The role of radiotherapy in the management of patients with diffuse low grade glioma: A systematic review and evidence-based clinical practice guideline

American Association of Neurological Surgeons/Congress of the Neurological Surgeons Section on Tumors Guidelines: Assessing Their Impact on Brain Tumor Clinical Practice

Clinical guidelines direct healthcare professionals toward evidence-based practices. Evaluating guideline impact can elucidate information penetration, relevance, effectiveness, and alignment with evolving medical knowledge and technological advancements. As the American Association of Neurological Surgeons/Congress of Neurological Surgeons Section on Tumors marks its 40th anniversary in 2024, this article reflects on the tumor guidelines established by the Section over the past decade and explores their impact on other publications, patents, and information dissemination. Six tumor guideline categories were reviewed: low-grade glioma, newly diagnosed glioblastoma, progressive glioblastoma, metastatic brain tumors, vestibular schwannoma, and pituitary adenomas. Citation data were collected from Google Scholar and PubMed. Further online statistics, such as social media reach, and features in policy, news, and patents were sourced from Altmetric. Online engagement was assessed through website and CNS+ mobile application visits. Data were normalized to time since publication. Metastatic Tumor guidelines (2019) had the highest PubMed citation rate at 26.1 per year and webpage visits (29 100 page views 1/1/2019-9/30/2023). Notably, this guideline had two endorsement publications by partner societies, the Society of Neuro-Oncology and American Society of Clinical Oncology, concerning antiepileptic prophylaxis and steroid use, and the greatest reach on X (19.7 mentions/y). Citation rates on Google Scholar were led by Vestibular Schwannoma (2018). Non-Functioning Pituitary Adenoma led Mendeley reads. News, patent, or policy publications were led by low-grade glioma at 1.5/year. Our study shows that the American Association of Neurological Surgeons/Congress of Neurological Surgeons Section on Tumors guidelines go beyond citations in peer-reviewed publications to include patents, online engagement, and information dissemination to the public.

Pre-operative predictors of post-operative seizure control in low-grade glioma: a systematic review and meta-analysis

As many as 80% of low-grade gliomas (LGGs) present with seizures, negatively impacting quality of life. While seizures are associated with gliomas regardless of grade, the importance of minimizing impact of seizures for patients with low grade tumors cannot be understated given the prolonged survival period in this population. The objective of this systematic review and meta-analysis was to summarize existing literature and identify factors associated with post-operative seizure control (defined as Engel I classification) in patients with LGGs, with a focus on pre-operative factors. Patient data extracted include tumor location and histology, pre-operative anti-seizure medication use, extent of resection (EOR), adjuvant treatment, pre-operative seizure type, duration, and frequency, and post-operative Engel classification. A random-effects model was used to calculate the effects of EOR, pre-operative seizure duration, adjuvant radiation, and adjuvant chemotherapy on post-operative seizure control. The effect of tumor location and histology on post-operative Engel I classification was determined using contingency analyses. Thirteen studies including 1628 patients with seizures were included in the systematic review. On meta-analyses, Engel I classification was associated with pre-operative seizure type (OR = 0.79 (0.63-0.99), p = 0.0385, focal versus generalized), frontal lobe LGGs (OR = 1.5 (1.1-2.0), p = 0.0195), and EOR (OR (95% CI) = 4.5 (2.3-6.7), p < 0.0001 gross-total versus subtotal). Pre-operative seizure duration less than one year, adjuvant radiation, adjuvant chemotherapy, and tumor histology were not associated with achieving Engel I classification. In addition to the known effects of EOR, Engel I classification is less likely to be achieved in patients with focal pre-operative seizures and more likely to be achieved in patients with frontal lobe LGGs.

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.

Foundations of the Diagnosis and Management of Low-Grade Gliomas

In the past, low-grade gliomas-World Health Organization (WHO) grade I and II tumors-were generally expected to have a much better prognosis than higher-grade (WHO grade III and IV) gliomas. However, diffuse gliomas (WHO grade II), unlike WHO grade I gliomas, are by definition infiltrative, limiting resection and potentially contributing to poor outcomes like those seen with malignant gliomas. Rapid progress in the understanding of the pathogenesis of these tumors indicates that specific molecular factors, especially isocitrate dehydrogenase mutation status and the presence or absence of the 1p/19q codeletion (deletion of the short arm of chromosome 1 and long arm of chromosome 19), are much more important than grade in determining prognosis and response to treatment. These molecular characteristics outweigh the histologic distinctions and have been quickly incorporated into the WHO classification of gliomas. Management of these tumors with surgery, radiation, and chemotherapy has similarly been transformed by these developments, highlighting the need for a customized approach for patients with low-grade gliomas.

The Role of TGF-β in Cognitive Decline Associated with Radiotherapy in Brain Tumor

Cognitive decline is a late adverse event in brain tumor survivors. The patients receiving radiation treatment exhibit a wide range of damage and impairment in attention, memory, and executive function compared to the untreated group. After radiation treatment, various changes are observed in astrocytes, oligodendrocytes, white matter, and vasculature. The major affected areas are the hippocampus and prefrontal cortex. Neurogenesis impairment is one of the primary mechanisms responsible for cognitive dysfunction. Various cytokines and growth factors are responsible for inducing apoptosis of neural cells, which results in impaired neurogenesis in response to radiotherapy. Transforming growth factor (TGF-β) is one of the key cytokines released in response to radiation. TGF-β plays a major role in neuronal apoptosis through various pathways such as the MAP kinase pathway, JAK/STAT pathway, and protein kinase pathway. In contrast, activation of the ALK5 pathway via TGF-β improves neurogenesis. So, the current review article focuses on the detailed effects of TGF-β on neuronal cells concerning radiation exposure. This in-depth knowledge will help researchers focus more on the TGF-β pathway and come up with new treatment schedules which will help reduce cognitive dysfunctions in brain tumor patients produced as a result of radiation therapy.

