the optimal (re-)treatment(s) (some of them possibly kept in reserve), at the appropriate time(s) in the evolution of this chronic disease, before malignization and clinical worsening. Here, predictive tumoral and non-tumoral factors, and their ever-changing interactions, are reviewed to guide individual decisions in advance based on patient-specific markers, for the treatment of LGG.

Repeated Awake Surgical Resection(s) for Recurrent Diffuse Low-Grade Gliomas: Why, When, and How to Reoperate?

Early maximal surgical resection is the first treatment in diffuse low-grade glioma (DLGG), because the reduction of tumor volume delays malignant transformation and extends survival. Awake surgery with intraoperative mapping and behavioral monitoring enables to preserve quality of life (QoL). However, because of the infiltrative nature of DLGG, relapse is unavoidable, even after (supra)total resection. Therefore, besides chemotherapy and radiotherapy, the question of reoperation(s) is increasingly raised, especially because patients with DLGG usually enjoy a normal life with long-lasting projects. Here, the purpose is to review the literature in the emerging field of iterative surgeries in DLGG. First, long-term follow-up results showed that patients with DLGG who underwent multiple surgeries had an increased survival (above 17 years) with preservation of QoL. Second, the criteria guiding the decision to reoperate and defining the optimal timing are discussed, mainly based on the dynamic intercommunication between the glioma relapse (including its kinetics and pattern of regrowth) and the reactional cerebral reorganization—i.e., mechanisms underpinning reconfiguration within and across neural networks to enable functional compensation. Third, how to adapt medico-surgical strategy to this individual spatiotemporal brain tumor interplay is detailed, by considering the perpetual changes in connectome. These data support early reoperation in recurrent DLGG, before the onset of symptoms and before malignant transformation. Repeat awake resection(s) should be integrated in a global management including (neo)adjuvant medical treatments, to enhance long-lasting functional and oncological outcomes. The prediction of potential and limitation of neuroplasticity at each step of the disease must be improved to anticipate personalized multistage therapeutic attitudes.

Factors Associated With Long-term Survival in Women Who Get Pregnant After Surgery for WHO Grade II Glioma

BACKGROUND AND OBJECTIVES

Women with a WHO grade II glioma (GIIG) often question clinicians on the effects of pregnancy on their disease. Previous reports have indicated a higher risk of glioma progression during and after pregnancy. Here, the aim was to investigate post-pregnancy outcomes and predictive factors impacting overall survival in female patients who underwent GIIG surgery.

METHODS

Inclusion criteria were adult women who have been pregnant after a GIIG resection and with a stable oncological status at the time of pregnancy (no ongoing oncological treatment, no contrast enhancement, no debilitating clinical condition). Relevant cases were identified from a databank (1998-2021) of patients who underwent surgical resection for a histologically-confirmed GIIG in our department.

RESULTS

Among 345 GIIG women within their reproductive years (age<45y), 16 patients (4.6%, mean age at delivery: 30.9±5.1 years) were pregnant (twice in 5 cases). The mean interval between the last oncological treatment (surgery alone in 11 patients while followed by chemotherapy and/or radiotherapy in 5 patients) and pregnancy was 3.5 years (range 0.75-10 years). Two patients experienced seizures during pregnancy. The delivery was vaginal and uneventful in all cases but one (1 caesarean). All children had normal mental and physical development. The glioma behavior changed in 7 patients (43.7%), with an acceleration of the velocity of diameter expansion (VDE) and/or the occurrence of a contrast enhancement during or within the 3 months after pregnancy, resulting in medical treatment and/or reoperation in the early post-partum period in 7 cases. The median clinical follow-up from delivery was 5.3 years (range 1.25-11.6 years). Four other patients received delayed adjuvant therapy for glioma progression. Seven patients (43.7%) died at a median time from delivery of 3.9 years (range 1.25-5.9 years). Overall, the median survival from delivery was 5.75 years. Crucially, patients who underwent a complete surgical resection and patients with stable lesions before pregnancy lived longer (log rank, p=0.046 and p=0.0026, respectively).

CONCLUSIONS

Tumor residual volume and tumor speed growth are strong predictive factors conditioning post-pregnancy long-term survival in patients with GIIG. Identifying patients at risk is critical to provide relevant counsel to GIIG women with a desire for motherhood.

Modification Patterns of DNA Methylation-Related lncRNAs Regulating Genomic Instability for Improving the Clinical Outcomes and Tumour Microenvironment Characterisation of Lower-Grade Gliomas

Background: DNA methylation is an important epigenetic modification that affects genomic instability and regulates gene expression. Long non-coding RNAs (lncRNAs) modulate gene expression by interacting with chromosomal modifications or remodelling factors. It is urgently needed to evaluate the effects of DNA methylation-related lncRNAs (DMlncRNAs) on genome instability and further investigate the mechanism of action of DMlncRNAs in mediating the progression of lower-grade gliomas (LGGs) and their impact on the immune microenvironment.

Methods: LGG transcriptome data, somatic mutation profiles and clinical features analysed in the present study were obtained from the CGGA, GEO and TCGA databases. Univariate, multivariate Cox and Lasso regression analyses were performed to establish a DMlncRNA signature. The KEGG and GO analyses were performed to screen for pathways and biological functions associated with key genes. The ESTIMATE and CIBERSORT algorithms were used to determine the level of immune cells in LGGs and the immune microenvironment fraction. In addition, DMlncRNAs were assessed using survival analysis, ROC curves, correlation analysis, external validation, independent prognostic analysis, clinical stratification analysis and qRT-PCR.

