Neurocognitive Function Following Therapy for Low-Grade Gliomas

Longitudinal analysis of cognitive function in patients treated with postoperative radiotherapy for grade 2 and 3 IDH mutant diffuse glioma

BACKGROUND

Postoperative radiotherapy and chemotherapy improve survival in IDH mutant diffuse glioma. We investigated whether neurocognitive function declines over time, and whether mean dose to the brain outside of CTV (mean brain dose) is related to neurocognitive function.

PATIENTS AND METHODS

Patients that underwent resection and postoperative radiotherapy for grade 2 or 3 IDH mutant diffuse glioma were tested using the Hopkins Verbal Learning Test, Letter Fluency and Trail Making Test before surgery and afterwards up until disease progression. Mixed effects models were fitted for each of three cognitive test scores, using time from surgery, mean brain dose, CTV volume, and tumor grade as fixed effects.

RESULTS

Between 1-10-2013 and 31-12-2022, 49 patients underwent longitudinal neurocognitive testing. Average mean dose to brain minus CTV was 17.8 Gy (95 % CI 16.1 - 19.4). At the time of analysis, median follow-up in patients free from disease progression was 5.8 years (range 1.1 - 20.8). Attrition rate during the first five years of follow up was 14.1 %. There was no decline of test performance over time (p ≥ 0.526). However, there was a negative effect of increasing mean brain dose on TMT score A (-0.11, p = 0.008) and TMT score B (-0.13, p = 0.004).

CONCLUSIONS

In this study, no effect of time after resection on test scores was found. Multivariable modelling indicates an negative relationship between mean brain dose and specific neurocognitive test scores, accounting for effects of tumor grade and CTV volume.

Long-term quality of survival after pediatric low-grade glioma

BACKGROUND

Low-grade glioma is the most common brain tumor in children with different modes of treatment and a high overall survival. Low-grade glioma is considered a chronic disease, since residual tumor is present in many children. The tumor and its treatment lead to acquired brain injury with diverse consequences for later life based on factors like the diverse tumor locations, treatment(s) applied, neurofibromatosis type 1, and age at diagnosis.

METHODS

An overview of affected domains is provided based upon cohort studies from literature and partially based on clinical experience with a practical approach regarding each domain of functioning in order to provide insight in the requirements for long-term care assistance after childhood low-grade glioma.

RESULTS

The diverse domains that can potentially be affected are described as follows: motor function, speech, eating and swallowing, sensory functions, seizures, neuropathy, organ function after systemic treatment, late effects due to cranial radiation (vascular changes and secondary tumors, endocrine and hypothalamic function, sleep and energy, neuro-cognition and education, psychosocial effects, and quality of life.

CONCLUSION

Insight in affected domains guides advices for medical follow-up, diagnostics, supportive instructions, and assistive measures per domain of functioning and provide insight in the requirements for long-term care assistance after childhood low-grade glioma.

Oncological Outcomes, Long-Term Toxicities, Quality of Life and Sexual Health after Pencil-Beam Scanning Proton Therapy in Patients with Low-Grade Glioma

PURPOSE

To assess oncological outcomes, toxicities, quality of life (QoL) and sexual health (SH) of low-grade glioma (LGG) patients treated with pencil-beam scanning proton therapy (PBS-PT).

MATERIAL AND METHODS

We retrospectively analyzed 89 patients with LGG (Neurofibromatosis type 1; n = 4 (4.5%) patients) treated with PBS-PT (median dose 54 Gy (RBE)) from 1999 to 2022 at our institution. QoL was prospectively assessed during PBS-PT and yearly during follow-up from 2015 to 2023, while a cross-sectional exploration of SH was conducted in 2023.

RESULTS

Most LGGs (n = 58; 65.2%) were CNS WHO grade 2 and approximately half (n = 43; 48.3%) were located in the vicinity of the visual apparatus/thalamus. After a median follow-up of 50.2 months, 24 (27%) patients presented with treatment failures and most of these (n = 17/24; 70.8%) were salvaged. The 4-year overall survival was 89.1%. Only 2 (2.2%) and 1 (1.1%) patients presented with CTCAE grade 4 and 3 late radiation-induced toxicity, respectively. No grade 5 late adverse event was observed. The global health as a domain of QoL remained stable and comparable to the reference values during PBS-PT and for six years thereafter. Sexual satisfaction was comparable to the normative population.

