Seizure burden pre- and postresection of low-grade gliomas as a predictor of tumor progression in low-grade gliomas

Risk Factors and Prognostic Implications of Tumor-Related Epilepsy in Diffuse Glioma Patients: A Real-World Multicenter Study

PURPOSE

The relevance of tumor-related epilepsy (TRE) to glioma survival is controversial. This study aimed to assess the risk factors and prognostic impact of TRE in adult patients with diffuse gliomas by integrating clinical, radiological, and molecular data.

METHODS

This multicenter retrospective study included 1036 adult patients with diffuse gliomas from local hospitals and the POLA Network. Patients were categorized into three prognostic groups: lower-grade oligodendroglioma/astrocytoma (OD/AC, II-III, IDH-MT), not otherwise specified or not elsewhere classified (NOS/NEC, II-III, IDH-WT), and high-grade gliomas (HGG, IV). Clinico-radiological, molecular, and therapeutic factors were analyzed using univariate and multivariate logistic regression, with the Cox proportional hazards model applied to identify independent prognostic factors for progression-free survival (PFS) and overall survival (OS).

RESULTS

TRE occurred in 44.4% of OD/AC patients, 25.8% of NOS/NEC patients, and 16.5% of HGG patients. Multivariate analysis identified age as the only significant independent correlate of TRE in the OD/AC group (OR = 0.961; p = 0.004), while the absence of deep structure involvement was independently associated with TRE in the NOS/NEC and HGG groups. In univariate analysis, the presence of TRE was associated with longer PFS and OS across all groups, particularly in the NOS/NEC group, where patients with TRE had a median PFS of 35.2 months compared to 13.6 months in those without TRE (p = 0.02), but was not a significant predictor in multivariate analyses. TRE was the only factor significantly associated with maintaining histological grade at recurrence (HR = 0.094; p = 0.005).

CONCLUSION

TRE was not a strong independent prognostic factor after controlling for clinical and molecular tumor features, suggesting that the prognostic relevance of TRE is likely driven by underlying glioma biology and other associated clinical factors.

Identification and validation of LY6H and GRM3 as candidate biomarkers for Glioma-related epilepsy

Gliomas are the most common primary tumors of the central nervous system, with epilepsy serving as a frequent clinical manifestation. Glioma-related epilepsy (GRE) significantly affects patients' quality of life and prognosis. In this study, we integrated bioinformatics and multiple machine learning methods to perform a proteomic analysis of brain tumor samples from patients with GRE and from those with gliomas none epilepsy (GNE). Our findings identified LY6H and GRM3 as potential signature proteins of GRE. Further investigation showed that LY6H and GRM3 expression levels were markedly reduced in GRE samples, with favorable diagnostic performance according to ROC curve analyses. Finally, we conducted an independent external validation using the Bluk-RNA dataset GSE199759, and the results corroborated our prior analyses. This work not only provides new biomarkers for the early detection of GRE but also offers valuable insights into its molecular mechanisms and potential therapeutic strategies.

Glioma-related epilepsy following low-grade glioma surgery

Background

Epileptic seizures commonly burden low-grade glioma (LGG) patients and negatively impact quality of life, neurocognition, and general patient health. Anti-seizure medications (ASMs) are used to manage seizures but can result in undesired side effects. Our aim was to report our experience in epilepsy in one of the largest case series of LGG patients (reclassified in accordance with the WHO 2021 classification). Furthermore, we evaluate our postoperative seizure frequency difference between LGG patients who use preoperative ASMs and ones with no ASMs.

Methods

Data were retrospectively collected from Salford Royal Hospital electronic records and Neuro-Oncology database from 2006 to 2022. Descriptive statistics were performed for demographic analysis, while multivariable analysis was used to determine postoperative seizure-free outcomes.