Results: We identified five DMlncRNAs with prognostic value for LGGs and established a prognostic signature using them. The Kaplan–Meier analysis revealed 10-years survival rate of 10.10% [95% confidence interval (CI): 3.27–31.40%] in high-risk patients and 57.28% (95% CI: 43.17–76.00%) in low-risk patients. The hazard ratio (HR) and 95% CI of risk scores were 1.013 and 1.009–1.017 (p &lt; 0.001), respectively, based on the univariate Cox regression analysis and 1.009 and 1.004–1.013 (p &lt; 0.001), respectively, based on the multivariate Cox regression analysis. Therefore, the five-lncRNAs were identified as independent prognostic markers for patients with LGGs. Furthermore, GO and KEGG analyses revealed that these lncRNAs are involved in the prognosis and tumorigenesis of LGGs by regulating cancer pathways and DNA methylation.

Conclusion: The findings of the study provide key information regarding the functions of lncRNAs in DNA methylation and reveal that DNA methylation can regulate tumour progression through modulation of the immune microenvironment and genomic instability. The identified prognostic lncRNAs have high potential for clinical grouping of patients with LGGs to ensure effective treatment and management.

Malignant Progression of Diffuse Low-grade Gliomas: A Systematic Review and Meta-analysis on Incidence and Related Factors

Malignant progression of diffuse low-grade glioma (LGG) is a critical event affecting patient survival; however, the incidence and related factors have been inconsistent in literature. According to the PRISMA guidelines, we systematically reviewed articles from 2009, meta-analyzed the incidence of malignant progression, and clarified factors related to the transformation. Forty-one articles were included in this study (n = 7,122; n, number of patients). We identified two definitions of malignant progression: histologically proven (Htrans) and clinically defined (Ctrans). The malignant progression rate curves of Htrans and Ctrans were almost in parallel when constructed from the results of meta-regression by the mean follow-up time. The true transformation rate was supposed to lie between the two curves, approximately 40% at the 10-year mean follow-up. Risk of malignant progression was evaluated using hazard ratio (HR). Pooled HRs were significantly higher in tumors with a larger pre- and postoperative tumor volume, lower degree of resection, and notable preoperative contrast enhancement on magnetic resonance imaging than in others. Oligodendroglial histology and IDH mutation (IDHm) with 1p/19q codeletion (Codel) also significantly reduced the HRs. Using Kaplan-Meier curves from eight studies with molecular data, we extracted data and calculated the 10-year malignant progression-free survival (10yMPFS). The 10yMPFS in patients with IDHm without Codel was 30.4% (95% confidence interval [95% CI]: 22.2-39.0) in Htrans and 38.3% (95% CI: 32.3-44.3) in Ctrans, and that with IDHm with Codel was 71.7% (95% CI: 61.7-79.5) in Htrans and 62.5% (95% CI: 55.9-68.5) in Ctrans. The effect of adjuvant radiotherapy or chemotherapy could not be determined.

A Multielement Prognostic Nomogram Based on a Peripheral Blood Test, Conventional MRI and Clinical Factors for Glioblastoma

Background

Glioblastoma (GBM) is one of the most malignant types of tumors in the central nervous system, and the 5-year survival remains low. Several studies have shown that preoperative peripheral blood tests and preoperative conventional Magnetic Resonance Imaging (MRI) examinations affect the prognosis of GBM patients. Therefore, it is necessary to construct a risk score based on a preoperative peripheral blood test and conventional MRI and develop a multielement prognostic nomogram for GBM.

Methods

This study retrospectively analyzed 131 GBM patients. Determination of the association between peripheral blood test variables and conventional MRI variables and prognosis was performed by univariate Cox regression. The nomogram model, which was internally validated using a cohort of 56 GBM patients, was constructed by multivariate Cox regression. RNA sequencing data from Gene Expression Omnibus (GEO) and Chinese Glioma Genome Atlas (CGGA datasets were used to determine peripheral blood test-related genes based on GBM prognosis.

Results

The constructed risk score included the neutrophil/lymphocyte ratio (NLR), lymphocyte/monocyte ratio (LMR), albumin/fibrinogen (AFR), platelet/lymphocyte ratio (PLR), and center point–to-ventricle distance (CPVD). A final nomogram was developed using factors associated with prognosis, including age, sex, the extent of tumor resection, IDH mutation status, radiotherapy status, chemotherapy status, and risk. The Area Under Curve (AUC) values of the receiver operating characteristic curve (ROC) curve were 0.876 (12-month ROC), 0.834 (24-month ROC) and 0.803 (36-month ROC) in the training set and 0.906 (12-month ROC), 0.800 (18-month ROC) and 0.776 (24-month ROC) in the validation set. In addition, vascular endothelial growth factor A (VEGFA) was closely associated with NLR and LMR and identified as the most central negative gene related to the immune microenvironment and influencing immune activities.

Conclusion

The risk score was established as an independent predictor of GBM prognosis, and the nomogram model exhibit appropriate predictive power. In addition, VEGFA is the key peripheral blood test-related gene that is significantly associated with poor prognosis.

Surveillance imaging frequency in adult patients with lower-grade (WHO Grade 2 and 3) gliomas

With improved outcome following aggressive treatment in patients with grade 2 and 3 IDH-mutant (IDHmt), 1p/19q codeleted oligodendroglioma and IDHmt, non-codeleted astrocytoma, prolonged surveillance is desirable for early detection of tumor growth and malignant transformation. Current National Comprehensive Cancer Network (NCCN) guidelines provide imaging follow-up recommendations based on molecular classification of lower-grade gliomas, although individualized imaging guidelines based on treatments received and after tumor recurrence are not clearly specified. Other available guidelines have yet to incorporate the molecular biomarkers that inform the WHO classification of gliomas, and in some cases do not adequately consider current knowledge on IDHmt glioma growth rate and recurrence patterns. Moreover, these guidelines also do not provide specific recommendations for concerning clinical symptoms or radiographic findings warranting imaging studies out of prespecified intervals. Focusing on molecularly defined grade 2 and 3 IDHmt astrocytomas and oligodendrogliomas, we review current knowledge of tumor growth rates and time to tumor progression for each tumor type and propose a range of recommended MRI surveillance intervals for both the newly diagnosed and recurrent tumor setting. Additionally, we summarize situations in which imaging is advisable outside of these intervals.