CONCLUSIONS

LGG patients treated with PBS-PT achieved excellent long-term survival and tumor control, with exceptionally low rates of high-grade late toxicity, and favorable QoL and SH.

Subjective executive dysfunction in patients with primary brain tumors and their informants: relationships with neurocognitive, psychological, and daily functioning

OBJECTIVE

We assessed agreement between patient- and informant-report on the Behavior Rating Inventory of Executive Function - Adult (BRIEF-A) in patients with primary brain tumors (PBT) and differences on BRIEF-A in neurocognitive (intact v. impaired), psychological (asymptomatic v. distressed), and functional (independent v. dependent) categories using both patient- and informant-report.

METHOD

PBT patients (n = 102) completed neuropsychological evaluations including the BRIEF-A, clinical interview, neurocognitive tests, and mood questionnaires. Correlations between the BRIEF-A and Informant (n = 39) were conducted. Differences in patient and informant BRIEF-A indices were investigated across five classifications: neurocognitive functioning, psychological functioning, medication management, appointment management, and finance management.

RESULTS

Patient and informant BRIEF were correlated. There was no difference on BRIEF-A or Informant indices for intact v. impaired neurocognitive status. Higher BRIEF-A and Informant indices were observed among psychologically distressed v. asymptomatic patients. Results showed higher BRIEF indices among those requiring assistance with medication, appointments, and finances.

CONCLUSIONS

Patients and informants agreed in their reports of executive function (EF). These reports, while not different in neurocognitive classification, were different in psychological functioning and in those needing assistance with instrumental activities of daily living (IADL). Patient- and informant-reported EF may provide important data regarding psychological and IADL functioning in this population.

Associations between patient-reported outcomes and radiation dose in patients treated with radiation therapy for primary brain tumours

AIM

This study aimed to explore associations between radiation dose and patient-reported outcomes in patients with a primary non-glioblastoma brain tumour treated with radiation therapy (RT), with a focus on health-related quality-of-life (HRQoL) and self-reported cognitive function.

METHODS

In this cross-sectional study, 78 patients who had received RT for a non-glioblastoma primary brain tumour, underwent neuropsychological testing and completed questionnaires on HRQoL, cognitive function, fatigue, depression, anxiety and perceived stress. The study explores the association between HRQoL scores, self-reported cognitive function and radiation doses to total brain, brainstem, hippocampus, thalamus, temporal lobes and frontal lobes. In addition, we examined correlations between neuropsychological test scores and self-reported cognitive function.

RESULTS

The median time between RT and testing was 4.6 years (range 1-9 years). Patients who had received high mean radiation doses to the total brain had low HRQoL scores (Cohen's d = 0.50, p = 0.04), brainstem (d = 0.65, p = 0.01) and hippocampus (d = 0.66, p = 0.01). High mean doses to the total brain were also associated with low scores on self-reported cognitive functioning (Cohen's d = 0.64, p = 0.02), brainstem (d = 0.55, p = 0.03), hippocampus (d = 0.76, p < 0.01), temporal lobes (d = 0.70, p < 0.01) and thalamus (d = 0.64, p = 0.01). Self-reported cognitive function correlated well with neuropsychological test scores (correlation range 0.27-0.54.).

CONCLUSIONS

High radiation doses to specific brain structures may be associated with impaired HRQoL and self-reported cognitive function with potentially negative implications to patients' daily lives. Patient-reported outcomes of treatment-related side-effects and their associations with radiation doses to the brain and its sub-structures may provide important information on radiation tolerance to the brain and sub-structures.

