Level of evidence in the literature concerning brain tumor resection

The Impact of Extent of Resection on the Prognosis of Glioblastoma Multiforme: A Systematic Review and Meta-analysis

Purpose: To investigate the predictor factors of mortality describing the prognosis of primary surgical resection of Glioblastoma Multiforme (GBM). Materials and Methods: A systemic search was conducted from electronic databases (PubMed/Medline, Cochrane Library, and Google Scholar) from inception to 12th September 2021.  All statistical analysis was conducted in Review Manager 5.4.1. Studies meeting inclusion criteria were selected. A random-effect model was used when heterogeneity was seen to pool the studies, and the result were reported in the Hazards Ratio (HR) and corresponding 95% Confidence interval (CI). Result: Twenty-three cohort studies were selected for meta-analysis. There was statistically significant effect of extent of resection on prognosis of surgery in GBM patients (HR= 0.90 [0.86, 0.95]; p< 0.0001; I2= 96%), male gender (HR= 1.19 [1.06, 1.34]; p= 0.002; I2= 0%) and decrease Karnofsky Performance Status (HR= 0.97 [0.95, 0.99]; p= 0.003; I2= 90%). Age and tumor volume was also analyzed in the study. Conclusion: The results of our meta-analysis suggested that age, gender, pre-operative KPS score and extent of resection have significant effects on the post-surgical mortality rate, therefore, these factors can be used significant predictor of mortality in GBM patients.

Feasibility of removable balloon implant for simultaneous magnetic nanoparticle heating and HDR brachytherapy of brain tumor resection cavities

AIM

Hyperthermia (HT) has been shown to improve clinical response to radiation therapy (RT) for cancer. Synergism is dramatically enhanced if HT and RT are combined simultaneously, but appropriate technology to apply treatments together does not exist. This study investigates the feasibility of delivering HT with RT to a 5-10mm annular rim of at-risk tissue around a tumor resection cavity using a temporary thermobrachytherapy (TBT) balloon implant.

METHODS

A balloon catheter was designed to deliver radiation from High Dose Rate (HDR) brachytherapy concurrent with HT delivered by filling the balloon with magnetic nanoparticles (MNP) and immersing it in a radiofrequency magnetic field. Temperature distributions in brain around the TBT balloon were simulated with temperature dependent brain blood perfusion using numerical modeling. A magnetic induction system was constructed and used to produce rapid heating (>0.2°C/s) of MNP-filled balloons in brain tissue-equivalent phantoms by absorbing 0.5 W/ml from a 5.7 kA/m field at 133 kHz.

RESULTS

Simulated treatment plans demonstrate the ability to heat at-risk tissue around a brain tumor resection cavity between 40-48°C for 2-5cm diameter balloons. Experimental thermal dosimetry verifies the expected rapid and spherically symmetric heating of brain phantom around the MNP-filled balloon at a magnetic field strength that has proven safe in previous clinical studies.

CONCLUSIONS

These preclinical results demonstrate the feasibility of using a TBT balloon to deliver heat simultaneously with HDR brachytherapy to tumor bed around a brain tumor resection cavity, with significantly improved uniformity of heating over previous multi-catheter interstitial approaches. Considered along with results of previous clinical thermobrachytherapy trials, this new capability is expected to improve both survival and quality of life in patients with glioblastoma multiforme.

Biopsy versus resection for high-grade glioma

BACKGROUND

This is an update of the original review published in the Cochrane Database of Systematic Reviews Issue 1, 2000 and updated in 2003, 2007 and 2010.People with a presumed high-grade glioma (HGG) identified by clinical evaluation and radiological investigation have two initial surgical options: biopsy or resection. In certain situations, such as severe raised intracranial pressure, surgical resection is clinically indicated. Where surgical resection is not feasible, biopsy is the only reasonable option. Most people fall somewhere between these extremes, and in such circumstances it is uncertain which procedure is the best surgical option for the patient. Opinion is divided regarding the relative risks and benefits of each procedure.

OBJECTIVES

To estimate the clinical effectiveness of surgical resection compared to biopsy in people with a new presumptive diagnosis of HGG.

SEARCH METHODS

We updated our searches of the following databases to 12 September 2018: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase. We also handsearched the Journal of Neuro-Oncology and Neuro-Oncology from 2010 to 2018 (including all conference abstracts).