Adolescent and young adult glioma: systematic review of demographic, disease, and treatment influences on survival

BACKGROUND

Prognostic factors in adolescent and young adult (AYA) glioma are not well understood. Though clinical and molecular differences between pediatric and adult glioma have been characterized, their application to AYA populations is less clear. There is a major need to develop more robust evidence-based practices for managing AYA glioma patients.

METHODS

A systematic review using PRISMA methodology was conducted using multiple databases with the objective of identifying demographic, clinical, molecular and treatment factors influencing AYA glioma outcomes.

RESULTS

40 Studies met inclusion criteria. Overall survival was highly variable across studies depending on glioma grade, anatomic compartment and cohort characteristics. Thirty-five studies suffered from high risk of bias in at least one domain. Several studies included older adults within their cohorts; few captured purely AYA groups. Despite study heterogeneity, identified favorable prognosticators included younger age, higher functional status at diagnosis, low-grade pathology, oligodendroglioma histology and increased extent of surgical resection. Though isocitrate dehydrogenase (IDH) mutant status was associated with favorable prognosis, validity of this finding within AYA was compromised though may studies including older adults. The prognostic influence of chemotherapy and radiotherapy on overall survival varied across studies with conflicting evidence.

CONCLUSION

Existing literature is heterogenous, at high risk of bias, and rarely focused solely on AYA patients. Many included studies did not reflect updated pathological and molecular AYA glioma classification. The optimal role of chemotherapy, radiotherapy, and targeted agents cannot be determined from existing literature and should be the focus of future studies.

Glioma Imaging by O-(2-18F-Fluoroethyl)-L-Tyrosine PET and Diffusion-Weighted MRI and Correlation With Molecular Phenotypes, Validated by PET/MR-Guided Biopsies

Gliomas exhibit high intra-tumoral histological and molecular heterogeneity. Introducing stereotactic biopsy, we achieved a superior molecular analysis of glioma using O-(2-18F-fluoroethyl)-L-tyrosine (FET)-positron emission tomography (PET) and diffusion-weighted magnetic resonance imaging (DWI). Patients underwent simultaneous DWI and FET-PET scans. Correlations between biopsy-derived tumor tissue values, such as the tumor-to-background ratio (TBR) and apparent diffusion coefficient (ADC)/exponential ADC (eADC) and histopathological diagnoses and those between relevant genes and TBR and ADC values were determined. Tumor regions with human telomerase reverse transcriptase (hTERT) mutation had higher TBR and lower ADC values. Tumor protein P53 mutation correlated with lower TBR and higher ADC values. α-thalassemia/mental-retardation-syndrome-X-linked gene (ATRX) correlated with higher ADC values. 1p/19q codeletion and epidermal growth factor receptor (EGFR) mutations correlated with lower ADC values. Isocitrate dehydrogenase 1 (IDH1) mutations correlated with higher TBRmean values. No correlation existed between TBRmax/TBRmean/ADC/eADC values and phosphatase and tensin homolog mutations (PTEN) or O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation. Furthermore, TBR/ADC combination had a higher diagnostic accuracy than each single imaging method for high-grade and IDH1-, hTERT-, and EGFR-mutated gliomas. This is the first study establishing the accurate diagnostic criteria for glioma based on FET-PET and DWI.

Cognitive preservation following awake mapping-based neurosurgery for low-grade gliomas: a longitudinal, within-patient design study

BACKGROUND

Awake surgery with intraoperative electrical mapping emerged as a gold-standard approach in newly diagnosed diffuse low-grade glioma (DLGG) to optimize the extent of resection (EOR) while sparing critical brain structures. However, no study has assessed to what extent cognitive recovery occurs following awake mapping-guided neurosurgery in a large, longitudinal and homogeneous series of DLGG.

METHODS

A longitudinal study on the cognitive status of 157 DLGG patients was performed. Neuropsychological assessments were done before and three months after awake mapping-based surgery. Z-scores and variations of Z-scores were computed to determine the number of patients with cognitive deficit(s) or decline. Clinical, surgical, and histopathological variables were studied to investigate factors contributing to neurocognitive outcomes.

RESULTS

87 patients (55.4%) had preoperative cognitive impairments. Statistical analysis between the preoperative (baseline) and postoperative assessments demonstrated a significant difference in three domains (Executive, Psychomotor Speed and Attention, Verbal Episodic Memory). 86% of patients exhibited no postoperative cognitive decline and among them 10% exhibited cognitive improvement. The mean EOR was 92.3%±7.8%. The EOR, postoperative volume, and tumor lateralization had a significant association with cognitive decline. No patients demonstrated permanent post-operative neurologic deficits, but 5.8% did not resume their preoperative professional activities. The 5-year survival rate was 82.2%.

CONCLUSIONS

This is the largest series ever reported with systematic longitudinal neuropsychological assessment. 86% of patients demonstrated no cognitive decline despite large resections and only 5.8% did not return to work. This work supports the practice of awake surgery with cognitive mapping as safe and effective in DLGG patients.

Construction and comprehensive analysis of a competitive endogenous RNA network to reveal potential biomarkers for the malignant differentiation of glioma

BACKGROUND

Long noncoding RNAs (lncRNAs) can act as microRNA (miRNA) sponges to regulate protein-coding gene expression; therefore, lncRNAs are considered major components of the competitive endogenous RNA (ceRNA) network and have attracted growing attention. This study explored the regulatory mechanisms and functional roles of lncRNAs as ceRNAs in the malignant differentiation of low-grade glioma (LGG) to glioblastoma (GBM) and their potential impact on the prognosis of patients with GBM.