Working memory training for adult glioma patients: a proof-of-concept study

BACKGROUND

CogMed Working Memory Training (CWMT) is a computer-based program shown to improve working memory (WM) among those with cognitive impairments. No study to date has investigated its feasibility, acceptability, and satisfaction in adult patients with glioma, despite the well-documented incidence of WM impairment in this population.

METHODS

Twenty patients with glioma and objective and/or perceived WM deficits enrolled in the study: 52% high-grade, 60% female, Mage = 47 (range = 21-72 years). Adverse events were monitored to determine safety. Feasibility and acceptability were assessed based on established metrics. Satisfaction was explored by exit-interviews. Neurocognitive tests and psychological symptoms were analyzed at baseline and post-CWMT to estimate effect sizes.

RESULTS

Of 20 enrolled patients, 16 completed the intervention (80% retention rate). Reasons for withdrawal included time burden (n = 2); tumor-related fatigue (n = 1) or loss to follow-up (n = 1). No adverse events were determined to be study-related. Adherence was 69% with reasons for nonadherence similar to those for study withdrawal. The perceived degree of benefit was only moderate. Baseline to post-CWMT assessments showed medium to large effects on neurocognitive tasks. Psychological symptoms remained stable throughout the study period.

CONCLUSIONS

CWMT was found to be safe and acceptable in adult patients with glioma. Enrollment, retention rates, and treatment adherence were all adequate and comparable to studies recruiting similar populations. Only moderate perceived benefit was reported despite demonstrated improvements in objectively-assessed WM. This may indicate that the time commitment and intervention intensity (5 weeks of 50-min training sessions on 5 days/week) outweighed the perceived benefits of the program. (Trial Registration Number: NCT03323450 registered on 10/27/2017).

Neuropsychological assessments before and after awake surgery for incidental low-grade gliomas

OBJECTIVE

Early surgery in presumed asymptomatic patients with incidental low-grade glioma (ILGG) has been suggested to improve maximal resection rates and overall survival. However, no study has reported on the impact of such preventive treatment on cognitive functioning. The aim of this study was to investigate neuropsychological outcomes in patients with ILGG who underwent preventive surgery.

METHODS

This was a retrospective analysis of a consecutive series of patients with ILGG who underwent awake surgery and who had presurgical and 3-month postsurgical neuropsychological assessments. Data were normalized into z-scores and regrouped by cognitive domains. Clinicoradiological data, histomolecular profile, and differences in z-scores (Δz-scores) were analyzed.

RESULTS

Forty-seven patients were included (mean age 39.2 ± 11.3 years). Twenty-eight patients (59.6%) underwent supratotal or total resections. All patients were still alive after a mean follow-up of 33.0 ± 30.8 months. Forty-one patients (87.2%) had stable (n = 34, 72.3%) or improved (Δz-score > 1; n = 7, 14.9%) neurocognitive outcomes after surgery. Six patients (12.8%) presented a slight impairment (Δz-score < -1) in at least one cognitive domain. The mean presurgical and postsurgical z-scores were comparable except in the psychomotor speed and attention domain. A significant correlation between presurgical executive functioning and tumor volume was reported, whereas the extent of resection and histomolecular profile did not impact neuropsychological outcomes.

CONCLUSIONS

Early surgical treatment in presumed asymptomatic patients with ILGG was associated with stable or improved neuropsychological outcomes in 87.2% of patients at 3 months, with only mild cognitive decline observed in 6 patients. In return, supratotal or total resections were achieved in most patients, and all patients were still alive at the end of the follow-up.

Vorasidenib, a Dual Inhibitor of Mutant IDH1/2, in Recurrent or Progressive Glioma; Results of a First-in-Human Phase I Trial

PURPOSE

Lower grade gliomas (LGGs) are malignant brain tumors. Current therapy is associated with short- and long-term toxicity. Progression to higher tumor grade is associated with contrast enhancement on MRI. The majority of LGGs harbor mutations in the genes encoding isocitrate dehydrogenase 1 or 2 (IDH1/IDH2). Vorasidenib (AG-881) is a first-in-class, brain-penetrant, dual inhibitor of the mutant IDH1 and mutant IDH2 enzymes.

