The benefit of early surgery on overall survival in incidental low grade glioma patients: a multicenter study

IDH1 mutation is associated with improved resection rates, progression-free survival and overall survival in patients with anaplastic astrocytomas

PURPOSE

The introduction of molecular markers in to the diagnosis of gliomas has changed the therapeutic approach to this tumors. The aim of this study was to examine the impact of surgery on anaplastic astrocytomas (AA), which has not previously been fully elucidated.

METHODS

This was a retrospective study involving a total of 143 patients who underwent surgery for primary AA in our department between 1995 and 2020.

RESULTS

Total tumor resection was achieved more often in patients with IDH-mutant tumors (41.09%) than in patients with IDH-wildtype tumors (30.76%). The median PFS was 1876 days for patients with IDH1 mutations and 238 days for patients with IDH-wildtype tumors. The 1-, 3-, 5- and 10-year PFS were longer in patients with total tumor resection and IDH-mutant AA (86.2%, 69%, 65.5% and 44.8%, respectively) than in patients with subtotal tumor resection and IDH-mutant AA (83.3%, 55.6%, 41.7% and 25%, respectively) and even longer compared to all IDH-wildtype tumors. The median OS was 2472 days for patients with IDH1 mutations and 434 days for patients with IDH-wildtype tumors. The 3-, 5- and 10-year OS times were longer in patients with total tumor resection and IDH-mutant AA (89.2%, 85.2% and 72.6%, respectively) than in patients with subtotal tumor resection and IDH-mutant AA (85.9%, 73.7% and 52.6%, respectively) and were even longer compared to all IDH-wildtype tumors.

CONCLUSION

Total tumor resection is more common with IDH-mutant AA than with IDH-wildtype tumors. Patients with IDH-mutant AA had significantly better PFS and OS after total tumor resection than after subtotal tumor resection and biopsy.

Multidisciplinary Management of Isocitrate Dehydrogenase-Mutated Gliomas in a Contemporary Molecularly Defined Era

Mutations in isocitrate dehydrogenase (IDH) genes, an early step in the ontogeny of lower-grade gliomas, induce global epigenetic changes characterized by a hypermethylation phenotype and are critical to tumor classification, treatment decision making, and estimation of patient prognosis. The introduction of IDH inhibitors to block the oncogenic neomorphic function of the mutated protein has resulted in new therapeutic options for these patients. To appreciate the implications of these recent IDH inhibitor results, it is important to juxtapose historical outcomes with chemoradiotherapy. Herein, we rationally evaluate recent IDH inhibitor data within historical precedents to guide contemporary decisions regarding the role of observation, maximal safe resection, adjuvant therapies, and the import of patient and tumor variables. The biological underpinnings of the IDH pathway and the mechanisms, impact, and limitations of IDH inhibitors, the actual magnitude of tumor regression and patient benefit, and emergence of resistance pathways are presented to guide future trial development. Management in the current, molecularly defined era will require careful patient selection and risk factor assessment, followed by an open dialog about the results of studies such as INDIGO, as well as mature data from legacy trials, and a discussion about risk-versus-benefit for the choice of treatment, with multidisciplinary decision making as an absolute prerequisite.

SEOM-GEINO clinical guidelines for grade 2 gliomas (2023)

The 2021 World Health Organization (WHO) classification has updated the definition of grade 2 gliomas and the presence of isocitrate dehydrogenase (IDH) mutation has been deemed the cornerstone of diagnosis. Though slow-growing and having a low proliferative index, grade 2 gliomas are incurable by surgery and complementary treatments are vital to improving prognosis. This guideline provides recommendations on the multidisciplinary treatment of grade 2 astrocytomas and oligodendrogliomas based on the best evidence available.

