The impact of adjuvant therapy for patients with high-risk diffuse WHO grade II glioma

Congress of Neurological Surgeons systematic review and evidence-based guidelines for the role of chemotherapy in newly diagnosed WHO Grade II diffuse glioma in adults: update

Questions and recommendations from the prior version of these guidelines without changeTarget populationAdult patients (older than 18 years of age) with newly diagnosed World Health Organization (WHO) Grade II gliomas (Oligodendroglioma, astrocytoma, mixed oligoastrocytoma).QuestionIs there a role for chemotherapy as adjuvant therapy of choice in treatment of patients with newly diagnosed low-grade gliomas?RecommendationLevel III: Chemotherapy is recommended as a treatment option to postpone the use of radiotherapy, to slow tumor growth and to improve progression free survival (PFS), overall survival (OS) and clinical symptoms in adult patients with newly diagnosed LGG.QuestionWho are the patients with newly diagnosed LGG that would benefit the most from chemotherapy?RecommendationLevel III: Chemotherapy is recommended as an optional component alone or in combination with radiation as the initial adjuvant therapy for all patients who cannot undergo gross total resection (GTR) of a newly diagnosed LGG. Patients with residual tumor >1 cm on post-operative MRI, presenting diameter of 4 cm or older than 40 years of age should be considered for adjuvant therapy as well.QuestionAre there tumor markers that can predict which patients can benefit the most from initial treatment with chemotherapy?RecommendationLevel III: The addition of chemotherapy to standard RT is recommended in LGG patients that carry IDH mutation. In addition, temozolomide (TMZ) is recommended as a treatment option to slow tumor growth in patients who harbor the 1p/19q co-deletion.QuestionHow soon should the chemotherapy be started once the diagnosis of LGG is confirmed?RecommendationThere is insufficient evidence to make a definitive recommendation on the timing of starting chemotherapy after surgical/pathological diagnosis of LGG has been made. However, using the 12 weeks mark as the latest timeframe to start adjuvant chemotherapy is suggested. It is recommended that patients be enrolled in properly designed clinical trials to assess the timing of chemotherapy initiation once diagnosis is confirmed for this target population.QuestionWhat chemotherapeutic agents should be used for treatment of newly diagnosed LGG?RecommendationThere is insufficient evidence to make a recommendation of one particular regimen. Enrollment of subjects in properly designed trials comparing the efficacy of these or other agents is recommended so as to determine which of these regimens is superior.QuestionWhat is the optimal duration and dosing of chemotherapy as initial treatment for LGG?RecommendationInsufficient evidence exists regarding the duration of any specific cytotoxic drug regimen for treatment of newly diagnosed LGG. Enrollment of subjects in properly designed clinical investigations assessing the optimal duration of this therapy is recommended.QuestionShould chemotherapy be given alone or in conjunction with RT as initial therapy for LGG?RecommendationInsufficient evidence exists to make recommendations in this regard. Hence, enrollment of patients in properly designed clinical trials assessing the difference between chemotherapy alone, RT alone or a combination of them is recommended.QuestionShould chemotherapy be given in addition to other type of adjuvant therapy to patients with newly diagnosed LGG?RecommendationLevel II: It is recommended that chemotherapy be added to the RT in patients with unfavorable LGG to improve their progression free survival.Updated Question and Recommendations from the Prior Version of These GuidelinesQuestionIn adult patients with pathologically confirmed WHO Grade II diffuse glioma does chemotherapy alone, combined with radiation therapy or after radiation therapy compared to radiotherapy alone result in better overall survival, progression free survival, local control, fewer complications, neurocognitive preservation, and quality of life?RecommendationLevel I: It is recommended that chemotherapy (PCV) be added to radiation therapy (RT) in all patients with newly diagnosed high-risk WHO Grade II diffuse glioma (Patients younger than 40 unable to get gross total resection and older than 40 regardless of the degree of resection) to improve their overall survival.