PATIENTS AND METHODS

We conducted a multicenter, open-label, phase I, dose-escalation study of vorasidenib in 93 patients with mutant IDH1/2 (mIDH1/2) solid tumors, including 52 patients with glioma that had recurred or progressed following standard therapy. Vorasidenib was administered orally, once daily, in 28-day cycles until progression or unacceptable toxicity. Enrollment is complete; this trial is registered with ClinicalTrials.gov, NCT02481154.

RESULTS

Vorasidenib showed a favorable safety profile in the glioma cohort. Dose-limiting toxicities of elevated transaminases occurred at doses ≥100 mg and were reversible. The protocol-defined objective response rate per Response Assessment in Neuro-Oncology criteria for LGG in patients with nonenhancing glioma was 18% (one partial response, three minor responses). The median progression-free survival was 36.8 months [95% confidence interval (CI), 11.2-40.8] for patients with nonenhancing glioma and 3.6 months (95% CI, 1.8-6.5) for patients with enhancing glioma. Exploratory evaluation of tumor volumes in patients with nonenhancing glioma showed sustained tumor shrinkage in multiple patients.

CONCLUSIONS

Vorasidenib was well tolerated and showed preliminary antitumor activity in patients with recurrent or progressive nonenhancing mIDH LGG.

Effects of brain radiotherapy on cognitive performance in adult low-grade glioma patients: A systematic review

Grade II gliomas are slow growing tumours that usually affect younger patients. The mainstream treatment modality at present is surgical. The role of radiation therapy in the management of grade II gliomas has been the subject of considerable debate. Radiation therapy has a proven potential to prolong progression free and overall survival in high-risk patients, but may also produce long-term cognitive deficits. Since grade II glioma patients are expected to live several years, retention of cognitive capacity and quality of life is an equally important endpoint as prolonging progression free survival. Our overarching goal is to critically review the available evidence on the possible neuropsychological effects of postoperative radiotherapy in adult grade II glioma patients. We performed a systematic literature search in Medline, Embase and Cochrane databases up to 1st of May 2020 for studies assessing the cognitive effects of radiation therapy on grade II glioma patients. Eleven studies meeting our inclusion criteria provide either negative or contradictory data regarding the cognitive domains affected, while major confounding variables remain incompletely addressed. The available evidence does not adequately support the notion that current radiation therapy protocols independently produce substantial cognitive decline in grade II glioma patients and therefore it would be premature to argue that radiation associated cognitive morbidity outweighs the benefit of prolonged survival. A large prospective study incorporating a full battery of neuropsychological testing, sufficiently long-term follow-up period and tight control of confounders is due to provide high quality data.

Long-term cognitive deficits in pediatric low-grade glioma (LGG) survivors reflect pretreatment conditions-report from the German LGG studies

Background

Disease and treatment contribute to cognitive late effects following pediatric low-grade glioma (LGG). We analyzed prospectively collected neuropsychological data of German pediatric LGG survivors and focused on the impact of hydrocephalus at diagnosis, neurofibromatosis type 1 (NF1) status, and extent of surgery.

Methods

We used the Neuropsychological Basic Diagnostic screening tool based on the Cattell-Horn-Carroll model for intelligence and the concept of cross-battery assessment at 2 and 5 years from diagnosis for 316 patients from the German pediatric LGG study and LGG registry (7.1 years median age; 45 NF1; cerebral hemispheres 16%, supratentorial midline 39%, infratentorial 45%). Hydrocephalus was classified radiologically in 137 non-NF1 patients with infratentorial tumors (95/137 complete/subtotal resection).

Results

Patients with NF1 versus non-NF1 exhibited inferior verbal short-term memory and visual processing (P < .001-.021). In non-NF1 patients, infratentorial tumor site and complete/subtotal resection were associated with sequelae in visual processing, psychomotor speed, and processing speed (P < .001-.008). Non-NF1 patients without surgical tumor reduction and/or nonsurgical treatment experienced similar deficits. Degree of hydrocephalus at diagnosis had no further impact. Psychomotor and processing speed were impaired comparably following chemo-/radiotherapy (P < .001-.021). Pretreatment factors such as NF1 or tumor site were relevant at multivariate analysis.