Multi-institutional study of the frequency, genomic landscape, and outcome of IDH-mutant glioma in pediatrics

BACKGROUND

The incidence and biology of IDH1/2 mutations in pediatric gliomas are unclear. Notably, current treatment approaches by pediatric and adult providers vary significantly. We describe the frequency and clinical outcomes of IDH1/2-mutant gliomas in pediatrics.

METHODS

We performed a multi-institutional analysis of the frequency of pediatric IDH1/2-mutant gliomas, identified by next-generation sequencing (NGS). In parallel, we retrospectively reviewed pediatric IDH1/2-mutant gliomas, analyzing clinico-genomic features, treatment approaches, and outcomes.

RESULTS

Incidence: Among 851 patients with pediatric glioma who underwent NGS, we identified 78 with IDH1/2 mutations. Among patients 0-9 and 10-21 years old, 2/378 (0.5%) and 76/473 (16.1%) had IDH1/2-mutant tumors, respectively. Frequency of IDH mutations was similar between low-grade glioma (52/570, 9.1%) and high-grade glioma (25/277, 9.0%). Four tumors were graded as intermediate histologically, with one IDH1 mutation. Outcome: Seventy-six patients with IDH1/2-mutant glioma had outcome data available. Eighty-four percent of patients with low-grade glioma (LGG) were managed observantly without additional therapy. For low-grade astrocytoma, 5-year progression-free survival (PFS) was 42.9% (95%CI:20.3-63.8) and, despite excellent short-term overall survival (OS), numerous disease-related deaths after year 10 were reported. Patients with high-grade astrocytoma had a 5-year PFS/OS of 36.8% (95%CI:8.8-66.4) and 84% (95%CI:50.1-95.6), respectively. Patients with oligodendroglioma had excellent OS.

CONCLUSIONS

A subset of pediatric gliomas is driven by IDH1/2 mutations, with a higher rate among adolescents. The majority of patients underwent upfront observant management without adjuvant therapy. Findings suggest that the natural history of pediatric IDH1/2-mutant glioma may be similar to that of adults, though additional studies are needed.

What matters for people with brain cancer? Selecting clinical quality indicators for an Australian Brain Cancer Registry

BACKGROUND

The goal of a clinical quality registry is to deliver immediate gains in survival and quality of life by delivering timely feedback to practitioners, thereby ensuring every patient receives the best existing treatment. We are developing an Australian Brain Cancer Registry (ABCR) to identify, describe, and measure the impact of the variation and gaps in brain cancer care from the time of diagnosis to the end of life.

METHODS

To determine a set of clinical quality indicators (CQIs) for the ABCR, a database and internet search were used to identify relevant guidelines, which were then assessed for quality using the AGREE II Global Rating Scale. Potential indicators were extracted from 21 clinical guidelines, ranked using a modified Delphi process completed in 2 rounds by a panel of experts and other stakeholders, and refined by a multidisciplinary Working Group.

RESULTS

Nineteen key quality reporting domains were chosen, specified by 57 CQIs detailing the specific inclusion and outcome characteristics to be reported.

CONCLUSION

The selected CQIs will form the basis for the ABCR, provide a framework for achievable data collection, and specify best practices for patients and health care providers, with a view to improving care for brain cancer patients. To our knowledge, the systematic and comprehensive approach we have taken is a world first in selecting the reporting specifications for a brain cancer clinical registry.

Combination of the Distance From Tumor Edge to Subventricular Zone and IDH Mutation Predicts Prognosis of Patients With Glioma

Both subventricular zone (SVZ) contact and isocitrate dehydrogenase 1 (IDH1) mutation have been reported to be related to the outcome of glioma, respectively. However, far too little attention has been paid to the role of tumor edge-SVZ distance in the outcome of glioma. We aim to assess the value of tumor-SVZ distance, as well as combined tumor-SVZ distance and IDH status, in predicting the outcome of gliomas (WHO grade II-IV). Here, the MR images and clinical data from 146 patients were included in the current study. The relationship between survival and the tumor-SVZ distance as well as survival and combination of tumor-SVZ distance and IDH status were determined via univariate and multivariate analyses. In univariate analysis of tumor-SVZ distance, the patients were divided into three types (SVZ involvement, tumor-SVZ distance from 0 to 10 mm, and tumor-SVZ distance >10 mm). The results showed that the OS (p = 0.02) and PFS (p = 0.002) for the patients had a positive correlation with the tumor-SVZ distance. In addition, simple linear correlation found a significant relationship between the two parameters (OS and PFS) and tumor-SVZ distance in patients with non-SVZ-contacting glioma. Combination analysis of the tumor-SVZ distance and IDH status showed that IDH1 mutation and SVZ non-involvement enable favorable outcomes, whereas IDH1 wild type with SVZ involvement indicates a significantly worse prognosis in all patients. Moreover, in patients with non-SVZ-contacting glioma, IDH1 mutation concurrent with tumor-SVZ distance >10 mm has better OS and PFS. IDH1 wild type and tumor-SVZ distance from 0 to 10 mm suggest poorer OS and PFS. Multivariate analysis showed WHO grade IV, SVZ involvement, tumor-SVZ distance from 0 to 10 mm, IDH1 mutation, gross total resection, and chemotherapy serve as independent predictors of OS. WHO grade IV, SVZ involvement, tumor-SVZ distance from 0 to 10 mm, IDH1 mutation, and chemotherapy serve as independent predictors of PFS of patients with glioma. In conclusion, tumor-SVZ distance and IDH1 mutation status are the determinants affecting patient outcome.