Focus on current and emerging treatment options for glioma: A comprehensive review

This comprehensive review delves into the current updates and challenges associated with the management of low-grade gliomas (LGG), the predominant primary tumors in the central nervous system. With a general incidence rate of 5.81 per 100000, gliomas pose a significant global concern, necessitating advancements in treatment techniques to reduce mortality and morbidity. This review places a particular focus on immunotherapies, discussing promising agents such as Zotiraciclib and Lerapolturev. Zotiraciclib, a CDK9 inhibitor, has demonstrated efficacy in glioblastoma treatment in preclinical and clinical studies, showing its potential as a therapeutic breakthrough. Lerapolturev, a viral immunotherapy, induces inflammation in glioblastoma and displays positive outcomes in both adult and pediatric patients. Exploration of immunotherapy extends to Pembrolizumab, Nivolumab, and Entrectinib, revealing the challenges and variabilities in patient responses. Despite promising preclinical data, the monoclonal antibody Depatuxizumab has proven ineffective in glioblastoma treatment, emphasizing the critical need to understand resistance mechanisms. The review also covers the success of radiation therapy in pediatric LGG, with evolving techniques, such as proton therapy, showing potential improvements in patient quality of life. Surgical treatment is discussed in the context of achieving a balance between preserving the patient's quality of life and attaining gross total resection, with the extent of surgical resection significantly influencing the survival outcomes. In addition to advancements in cancer vaccine development, this review highlights the evolving landscape of LGG treatment, emphasizing a shift toward personalized and targeted therapies. Ongoing research is essential for refining strategies and enhancing outcomes in the management of LGG.

Functional MRI applications for intra-axial brain tumours: uses and nuances in surgical practise

PURPOSE

Functional MRI (fMRI) has well-established uses to inform risks and plan maximally safe approaches in neurosurgery. In the field of brain tumour surgery, however, fMRI is currently in a state of clinical equipoise due to debate around both its sensitivity and specificity.

MATERIALS AND METHODS

In this review, we summarise the role and our experience of fMRI in neurosurgery for gliomas and metastases. We discuss nuances in the conduct and interpretation of fMRI that, based on our practise, most directly impact fMRI's usefulness in the neurosurgical setting.

RESULTS

Illustrated examples in which fMRI in our hands directly influences the neurosurgical treatment of brain tumours include evaluating the probability and nature of functional risks, especially for language functions. These presurgical risk assessments, in turn, help to predict the resectability of tumours, select or deselect patients for awake surgery, indicate the need for neurophysiological monitoring and guide the optimal use of intra-operative stimulation mapping. A further emerging application of fMRI is in measuring functional adaptation of functional networks after (partial) surgery, of potential use in the timing of further surgery.

CONCLUSIONS

In appropriately selected patients with a clearly defined surgical question, fMRI offers a valuable complementary tool in the pre-surgical evaluation of brain tumours. However, there is a great need for standards in the administration and analysis of fMRI as much as in the techniques that it is commonly evaluated against. Surprisingly little data exists that evaluates the accuracy of fMRI not just against complementary methods, but in terms of its ultimate clinical aim of minimising post-surgical morbidity.

Functional Magnetic Resonance Imaging and Diffusion Tensor Imaging-Tractography in Resective Brain Surgery: Lesion Coverage Strategies and Patient Outcomes

Diffusion tensor imaging (DTI)-tractography and functional magnetic resonance imaging (fMRI) have dynamically entered the presurgical evaluation context of brain surgery during the past decades, providing novel perspectives in surgical planning and lesion access approaches. However, their application in the presurgical setting requires significant time and effort and increased costs, thereby raising questions regarding efficiency and best use. In this work, we set out to evaluate DTI-tractography and combined fMRI/DTI-tractography during intra-operative neuronavigation in resective brain surgery using lesion-related preoperative neurological deficit (PND) outcomes as metrics. We retrospectively reviewed medical records of 252 consecutive patients admitted for brain surgery. Standard anatomical neuroimaging protocols were performed in 127 patients, 69 patients had additional DTI-tractography, and 56 had combined DTI-tractography/fMRI. fMRI procedures involved language, motor, somatic sensory, sensorimotor and visual mapping. DTI-tractography involved fiber tracking of the motor, sensory, language and visual pathways. At 1 month postoperatively, DTI-tractography patients were more likely to present either improvement or preservation of PNDs (p = 0.004 and p = 0.007, respectively). At 6 months, combined DTI-tractography/fMRI patients were more likely to experience complete PND resolution (p < 0.001). Low-grade lesion patients (N = 102) with combined DTI-tractography/fMRI were more likely to experience complete resolution of PNDs at 1 and 6 months (p = 0.001 and p < 0.001, respectively). High-grade lesion patients (N = 140) with combined DTI-tractography/fMRI were more likely to have PNDs resolved at 6 months (p = 0.005). Patients with motor symptoms (N = 80) were more likely to experience complete remission of PNDs at 6 months with DTI-tractography or combined DTI-tractography/fMRI (p = 0.008 and p = 0.004, respectively), without significant difference between the two imaging protocols (p = 1). Patients with sensory symptoms (N = 44) were more likely to experience complete PND remission at 6 months with combined DTI-tractography/fMRI (p = 0.004). The intraoperative neuroimaging modality did not have a significant effect in patients with preoperative seizures (N = 47). Lack of PND worsening was observed at 6 month follow-up in patients with combined DTI-tractography/fMRI. Our results strongly support the combined use of DTI-tractography and fMRI in patients undergoing resective brain surgery for improving their postoperative clinical profile.