Results

In total, 257 operations were performed on 206 patients. Postoperatively, 114 patients suffered from seizures, and approximately 45.2% of patients developed seizures at 3-12 months postsurgery, with the odds higher in patients on preoperative ASMs. There was no evidence to suggest a higher postoperative seizure rate in patients undergoing awake craniotomy versus general anesthetic. The extent of resection (EOR) was inversely related to seizure failure, with gross-total resection showing a statistically significant reduction in seizures in comparison to all other surgical resections.

Conclusions

In our experience, there is no evidence to suggest a reduced postoperative seizure outcome when prescribing preoperative ASMs. EOR is an independent prognosticator for postoperative seizure failure with all other variables demonstrating nonsignificance. Overall, a larger study can investigate the role of ASMs in LGG in greater detail.

Unexplained Causes of Glioma-Associated Epilepsies: A Review of Theories and an Area for Research

Approximately 30% of glioma patients are able to survive beyond one year postdiagnosis. And this short time is often overshadowed by glioma-associated epilepsy. This condition severely impairs the patient's quality of life and causes great suffering. The genetic, molecular and cellular mechanisms underlying tumour development and epileptogenesis remain incompletely understood, leading to numerous unanswered questions. The various types of gliomas, namely glioblastoma, astrocytoma and oligodendroglioma, demonstrate distinct seizure susceptibility and disease progression patterns. Patterns have been identified in the presence of IDH mutations and epilepsy, with tumour location in cortical regions, particularly the frontal lobe, showing a more frequent association with seizures. Altered expression of TP53, MGMT and VIM is frequently detected in tumour cells from individuals with epilepsy associated with glioma. However, understanding the pathogenesis of these modifications poses a challenge. Moreover, hypoxic effects induced by glioma and associated with the HIF-1a factor may have a significant impact on epileptogenesis, potentially resulting in epileptiform activity within neuronal networks. We additionally hypothesise about how the tumour may affect the functioning of neuronal ion channels and contribute to disruptions in the blood-brain barrier resulting in spontaneous depolarisations.

Benign Glioma

Benign glioma broadly refers to a heterogeneous group of slow-growing glial tumors with low proliferative rates and a more indolent clinical course. These tumors may also be described as "low-grade" glioma (LGG) and are classified as WHO grade I or II lesions according to the Classification of Tumors of the Central Nervous System (CNS) (Louis et al. in Acta Neuropathol 114:97-109, 2007). Advances in molecular genetics have improved understanding of glioma tumorigenesis, leading to the identification of common mutation profiles with significant treatment and prognostic implications. The most recent WHO 2016 classification system has introduced several notable changes in the way that gliomas are diagnosed, with a new emphasis on molecular features as key factors in differentiation (Wesseling and Capper in Neuropathol Appl Neurobiol 44:139-150, 2018). Benign gliomas have a predilection for younger patients and are among the most frequently diagnosed tumors in children and young adults (Ostrom et al. in Neuro Oncol 22:iv1-iv96, 2020). These tumors can be separated into two clinically distinct subgroups. The first group is of focal, well-circumscribed lesions that notably are not associated with an increased risk of malignant transformation. Primarily diagnosed in pediatric patients, these WHO grade I tumors may be cured with surgical resection alone (Sturm et al. in J Clin Oncol 35:2370-2377, 2017). Recurrence rates are low, and the prognosis for these patients is excellent (Ostrom et al. in Neuro Oncol 22:iv1-iv96, 2020). Diffuse gliomas are WHO grade II lesions with a more infiltrative pattern of growth and high propensity for recurrence. These tumors are primarily diagnosed in young adult patients, and classically present with seizures (Pallud et al. Brain 137:449-462, 2014). The term "benign" is a misnomer in many cases, as the natural history of these tumors is with malignant transformation and recurrence as grade III or grade IV tumors (Jooma et al. in J Neurosurg 14:356-363, 2019). For all LGG, surgery with maximal safe resection is the treatment of choice for both primary and recurrent tumors. The goal of surgery should be for gross total resection (GTR), as complete tumor removal is associated with higher rates of tumor control and seizure freedom. Chemotherapy and radiation therapy (RT), while not typically a component of first-line treatment in most cases, may be employed as adjunctive therapy in high-risk or recurrent tumors and in some select cases. The prognosis of benign gliomas varies widely; non-infiltrative tumor subtypes generally have an excellent prognosis, while diffusely infiltrative tumors, although slow-growing, are eventually fatal (Sturm et al. in J Clin Oncol 35:2370-2377, 2017). This chapter reviews the shared and unique individual features of the benign glioma including diffuse glioma, pilocytic astrocytoma and pilomyxoid astrocytoma (PMA), subependymal giant cell astrocytoma (SEGA), pleomorphic xanthoastrocytoma (PXA), subependymoma (SE), angiocentric glioma (AG), and chordoid glioma (CG). Also discussed is ganglioglioma (GG), a mixed neuronal-glial tumor that represents a notable diagnosis in the differential for other LGG (Wesseling and Capper 2018). Ependymomas of the brain and spinal cord, including major histologic subtypes, are discussed in other chapters.