Conclusions

All pediatric LGG survivors are at risk to experience long-term cognitive impairments in various domains. Even surgical only management of cerebellar LGG or no treatment at all, that is, biopsy only/radiological diagnosis did not protect cognitive function. Since pattern and extent of deficits are crucial to tailor rehabilitation, neuropsychological and quality of survival assessments should be mandatory in future LGG trials.

Evaluation of the Hippocampal Normal Tissue Complication Model in a Prospective Cohort of Low Grade Glioma Patients-An Analysis Within the EORTC 22033 Clinical Trial

Purpose: To evaluate the performance of the hippocampal normal tissue complication model that relates dose to the bilateral hippocampus to memory impairment at 18 months post-treatment in a population of low-grade glioma (LGG) patients.

Methods: LGG patients treated within the radiotherapy-only arm of the EORTC 22033-26033 trial were analyzed. Hippocampal dose parameters were calculated from the original radiotherapy plans. Difference in Rey Verbal Auditory Learning test delayed recall (AVLT-DR) performance pre-and 18 (±4) months post-treatment was compared to reference data from the Maastricht Aging study. The NTCP model published by Gondi et al. was applied to the dosimetric data and model predictions were compared to actual neurocognitive outcome.

Results: A total of 29 patients met inclusion criteria. Mean dose in EQD2 Gy to the bilateral hippocampus was 39.8 Gy (95% CI 34.3–44.4 Gy), the median dose to 40% of the bilateral hippocampus was 47.2 EQD2 Gy. The model predicted a risk of memory impairment exceeding 99% in 22 patients. However, only seven patients were found to have a significant decline in AVLT-dr score.

Conclusions: In this dataset of only LGG patients treated with radiotherapy the hippocampus NTCP model did not perform as expected to predict cognitive decline based on dose to 40% of the bilateral hippocampus. Caution should be taken when extrapolating this model outside of the range of dose-volume parameters in which it was developed.

Long-term cognitive dysfunction after radiation therapy for primary brain tumors

Background: The extent of radiation therapy (RT)-induced changes in cognitive function is unknown. RT with protons instead of photons spares the healthy brain tissue more and is believed to reduce the risk of cognitive dysfunction. There is modest knowledge on which parts of the brain we need to spare, to prevent cognitive dysfunction. To uncover which cognitive domains is most affected, we compared cognitive functioning in brain tumor patients treated with neurosurgery and RT with brain tumor patients treated with neurosurgery alone. Methods: A cross-sectional study assessing cognitive function in 110 patients with a primary brain tumor grades I-III or medulloblastoma (grade IV) treated at Aarhus University Hospital (AUH), Denmark between 2006 and 2016. Two cohorts were established: a cohort of 81 brain tumor patients who had received neurosurgery followed by RT (RT+), and a cohort of 29 brain tumor patients who had only received neurosurgery (RT-). The patients underwent questionnaires and neuropsychological assessment with standardized tests. Results: Mean age was 53.5 years with an average time since diagnosis of 7.3 years. Compared with normative data, lower average scores were observed for the entire group on domains concerning of verbal learning and memory (p < .001), attention and working memory (p < .001), processing speed (p < .001), and executive functioning (p < .001). Compared to RT- patients, RT + patients scored lower on domains concerning processing speed (p = .04) and executive function (p = .05) and had higher impairment frequency on verbal fluency (p = .02) with 16% of patients exceeding 1.5 SD below normative data. Conclusions: Our results indicate that treatment, including RT, for a primary brain tumor may have negative long-term impact on cognitive function, especially on processing speed and executive function.