LEVEL II

It is recommended that chemotherapy be added to radiation therapy in all patients with newly diagnosed high-risk WHO Grade II diffuse glioma to improve overall survival without a decline in neurocognitive function.

LEVEL III

It is suggested that chemotherapy (temozolomide) be added to RT in all patients with newly diagnosed high-risk WHO Grade II diffuse glioma to improve progression free survival and overall survival.

LEVEL III

It is suggested that chemotherapy alone should be considered in patients with newly diagnosed WHO Grade II diffuse glioma in cases with 1p/19q co-deletion.New questions and recommendationsTarget populationThese recommendations apply to adult patients diagnosed with WHO Grade II diffuse glioma.QuestionIn adult patients with newly diagnosed WHO grade II diffuse glioma does administration of chemotherapy prior to surgical resection improve extent of resection, provide longer progression free survival and overall survival when compared to chemotherapy alone?RecommendationLevel III: Neo-adjuvant temozolomide may be used in patients with WHO Grade II diffuse gliomas deemed unsafe for resection due to infiltration of eloquent areas or with large contralateral extension as an initial step to improve the extent of resection.There is insufficient evidence to support a recommendation regarding the ability of chemotherapy provided prior to surgical resection to improve progression free survival (PFS) and overall survival (OS).QuestionIn adult patients with newly diagnosed WHO grade II diffuse glioma does the administration of temozolomide increase the rate of malignant transformation when compared to no chemotherapy or other chemotherapy regimens?RecommendationThere is insufficient evidence to support a recommendation against the use of temozolomide for WHO Grade II diffuse gliomas due to concern over increasing the rate of malignant transformation.QuestionIn adult patients with newly diagnosed WHO grade II diffuse glioma does administration of multi-agent chemotherapy improve progression free survival and overall survival when compared to administration of single-agent chemotherapy?RecommendationThere is insufficient evidence to support a recommendation for or against the use of multi-agent chemotherapy to improve progression free survival and overall survival when compared to administration of single-agent chemotherapy in patients with newly diagnosed WHO Grade II diffuse glioma.

Effectiveness and Safety of Different Postoperative Adjuvant Regimens in Patients with Low-Grade Gliomas: A Network Meta-Analysis

OBJECTIVE

This study aimed to investigate the effectiveness and safety of various adjuvant regimens in patients with low-grade gliomas and to further explore the optimal adjuvant treatment for patients with low-grade gliomas and the differences in the efficacy of each treatment regimens in different tumor types.

METHODS

A comprehensive search of the PubMed, Cochrane Library, Ovid, Embase, and Web of Science databases was conducted to screen randomized and nonrandomized controlled trials related to adjuvant therapy in patients with low-grade gliomas. The Cochrane quality assessment method and the Newcastle-Ottawa Scale were used to assess the quality of the included randomized and nonrandomized controlled trials, respectively. The data from previous studies were extracted using Excel and GetData Graph Digitizer 2.26 software, and network meta-analysis was performed using RevMan 5.3 and Stata 16.0 statistical software.