SELECTION CRITERIA

We included randomised controlled trials (RCTs) involving people of all ages with a presumed diagnosis of HGG based upon clinical and radiological investigation. Interventions included any form of biopsy or resection. Surgery was at the time of initial presentation and not for recurrence.

DATA COLLECTION AND ANALYSIS

Two reviews authors independently assessed the search results for relevance and undertook critical appraisal according to prespecified guidelines. Outcome measures included survival, time to progression/progression-free survival, quality of life, symptom control, adverse events, and mortality.

MAIN RESULTS

We identified a single RCT of biopsy versus resection in presumed HGG. No other articles met the inclusion criteria. Personal communication revealed that an RCT of biopsy versus resection in elderly people with HGG is underway. Further communication as part of this 2018 update revealed that the results of this study are due to be published in 2019.

AUTHORS' CONCLUSIONS

There is no high-quality evidence on biopsy versus resection for HGG that can be used to guide management. The single included RCT was of inadequate methodology to reach reliable conclusions. Further large, multicentred RCTs are required to conclusively answer the question of whether biopsy or resection is the best initial surgical management for HGG.

Systematic Review of Brain Tumor Treatment in Dogs

Intracranial neoplasia is commonly diagnosed in dogs and can be treated by a variety of methods, but formal comparisons of treatment efficacy are currently unavailable. This review was undertaken to summarize the current state of knowledge regarding outcome after the treatment of intracranial masses in dogs, with the aim of defining optimal recommendations for owners. This review summarizes data from 794 cases in 22 previously published reports and follows PRISMA guidelines for systematic review. A Pubmed search was used to identify suitable articles. These then were analyzed for quality and interstudy variability of inclusion and exclusion criteria and the outcome data extracted for summary in graphs and tables. There was a high degree of heterogeneity among studies with respect to inclusion and exclusion criteria, definition of survival periods, and cases lost to follow‐up making comparisons among modalities troublesome. There is a need for standardized design and reporting of outcomes of treatment for brain tumors in dogs. The available data do not support lomustine as an effective treatment, but also do not show a clear difference in outcome between radiotherapy and surgery for those cases in which the choice is available.

Role of neurochemical navigation with 5-aminolevulinic acid during intraoperative MRI-guided resection of intracranial malignant gliomas

OBJECTIVE

To evaluate the role of the neurochemical navigation with 5-aminolevulinic acid (5-ALA) during intraoperative MRI (iMRI)-guided resection of the intracranial malignant gliomas.

METHODS

The analysis included 99 consecutive surgical cases. Resection of the bulk of the neoplasm was mainly guided by the updated neuronavigation based on the low-field-strength (0.3T) iMRI, whereas at the periphery of the lesion neurochemical navigation with 5-ALA was additionally used.

RESULTS

In total, 286 tissue specimens were obtained during surgeries for histopathological examination. According to iMRI 98 samples with strong (91 cases), weak (6 cases), or absent (1 case) fluorescence corresponded to the bulk of the lesion and all of those ones contained tumor. Out of 188 tissue specimens obtained from the "peritumoral brain," the neoplastic elements were identified in 89%, 81% and 29% of samples with, respectively, strong (107 cases), weak (47 cases) and absent (34 cases) fluorescence. Positive predictive values of the tissue fluorescence for presence of neoplasm within and outside of its boundaries on iMRI were 100% and 86%, respectively.

CONCLUSION

Neurochemical navigation with 5-ALA is useful adjunct during iMRI-guided resection of intracranial malignant gliomas, which allows identification of the tumor extension beyond its radiological borders.

Optimizing affinity measures for parcellating brain structures based on resting state fMRI data: a validation on medial superior frontal cortex

BACKGROUND

Parcellating brain structures into functionally homogeneous subregions based on resting state fMRI data could be achieved by grouping image voxels using clustering algorithms, such as normalized cut. The affinity between brain voxels adopted in the clustering algorithms is typically characterized by a combination of the similarity of their functional signals and their spatial distance with parameters empirically specified. However, improper parameter setting of the affinity measure may result in parcellation results biased to spatial smoothness.