Trends in physician reimbursements and procedural volumes for radiosurgery versus open surgery in brain tumor care: an analysis of Medicare data from 2009 to 2018

OBJECTIVE

Given its minimally invasive nature and effectiveness, stereotactic radiosurgery (SRS) has become a mainstay for the multimodal treatment of intracranial neoplasm. However, no studies have evaluated recent trends in the use of SRS versus those of open resection for the management of brain tumor or trends in the involvement of neurosurgeons in SRS (which is primarily delivered by radiation oncologists). Here, the authors used publicly available Medicare data from 2009 to 2018 to elucidate trends in the treatment of intracranial neoplasm and to compare reimbursements between these approaches.

METHODS

By using CPT Professional 2019, the authors identified 10 open resection and 9 SRS codes (4 for neurosurgery and 5 for radiation oncology) for the treatment of intracranial neoplasm. Medicare payments (inflation adjusted) and allowed services (number of reimbursed procedures) for each code were abstracted from the Centers for Medicare and Medicaid Services Part B National Summary Data File (2009-2018). Payments per procedure and procedures per 100,000 Medicare enrollees were analyzed with linear regression and compared with tests for equality of slopes (α = 0.05). The average payment per procedure over the study period was compared by using the 2-tailed Welsh unequal variances t-test, and more granular comparisons were conducted by using ANOVA with post hoc Tukey honestly significant difference (HSD) tests.

RESULTS

From 2009 to 2018, the number of SRS treatments per 100,000 Medicare enrollees for intracranial neoplasm increased by 3.97 cases/year (R2 = 0.99, p < 0.001), while comparable open resections decreased by 0.34 cases/year (R2 = 0.85, p < 0.001) (t16 = 7.5, p < 0.001). By 2018, 2.6 times more SRS treatments were performed per 100,000 enrollees than open resections (74.9 vs 28.7 procedures). However, neurosurgeon involvement in SRS treatment declined over the study period, from 23.4% to 11.5% of SRS treatments; simultaneously, the number of lesions treated per session increased from 1.46 to 1.84 (R2 = 0.98, p < 0.001). Overall, physician payments from 2013 to 2018 averaged $1816.08 (95% CI $1788.71-$1843.44) per SRS treatment and $1565.59 (95% CI $1535.83-$1595.34) per open resection (t10 = 15.9, p < 0.001). For neurosurgeons specifically, reimbursements averaged $1566 per open resection, but this decreased to $1031-$1198 per SRS session; comparatively, radiation oncologists were reimbursed even less (average $359-$898) per SRS session (p < 0.05 according to the Tukey HSD test for all comparisons).

CONCLUSIONS

Over a decade, the number of open resections for intracranial neoplasm in Medicare enrollees declined slightly, while the number of SRS procedures increased greatly. This latter expansion is largely attributable to radiation oncologists; meanwhile, neurosurgeons have shifted their involvement in SRS toward sessions for the management of multiple lesions.

Parenteral high‑dose ascorbate - A possible approach for the treatment of glioblastoma (Review)

For glioblastoma, the treatment with standard of care therapy comprising resection, radiation, and temozolomide results in overall survival of approximately 14-18 months after initial diagnosis. Even though several new therapy approaches are under investigation, it is difficult to achieve life prolongation and/or improvement of patient's quality of life. The aggressiveness and progression of glioblastoma is initially orchestrated by the biological complexity of its genetic phenotype and ability to respond to cancer therapy via changing its molecular patterns, thereby developing resistance. Recent clinical studies of pharmacological ascorbate have demonstrated its safety and potential efficacy in different cancer entities regarding patient's quality of life and prolongation of survival. In this review article, the actual glioblastoma treatment possibilities are summarized, the evidence for pharmacological ascorbate in glioblastoma treatment is examined and questions are posed to identify current gaps of knowledge regarding accessibility of ascorbate to the tumor area. Experiments with glioblastoma cell lines and tumor xenografts have demonstrated that high-dose ascorbate induces cytotoxicity and oxidative stress largely selectively in malignant cells compared to normal cells suggesting ascorbate as a potential therapeutic agent. Further investigations in larger cohorts and randomized placebo-controlled trials should be performed to confirm these findings as well as to improve delivery strategies to the brain, through the inherent barriers and ultimately to the malignant cells.

Guidelines in the management of CNS tumors

INTRODUCTION

Evidence-based, clinical practice guidelines in the management of central nervous system tumors (CNS) continue to be developed and updated through the work of the Joint Section on Tumors of the Congress of Neurological Surgeons (CNS) and the American Association of Neurological Surgeons (AANS).

METHODS

The guidelines are created using the most current and clinically relevant evidence using systematic methodologies, which classify available data and provide recommendations for clinical practice.

CONCLUSION

This update summarizes the Tumor Section Guidelines developed over the last five years for non-functioning pituitary adenomas, low grade gliomas, vestibular schwannomas, and metastatic brain tumors.

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

Background

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

Methods

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

Results

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

Conclusion

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

Long-term outcome of stereotactic brachytherapy with temporary Iodine-125 seeds in patients with WHO grade II gliomas

BACKGROUND

This long-term retrospective analysis aimed to investigate the outcome and toxicity profile of stereotactic brachytherapy (SBT) in selected low-grade gliomas WHO grade II (LGGII) in a large patient series.

METHODS

This analysis comprised 106 consecutive patients who received SBT with temporary Iodine-125 seeds for histologically verified LGGII at the University of Munich between March 1997 and July 2011. Investigation included clinical characteristics, technical aspects of SBT, the application of other treatments, outcome analyses including malignization rates, and prognostic factors with special focus on molecular biomarkers.