Resective surgery for patients with frontal lobe diffuse low-grade glioma-related epilepsy: predictors of seizure outcomes

Background

Diffuse low-grade gliomas (DLGGs) are prone to invade the frontal lobes, with seizures being the most common symptom. However, limited attention has been paid to surgical outcomes and their predictors in patients with frontal DLGG-related epilepsy.

Objective

This study aimed to analyze predictors of postoperative seizure outcomes in patients with frontal DLGG-related epilepsy.

Design

This is a single-center retrospective study.

Methods

This study retrospectively collected data of 115 patients with frontal DLGG-related epilepsy who underwent resective surgery between January 2014 and January 2021. Patients were categorized into favorable and unfavorable seizure outcome groups based on the International League Against Epilepsy (ILAE) classification. Univariate and multivariate analyses were used to identify potential predictors of seizure outcomes.

Results

The mean follow-up was 4.11 ± 2.06 years, and 77.4% (89 of 115) of patients were seizure-free. Permanent neurological deficits were observed in 7.0% (8 of 115) of patients. Univariate and multivariate analyses revealed that total tumor removal [odds ratio (OR), 0.31; 95% confidence interval (CI), 0.12-0.82; p = 0.018] and older age at seizure onset (OR, 0.96; 95% CI, 0.93-0.99; p = 0.042) were independent predictors of favorable seizure outcomes.

Conclusion

Surgical resection is an effective treatment for frontal DLGG-related epilepsy. Favorable seizure outcomes are more likely to be achieved in patients with complete tumor removal and those with older age at seizure onset.

Correlation of Clinicopathological Factors with Brain Tumor-Related Epilepsy in Glioma

Objectives. Glioma patients with brain tumor-related epilepsy (BTRE) have a complex profile due to the simultaneous presence of two pathologies, glioma and epilepsy; however, they have not traditionally received as much attention as those with more malignant brain tumors. The underlying pathophysiology of brain tumor-related epilepsy remains poorly understood. The purpose of this study was to investigate the possible correlation between molecular neuropathology and glioma with BTRE and a wide range of BTRE-associated molecular markers of glioma patients. Methods. A retrospective cohort study of 186 glioma patients was evaluated at our hospital, of which 64 had BTRE. The chi-square test, Spearman rank correlation, and multivariate logistic analyses were used to identify clinicopathological factors associated with BTRE in glioma patients. Results. Of the 186 patients examined in this study, 64 (34.4%) had BTRE. Based on the analysis of the characteristics of these patients, the results showed that patient age (over 40 years; $P=0.007$ ), low WHO grade (grade I, II; $P=0.001$ ), IDH-1 positive mutation ( $P=0.027$ ), low ATR-X expression level ( $\text{OR}=0.44$ ; 95% CI: 0.21, 0.92), and low Ki-67 PI ( $\text{OR}=0.25$ ; 95% CI: 0.10, 0.68) were associated with the occurrence of BTRE. In our cohort, BTRE patients did not differ by sex, tumor location, or expression of olig-2 and CD34. The results of the matching study showed that low Ki-67 PI and negative ATR-X expression levels were independent factors for a higher incidence of preoperative seizures in glioma patients. Conclusion. The current study updates existing information on genetic markers in gliomas with BTRE and explores the correlation of a wide range of clinicopathological factors and glioma patients with BTRE and suggests three putative biomarkers for BTRE: positive IDH1 mutation, low Ki-67 PI, and negative ATR-X expression. These factors may provide insights for developing a more thorough understanding of the pathogenesis of epilepsy and effective treatment strategies aimed at seizure control.