A preliminary study on corticospinal tract morphology in incidental and symptomatic insular low-grade glioma: implications for post-surgical motor outcomes

OBJECTIVE

Our study aimed to investigate the shape and diffusion properties of the corticospinal tract (CST) in patients with insular incidental and symptomatic low-grade gliomas (LGGs), especially those in the incidental group, and evaluate their association with post-surgical motor function.

METHODS

We performed automatic fiber tracking on 41 LGG patients, comparing macroscopic shape and microscopic diffusion properties of CST between ipsilateral and contralateral tracts in both incidental and symptomatic groups. A correlation analysis was conducted between properties of CST and post-operative motor strength grades.

RESULTS

In the incidental group, no significant differences in mean diffusion properties were found between bilateral CST. While decreased anisotropy of the CST around the superior limiting sulcus and increased axial diffusivity of the CST near the midbrain level were noted, there was no significant correlation between pre-operative diffusion metrics and post-operative motor strength. In comparison, we found significant correlations between the elongation of the affected CST in the preoperative scans and post-operative motor strength in short-term and long-term follow ups (p = 1.810 × 10-4 and p = 9.560 × 10-4, respectively).

CONCLUSIONS

We found a significant correlation between CST shape measures and post-operative motor function outcomes in patients with incidental insular LGGs. CST morphology shows promise as a potential prognostic factor for identifying functional deficits in this patient population.

Oncological and functional outcomes support early resection of incidental IDH-mutated glioma

PURPOSE

The main objective was to assess the neuropsychological, epileptical, and oncological outcomes in a series of patients operated on for a IDH-mutated diffuse low-grade glioma (DLGG) of incidental discovery (iDLGG).

METHODS

We retrospectively reviewed a consecutive series of surgically treated adults with DLGG and selected cases incidentally discovered. Tumor volumes, growth rates, and extents of resection (EOR) were assessed by volumetric measures of fluid-attenuated inversion recovery magnetic resonance imaging. The data on oncological, functional, and epileptical results were retrieved from the patients' digital files.

RESULTS

Among all patients with DLGG resected at our center between June 2011 and April 2022, we found eleven cases with an incidental discovery. Resection was supratotal, gross total, and subtotal in 45.5%, 26.4%, and 18.1% of cases, respectively. The rate of epileptic seizures after the surgery was 9.1%. There were 45.4% of patients that had tumor progressions and the overall mean time to tumor progression was 42 months. After the surgery, 3 (27.3%) patients had mild neurocognitive deteriorations, which impeded the return to work in one patient (9.1%). There were no differences with previous series regarding clinical, radiological, and molecular characteristics. Similar results were also found for functional, surgical, epileptical, and oncological outcomes.

CONCLUSION

Although the right approach for iDLGG is still a matter of debate, our data support the safety and effectiveness of early surgical resection. More studies are needed to firmly ground this early "preventive" surgery approach.

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.