RESULTS

For the entire study population, the 5- and 10-years overall survival (OS) rates were 79% and 62%, respectively, with a median follow-up of 115.9 months. No prognostic factors could be identified. Interstitial radiotherapy was applied in 51 cases as first-line treatment with a median number of two seeds (range 1-5), and a median total implanted activity of 21.8 mCi (range 4.2-43.4). The reference dose average was 54.0 Gy. Five- and ten-years OS and progression-free survival rates after SBT were 72% and 43%, and 40% and 23%, respectively, with a median follow-up of 86.7 months. The procedure-related mortality rate was zero, although an overall complication rate of 16% was registered. Patients with complications had a significantly larger tumor volume (p = 0.029).

CONCLUSION

SBT is a minimally invasive treatment modality with a favorable outcome and toxicity profile. It is both an alternative primary treatment method as well as an adjunct to open tumor resection in selected low-grade gliomas.

Translational approaches to treating dynamical diseases through in silico clinical trials

The primary goal of drug developers is to establish efficient and effective therapeutic protocols. Multifactorial pathologies, including dynamical diseases and complex disorders, can be difficult to treat, given the high degree of inter- and intra-patient variability and nonlinear physiological relationships. Quantitative approaches combining mechanistic disease modeling and computational strategies are increasingly leveraged to rationalize pre-clinical and clinical studies and to establish effective treatment strategies. The development of clinical trials has led to new computational methods that allow for large clinical data sets to be combined with pharmacokinetic and pharmacodynamic models of diseases. Here, we discuss recent progress using in silico clinical trials to explore treatments for a variety of complex diseases, ultimately demonstrating the immense utility of quantitative methods in drug development and medicine.

Adult Diffuse Low-Grade Gliomas: 35-Year Experience at the Nancy France Neurooncology Unit

Background

To report survival, spontaneous prognostic factors, and treatment efficacy in a French monocentric cohort of diffuse low-grade glioma (DLGG) patients over 35 years of follow-up.

Methods

A monocentric retrospective study of 339 patients diagnosed with a new DLGG between 01/01/1982 and 01/01/2017 was created. Inclusion criteria were patient age ≥18 years at diagnosis and histological diagnosis of WHO grade II glioma (according to 1993, 2007, and 2016 WHO classifications). The survival parameters were estimated using the Kaplan-Meier method with a 95% confidence interval. Differences in survival were tested for statistical significance by the log-rank test. Factors were considered significant when p ≤ 0.1 and p ≤ 0.05 in the univariate and multivariate analyses, respectively.

Results

A total of 339 patients were included with a median follow-up of 8.7 years. The Kaplan-Meier median overall survival was 15.7 years. At the time of radiological diagnosis, Karnofsky Performance Status score and initial tumor volume were significant independent prognostic factors. Oncological prognostic factors were the extent of resection for patients who underwent surgery and the timing of radiotherapy for those concerned. In this study, patients who had delayed radiotherapy (provided remaining low grade) did not have worse survival compared with patients who had early radiotherapy. The functional capabilities of the patients were preserved enough so that they could remain independent during at least three quarters of the follow-up.

Conclusion

This large monocentric series spread over a long time clarifies the effects of different therapeutic strategies and their combination in the management of DLGG.

Clinical Management of Diffuse Low-Grade Gliomas

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

Low Expression of APOB mRNA or Its Hypermethylation Predicts Favorable Overall Survival in Patients with Low-Grade Glioma

Background

This study was performed to explore the clinical and prognostic significance of APOB mRNA expression, DNA methylation and APOB mutation in patients with low-grade glioma (LGG).

Methods

Bioinformatic analysis was conducted using genomic, clinical and survival data from The Cancer Genome Atlas (TCGA) and Chinese Glioma Genome Atlas (CGGA) databases. Serum APOB protein levels were measured via immunoturbidimetry in 150 patients with LGG and 100 healthy controls from Hubei General Hospital.

Results

There was a negative association between the levels of APOB mRNA and DNA methylation (r=−0.355, P<0.0001) in patients with LGG from the TCGA database. Additionally, LGG patients with low levels of APOB mRNA exhibited better overall survival (OS) than those with high levels of APOB mRNA (HR=0.637, P=0.0085). The survival time of LGG patients with APOB hypermethylation was markedly longer than that of patients with APOB hypomethylation (HR=0.423, P=0.0185). The prognostic significance of APOB mRNA and DNA methylation was also validated with the CGGA cohort, and a similar conclusion was reached. APOB gene mutations were observed in 3% of patients with LGG from the TCGA database, and no association was detected between APOB mutations and OS (P=0.164). Furthermore, the levels of APOB protein were much lower in patients with LGG than in normal individuals (P=0.0022), and the expression of APOB protein was markedly different among groups when stratified by histological type (P<0.0001) and histological-molecular classification (P<0.0001).

Conclusion

APOB mRNA expression is negatively regulated by DNA methylation in patients with LGG. Low expression or hypermethylation of APOB might predict relatively favorable survival in patients with LGG.

Molecular genetic profiling reveals novel association between FLT3 mutation and survival in glioma

INTRODUCTION

Recent molecular characterization of gliomas has uncovered somatic gene variation and DNA methylation changes that are associated with etiology, prognosis, and therapeutic response. Here we describe genomic profiling of gliomas assessed for associations between genetic mutations and patient outcomes, including overall survival (OS) and recurrence-free survival (RFS).