Controversies in the Therapy of Low-Grade Gliomas

OPINION STATEMENT

In the context of the new WHO classification system, all low-grade gliomas must have an IDH mutation, with or without 1p/19q codeletion. Upon discovery of the tumor, maximal safe surgical resection is the most appropriate first step due to the current inability to differentiate between IDH mutant and IDH wild-type tumors by imaging alone. In the postoperative setting, based on the synthesis and interpretation of the available data, we recommend utilizing conventional radiation therapy and PCV in all high-risk-low-grade gliomas. For patients felt to be in a low risk category, we recommend maintaining a low threshold to initiate treatment. In the setting of tumor recurrence, consideration of all treatment options is reasonable, but treatment with alkylator therapy has the strongest supporting data.

Executive dysfunction in neuro-oncology: Behavior Rating Inventory of Executive Function in adult primary brain tumor patients

Adult primary brain tumor (PBT) survivors report persistent cognitive difficulties before, during, and after treatment, which are problematic for everyday functioning. Cognitive domains often affected by cancer treatment appear to be attention and executive functioning (EF). One validated measure developed to assess an individual's EF within daily living is the Behavior Rating Inventory of Executive Function-Adult (BRIEF-A). To date, no published research has investigated the EF profile of PBT patients using the BRIEF-A. Seventy-four PBT patients completed the BRIEF-A. Descriptive analyses were conducted to determine the self-reported EF profile in PBT patients. T-tests preliminarily compared the performance of PBT patients to four other comparison groups: mild cognitive impairment (MCI; n = 23), attention-deficit/hyperactivity disorder-unmedicated (ADHD-U; n = 27), traumatic brain injury (TBI; n = 23), and healthy controls (HC; n = 26). PBT BRIEF-A group means were average across subscales and indexes, yet the prevalence of significant elevations ranged from 12 to 50%. The Metacognition Index demonstrated 38% elevation prevalence compared to 22% in Behavioral Regulation. Approximately 61% of the sample had at least one clinically elevated scaled score. PBT patients reported significantly more EF impairment than HC and significantly less than ADHD-U. No significant differences were found between the PBT and MCI groups or PBT and TBI groups. Despite group means not reaching clinical impairment, a substantial proportion of patients with PBTs endorse executive dysfunction. Elevations were most prominent in metacognitive abilities over behavioral dysregulation. Notably, the EF profile of PBT patients was remarkably similar to that of MCI and TBI, increased when compared to HC, and well below ADHD-U.

Improvement in cognitive function after surgery for low-grade glioma

OBJECTIVE

Cognition is a key component in health-related quality of life (HRQoL) and is currently incorporated as a major parameter of outcome assessment in patients treated for brain tumors. The effect of surgery on cognition and HRQoL remains debatable. The authors investigated the impact of resection of low-grade gliomas (LGGs) on cognition and the correlation with various histopathological markers.

METHODS

A retrospective analysis of patients with LGG who underwent craniotomy for tumor resection at a single institution between 2010 and 2014 was conducted. Of 192 who underwent resective surgery for LGG during this period, 49 had complete pre- and postoperative neurocognitive evaluations and were included in the analysis. These patients completed a full battery of neurocognitive tests (memory, language, attention and working memory, visuomotor organization, and executive functions) pre- and postoperatively. Tumor and surgical characteristics were analyzed, including volumetric measurements and histopathological markers (IDH, p53, GFAP).

RESULTS

Postoperatively, significant improvement was found in memory and executive functions. A subgroup analysis of patients with dominant-side tumors, most of whom underwent intraoperative awake mapping, revealed significant improvement in the same domains. Patients whose tumors were on the nondominant side displayed significant improvement only in memory functions. Positive staining for p53 testing was associated with improved language function and greater extent of resection in dominant-side tumors. GFAP positivity was associated with improved memory in patients whose tumors were on the nondominant side. No correlation was found between cognitive outcome and preoperative tumor volume, residual volume, extent of resection, or IDH1 status.

CONCLUSIONS

Resection of LGG significantly improves memory and executive function and thus is likely to improve functional outcome in addition to providing oncological benefit. GFAP and pP53 positivity could possibly be associated with improved cognitive outcome. These data support early, aggressive, surgical treatment of LGG.