Pre- and Post-surgical Poor Seizure Control as Hallmark of Malignant Progression in Patients With Glioma?

Background

Regarding brain tumor-related epilepsy (BTRE), there is an increasing number of evidence about a relationship between epileptogenesis and oncogenesis. A recent study suggests a role of post-surgery seizure outcome on the survival of patients with low-grade glioma (LGG), underlying the need for a targeted and aggressive epilepsy treatment.

Objective

This study aims at investigating the possible correlation between pre- and post-surgical seizure control and tumor progression in patients who underwent surgery for LGG.

Methods

We performed a retrospective analysis of patients affected by LGGs and BTRE, in a single high-volume neurosurgical center. Seizure control was assessed before surgery and at 3 years of follow-up. Patients with histological progression in high-grade glioma (HGG) have been evaluated. Clinical features, pre-surgical electroencephalograms (EEGs), and electrocorticography (ECoG) have been analyzed.

Results

Among 154 subjects, we collected 32 patients who presented a tumor progression in HGG during the follow-up period. The majority had poor seizure control both pre- and post-surgery, never being in Engel class Ia throughout the whole history of their disease. Almost all patients with poor seizure control had pathological ECoG recording. Clinical features of seizures did not correlate with seizure outcome. On the univariate analysis, the age, the post-operative Engel class, and the extent of resection (EOR) were the prognostic factors significantly associated with oncological outcome; nevertheless, on multivariate analysis, Engel class significance was not confirmed, and the only predicting factor were age and EOR.

Conclusions

Although not confirmed on multivariate analysis, post-surgical seizure control could be a relevant factor to consider during follow-up of BRTE, in particular, when gross total resection is not achieved. Pathological findings on the ECoG may suggest a “hidden” propensity to malignant progression, strictly related to the persistent neuronal hyper-excitability. Further studies with longer follow-up period are needed to confirm our observations.

Postoperative epilepsy and survival in glioma patients: a nationwide population-based cohort study from 2009 to 2018

PURPOSE

Postoperative epilepsy is common in glioma patients and has been suggested to indicate disease progression, yet knowledge of its role as a prognostic factor is limited. This study investigates the association between postoperative epilepsy and survival amongst patients with gliomas.

METHODS

We included 3763 patients with histopathologically diagnosed grade II, III, and IV gliomas from 2009 to 2018 according to the Danish Neuro-Oncology Registry. Information on epilepsy diagnosis was redeemed from the Danish National Patient Registry, the National Prescription Registry and the Danish Neuro-Oncology Registry. We used Cox proportional hazards models with 95% confidence intervals (CIs) to examine hazard ratios (HRs) for the association between postoperative epilepsy and risk of death. We examined the role of the timing of epilepsy in three different samples: Firstly, in all glioma patients with postoperative epilepsy; secondly, in patients with postoperative de novo epilepsy; thirdly, exclusively in a homogeneous sub-group of grade IV patients with postoperative de novo epilepsy.

RESULTS

Glioma patients with postoperative epilepsy had an increased risk of death, regardless of prior epilepsy status (HR = 4.03; CI 2.69-6.03). A similar increase in the risk of death was also seen in patients with postoperative de novo epilepsy (HR = 2.08; CI 1.26-3.44) and in the sub-group of grade IV patients with postoperative de novo epilepsy (HR = 1.83; CI 1.05-3.21).

CONCLUSIONS

Postoperative epilepsy may negatively impact survival after glioma diagnosis, regardless of preoperative epilepsy status. Postoperative epilepsy may be an expression of a more invasive growth pattern of the gliomas following primary tumor treatment.