METHODS

Mutations in a 50-gene cancer panel, 1p19q co-deletion, and MGMT promoter methylation (MGMT methylation) status were obtained from tumor tissue of 293 glioma patients. Multivariable regression models for overall survival (OS) and recurrence-free survival (RFS) were constructed for MGMT methylation, 1p19q co-deletion, and gene mutations controlling for age, treatment status, and WHO grade.

RESULTS

Mutational profiles of gliomas significantly differed based on WHO Grade, such as high prevalence of BRAF V600E, IDH1, and PTEN mutations in WHO Grade I, II/III, and IV tumors, respectively. In multivariate regression analysis, MGMT methylation and IDH1 mutations were significantly associated with improved OS (HR = 0.44, p = 0.0004 and HR = 0.21, p = 0.007, respectively), while FLT3 and TP53 mutations were significantly associated with poorer OS (HR = 19.46, p < 0.0001 and HR = 1.67, p = 0.014, respectively). MGMT methylation and IDH1 mutations were the only significant alterations associated with improved RFS in the model (HR = 0.42, p < 0.0001 and HR = 0.37, p = 0.002, respectively). These factors were then included in a combined model, which significantly exceeded the predictive value of the base model alone (age, surgery, radiation, chemo, grade) (likelihood ratio test OS p = 1.64 × 10^-8 and RFS p = 3.80 × 10^-7).

CONCLUSIONS

This study highlights the genomic landscape of gliomas in a single-institution cohort and identifies a novel association between FLT3 mutation and OS in gliomas.

A three-lncRNA signature predicts clinical outcomes in low-grade glioma patients after radiotherapy

Although radiation therapy (RT) plays a critical role in the treatment of low-grade glioma (LGG), many patients suffer from adverse effects without experiencing survival benefits. In various carcinomas, long non-coding RNAs (lncRNAs) contribute to pathogenic processes, including tumorigenesis, metastasis, chemoresistance, and radioresistance. Currently, the role of lncRNAs in the radiosensitivity of LGG is largely unknown. Here, we downloaded clinical data for 167 LGG patients from The Cancer Genome Atlas database and divided them between radiosensitive and radioresistant groups based on their clinical outcomes after receiving radiotherapy. We identified 37 lncRNAs that were differentially expressed (DElncRNAs) between the groups. Functional enrichment analysis revealed that their potential target mRNAs were mainly enriched in the PI3K-Akt and MAPK signaling pathways and in DNA damage response. Kaplan-Meier survival analysis revealed that increased expression of six lncRNAs was significantly associated with radiosensitivity. We then developed a risk signature based on three of the DElncRNAs that served as an independent biomarker for predicting LGG patient outcomes after radiotherapy. In vitro experiments further validated the biological function of these lncRNAs on low-grade glioma radiation response.

Educational Case: Histologic and Molecular Features of Diffuse Gliomas

The following fictional cases are intended as a learning tool within the Pathology Competencies for Medical Education (PCME), a set of national standards for teaching pathology. These are divided into three basic competencies: Disease Mechanisms and Processes, Organ System Pathology, and Diagnostic Medicine and Therapeutic Pathology. For additional information, and a full list of learning objectives for all three competencies, seehttp://journals.sagepub.com/doi/10.1177/2374289517715040.¹

Acute and chronic hemorrhage from radiation-induced cavernous malformation associated with late-delayed radiation necrosis in long surviving glioma patients: A case report

Although radiation therapy is a standard treatment strategy for patients with glioma, its delayed complications are not clearly understood. Radiation-induced cavernous malformation (RICM) is one of the complications in the delayed phase following radiation therapy, which usually occurs in children. Herein we present three cases of RICM with radiation necrosis in long surviving adult glioma patients, 2 with oligoastrocytoma and one with anaplastic ependymoma. Two of three patients had received an obvious overdose of radiation by additional stereotactic radiation therapy. Repeated episodes of either acute or chronic hemorrhages from RICM worsened the neurological symptoms in all cases. The interval between the last irradiation and the occurrence of symptoms was 45-173 months. The presence of hypointense rim on FLAIR or T2* on magnetic resonance imaging, which resembles the appearance of sporadic cavernous malformations, could be helpful in differentiating RICM from tumor recurrence. Surgical resection was effective in alleviating the symptoms. Microscopically, RICM is a vascular lesion with vulnerable vessels, which are observed in the center of the radiation necrosis. Repeated hemorrhages from these vessels cause either gradual or sudden worsening of neurological symptoms. Therefore, radiation overdose, which results in radiation injury, should be avoided in low grade glioma patients, who could potentially survive for a long period.

The Treatment of Gliomas in Adulthood

BACKGROUND

Gliomas are the most common intrinsic tumors of the brain, with an incidence of 6 per 100 000 persons per year. Recent years have seen marked changes in the diagnosis and treatment of gliomas, with molecular parameters now being an integral part of the diagnostic evaluation.

METHODS

This review is based on pertinent articles retrieved by a selective search in PubMed, with special attention to the new WHO glioma classification.

RESULTS

The classification of gliomas on the basis of additional molecular parameters enables more accurate prognostication and serves as a basis for therapeutic decision-making and treatment according to precisely specified algorithms. PET scanning with 18F-fluoroethyl tyrosine and 11C-methionine for the measurement of metabolic activity in gliomas has further refined the diagnostic evaluation. The median overall survival of patients with glioblastoma who have undergone resection of all tumor tissue with a disrupted blood-brain barrier (i.e., all contrast-enhancing tumor tissue) has been prolonged to up to 20 months. The 5-year survival of patients with WHO grade II gliomas is now as high as 97% after near-total resection. The surgical resection of all contrast-enhancing tumor tissue and subsequent radiotherapy and chemotherapy remain the key elements of treatment. New surgical strategies and new methods of planning radiotherapy have made these techniques safer and more effective. The percutaneous application of tumor-treating fields is a new therapeutic option that has gained a degree of acceptance. Accompanying measures such as psycho-oncology and palliative care are very important for patients and should be considered mandatory.