Repeatable Battery for the Assessment of Neuropsychological Status (RBANS): preliminary utility in adult neuro-oncology

Background

Neurocognitive assessments have become integral to comprehensive neuro-oncology care. Existing screening tools may be insensitive to cognitive changes caused by medical treatments. Research supports the clinical value and psychometric properties of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) in various medical populations; however, there is minimal evidence for its use in neuro-oncology. The purpose of the current study was to further explore the cognitive profile of patients with primary brain tumor (PBT) using the RBANS and to assess rates of below-expectation performance compared to normative data and estimated intellectual functioning.

Methods

Data were collected on 82 PBT patients (54% male; age range, 19-81 years). All patients were administered the RBANS-Update and the Advanced Clinical Solutions-Test of Premorbid Functioning (TOPF) according to standardized instructions. Cognitive strengths and weaknesses were identified for PBT patients. Descriptive analyses, t tests, and chi-squared tests were utilized to identify and compare cognitive profiles.

Results

Overall, cognitive performance was low average for PBT patients. When compared to standardization data, PBT patients performed significantly worse across all 5 RBANS indexes, with Attention and Memory showing the largest discrepancies. Estimated intelligence analyses reflected greater deficits in cognitive functioning than when compared to a normal distribution.

Conclusions

Preliminary research demonstrates the RBANS is an efficient screening tool to assess cognitive deficits in PBT patients. Data also support the importance of comparison to self, rather than normative distribution in ensuring proper identification and classification of patients.

Radiotherapy in the Management of Paediatric Low-Grade Gliomas

Paediatric low-grade (World Health Organization grade I-II) gliomas (LGGs) represent a spectrum of primary central nervous system tumours. Local tumour control is the cornerstone in the general management of childhood gliomas. Surgery is the primary treatment of choice in the majority. Non-surgical treatments are recommended for progressive or symptomatic inoperable disease. Although chemotherapy is increasingly used as first non-surgical treatment, radiotherapy remains standard as salvage treatment or as primary treatment in selected cases in which surrounding normal tissue can be optimally preserved. The role of targeted therapies is currently under investigation in clinical trials. Modern high-precision radiotherapy techniques, including proton therapy, have the potential to improve long-term toxicities. There is therefore an urgent need for prospective studies to compare the efficacy and safety of modern radiotherapy with systemic treatment in children with LGGs. New information on molecular genetic patterns in LGGs may also have an impact on the selection and sequencing of radiotherapy.

Chemotherapy for adult low-grade gliomas: clinical outcomes by molecular subtype in a phase II study of adjuvant temozolomide

Background

Optimal adjuvant management of adult low-grade gliomas is controversial. Recently described tumor classification based on molecular subtype has the potential to individualize adjuvant therapy but has not yet been evaluated as part of a prospective trial.

Methods

Patients aged 18 or older with newly diagnosed World Health Organization grade II low-grade gliomas and gross residual disease after surgical resection were enrolled in the study. Patients received monthly cycles of temozolomide for up to 1 year or until disease progression. For patients with available tissue, molecular subtype was assessed based upon 1p/19q codeletion and isocitrate dehydrogenase-1 R132H mutation status. The primary outcome was radiographic response rate; secondary outcomes included progression-free survival (PFS) and overall survival (OS).

Results

One hundred twenty patients were enrolled with median follow-up of 7.5 years. Overall response rate was 6%, with median PFS and OS of 4.2 and 9.7 years, respectively. Molecular subtype was associated with rate of disease progression during treatment (P<.001), PFS (P=.007), and OS (P<.001). Patients with 1p/19q codeletion demonstrated a 0% risk of progression during treatment. In an exploratory analysis, pretreatment lesion volume was associated with both PFS (P<.001) and OS (P<.001).

Conclusions

While our study failed to meet the primary endpoint for objective radiographic response, patients with high-risk low-grade glioma receiving adjuvant temozolomide demonstrated a high rate of radiographic stability and favorable survival outcomes while meaningfully delaying radiotherapy. Patients with 1p/19q codeletion are potential candidates for omission of adjuvant radiotherapy, but further work is needed to directly compare chemotherapy with combined modality therapy.