NEW METHOD

To obtain a functionally homogeneous and spatially contiguous brain parcellation result, we propose to optimize the affinity measure of image voxels using a constrained bi-level programming optimization method. Particularly, we first identify the space of all possible parameters that are able to generate spatially contiguous brain parcellation results. Then, within the constrained parameter space we search those leading to the brain parcellation results with optimal functional homogeneity and spatial smoothness.

RESULTS AND COMPARISON WITH EXISTING METHODS

The method has successfully parcellated medial superior frontal cortex into supplementary motor area (SMA) and pre-SMA for 106 subjects based on their resting state fMRI data. These results have been validated through functional connectivity analysis and meta-analysis of existing functional imaging studies and compared with those obtained by state-of-the-art brain parcellation methods.

CONCLUSIONS

The validation results have demonstrated that our method could obtain brain parcellation results consistent with the existing functional anatomy knowledge, and the comparison results have further demonstrated that optimizing affinity measure could improve the brain parcellation's robustness and functional homogeneity.

The level of evidence in two leading endodontic journals

INTRODUCTION

The successful practice of dentistry, including endodontics, relies on a wide spectrum of dental research. The quantity and quality of research evidence in endodontics have seldom been evaluated. The aim of this study was to evaluate the level of evidence in current leading endodontic journals.

MATERIALS AND METHODS

All the articles published in 2000, 2006 and 2010 in two major endodontic journals (Journal of Endodontics and International Endodontic Journal) were evaluated. These articles were classified according to the level of evidence (LOE) using Oxford Scale from 0 to 5 and type of the study.

RESULTS

Of the articles assessed, 3.2% were clinical trials, 47.8% were experimental, 5.6% were animal studies and 43.4% were of other types. Subdivisions according to LOE were 4.3% as level 1, 0.9 % level 2, 7.3% level 3, 0.4% level 4 and 3.5% level 5. Overall, 83.6% of the articles were classified as "non-evidence-based". There was a marginally significant increase in the percentage of articles with high level of evidence in recent years.

CONCLUSION

There is a substantial shortage of articles with high level of evidence in clinical endodontics. However, there was a gradual increase in the number of high LOE articles published in both journals.

Intraoperative image guidance in neurosurgery: development, current indications, and future trends

Introduction. As minimally invasive surgery becomes the standard of care in neurosurgery, it is imperative that surgeons become skilled in the use of image-guided techniques. The development of image-guided neurosurgery represents a substantial improvement in the microsurgical treatment of tumors, vascular malformations, and other intracranial lesions. Objective. There have been numerous advances in neurosurgery which have aided the neurosurgeon to achieve accurate removal of pathological tissue with minimal disruption of surrounding healthy neuronal matter including the development of microsurgical, endoscopic, and endovascular techniques. Neuronavigation systems and intraoperative imaging should improve success in cranial neurosurgery. Additional functional imaging modalities such as PET, SPECT, DTI (for fiber tracking), and fMRI can now be used in order to reduce neurological deficits resulting from surgery; however the positive long-term effect remains questionable for many indications. Method. PubMed database search using the search term "image guided neurosurgery." More than 1400 articles were published during the last 25 years. The abstracts were scanned for prospective comparative trials. Results and Conclusion. 14 comparative trials are published. To date significant data amount show advantages in intraoperative accuracy influencing the perioperative morbidity and long-term outcome only for cerebral glioma surgery.

Prognostic factors and survival in a prospective cohort of patients with high-grade glioma treated with carmustine wafers or temozolomide on an intention-to-treat basis

BACKGROUND

Patients with high-grade glioma can be treated with carmustine wafers or following the Stupp protocol. As far as we are aware, no scientific evidence has been published comparing the two treatments. The primary objective of this study was to analyse the survival of groups of patients with each of these treatment modalities. The secondary objective was to assess the influence of the usual prognostic factors on the patients in our hospital.

METHODS

A prospective cohort of 110 patients with single, supratentorial high-grade glioma treated by craniotomy and tumour resection was retrospectively studied. Half of the patients had carmustine wafers placed during this operation while the others (55) did not, the latter group receiving first-line systemic chemotherapy on an intention-to-treat basis.