Supratotal Surgical Resection for Low-Grade Glioma: A Systematic Review

Low-grade gliomas (LGGs) are optimally treated with up-front maximal safe surgical resection, typically defined as maximizing the extent of tumor resection while minimizing neurologic risks of surgery. Supratotal resection of LGG may improve outcomes beyond gross total resection by removing tumor cells invading beyond the tumor border as defined on MRI. However, the evidence regarding supratotal resection of LGG, in terms of impact on clinical outcomes, such as overall survival and neurologic morbidities, remains unclear. Authors independently searched the PubMed, Medline, Ovid, CENTRAL (Cochrane Central Register of Controlled Trials), and Google Scholar databases for studies evaluating overall survival, time to progression, seizure outcomes, and postoperative neurologic and medical complications of supratotal resection/FLAIRectomy of WHO-defined LGGs. Papers in languages other than English, lacking full-text availability, evaluating supratotal resection of WHO-defined high-grade gliomas only, and nonhuman studies were excluded. After literature search, reference screening, and initial exclusions, 65 studies were screened for relevancy, of which 23 were evaluated via full-text review, and 10 were ultimately included in the final evidence review. Studies were evaluated for quality using the MINORS criteria. After data extraction, a total of 1301 LGG patients were included in the analysis, with 377 (29.0%) undergoing supratotal resection. The main measured outcomes were extent of resection, pre- and postoperative neurological deficits, seizure control, adjuvant treatment, neuropsychological outcomes, ability to return to work, progression-free survival, and overall survival. Overall, low- to moderate-quality evidence was supportive of aggressive, functional boundary-based resection of LGGs due to improvements in progression-free survival and seizure control. The published literature provides a moderate amount of low-quality evidence supporting supratotal surgical resection along functional boundaries for low-grade glioma. Among patients included in this analysis, the occurrence of postoperative neurological deficits was low, and nearly all patients recovered within 3 to 6 months after surgery. Notably, the surgical centers represented in this analysis have significant experience in glioma surgery in general, and supratotal resection specifically. In this setting, supratotal surgical resection along functional boundaries appears to be appropriate for both symptomatic and asymptomatic low-grade glioma patients. Larger clinical studies are needed to better define the role of supratotal resection in LGG.

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.

Incidental diffuse low-grade gliomas: A systematic review and meta-analysis of treatment results with correction of lead-time and length-time biases

Background

Better overall survival (OS) reported in patients with incidental diffuse low-grade glioma (iLGG) in comparison to symptomatic LGG (sLGG) may be overestimated by lead-time and length-time.

Methods

We performed a systematic review and meta-analysis of studies on adult hemispheric iLGGs according to the PRISMA statement to adjust for biases in their outcomes. Survival data were extracted from Kaplan-Meier curves. Lead-time was estimated by 2 methods: Pooled data of time to become symptomatic (LTs) and time calculated from the tumor growth model (LTg).

Results

We selected articles from PubMed, Ovid Medline, and Scopus since 2000. Five compared OS between patients with iLGG (n = 287) and sLGG (n = 3117). The pooled hazard ratio (pHR) for OS of iLGG to sLGG was 0.40 (95% confidence interval [CI] {0.27-0.61}). The estimated mean LTs and LTg were 3.76 years (n = 50) and 4.16-6.12 years, respectively. The corrected pHRs were 0.64 (95% CI [0.51-0.81]) by LTs and 0.70 (95% CI [0.56-0.88]) by LTg. In patients with total removal, the advantage of OS in iLGG was lost after the correction of lead-time. Patients with iLGG were more likely to be female pooled odds ratio (pOR) 1.60 (95% CI [1.25-2.04]) and have oligodendrogliomas (pOR 1.59 [95% CI {1.05-2.39}]). Correction of the length-time bias, which increased the pHR by 0.01 to 0.03, preserved the statistically significant difference in OS.

Conclusions

The reported outcome in iLGG was biased by lead-time and length-time. Although iLGG had a longer OS after correction of biases, the difference was less than previously reported.