METHODS

LncRNA and messenger RNA (mRNA) data were extracted from the Cancer Genome Atlas (TCGA) database from 156 GBM samples and 529 LGG samples. Separately, the miRNA expression data were downloaded from the Gene Expression Omnibus database, with the GSE112009 dataset containing miRNA expression data from 10 GBM samples and 15 LGG samples. Weighted gene coexpression network analysis was performed to screen the glioma grade-related lncRNAs. Then, a ceRNA network was established. The database for annotation, visualization, and integrated discovery was adopted to conduct functional enrichment analysis based on 57 upregulated differentially expressed mRNAs in the ceRNA network. Finally, Kaplan-Meier curves were created for the survival analysis of 13 hub lncRNA by combining the clinical data of GBM patients in TCGA.

RESULTS

A ceRNA network including 16 lncRNAs, 18 miRNAs, and 78 mRNAs specific to the malignant differentiation of LGG to GBM was established. The 57 upregulated differentially expressed mRNAs in the ceRNA network were significantly enriched in 35 gene ontology terms and 5 pathways. The survival analysis showed that 2 lncRNAs (LINC00261 and HOXA10-AS) were prognostic biomarkers for patients with GBM in TCGA.

CONCLUSION

The proposed ceRNA network may help elucidate the regulatory mechanism by which lncRNAs function as ceRNAs and contribute to the malignant differentiation of LGG to GBM. Importantly, the candidate lncRNAs, miRNAs, and mRNAs involved in the ceRNA network can be further evaluated as potential therapeutic targets and prognostic biomarkers for GBM.

Dynamic Interplay between Lower-Grade Glioma Instability and Brain Metaplasticity: Proposal of an Original Model to Guide the Therapeutic Strategy

The behavior of lower-grade glioma (LGG) is changing over time, spontaneously, and in reaction to treatments. First, due to genomic instability and clonal expansion, although LGG progresses slowly during the early period of the disease, its growth velocity will accelerate when this tumor will transform to a higher grade of malignancy. Furthermore, its pattern of progression may change following therapy, e.g., by switching from a proliferative towards a more diffuse profile, in particular after surgical resection. In parallel to this plasticity of the neoplasm, the brain itself is constantly adapting to the tumor and possible treatment(s) thanks to reconfiguration within and between neural networks. Furthermore, the pattern of reallocation can also change, especially by switching from a perilesional to a contrahemispheric functional reorganization. Such a reorientation of mechanisms of cerebral reshaping, related to metaplasticity, consists of optimizing the efficiency of neural delocalization in order to allow functional compensation by adapting over time the profile of circuits redistribution to the behavioral modifications of the glioma. This interplay between LGG mutations and reactional connectomal instability leads to perpetual modulations in the glioma-neural equilibrium, both at ultrastructural and macroscopic levels, explaining the possible preservation of quality of life despite tumor progression. Here, an original model of these dynamic interactions across LGG plasticity and the brain metanetwork is proposed to guide a tailored step-by-step individualized therapeutic strategy over years. Integration of these new parameters, not yet considered in the current guidelines, might improve management of LGG patients.

Systematic review-Time to malignant transformation in low-grade gliomas: Predicting a catastrophic event with clinical, neuroimaging, and molecular markers

Background

Despite an initially indolent course, all WHO grade II, LGGs inevitably transform to malignant, WHO grades III and IV, without current curative options. Malignant transformation (MT) remains unpredictable with limited prognostic markers to steer timing of interventions. The aim of this study was to review and assign predictive value to specific clinical, molecular, and radiological markers impacting MT, thereby justifying timely therapeutic interventions.

Methods

Searches of MEDLINE, Embase, and Cochrane databases were conducted from inception to April 28, 2021 and outputs were analysed in accordance with PRISMA protocol.

Results

From an initial 5,032 articles, 33 articles were included, totalling 5672 patients. Forty-three prognostic factors were registered to significantly impact MT. These were categorised as 7 clinical; 14 neuroimaging; 8 biological/molecular; 3 volumetric; 5 topological; 3 histological; and 3 treatment-related. Following analysis, 10 factors were highlighted: the pre-operative prognosticators were 1. presentation with epileptic seizures; 2. VDE > 8 mm/y; 3. VDE > 4 mm/y; 4. rCBV > 1.75; 5. PTV ≥ 5 cm (65 ml); 6. PTV ≥ 100 ml; and 7. cortical involvement. The post-operative prognosticators were: (1) IDH-wt, (2) TP53 mutation, and (3) temozolomide monotherapy.

Conclusions

The management of LGGs remains controversial, as conservative and invasive treatment may be associated with MT and impaired quality of life, respectively. Our review indicates that MT can be predicted by specific metrics in VDE, PTV, and rCBV, alongside cortical involvement. Additionally, patients with IDH-wt tumours TP53 mutations, or receiving TMZ monotherapy are more likely to undergo MT. Our data may form the basis of a predictive scoring system.

Current State of Health Economic Analyses for Low-Grade Glioma Management: A Systematic Review

BACKGROUND

Health economic analyses help determine the value of a medical intervention by assessing the costs and outcomes associated with it. The objective of this study was to assess the level of evidence in economic evaluations for low-grade glioma (LGG) management.

METHODS

Following the PRISMA guidelines, we conducted a systematic review of English articles in Medline, Embase, The Central Registration Depository, EconPapers, and EconLit. The results were screened, and data were extracted by 2 independent reviewers for studies reporting economic evaluations for LGG. The quality of each study was evaluated using the CHEERS (Consolidated Health Economic Evaluation Reporting Standards) checklist, the hierarchy scale developed by Cooper et al. (2005), and the Quality of Health Economic Studies instrument.

RESULTS

Three studies met our inclusion criteria. The adjusted incremental cost-effectiveness ratio (ICER) values for the included studies ranged from $3934 to $9936, but each evaluated a different aspect of LGG management. All had a good quality of reporting per the CHEERS checklist. Based on the Cooper et al. hierarchy scale, the quality of data use was lacking most for utilities. The quality of study design was scored as 82, 92, and 100 for each study using the Quality of Health Economic Studies instrument.

CONCLUSIONS

Although a limited number of economic evaluations were identified, the studies evaluated here were well designed. The interventions assessed were all considered cost-effective, but pooled analysis was not possible because of heterogeneity in the interventions assessed. Given the importance of value and cost-effectiveness in medical care, more evidence is needed in this area.