FINDINGS

Patients treated with carmustine wafers had a median survival of 13.414 months compared with 11.047 in the group without implants (p = 0.856). For the overall cohort of patients, the following factors were found to influence survival: age (p < 0.0001), postoperative KPS score (p = 0.001), histological grade (p = 0.004), RPA class (p = 0.001), extent of resection (p = 0.002) and salvage surgery (p = 0.028).

CONCLUSIONS

In this prospective cohort of patients, analysed on the basis of intention-to-treat at the time of the first surgery, no statistically significant differences in survival were found between the two treatment modalities (carmustine wafers vs. first-line systemic chemotherapy). On the other hand, age, preoperative KPS, histological grade, and RPA class were confirmed to be prognostic factors in this cohort. Finally, the extent of resection was also found to influence survival.

Temozolomide plus radiotherapy for glioblastoma in a Canadian province: Efficacy versus effectiveness and the impact of O6-methylguanine-DNA-methyltransferase promoter methylation

Background: Radiotherapy with concomitant and adjuvant temozolomide has been the standard of care for newly diagnosed glioblastoma in adults since the pivotal trial by Roger Stupp and colleagues. The effectiveness of this regimen has not been evaluated in Canada. Additionally, the impact of O6-methylguanine-DNA-methyltransferase (MGMT) promoter methylation on patient survival has not been confirmed. Hence, survival outcomes and MGMT predictive value were compared for the patients in Alberta versus the Stupp trial population.

Methods: Retrospective chart review of 215 adult glioblastoma patients who started radiotherapy and temozolomide between January 2007 and December 2010 at the Cross Cancer Institute (Edmonton, Alberta) or the Tom Baker Cancer Centre (Calgary, Alberta).

Results: In the Alberta population, median overall survival was 14.3 months (vs. 14.6 months in trial, p = NS) and median progression-free survival was 5.8 months (vs. 6.9 months in trial, p = NS). However, unlike the trial, the Alberta MGMT subgroup analysis for overall survival was not statistically significant, despite a hazard ratio of 0.65 in favor of the methylated group. More Alberta patients received corticosteroids ( p < 0.0001) and fewer underwent complete resection ( p = 0.0001) or a postprogression second surgery ( p = 0.01) than the Stupp population, but characteristics were otherwise similar.

Conclusion: Current practice in Alberta enables patients to achieve overall and progression-free survival similar to the clinical trial. Further follow-up is required to confirm the predictive value of the MGMT assay. Until that is clarified or better treatments are developed, it is reasonable to continue offering this treatment regimen to patients regardless of MGMT methylation status.

Intraoperative stimulation techniques for functional pathway preservation and glioma resection

Although a primary tenet of neurosurgical oncology is that survival can improve with greater tumor resection, this principle must be tempered by the potential for functional loss following a radical removal. Preoperative planning with functional and physiological imaging paradigms, combined with intraoperative strategies such as cortical and subcortical stimulation mapping, can effectively reduce the risks associated with operating in eloquent territory. In addition to identifying critical motor pathways, these techniques can be adapted to identify language function reliably. The authors review the technical nuances of intraoperative mapping for low- and high-grade gliomas, demonstrating their efficacy in optimizing resection even in patients with negative mapping data. Collectively, these surgical strategies represent the cornerstone for operating on gliomas in and around functional pathways.

ASSOCIATION OF SURGICALLY ACQUIRED MOTOR AND LANGUAGE DEFICITS ON OVERALL SURVIVAL AFTER RESECTION OF GLIOBLASTOMA MULTIFORME

OBJECTIVE

Balancing the benefits of extensive tumor resection with the consequence of potential postoperative deficits remains a challenge in malignant astrocytoma surgery. Although studies have suggested that increasing extent of resection may benefit survival, the effect of new postoperative deficits on survival remains unclear. We set out to determine whether new-onset postoperative motor or speech deficits were associated with survival in our institutional experience with glioblastoma multiforme (GBM).

METHODS

We retrospectively reviewed records of all patients (age range, 18–70 years; Karnofsky Performance Scale score, 80–100) who had undergone GBM resection between 1996 and 2006 at a single institution. Survival was compared between patients who had experienced surgically acquired motor or language deficits versus those who did not experience these deficits.