Effects of gross total resection and subtotal resection on survival outcomes of glioma patients: a meta-analysis

This study was to conduct a meta-analysis to explore the impact of gross total resection (GTR) and subtotal resection (STR) on survival outcomes in glioma patients. Relevant studies were searched in multiple databases from the available date of inception through 30 December 2021. The weighted mean differences (WMDs), relative risks (RRs), or hazard ratios (HRs) with 95% confidence intervals (CIs) were used to access the effect of GTR versus STR treatments on the outcomes. The histology (low-grade or high-grade) and study population (children and adults) were used for subgroup analysis. Sensitivity analysis was performed for all outcomes. Begg's test and trim-and-fill method were used for publication bias. Totally 100 studies enrolling 62,129 patients were selected in this meta-analysis. The summary results showed that GTR was superior in improving 1-, 2-, 3-, 5-, 10-, 15-year overall survival (OS), OS time, 1-, 3-, 5-year progression-free survival (PFS), recurrence, local control and seizure control among glioma patients. In addition, high-grade patients who underwent GTR had improvements in 1-, 2- and 3-year OS, OS time, and 1-year PFS, while low-grade patients receiving GTR had improvements in 2-, 5- and 15-year OS, recurrence, seizure control, and tumor progression compared with those receiving STR. GTR was likely to be more effective on survival outcomes than STR among patients with gliomas.

Impact of GAP-43, Cx43 and actin expression on the outcome and overall survival in diffuse and anaplastic gliomas

Distant intercellular communication in gliomas is based on the expansion of tumor microtubuli, where actin forms cytoskeleton and GAP-43 mediates the axonal conus growth. We aimed to investigate the impact of GAP-43 and actin expression on overall survival (OS) as well as crucial prognostic factors. FFPE tissue of adult patients with diffuse and anaplastic gliomas, who underwent first surgery in our center between 2010 and 2019, were selected. GAP-43, Cx43 and actin expression was analyzed using immunohistochemistry and semi-quantitatively ranked. 118 patients with a median age of 46 years (IqR: 35-57) were evaluated. 48 (41%) presented with a diffuse glioma and 70 (59%) revealed anaplasia. Tumors with higher expression of GAP-43 (p = 0.024, HR = 1.71/rank) and actin (p < 0.001, HR = 2.28/rank) showed significantly reduced OS. IDH1 wildtype glioma demonstrated significantly more expression of all proteins: GAP-43 (p = 0.009), Cx43 (p = 0.003) and actin (p < 0.001). The same was confirmed for anaplasia (GAP-43 p = 0.028, actin p = 0.029), higher proliferation rate (GAP-43 p = 0.016, actin p = 0.038), contrast-enhancement in MRI (GAP-43 p = 0.023, actin p = 0.037) and age (GAP-43 p = 0.004, actin p < 0.001; Cx43 n.s. in all groups). The intercellular distant communication network in diffuse and anaplastic gliomas formed by actin and GAP-43 is associated with a negative impact on overall survival and with unfavorable prognostic features. Cx43 did not show relevant impact on OS.

Isocitrate dehydrogenase (IDH) mutant gliomas: A Society for Neuro-Oncology (SNO) consensus review on diagnosis, management, and future directions

Isocitrate dehydrogenase (IDH) mutant gliomas are the most common adult, malignant primary brain tumors diagnosed in patients younger than 50, constituting an important cause of morbidity and mortality. In recent years, there has been significant progress in understanding the molecular pathogenesis and biology of these tumors, sparking multiple efforts to improve their diagnosis and treatment. In this consensus review from the Society for Neuro-Oncology (SNO), the current diagnosis and management of IDH-mutant gliomas will be discussed. In addition, novel therapies, such as targeted molecular therapies and immunotherapies, will be reviewed. Current challenges and future directions for research will be discussed.

Magnetic Resonance-Guided Laser Interstitial Thermal Therapy for Management of Low-Grade Gliomas and Radiation Necrosis: A Single-Institution Case Series

BACKGROUND

Laser interstitial thermal therapy (LITT) has emerged as a minimally invasive treatment modality for ablation of low-grade glioma (LGG) and radiation necrosis (RN).

OBJECTIVE

To evaluate the efficacy, safety, and survival outcomes of patients with radiographically presumed recurrent or newly diagnosed LGG and RN treated with LITT.

METHODS

The neuro-oncological database of a quaternary center was reviewed for all patients who underwent LITT for management of LGG between 1 January 2013 and 31 December 2020. Clinical data including demographics, lesion characteristics, and clinical and radiographic outcomes were collected. Kaplan-Meier analyses comprised overall survival (OS) and progression-free survival (PFS).