Seizures in patients with IDH-mutated lower grade gliomas

PURPOSE

Most patients with Lower Grade Gliomas (LGG) present with epileptic seizures. Since the advent of molecular diagnostics, more homogenous sub-entities have emerged, including the isocitrate dehydrogenase-mutated (IDH-mutated) astrocytomas and 1p19q-codeleted oligodendrogliomas. We aimed to describe the occurrence of seizures in patients with molecularly defined LGG pre- and postoperatively and to analyze factors affecting seizure status postoperatively.

METHODS

A population-based cohort of 130 adult patients with IDH-mutated WHO grade 2 or 3 astrocytomas and oligodendrogliomas was assessed pertaining to seizure burden before and after surgery.

RESULTS

Fifty-four (79.4%) patients with astrocytoma and 45 (72.6%) patients with oligodendroglioma had a history of seizures before surgery. At 12 months postoperatively, 51/67 (76.1%) patients with astrocytoma and 47/62 (75.8%) patients with oligodendrogliomas were seizure free. In a multivariable logistic regression analysis, lower extent of resection (EOR) (OR 0.98; 95% CI 0.97-1.00, p = 0.01) and insular tumor location (OR 5.02; 95% CI 1.01-24.87, p = 0.048) were associated with presence of seizures within 1 year postoperatively in the entire LGG cohort. In sub-entities, EOR was in a similar manner associated with seizures postoperatively in astrocytomas (OR 0.98; 95% CI 0.96-0.99, p < 0.01) but not in oligodendrogliomas (p = 0.34).

CONCLUSION

Our results are well in line with data published for non-molecularly defined LGG with a large proportion of patients being seizure free at 1 year postoperative. Better seizure outcome was observed with increased EOR in astrocytomas, but this association was absent in oligodendrogliomas.

The persistence of seizures after tumor resection negatively affects survival in low-grade glioma patients: a clinical retrospective study

INTRODUCTION

Seizures are the most common clinical manifestation of low-grade glioma (LGG). Many papers hypothesized an influence of epilepsy on glioma progression. To our knowledge, no clinical study demonstrated a direct relationship between persistence of epileptic seizures after surgery and overall survival (OS) in LGG patients. The present study aims at investigating the correlation between post-operative seizure outcome and survival in tumor-related epilepsy (TRE) patients.

METHODS

We performed a retrospective analysis of adult patients affected by TRE who underwent surgery for resection of LGG in a single high-volume neurosurgical center. Seizure outcome was assessed 1 year after surgery and categorized according to Engel classification. Clinical, molecular and radiological features were evaluated in univariate and multivariate analyses to investigate the correlation with OS.

RESULTS

A total of 146 patients met the inclusion criteria. Histopathological diagnosis was Diffuse Astrocytoma isocitrate dehydrogenase (IDH) wild type in 16 patients (11%), Diffuse astrocytoma IDH mutated in 89 patients (61%) and oligodendroglioma IDH mutated, 1p 19q codeleted in 41 patients (28%). 1 year after surgery, 103 (70.6%) patients were in Engel class 1. Median duration of follow-up period was 69.5 months. Median OS was 79.3 (72.2-86.4) months in the whole population, while it was 86.8 (78.4-95.2), 63.9 (45.7-82), 63.7 (45.2-82.2) and 47.5 (18.3-76.6) months for patients in Engel class 1, 2, 3 and 4, respectively. In a univariate analysis, Engel class evaluated 1 year after surgery significantly influenced OS (p < 0.01). Multivariate analysis showed that OS was independently associated with extent of resection (p = 0.02), molecular class (p < 0.01) and Engel class (p = 0.04).

CONCLUSIONS

Seizure control 1 year after surgery significantly predicted survival of patients affected by LGG-related epilepsy in a large monocentric retrospective series. Future studies are needed to confirm these results and to assess if an epilepsy-surgical therapeutic approach may improve OS.