CONCLUSION

The consistent application of the existing multimodal treatment options for glioma has led in recent years to improved survival. Areas of important current and future scientific activity include immunotherapy and targeted and combined chemotherapy, as well as altered neurocognition, modern approaches to palliative care, and complementary therapies.

Seizures in glioma patients: An overview of incidence, etiology, and therapies

Gliomas are fatal brain tumors, and even low-grade gliomas (LGGs) have an average survival of less than a decade. Seizures are a common presentation of gliomas, particularly LGGs, and substantially impact quality of life. Glioma-related seizures differ from other focal epilepsies in their pathogenesis and in the likelihood of refractory epilepsy. We review factors that predict seizure activity and response to treatment, optimal pharmacologic and surgical management of glioma-related epilepsy, and the benefit of using newer anti-seizure medications in patients with gliomas. As surgery is so often beneficial with seizure reduction, we discuss oncologic and epilepsy surgery perspectives. Treatment of gliomas has the potential to ameliorate seizures and increase rates of seizure freedom. Prospective, well-powered studies are needed to provide more definitive answers for practitioners taking care of glioma patients with seizures.

Computational design of improved standardized chemotherapy protocols for grade II oligodendrogliomas

Here we put forward a mathematical model describing the response of low-grade (WHO grade II) oligodendrogliomas (LGO) to temozolomide (TMZ). The model describes the longitudinal volumetric dynamics of tumor response to TMZ of a cohort of 11 LGO patients treated with TMZ. After finding patient-specific parameters, different therapeutic strategies were tried computationally on the 'in-silico twins' of those patients. Chemotherapy schedules with larger-than-standard rest periods between consecutive cycles had either the same or better long-term efficacy than the standard 28-day cycles. The results were confirmed in a large trial of 2000 virtual patients. These long-cycle schemes would also have reduced toxicity and defer the appearance of resistances. On the basis of those results, a combination scheme consisting of five induction TMZ cycles given monthly plus 12 maintenance cycles given every three months was found to provide substantial survival benefits for the in-silico twins of the 11 LGO patients (median 5.69 years, range: 0.67 to 68.45 years) and in a large virtual trial including 2000 patients. We used 220 sets of experiments in-silico to show that a clinical trial incorporating 100 patients per arm (standard intensive treatment versus 5 + 12 scheme) could demonstrate the superiority of the novel scheme after a follow-up period of 10 years. Thus, the proposed treatment plan could be the basis for a standardized TMZ treatment for LGO patients with survival benefits.

What Neuroradiologists Need to Know About Radiation Treatment for Neural Tumors

Radiation oncologists and radiologists have a unique and mutually dependent relationship. Radiation oncologists rely on diagnostic imaging to locate the tumor and define the treatment target volume, evaluation of response to therapy, and follow-up. Accurate interpretation of post-treatment imaging requires diagnostic radiologists to have a basic understanding of radiation treatment planning and delivery. There are various radiation treatment modalities such as 3D conformal radiation therapy, intensity modulated radiation therapy and stereotactic radiosurgery as well as different radiation modalities such as photons and protons that can be used for treatment. All of these have subtle differences in how the treatment is planned and how the imaging findings might be affected. This paper provides an overview of the basic principles of radiation oncology, different radiation treatment modalities, how radiation therapy is planned and delivered, how knowledge of this process can help interpretation of images, and how the radiologist can contribute to this process.

Evidence-based Treatment for Low-grade Glioma

OBJECTIVES

To identify the tumors included in the WHO classification of low-grade gliomas, and review the importance of molecular biomarkers and their implication for treatment, prognosis, and outcomes.

DATA SOURCES

Published research, clinical guidelines, educational articles in oncology journals, and Web-based resources.

CONCLUSION

Molecular neuropathology has influenced the reclassification of low-grade gliomas and, as such, has provided patient-specific treatments with improving outcomes.

IMPLICATIONS FOR NURSING PRACTICE

Nurses play a key role in patient education and communication with the patient's interdisciplinary care team. Understanding the molecular neuropathology that determine treatment recommendations and in turn recognizing and identifying complications provides improved patient/caregiver satisfaction and outcomes.

Patterns of care and outcomes of postoperative radiation for low-grade gliomas in United States hospitals

It is unclear whether there is a survival benefit with postoperative radiation for low-grade gliomas deemed to be high-risk. We sought to analyze patterns of care and outcomes of radiation use. We accessed the National Cancer Database to identify patients with WHO grade II oligodendroglioma or astrocytoma between 2010 and 2012. Multivariable logistic regression was used to identify predictors of radiation use and multivariable Cox regression was used to identify covariables associated with differences in survival. There were 1952 patients included in this study, of which 518 (26.5%) received postoperative radiation. The majority had oligodendroglioma histology (n = 1121, 57.4%) compared to astrocytoma (n = 831, 42.6%). There were 1626 patients who were either ≥40 years old or underwent a subtotal resection ("high-risk"), and from these 495 (30.4%) received postoperative radiation. On multivariable logistic regression treatment at an academic facility (OR 0.72) was associated with a lower likelihood of receiving postoperative radiation. Astrocytoma histology (OR 2.08), age ≥40 years (OR 2.23), tumor size ≥6 cm (OR 1.64), subtotal resection (OR 1.55), and chemotherapy use (OR 3.93) were associated with an increased likelihood of postoperative radiation. On multivariable analysis, astrocytoma histology (HR 3.49, p < 0.001) and receipt of radiation (HR 2.06, p < 0.001) were associated with worse overall survival. GTR (HR 0.51, p = 0.001) was associated with improved overall survival. Patients treated in United States hospitals are not routinely referred for postoperative radiation for high-risk, low-grade gliomas. Patients who received radiation did not do better than those who did not receive radiation.