RESULTS

Nine patients (7 men, 2 women; mean [SD] age 50 [16] years) were included. Patients underwent LITT at a mean (SD) of 11.6 (8.5) years after diagnosis. Two (22%) patients had new lesions on radiographic imaging without prior treatment. In the other 7 patients, all (78%) had surgical resection, 6 (67%) had intensity-modulated radiation therapy and chemotherapy, respectively, and 4 (44%) had stereotactic radiosurgery. Two (22%) patients had lesions that were wild-type IDH1 status. Volumetric assessment of preoperative T1-weighted contrast-enhancing and T2-weighted fluid-attenuated inversion recovery (FLAIR) sequences yielded mean (SD) lesion volumes of 4.1 (6.5) cm³ and 26.7 (27.9) cm³, respectively. Three (33%) patients had evidence of radiographic progression after LITT. The pooled median (IQR) PFS for the cohort was 52 (56) months, median (IQR) OS after diagnosis was 183 (72) months, and median (IQR) OS after LITT was 52 (60) months. At the time of the study, 2 (22%) patients were deceased.

CONCLUSIONS

LITT is a safe and effective treatment option for management of LGG and RN, however, there may be increased risk of permanent complications with treatment of deep-seated subcortical lesions.

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.

Modern surgical management of incidental gliomas

Purpose

Gliomas are the most common primary tumors of the central nervous system and are categorized by the World Health Organization into either low-grade (grades 1 and 2) or high-grade (grades 3 and 4) gliomas. A subset of patients with glioma may experience no tumor-related symptoms and be incidentally diagnosed. These incidental low-grade gliomas (iLGG) maintain controversial treatment course despite scientific advancements. Here we highlight the recent advancements in classification, neuroimaging, and surgical management of these tumors.

Methods

A review of the literature was performed. The authors created five subtopics of focus: histological criteria, diagnostic imaging, surgical advancements, correlation of surgical resection and survival outcomes, and clinical implications.

Conclusions

Alternating studies suggest that these tumors may experience higher mutational rates than their counterparts. Significant progress in management of gliomas, regardless of the grade, has been made through modern neurosurgical treatment modalities, diagnostic neuroimaging, and a better understanding of the genetic composition of these tumors. An optimal treatment approach for patients with newly diagnosed iLGG remains ill-defined despite multiple studies arguing in favor of safe maximal resection. Our review emphasizes the not so benign nature of incidental low grade glioma and further supports the need for future studies to evaluate survival outcomes following surgical resection.

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.

Mini-craniotomy for intra-axial brain tumors: a comparison with conventional craniotomy in 306 patients harboring non-dural based lesions

The use of a mini-craniotomy approach involving linear skin incision and a bone flap of about 3 cm has been reported for several neurosurgical diseases, such as aneurysms or cranial base tumors. More superficial lesions, including intra-axial tumors, may occasionally raise concerns due to insufficient control of the tumor boundaries. The convenience of a minimally invasive approach to intrinsic brain tumors was evaluated by comparing 161 patients who underwent mini-craniotomy (MC) for intra-axial brain tumors with a group of 145 patients operated on by the same surgical team through a conventional craniotomy (CC). Groups were propensity-matched for age, preoperative condition, size and location of the tumor, and pathological diagnosis. Results were analyzed focusing on operative time, the extent of resection, clinical outcome, hospitalization time, and time to start adjuvant therapy. Mini-craniotomy was equally effective in terms of extent of resection (GTR: 70.9% in the MC group vs 70.5% in the CC group) but had shorter operative time (average: 165 min in the MC group vs 205 min in the CC group p < 0.001) and lower rate of postoperative complications both superficial (1.03% vs 6.5% in the CC group p = 0.009) and deep (4% in the MC group vs 5.5% in the CC group p = 0,47). No relationship was found between the size or location of the tumor and resection rate. The MC group had reduced hospitalization time (average: 5.8 days vs 7.6 in CC group p < 0.001) and faster access to adjuvant therapies. 92.5% of the MC patients, which were scheduled for treatment, started radiotherapy within 8 weeks after surgery as opposed to 84.1% in the CC group (p = 0.04). These findings support the increasing use of mini-craniotomy for intra-axial brain tumors.

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.