Identifying clinical risk in low grade gliomas and appropriate treatment strategies, with special emphasis on the role of surgery

INTRODUCTION

Diffuse low-grade glioma (DLGG) is a chronic tumoral disease that ineluctably grows, migrates along white matter pathways, and progresses to a higher grade of malignancy. Areas covered: To determine the best individualized treatment attitude for each DLGG patient, and to redefine it over the years, i.e. to optimize the 'onco-functional balance' of serial and multimodal therapies, the understanding of the natural history of this chronic disease is crucial but not sufficient. A paradigmatic shift is to tailor the individual management according to the dynamic relationships between DLGG course and neural remodeling. In this spirit, a better knowledge of brain plasticity in a connectomal account of cerebral processing has enabled a dramatic improvement of both oncological and functional outcomes in DLGG patients, by increasing overall survival while preserving (or even improving) the quality of life. Expert commentary: Here, we propose an individualized and recursive therapeutic strategy in DLGG, leading to the concept of a 'personalized functional neuro-oncology', by emphasizing the role of early and maximal safe surgical resection(s) reliably achieved using intraoperative mapping of cortico-subcortical networks in awake patients.

Reducing radiation dose to normal brain through a risk adapted dose reduction protocol for patients with favourable subtype anaplastic glioma

AIM

In patients with isocitrate dehydrogenase (IDH) mutated anaplastic glioma determine the dosimetric benefits of delivering radiation therapy using a PET guided integrated boost IMRT technique (ib-IMRT) compared with standard IMRT (s-IMRT) in reducing dose to normal brain.

METHODS

Ten patients with anaplastic glioma, identified as a favourable molecular subgroup through presence of IDH mutation, and managed with radiation therapy using an ib-IMRT were enrolled into a dosimetric study comparing two RT techniques: s-IMRT to 59.4Gy or ib-IMRT with 59.4/54Gy regions. Gross Tumour volume (GTV) and Clinical Target Volumes (CTV) were determined by MRI, 18F-Fluoroethyltyrosine (FET) and 18F-Fluorodeoxyglucose (FDG) PET imaging. A standard risk Planning Target Volume (PTVsr) receiving 59.4Gy (PTV59.4) in the s-IMRT technique was determined by MRI T2Flair and FET PET. For the ib-IMRT technique this PTVsr volume was treated to 54Gy, and the high-risk PTV (PTVhr) receiving 59.4Gy was determined as a higher risk region by FDG PET and MRI gadolinium enhancement. Standard dosimetric criteria and normal tissue constraints based on recent clinical trials were used in target delineation and planning. Normal Brain was defined as Brain minus CTV. Endpoints for dosimetric evaluation related to mean Brain dose (mBrainDose), brain volume receiving 40Gy (Brainv40) and 20Gy (Brainv20). The variation between the dosimetric endpoints for both techniques was examined using Wilcoxon analysis.

RESULTS

The 10 patients had tumours located in temporal (1), parietal (3), occipital (2) and bifrontal (4) regions. In ib-IMRT technique the median volume of PTVhr was 25.5 cm3 compared with PTVsr of 300.0 cm3. For dose to PTVhr the two treatments were equivalent (p = 0.33), and although the ibIMRT had a prescribed 10% dose reduction from 59.4Gy to 54Gy the median reduction was only 5.9%. The ib-IMRT dosimetry was significantly improved in normal brain endpoints specifically mBrainDose (p = 0.007), Brainv40 (p = 0.005) and Brainv20 (p = 0.001), with a median reduction of 9.3%, 19.0 and 10.8% respectively. After a median follow-up of 38 months two patients have progressed, with no isolated relapse in the dose reduction region.

CONCLUSION

An approach using ib-IMRT for anaplastic glioma produces significant dosimetric advantages in relation to normal brain dose compared with s-IMRT plan. This is achieved without a significant reduction to the target volume dose despite the reduction in prescribed dose. This technique has advantages to minimise potential late neurocognitive effects from high dose radiation in patients with favorable subtype anaplastic glioma with predicted median survival beyond ten years.