Prognostic relevance of mutations and copy number alterations assessed with targeted next generation sequencing in IDH mutant grade II glioma

Background

At current prognostication of low grade glioma remains suboptimal and might be improved with additional markers. These may guide treatment decisions, in particular on early adjuvant therapy versus wait and see after surgery.

Methods

We used a targeted Next-Generation Sequencing panel to assess mutational and copy number status of selected genes and chromosomes in a consecutive series of adult grade II supratentorial glioma, and assessed the impact of molecular markers of interest on overall survival.

Results

207 IDH mutated grade II glioma samples were analyzed with a median follow-up of 6.9 years. Loss of region 9p21.3 did not show a correlation with outcome in IDH mutated 1p/19q-codeleted oligodendroglioma or IDH mutated astrocytoma. We found a significant shorter overall survival with univariable analysis in IDH mutated astrocytoma patients with trisomy of chromosome 7 (Log rank P = 0.044) and in IDH mutated 1p/19q-codeleted oligodendroglioma patients with a PTEN mutation (Log rank P = 0.033). We could not validate these findings in multivariate analysis or in the TCGA dataset.

Conclusions

Loss of 9p21.3 is not associated with outcome in a molecularly defined cohort of grade II glioma and therefore it remains unclear if loss of 9p21.3 can be used as additional marker of anaplasia or to guide treatment decisions. Trisomy of chromosome 7 in IDH mutated astrocytoma and PTEN mutations in IDH mutated oligodendroglioma are potential markers of poor prognosis, but require confirmation in larger series.

Electronic supplementary material

The online version of this article (10.1007/s11060-018-2867-8) contains supplementary material, which is available to authorized users.

Volumetric Modulated Arc (Radio) Therapy in Pets Treatment: The "La Cittadina Fondazione" Experience

Volumetric Modulated Arc Therapy (VMAT) is a modern technique, widely used in human radiotherapy, which allows a high dose to be delivered to tumor volumes and low doses to the surrounding organs at risk (OAR). Veterinary clinics takes advantage of this feature due to the small target volumes and distances between the target and the OAR. Sparing the OAR permits dose escalation, and hypofractionation regimens reduce the number of treatment sessions with a simpler manageability in the veterinary field. Multimodal volumes definition is mandatory for the small volumes involved and a positioning device precisely reproducible with a setup confirmation is needed before each session for avoiding missing the target. Additionally, the elaborate treatment plan must pursue hard constraints and objectives, and its feasibility must be evaluated with a per patient quality control. The aim of this work is to report results with regard to brain meningiomas and gliomas, trigeminal nerve tumors, brachial plexus tumors, adrenal tumors with vascular invasion and rabbit thymomas, in comparison with literature to determine if VMAT is a safe and viable alternative to surgery or chemotherapy alone, or as an adjuvant therapy in pets.

Impact of concurrent versus adjuvant chemotherapy on the severity and duration of lymphopenia in glioma patients treated with radiation therapy

Prolonged severe lymphopenia has been shown to persist beyond a year in glioma patients after radiation therapy (RT) with concurrent and adjuvant chemotherapy. This study examines the differential impact of concurrent versus adjuvant chemotherapy on lymphopenia after RT. WHO grade II-III glioma patients who received RT with concurrent and/or adjuvant chemotherapy from 2007 to 2016 were retrospectively analyzed. Concurrent chemotherapy was temozolomide (TMZ), and adjuvant chemotherapy was either TMZ or procarbazine/lomustine/vincristine (PCV). Absolute lymphocyte count (ALC) was analyzed at baseline, 1.5, 3, 6, and 12 months after the start of RT. Univariable and multivariable logistic regression were used to identify the clinical variables in predicting acute or late lymphopenia. There were 151 patients with evaluable ALC: 91 received concurrent and adjuvant TMZ (CRT + ADJ), 32 received only concurrent TMZ (CRT), and 28 received only adjuvant TMZ or PCV (ADJ). There were 9 (10%) versus 6 (19%) versus 0 (0%) cases of grade 3 lymphopenia (ALC < 500/mm³) at 6 weeks and 4 (6%) versus 0 (0%) versus 3 (17%) cases at 12 months in CRT + ADJ, CRT and ADJ groups, respectively. On multivariable analyses, concurrent chemotherapy (odds ratio [OR] 72.3, p < 0.001), female sex (OR 10.8, p < 0.001), and older age (OR 1.06, p = 0.002) were the most significant predictors for any grade ≥ 1 lymphopenia (ALC < 1000/mm³) at 1.5 months. Older age (OR 1.08, p = 0.02) and duration of adjuvant chemotherapy (OR 1.19, p = 0.003) were significantly associated with grade ≥ 1 lymphopenia at 12 months. Thus, concurrent chemotherapy appears as the dominant contributor to the severity of acute lymphopenia after RT in WHO grade II-III glioma patients, and duration of adjuvant chemotherapy appears as the key factor to prolonged lymphopenia.