RESULTS

Three hundred six consecutive patients (age, 54 ± 11 years; median Karnofsky Performance Scale score, 80) underwent primary GBM resection. Nineteen patients (6%) developed surgically acquired motor deficits and 15 (5%) developed surgically acquired language deficits. Median survival was decreased in patients who acquired language deficits (9.6 months; P &lt; 0.05) or motor deficits (9.0 months; P &lt; 0.05) versus patients without surgically acquired deficits (12.8 months). Two-year survival was 8% and 0% for patients with surgically acquired motor or language deficits, respectively, versus 23% for patients without new-onset deficits.

CONCLUSION

In our experience, the development of new perioperative motor or language deficits was associated with decreased overall survival despite similar extent of resection and adjuvant therapy. Although it is well known that surgically induced neurological deficits affect quality of life, our results suggest that these surgical morbidities may also affect survival. Care should be taken to avoid surgically induced deficits in the management of GBM.

Operative techniques for gliomas and the value of extent of resection

Refinement of neurosurgical technique has enabled safer operations with more aggressive outcomes. One cornerstone of modern-day practice is the utilization of intraoperative stimulation mapping. In addition to identifying critical motor pathways, this technique can be adapted to reliably identify language pathways. Given the individual variability of cortical language localization, such awake language mapping is essential to minimize language deficits following tumor resection. Our experience suggests that cortical language mapping is a safe and efficient adjunct to optimize tumor resection while preserving essential language sites, even in the setting of negative mapping data. However, the value of maximizing glioma resections remains surprisingly unclear, as there is no general consensus in the literature regarding the efficacy of extent of glioma resection in improving patient outcome. While the importance of resection in obtaining tissue diagnosis and alleviating symptoms is clear, a lack of Class I evidence prevents similar certainty in assessing the influence of extent of resection. Beyond an analysis of modern intraoperative mapping techniques, we examine every major clinical publication since 1990 on the role of extent of resection in glioma outcome. The mounting evidence suggests that, despite persistent limitations in the quality of available studies, a more extensive surgical resection is associated with longer life expectancy for both low-grade and high-grade gliomas.

Glioma extent of resection and its impact on patient outcome

OBJECTIVE

There is still no general consensus in the literature regarding the role of extent of glioma resection in improving patient outcome. Although the importance of resection in obtaining tissue diagnosis and alleviating symptoms is clear, a lack of Class I evidence prevents similar certainty in assessing the influence of extent of resection.

METHODS

We reviewed every major clinical publication since 1990 on the role of extent of resection in glioma outcome.

RESULTS

Twenty-eight high-grade glioma articles and 10 low-grade glioma articles were examined in terms of quality of evidence, expected extent of resection, and survival benefit.

CONCLUSION

Despite persistent limitations in the quality of data, mounting evidence suggests that more extensive surgical resection is associated with longer life expectancy for both low- and high-grade gliomas.

Clinical course of high-grade glioma patients with a "biopsy-only" surgical approach: a need for individualised treatment

INTRODUCTION

'Biopsy-only' high-grade glioma (HGG) patients get limited benefit from post-operative treatments, and as a group, negatively impact median survival outcomes.

MATERIAL AND METHODS

We retrospectively evaluated clinical characteristics, treatment and overall survival of HGG patients with a 'biopsy- only' surgical approach diagnosed between 1997 and 2005 at a University Hospital in Spain.

RESULTS

In 31% of 294 suspected gliomas, only a diagnostic biopsy was undertaken. Reasons for 'biopsy-only' for all patients were either location in eloquent areas: (motor area 18.7%, language area 25,3%, basal ganglia 7.7%, visual area 4.4%) or extension of the disease (corpus callosum invasion 14.3% and multicentricity/multifocality 28.6%). Seventy-four patients (80.4%) were HGG: 26% of all grade IV and 49% of all grade III tumours. For these patients, post-operative Karnofsky Performance Status of over 70%, median age and median survival were, respectively: 64 and 70%, 60.7 and 57 years old, and 23.1 and 42.7 weeks (p=0.0006). Patients lived longer if post-operative treatment was given, in all grades (p<0.0001). Nineteen patients (25.6%) died within 42 days after surgery. Only 60% of them initiated radiotherapy and 10% of them did not complete it. However, tumour grade, radiotherapy and temozolomide- based chemotherapy were independently associated with longer survival in multivariate analysis (p<0.05).