From Laboratory Studies to Clinical Trials: Temozolomide Use in IDH-Mutant Gliomas

In this review, we discuss the use of the alkylating agent temozolomide (TMZ) in the treatment of IDH-mutant gliomas. We describe the challenges associated with TMZ in clinical (drug resistance and tumor recurrence) and preclinical settings (variabilities associated with in vitro models) in treating IDH-mutant glioma. Lastly, we summarize the emerging therapeutic targets that can potentially be used in combination with TMZ.

The role of 11C-methionine PET in patients with negative diffusion-weighted magnetic resonance imaging: correlation with histology and molecular biomarkers in operated gliomas

OBJECTIVE

To compare 11C-methionine (11C-METH) PET with diffusion-weighted MRI (DWI-MRI) diagnostic accuracy and prognostic value in patients with glioma candidate to neurosurgery.

METHODS

We collected and analyzed data from 124 consecutive patients (n = 124) investigated during preoperative work-up. Both visual and semiquantitative parameters were utilized for image analysis. The reference standard was based on histopathology. The median follow-up was 14.3 months.

RESULTS

Overall, 47 high-grade gliomas (HGG) and 77 low-grade gliomas (LGG) were diagnosed. On visual assessment, sensitivity and specificity for differentiating HGG from LGG were 80.8 and 59.7% for DWI-MRI, versus 95.7 and 41.5% for 11C-METH PET, respectively. On semiquantitative analysis, the sensitivity, specificity, and area under the curve were 78.7, 71.4, and 80.4% for SUVmax, 78.7, 70.1, and 81.1% for SUVratio, and 74.5, 61, and 76.7% for MTB (metabolic tumor burden), respectively. In patients with negative DWI-MRI and IDH-wild type, SUVmax and SUVratio were higher compared to IDH-mutated (P = 0.025 and P = 0.01, respectively). In LGG, patients with 1p/19q codeletion showed higher SUVmax (P = 0.044). In all patients with negative DWI-MRI, median PFS was longer for SUVmax <3.9 (median not reached vs 34.2 months, P = 0.004), SUVratio <2.3 (median not reached vs 21.5 months, P < 0.001), and MTB <3.1 (median not reached vs 45.7 months, P = 0.05). In LGG patients with negative DWI-MRI, only SUVratio <2.3 and MTB <3.1 were associated with longer PFS (P = 0.016 and P = 0.024, respectively).

CONCLUSION

C-METH PET was found highly sensitive for glioma differentiation and molecular characterization. In DWI-negative patients, PET parameters correlated with molecular profile were associated with clinical outcome.

Patterns of Interaction Between Diffuse Low-Grade Glioma and Pregnancy: An Institutional Case Series

BACKGROUND

The occurrence of pregnancy in patients with low-grade glioma (LGG) constitutes a unique therapeutic challenge. Owing to the rarity of cases, there is a dearth of information in existing literature.

METHODS

We retrospectively identified all patients with a diagnosis of LGG and pregnancy at some point during their illness. Clinical course and obstetrical outcomes were reviewed. A volumetric analysis of tumor growth rate in association with pregnancy was performed.

RESULTS

Of 15 women identified, 13 (86.7%) had a prepregnancy LGG diagnosis. Of the 2 patients in whom LGG was diagnosed during pregnancy, one underwent upfront surgery, and the other had watchful waiting with resection after 60 weeks. Nine patients (60.0%) remained asymptomatic during pregnancy, while 5 (33.3%) experienced recurrence of seizures. There was one case of transformation of an astrocytoma to glioblastoma during the third trimester, which was resected emergently. In 10 cases, progression occurred after pregnancy at a median interval of 24.2 months (interquartile range 6.6-37.5 months), with progression within 6 months of delivery in 2 cases. Mean (SD) growth rate during pregnancy was 7.8 (22.2) mm/year compared with 0.62 (1.12) mm/year before pregnancy and 0.29 (1.18) mm/year after pregnancy; the difference did not reach statistical significance (P = 0.306).

CONCLUSIONS

Pregnancy was associated with clinical deterioration in one third of patients. No significant change in growth rate was identified. Time to progression and malignant dedifferentiation were unaffected. Patients with LGG wishing to pursue pregnancy should be counseled regarding the risk of complications, and if pregnancy is pursued, close neurological and obstetrical follow-up is recommended.

Improved detection of diffuse glioma infiltration with imaging combinations: a diagnostic accuracy study

Background

Surgical resection and irradiation of diffuse glioma are guided by standard MRI: T2/fluid attenuated inversion recovery (FLAIR)–weighted MRI for non-enhancing and T1-weighted gadolinium-enhanced (T1G) MRI for enhancing gliomas. Amino acid PET has been suggested as the new standard. Imaging combinations may improve standard MRI and amino acid PET. The aim of the study was to determine the accuracy of imaging combinations to detect glioma infiltration.

Methods

We included 20 consecutive adults with newly diagnosed non-enhancing glioma (7 diffuse astrocytomas, isocitrate dehydrogenase [IDH] mutant; 1 oligodendroglioma, IDH mutant and 1p/19q codeleted; 1 glioblastoma IDH wildtype) or enhancing glioma (glioblastoma, 9 IDH wildtype and 2 IDH mutant). Standardized preoperative imaging (T1-, T2-, FLAIR-weighted, and T1G MRI, perfusion and diffusion MRI, MR spectroscopy and O-(2-[18F]-fluoroethyl)-L-tyrosine ([¹⁸F]FET) PET) was co-localized with multiregion stereotactic biopsies preceding resection. Tumor presence in the biopsies was assessed by 2 neuropathologists. Diagnostic accuracy was determined using receiver operating characteristic analysis.