Efficacy of antiepileptic drugs in glioma patients with epilepsy: a systematic review

Background

Comprehensive data on the efficacy and tolerability of antiepileptic drugs (AED) treatment in glioma patients with epilepsy are currently lacking. In this systematic review, we specifically assessed the efficacy of AEDs in patients with a grade II-IV glioma.

Methods

Electronic databases PubMed/MEDLINE, EMBASE, Web of Science, and Cochrane Library were searched up to June 2020. Three different outcomes for both mono- and polytherapy were extracted from all eligible articles: (i) seizure freedom; (ii) ≥50% reduction in seizure frequency; and (iii) treatment failure. Weighted averages (WA) were calculated for outcomes at 6 and 12 months.

Results

A total of 66 studies were included. Regarding the individual outcomes on the efficacy of monotherapy, the highest seizure freedom rate at 6 months was with phenytoin (WA = 72%) while at 12-month pregabalin (WA = 75%) and levetiracetam (WA = 74%) showed highest efficacy. Concerning ≥50% seizure reduction rates, levetiracetam showed highest efficacy at 6 and 12 months (WAs of 82% and 97%, respectively). However, treatment failure rates at 12 months were highest for phenytoin (WA = 34%) and pregabalin (41%). When comparing the described polytherapy combinations with follow-up of ≥6 months, levetiracetam combined with phenytoin was most effective followed by levetiracetam combined with valproic acid.

Conclusion

Given the heterogeneous patient populations and the low scientific quality across the different studies, seizure rates need to be interpreted with caution. Based on the current limited evidence, with the ranking of AEDs being confined to the AEDs studied, levetiracetam, phenytoin, and pregabalin seem to be most effective as AED monotherapy in glioma patients with epilepsy, with levetiracetam showing the lowest treatment failure rate, compared to the other AEDs studied.

Radiomics Analysis of Postoperative Epilepsy Seizures in Low-Grade Gliomas Using Preoperative MR Images

Purpose: The present study aimed to evaluate the performance of radiomics features in the preoperative prediction of epileptic seizure following surgery in patients with LGG. Methods: This retrospective study collected 130 patients with LGG. Radiomics features were extracted from the T2-weighted MR images obtained before surgery. Multivariable Cox-regression with two nested leave-one-out cross validation (LOOCV) loops was applied to predict the prognosis, and elastic net was used in each LOOCV loop to select the predictive features. Logistic models were then built with the selected features to predict epileptic seizures at two time points. Student's t-tests were then used to compare the logistic model predicted probabilities of developing epilepsy in the epilepsy and non-epilepsy groups. The t-test was used to identify features that differentiated patients with early-onset epilepsy from their late-onset counterparts. Results: Seventeen features were selected with the two nested LOOCV loops. The index of concordance (C-index) of the Cox model was 0.683, and the logistic model predicted probabilities of seizure were significantly different between the epilepsy and non-epilepsy groups at each time point. Moreover, one feature was found to be significantly different between the patients with early- or late-onset epilepsy. Conclusion: A total of 17 radiomics features were correlated with postoperative epileptic seizures in patients with LGG and one feature was a significant predictor of the time of epilepsy onset.

Seizures in patients with cancer

Seizures are common in patients with cancer and either result from brain lesions, paraneoplastic syndromes, and complications of cancer treatment or are provoked by systemic illness (metabolic derangements, infections). Evaluation should include a tailored history, neurologic examination, laboratory studies, neuroimaging, and electroencephalogram. In unprovoked seizures, antiepileptic drug (AED) treatment is required, and a nonenzyme-inducing AED is preferred. Treatment of the underlying cancer with surgery, chemotherapy, and radiation therapy also can help reduce seizures. Benzodiazepines are useful in the treatment of both provoked seizures and breakthrough epileptic seizures and as first-line treatment for status epilepticus. Counseling for safety is an important component in the care of a patient with cancer who has seizures. Good seizure management can be challenging but significantly improves the quality of life during all phases of care, including end-of-life care.