CONCLUSION

Almost one third of HGG patients can undergo only a biopsy and not debulking surgery. Although radiotherapy improves survival, only 50% of them complete the treatment. An individualised approach to these patients is needed to facilitate a correct analysis of therapy results. New therapies must be investigated in these patients.

The Role of Surgery in High-grade Glioma – Is Surgical Resection Justified? A Review of the Current Knowledge

Introduction: The aims of this article were to review the role of surgical resection in the management of high-grade gliomas and to determine whether there is any survival benefit from surgical resection. Methods: A literature review of the influence of surgical resection on outcome was carried out. Relevant original and review papers were obtained through a PubMed search using the following keywords: glioma, resection, prognosis and outcome. Results: Presently, there is a lack of evidence to support a survival benefit with aggressive glioma resection, but this should not detract patients from undergoing surgery as there are many other clinical benefits of glioma excision. In addition, limiting surgical morbidity through the use of adjuvant techniques such as intraoperative magnetic resonance imaging (MRI), functional MRI and awake craniotomy is becoming increasingly important. Conclusions: Ideally, a randomised controlled trial would be the best way to resolve the issue of whether (and to what extent) surgical resection leads to improvements in patient outcome and survival, but this would not be ethical. The second best option would be well-controlled retrospective studies with a multivariate analysis of all potential confounding factors. Key words: Astrocytoma, Brain tumour, Glioma, Outcome, Resection, Surgery, Survival

Connectivity-based parcellation of human cortex using diffusion MRI: Establishing reproducibility, validity and observer independence in BA 44/45 and SMA/pre-SMA

The identification of specialized, functional regions of the human cortex is a vital precondition for neuroscience and clinical neurosurgery. Functional imaging modalities are used for their delineation in living subjects, but these methods rely on subject cooperation, and many regions of the human brain cannot be activated specifically. Diffusion tractography is a novel tool to identify such areas in the human brain, utilizing underlying white matter pathways to separate regions of differing specialization. We explore the reproducibility, generalizability and validity of diffusion tractography-based localization in four functional areas across subjects, timepoints and scanners, and validate findings against fMRI and post-mortem cytoarchitectonic data. With reproducibility across modalities, clustering methods, scanners, timepoints, and subjects in the order of 80-90%, we conclude that diffusion tractography represents a useful and objective tool for parcellation of the human cortex into functional regions, enabling studies into individual functional anatomy even when there are no specific activation paradigms available.

Biopsy versus resection for malignant glioma

BACKGROUND

Patients with isolated supratentorial brain tumours, presumed to be primary on imaging, have two surgical management options - biopsy or resection. Surgical opinions appear to be equally divided when considering the relative risks and benefits of these two procedures.

OBJECTIVES

To estimate the clinical effectiveness of radical surgical resection compared to simple biopsy in patients with malignant glioma.

SEARCH STRATEGY

Electronic database searches of COCHRANE CONTROLLED TRIALS REGISTER (including the Cochrane Cancer Network Specialised Register of Trials), MEDLINE, CANCERLIT, EMBASE, BIOSIS and SCIENCE CITATION INDEX. Hand searching the references of all identified studies; hand searching the Journal of Neuro-Oncology over the previous 10 years, including all conference abstracts; personal communication.

SELECTION CRITERIA

Randomised and clinical controlled trials were included if they compared biopsy to resection, or looked at effect of extent of resection on survival, time to progression or quality of life, for malignant glioma patients of all ages.

DATA COLLECTION AND ANALYSIS

Studies were to be identified, critically appraised and data extracted by the author (SEM). For dichotomous data, Peto odds ratios (OR) with 95% confidence intervals (CI) were hoped to have been estimated. Normal continuous data were to have been summated using the weighted mean difference (WMD).

MAIN RESULTS

The electronic database search yielded 2100 citations. Of these, two articles were identified for possible inclusion, however both were excluded. The hand search and personal communication were similarly unproductive. No studies were included in the review and no data was synthesised.

REVIEWER'S CONCLUSIONS

Given that no qualifying studies were identified and because this is an important issue, both in terms of patient risk and benefit and health economics, the author feels it important to conduct a randomised controlled trial in this subject.