Results

A total of 174 biopsies were obtained (63 from 9 non-enhancing and 111 from 11 enhancing gliomas), of which 129 contained tumor (50 from non-enhancing and 79 from enhancing gliomas). In enhancing gliomas, the combination of apparent diffusion coefficient (ADC) with [¹⁸F]FET PET (area under the curve [AUC], 95% CI: 0.89, 0.79‒0.99) detected tumor better than T1G MRI (0.56, 0.39‒0.72; P < 0.001) and [¹⁸F]FET PET (0.76, 0.66‒0.86; P = 0.001). In non-enhancing gliomas, no imaging combination detected tumor significantly better than standard MRI. FLAIR-weighted MRI had an AUC of 0.81 (0.65–0.98) compared with 0.69 (0.56–0.81; P = 0.019) for [¹⁸F]FET PET.

Conclusion

Combining ADC and [¹⁸F]FET PET detects glioma infiltration better than standard MRI and [¹⁸F]FET PET in enhancing gliomas, potentially enabling better guidance of local therapy.

Radiological evaluation of ex novo high grade glioma: velocity of diametric expansion and acceleration time study

Background

One of the greatest neuro-oncological concern remains the lack of knowledge about the etiopathogenesis and physiopathology of gliomas. Several studies reported a strict correlation between radiological features and biological behaviour of gliomas; in this way the velocity of diametric expansion (VDE) correlate with lower grade glioma aggressiveness. However, there are no the same strong evidences for high grade gliomas (HGG) because of the lack of several preoperative MRI.

Patients and methods

We describe a series of 4 patients affected by HGG followed from 2014 to January 2019. Two patients are male and two female; two had a pathological diagnosis of glioblastoma (GBM), one of anaplastic astrocytoma (AA) and one had a neuroradiological diagnosis of GBM. The VDE and the acceleration time (AT) was calculated for fluid attenuated inversion recovery (FLAIR) volume and for the enhancing nodule (EN). Every patients underwent sequential MRI study along a mean period of 413 days.

Results

Mean VDE evaluated on FLAIR volume was 39.91 mm/year. Mean percentage ratio between peak values and mean value of acceleration was 282.7%. Median appearance time of EN after first MRI scan was 432 days. Mean VDE was 45.02 mm/year. Mean percentage ratio between peak values and mean value of acceleration was 257.52%.

Conclusions

To our knowledge, this is the first report on VDE and acceleration growth in HGG confirming their strong aggressiveness. In a case in which we need to repeat an MRI, time between consecutive scans should be reduced to a maximum of 15–20 days and surgery should be executed as soon as possible.

Clinical Management of Diffuse Low-Grade Gliomas

Diffuse low-grade gliomas (LGG) represent a heterogeneous group of primary brain tumors arising from supporting glial cells and usually affecting young adults. Advances in the knowledge of molecular profile of these tumors, including mutations in the isocitrate dehydrogenase genes, or 1p/19q codeletion, and in neuroradiological techniques have contributed to the diagnosis, prognostic stratification, and follow-up of these tumors. Optimal post-operative management of LGG is still controversial, though radiation therapy and chemotherapy remain the optimal treatments after surgical resection in selected patients. In this review, we report the most important and recent research on clinical and molecular features, new neuroradiological techniques, the different therapeutic modalities, and new opportunities for personalized targeted therapy and supportive care.

Usefulness of 18F-FDOPA PET for the management of primary brain tumors: a systematic review of the literature

Contrast-enhanced magnetic resonance imaging is currently the standard of care in the management of primary brain tumors, although certain limitations remain. Metabolic imaging has proven useful for an increasing number of indications in oncology over the past few years, most particularly 18F-FDG PET/CT. In neuro-oncology, 18F-FDG was insufficient to clearly evaluate brain tumors. Amino-acid radiotracers such as 18F-FDOPA were then evaluated in the management of brain diseases, notably tumoral diseases. Even though European guidelines on the use of amino-acid PET in gliomas have been published, it is crucial that future studies standardize acquisition and interpretation parameters. The aim of this article was to systematically review the potential effect of this metabolic imaging technique in numerous steps of the disease: primary and recurrence diagnosis, grading, local and systemic treatment assessment, and prognosis. A total of 41 articles were included and analyzed in this review. It appears that 18F-FDOPA PET holds promise as an effective additional tool in the management of gliomas. More consistent prospective studies are still needed.

Extent of resection in diffuse low-grade gliomas and the role of tumor molecular signature-a systematic review of the literature

There is a lack of class I evidence concerning the impact of surgery in the treatment of diffuse low-grade glioma; the early maximal resection with preservation of eloquent brain areas has been accepted as the first therapeutic option. We performed a systematic review of the literature using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and protocol. Inclusion criteria: only case series with at least 100 patients containing supratentorial hemispheric diffuse low-grade glioma (according to any of the WHO classification used in papers published between 2000 to 2019), with pre- and postoperative MRI study were included in the qualitative and quantitative analyses. The extent of resection should be defined based on MRI at least in two categories and correlated with patients' outcomes (with univariate or multivariate analyses) using overall survival (OS) or malignant progression-free survival (MPFS). A total of 18 series with 4386 patients, published in 20 papers, were included in this systematic review. All the series that evaluates the relation between the extent of resection (EOR) and OS showed a statistically significant improvement of OS at univariate and/or multivariate analyzes with a greater EOR. Six studies showed a statistically significant improvement of MPFS with a greater EOR. We demonstrate that when a more rigorous analysis of EOR is performed, a benefit of a more aggressive resection on OS and MPFS is observed. Our review about EOR in different molecular groups of DLGG also suggests a benefit of maximum safe resection for all different subtypes, even though "radical surgery" may be associated with better OS and MPFS in tumors with a more aggressive signature.