Elevated expression of HSP10 protein inhibits apoptosis and associates with poor prognosis of astrocytoma

Astrocytoma is the most common type of primary malignant brain tumor, with pretty lowly 5-year survival rate in patients. Although extended surgical removal of the tumor and postoperative chemotherapy/radiotherapy executed, still there is large recurrence rate, mainly because diffuse glioma tumor cells ubiquitously infiltrate into normal parenchyma. So it becomes a priority to hunt novel molecular and signaling pathway targets to suppress astrocyma progression. HSP10, an important member of Heat shock proteins (Hsps) family, classically works as molecular chaperone folding or degradating of target proteins. Evolutionarily, HSP10 is also reported to be involved in immunomodulation and tumor progression. Poly (ADP-ribose) polymerase (PARP), important in DNA repair, is one of the main cleavage targets of caspase. And cleaved PARP (c-PARP) can serve as a marker of cells undergoing apoptosis. So far, whether the expression of HSP10 or c-PARP is associated with clinicopathologic implication for astrocytoma has not been reported. Meanwhile, it is unclear about the relationship between HSP10 and cell apoptosis. The purpose of this research is to elucidate the association between the expression of HSP10 and c-PARP and clinicopathological characteristics of astrocytoma by immunohistochemistry. The results showed that positive percentage of high HSP10 expression in astrocytoma 42/103, 40.8%) was significantly higher than that in the non-tumor control brain tissues (8/43, 18.6%) (P = 0.01). While no apparent difference of high c-PARP expression existed between astrocytoma and non-tumor control brain tissues. Furthermore, elevated expression of HSP10 was negative related to low expression of c-PARP (r = -0.224, P = 0.023), indicating high expression of HSP10 in astrocytoma inhibited apoptosis process effectively. And overexpression of HSP10 was proved to be the independent poor prognostic factor for astrocytoma by multivariate analysis. Taken together, our results suggest that elevated expression of HSP10 protein inhibits apoptosis and associates with poor prognosis of astrocytoma.

Management of diffuse low-grade gliomas in adults - use of molecular diagnostics

Diffuse WHO grade II gliomas are histologically and genetically heterogeneous. The 2016 WHO classification redefines grade II gliomas with respect to morphological and molecular tumour alterations: grade II oligodendrogliomas are defined by the presence of whole-arm codeletion in chromosomal arms 1p/19q, whereas isocitrate dehydrogenase (IDH) mutations define subclasses of astrocytoma. Although histological grade remains useful, the prognoses of patients with glioma are more tightly associated with molecular alterations than with grade, and chromosomal and gene array technologies are becoming increasingly beneficial in understanding tumour genetic heterogeneity. The indolent nature of the disease often creates subtle neurological symptoms that can be overlooked or misunderstood, resulting in delayed diagnosis. Seizures often herald the diagnosis, especially in patients who have IDH mutations, which are associated with an increased production of 2-hydroxyglutarate. Treatment paradigms have shifted, owing to new diagnostic criteria and new clinical trial evidence. Patients benefit more from chemoradiation than radiation alone, especially those with tumour IDH1 Arg132His mutations; gross total resection of the tumour, including tumours with IDH mutations, is associated with prolonged survival. Initial observation remains appropriate in patients whose rate of disease growth is not yet completely defined; such patients could include those with completely resected disease and those with 1p/19q codeleted tumours.

Impact of Resection on Survival of Isocitrate Dehydrogenase 1-Mutated World Health Organization Grade II Astrocytoma After Malignant Progression

OBJECTIVE

To evaluate the impact of surgical resection and adjuvant treatment on the course of patients after malignant progression of previously treated isocitrate dehydrogenase 1 (IDH1)-mutated World Health Organization (WHO) grade II astrocytoma.

METHODS

This retrospective study explored 56 patients undergoing tumor resection for malignant progression after previously treated IDH1-mutated WHO grade II astrocytoma. We analyzed survival after malignant progression, analyzed overall survival (OS), and identified prognostic factors using Kaplan-Meier estimates and log-rank test.

RESULTS

By the time of malignant transformation, median age was 44 years, and median Karnofsky Performance Status (KPS) score was 90. Complete resection of contrast-enhancing tissue was achieved in 18 (32.1%) patients. Median survival after re-resection was 33 months (95% confidence interval [CI], 20-46); median OS was 123 months (95% CI, 77-170). Gross total tumor resection, postoperative KPS score ≥80, adjuvant radiochemotherapy, and prior radiotherapy significantly correlated with post-malignant progression survival.

CONCLUSIONS

Patients in good clinical condition with malignant progression of previously treated low-grade gliomas should receive aggressive treatment, including re-resection.

Induction of G1 Cell Cycle Arrest in Human Glioma Cells by Salinomycin Through Triggering ROS-Mediated DNA Damage In Vitro and In Vivo

Chemotherapy has always been one of the most effective ways in combating human glioma. However, the high metastatic potential and resistance toward standard chemotherapy severely hindered the chemotherapy outcomes. Hence, searching effective chemotherapy drugs and clarifying its mechanism are of great significance. Salinomycin an antibiotic shows novel anticancer potential against several human tumors, including human glioma, but its mechanism against human glioma cells has not been fully elucidated. In the present study, we demonstrated that salinomycin treatment time- and dose-dependently inhibited U251 and U87 cells growth. Mechanically, salinomycin-induced cell growth inhibition against human glioma was mainly achieved by induction of G1-phase arrest via triggering reactive oxide species (ROS)-mediated DNA damage, as convinced by the activation of histone, p53, p21 and p27. Furthermore, inhibition of ROS accumulation effectively attenuated salinomycin-induced DNA damage and G1 cell cycle arrest, and eventually reversed salinomycin-induced cytotoxicity. Importantly, salinomycin treatment also significantly inhibited the U251 tumor xenograft growth in vivo through triggering DNA damage-mediated cell cycle arrest with involvement of inhibiting cell proliferation and angiogenesis. The results above validated the potential of salinomycin-based chemotherapy against human glioma.