Recent developments and future directions in adult lower-grade gliomas: Society for Neuro-Oncology (SNO) and European Association of Neuro-Oncology (EANO) consensus

The finding that most grades II and III gliomas harbor isocitrate dehydrogenase (IDH) mutations conveying a relatively favorable and fairly similar prognosis in both tumor grades highlights that these tumors represent a fundamentally different entity from IDH wild-type gliomas exemplified in most glioblastoma. Herein we review the most recent developments in molecular neuropathology leading to reclassification of these tumors based upon IDH and 1p/19q status, as well as the potential roles of methylation profiling and deletional analysis of cyclin-dependent kinase inhibitor 2A and 2B. We discuss the epidemiology, clinical manifestations, benefit of surgical resection, and neuroimaging features of lower-grade gliomas as they relate to molecular subtype, including advanced imaging techniques such as 2-hydroxyglutarate magnetic resonance spectroscopy and amino acid PET scanning. Recent, ongoing, and planned studies of radiation therapy and both cytotoxic and targeted chemotherapies are summarized, including both small molecule and immunotherapy approaches specifically targeting the mutant IDH protein.

Imaging growth as a predictor of grade of malignancy and aggressiveness of IDH-mutant and 1p/19q-codeleted oligodendrogliomas in adults

BACKGROUND

We quantified the spontaneous imaging growth rate of oligodendrogliomas. We assessed whether (i) it discriminates between World Health Organization (WHO) grade II and grade III oligodendrogliomas, and (ii) grade III oligodendrogliomas with neo-angiogenesis are associated with more fast growth rates (≥8 mm/y).

METHODS

This work employed a retrospective bicentric cohort study (2010-2016) of adult patients harboring a newly diagnosed supratentorial oligodendroglioma, isocitrate dehydrogenase (IDH) mutant and 1p/19q codeleted (WHO 2016 classification), with a minimum of 2 available MRIs before any treatment (minimum 6-week interval) to measure the spontaneous tumor growth rate.

RESULTS

We included 108 patients (age 44.7 ± 14.1 y, 60 males). The tumor growth rate was higher in grade III oligodendrogliomas with neo-angiogenesis (n = 37, median 10.4 mm/y, mean 10.0 ± 6.9) than in grade III oligodendrogliomas with increased mitosis count only (cutoff ≥6 mitoses, n = 18, median 3.9 mm/y, mean 4.5 ± 3.2; P = 0.004), and higher than in grade II oligodendrogliomas (n = 53, median 2.3 mm/y, mean 2.8 ± 2.2; P < 0.001). There was increased prevalence of fast tumor growth rates in grade III oligodendrogliomas with neo-angiogenesis (54.1%) compared with grade III oligodendrogliomas with increased mitosis count only (11.1%; P < 0.001), and in grade II oligodendrogliomas (0.0%; P < 0.001). The tumor growth rate trends did not differ between centers (P = 0.121). Neo-angiogenesis (P < 0.001) and mitosis count at ≥9 (P = 0.013) were independently associated with tumor growth rates ≥8 mm/year. A tumor growth rate ≥8 mm/year was the only predictor independently associated with shorter progression-free survival (P = 0.041).

CONCLUSIONS

The spontaneous tumor growth rate recapitulates oligodendroglioma aggressiveness, permits identification of grade III oligodendrogliomas preoperatively when ≥8 mm/year, and questions the grading by mitosis count.

Considerations for a surgical RCT for diffuse low-grade glioma: a survey

Background

Diffuse low-grade gliomas (DLGGs) are heterogeneous tumors that inevitably differentiate into malignant entities, leading to disability and death. Recently, a shift toward up-front maximal safe resection of DLGGs has been favored. However, this transition is not supported by randomized controlled trial (RCT) data. Here, we sought to survey the neuro-oncology community on considerations for a surgical RCT for DLGGs.

Methods

A 21-question survey focusing on a surgical RCT for DLGGs was developed and validated by 2 neurosurgeons. A sample case of a patient for whom management might be debatable was presented to gather additional insight. The survey was disseminated to members of the Society for Neuro-Oncology (SNO) and responses were collected from March 16 to July 10, 2018.

Results

A total of 131 responses were collected. Sixty-three of 117 (54%) respondents thought an RCT would not be ethical, 39 of 117 (33%) would consider participating, and 56 of 117 (48%) believed an RCT would be valuable for determining the differing roles of biopsy, surgery, and observation. This was exemplified by an evenly distributed selection of the latter management options for our sample case. Eighty-three of 120 (69.2%) respondents did not believe in equipoise for DLGG patients. Quality of life and overall survival were deemed equally important end points for a putative RCT.

Conclusions

Based on our survey, it is evident that management of certain DLGG patients is not well defined and an RCT may be justified. As with any surgical RCT, logistic challenges are anticipated. Robust patient-relevant end points and standardization of perioperative adjuncts are necessary if a surgical RCT is undertaken.

Differences in the preferential location and invasiveness of diffuse low-grade gliomas and their impact on outcome

Background

Low‐grade gliomas (LGGs) are primary diffuse slow‐growing brain tumors derived from glial cells. The management of these tumors is dependent on their location, which often harbors eloquent areas. We retrospectively recorded the location of diffuse gliomas to identify whether specific differences exist between the histological types.

Methods

We analyzed 102 patients with previous histological diagnosis of WHO‐II astrocytomas (62) and WHO‐II oligodendrogliomas (40) according to WHO‐2016 classification. MRI sequences (T2‐FLAIR) were used for tumor volume segmentation and to create a frequency map of their locations within the Montreal Neurological Institute (MNI) space. The Brain‐Grid (BG) system (standardized radiological tool of intersected lines according to anatomical landmarks) was created and merged with a tractography atlas for infiltration analysis.

Results

Astrocytomas frequently infiltrated association and projection white matter pathways within fronto‐temporo‐insular regions on the left side. Oligodendrogliomas infiltrated larger white matter networks (association‐commissural‐projection) of the frontal lobe bilaterally. A critical number of infiltrated BG voxels (7 for astrocytomas, 10 for oligodendrogliomas) significantly predicted shorter overall survival (OS) in both groups. Bilateral tumor extension in astrocytomas and preoperative tumor volume in oligodendrogliomas were independent prognostic factors for shorter OS.

Conclusions

Astrocytomas and oligodendrogliomas differ in preferential location, and this has an impact on the type and the extent of white matter involvement. The number of BG voxels infiltrated reflected different tumor invasiveness and its impact on OS in both groups. All this new information may be valuable in neurosurgical oncology to classify and plan treatment for patients with diffuse gliomas.

Lower Grade Gliomas

PURPOSE OF REVIEW

Low-grade gliomas (LGG) are a group of primary brain tumors that arise from supporting glial cells. They are characterized by a mutation in the isocitrate dehydrogenase (IDH) enzyme and include astrocytomas and oligodendrogliomas. They usually affect young adults, and their main treatment consists of surgical resection, followed by radiation and chemotherapy in selected patients. This article reviews recent research on the clinical and molecular aspects of the disease and innovative therapeutic modalities in the process.

RECENT FINDINGS

Newly identified clinical and molecular features are currently used in the classification of LGG and applied in treatment-planning decisions. Advanced studies on the cellular level have an advanced understanding of the metabolic effects induced by IDH mutations, offering opportunities for specific targeted therapies that may improve patient outcomes. Such findings may lead to a paradigm shift in the treatment of these tumors. Although LGG are sensitive to radiation and chemotherapy, these therapies are not curative, and patient survival remains limited, raising the need for more creative and effective interventions.

Radiological Characteristics and Natural History of Adult IDH-Wildtype Astrocytomas with TERT Promoter Mutations

BACKGROUND

Adult IDH-wildtype astrocytomas with TERT promoter mutations (TERTp) are associated with a poor prognosis.

OBJECTIVE

To analyze the radiological presentation and natural history of adult IDH-wildtype astrocytomas with TERTp.

METHODS

We retrospectively reviewed the characteristics of 40 IDH-wildtype TERTp-mutant astrocytomas (grade II n = 19, grade III n = 21) and compared them to those of 114 IDH-mutant lower grade gliomas (LGG), of 92 IDH-wildtype TERTp-mutant glioblastomas, and of 15 IDH-wildtype TERTp-wildtype astrocytomas.

RESULTS

Most cases of IDH-wildtype TERTp-mutant astrocytomas occurred in patients aged >50 yr (88%) and presented as infiltrative lesions without contrast enhancement (73%) that were localized in the temporal and/or insular lobes (37.5%) or corresponded to a gliomatosis cerebri (43%). Thalamic involvement (33%) and extension to the brainstem (27%) were frequently observed, as was gyriform infiltration (33%). This radiological presentation was different from that of IDH-mutant LGG, IDH-wildtype TERTp-mutant glioblastomas, and IDH-wildtype TERTp-wildtype astrocytomas. Tumor evolution before treatment initiation was assessable in 17 cases. Ten cases demonstrated a rapid growth characterized by the apparition of a ring-like contrast enhancement and/or a median velocity of diametric expansion (VDE) ≥8 mm/yr but 7 cases displayed a slow growth (VDE <8 mm/yr) that could last several years before anaplastic transformation. Median overall survival of IDH-wildtype TERTp-mutant astrocytomas was 27 mo.

CONCLUSION

IDH-wildtype TERTp-mutant astrocytomas typically present as nonenhancing temporo-insular infiltrative lesions or as gliomatosis cerebri in patients aged >50 yr. In the absence of treatment, although rapid tumor growth is frequent, an initial falsely reassuring, slow growth can be observed.

Advancements in predicting outcomes in patients with glioma: a surgical perspective

Introduction: Diffuse glioma is a challenging neurosurgical entity. Although surgery does not provide a cure, it may greatly influence survival, brain function, and quality of life. Surgical treatment is by nature highly personalized and outcome prediction is very complex. To engage and succeed in this balancing act it is important to make best use of the information available to the neurosurgeon.Areas covered: This narrative review provides an update on advancements in predicting outcomes in patients with glioma that are relevant to neurosurgeons.Expert opinion: The classical 'gut feeling' is notoriously unreliable and better prediction strategies for patients with glioma are warranted. There are numerous tools readily available for the neurosurgeon in predicting tumor biology and survival. Predicting extent of resection, functional outcome, and quality of life remains difficult. Although machine-learning approaches are currently not readily available in daily clinical practice, there are several ongoing efforts with the use of big data sets that are likely to create new prediction models and refine the existing models.

Postoperative follow-up for selected diffuse low-grade gliomas with WHO grade III/IV foci

OBJECTIVE

Diffuse low-grade gliomas (DLGG) are defined by continuous growth and an almost unavoidable malignant transformation. Foci of malignant glioma can be found within DLGG samples obtained from surgical resections. As the medical management of patients is classically based on the higher tumor grade, an immediate adjuvant treatment is usually proposed. To determine whether postponing the medical treatment in selected patients is feasible, we conducted a single-center retrospective study.

METHODS

This was a single-center retrospective analysis of a consecutive series of DLGG managed with this conservative strategy. Inclusion criteria were at least 1 focus of malignant tumor (grade III-IV, WHO 2016), no previous chemotherapy or radiotherapy, no less than a subtotal resection of the fluid-attenuated inversion recovery tumor volume, no intention of treating with immediate adjuvant therapy, and minimum 2 years of follow-up. The time interval to the following oncologic medical treatment was analyzed, as well as the functional and survival results.

RESULTS

Forty-four patients met the inclusion criteria (median age 36, median time interval from diagnosis 7 months). Most tumors (88%) were IDH-mutant and 1p19q intact (59%); 9 presented with grade IV foci. With a median follow-up of 6.7 years, 75% of patients received a subsequent medical treatment, after a median time of 3.4 years since surgery. At the time of analysis, 9 patients (20.0%) had died (5- and 7-year survival rates: 95% and 67.0%). Most surviving patients were still active professionally, without seizures.

CONCLUSIONS

Postponing the medical treatment in DLGG with foci of malignant tumor following total or subtotal resection should be considered in selected patients.