RESULTS

The specific ranking of 5-year progression-free survival (5-year PFS) for each treatment regimen from the best to the worst in patients with low-grade gliomas was surgery (S) combined with procarbazine, lomustine, and vincristine (S + PCV); surgery combined with standard radiotherapy and PCV multidrug chemotherapy (S + RT + PCV); surgery combined with standard radiotherapy and temozolomide monotherapy (S + RT + TMZ); surgery combined with enhanced radiotherapy (S + H-RT); surgery combined with standard radiotherapy (S + RT); surgery combined with TMZ (S + TMZ); and S. The 5-year overall survival (OS) ranking was S + RT + TMZ, S + RT + PCV, surgery combined with enhanced radiotherapy and TMZ monotherapy (S + H-RT + TMZ), S + H-RT, S + RT, and S. The 2-year progression-free survival ranking was S + RT + TMZ, S + PCV, S + RT, S + RT + PCV, S + TMZ, S + H-RT, and S. The 2-year overall survival ranking was S + RT + TMZ, S + H-RT + TMZ, S + RT, S + RT + PCV, S + H-RT, and S. The incidence of adverse events (≥3) was ranked from highest to lowest as follows: S + RT + PCV, S + RT + TMZ, S + PCV, S + H-RT, S + TMZ, and S + RT. In the isocitrate dehydrogenase 1/2 mutation nonchromosome 1p and 19q chromosome whole arm codeletion (IDHmt/noncoder) group, the S + RT + PCV and S + H-RT regimens had better 5-year PFS and 5-year OS. In the isocitrate dehydrogenase 1/2 mutation and chromosome 1p and 19q chromosome whole arm codeletion (IDHmt/coder) group, the 5-year PFS of each treatment regimen ranked from the best to the worst was S + RT + TMZ, S + RT + PCV, S + H-RT, S + RT, S + TMZ, and S. The order of 5-year OS from the best to the worst was S + H-RT, S + RT + TMZ, S + RT + PCV, S + RT, and S. In the isocitrate dehydrogenase 1/2 wild-type (IDHwt) group, the S + H-RT and S + TMZ regimens had better 5-year PFS.

CONCLUSIONS

This study revealed that both the S + RT + TMZ and S + RT + PCV regimens might be effective therapies for treating patients with low-grade gliomas. Among these, the S + RT + TMZ regimen seemed to be safer but might lead to tumor deterioration. In the IDHmt/coder type, the S + RT + TMZ scheme might have a significant advantage. In the IDHmt/noncoder type, the S + RT + PCV scheme might be more dominant, while in the IDHwt type, the S + H-RT and S + TMZ schemes also might be good treatment options.

Role of Temozolomide Regimen on Survival Outcomes in Molecularly Stratified WHO Grade II Gliomas: A Systematic Review

OBJECTIVE/INTRODUCTION

Although a critical chemotherapeutic, temozolomide's optimal regimen for 2016 World Health Organization (WHO) Grade II gliomas remains elusive, hence there is utility in not only cataloging survival outcomes of Grade II glioma subtypes against the background of temozolomide regimens, but also quantifying differences in progression-free survival (PFS) and overall survival (OS).

MATERIALS AND METHODS

A systematic review of MEDLINE, Embase, and Cochrane Central Register of Controlled Trails was conducted by using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis and the Cochrane Handbook of Systemic Reviews of Interventions.

RESULTS

Each molecular subtype of WHO Grade II glioma had a different temozolomide regimen identified as optimal in prolonging PFS and OS. For PFS, with temozolomide, the 25th, 50th, and 75th percentiles, were as follows (in months), respectively-A-wt II: 6.90, 12.95, and 19.95; A-mt II: 34.45, 36.01, and 39.60; OD II: 37.90, 46.00, and 55.03 (P = 0.016). For OS, the first quartile (25%), median (50%), third quartile (75%), were respectively identified (in months-A-wt II: 21.6 (median; n = 1); A-mt II: 60.6, 85.2, and 109.8; OD II: 86.1, 96.2, and 106.3 (P = 0.37).

CONCLUSION

For each tumor molecular subtype, a different temozolomide regimen was identified as optimal for prolonging PFS and OS. Furthermore, regardless of temozolomide regimen, A-wt II had a significantly shorter PFS than A-mt II and OD-II. Overall, the data can provide useful prognostic insight to patients when making critical treatment decisions. Moreover, by cataloging and assessing survival outcomes per temozolomide regimen, such may facilitate future clinical trial design.

Clinical practice guidelines for the management of adult diffuse gliomas

To follow the revision of the fourth edition of WHO classification and the recent progress on the management of diffuse gliomas, the joint guideline committee of Chinese Glioma Cooperative Group (CGCG), Society for Neuro-Oncology of China (SNO-China) and Chinese Brain Cancer Association (CBCA) updated the clinical practice guideline. It provides recommendations for diagnostic and management decisions, and for limiting unnecessary treatments and cost. The recommendations focus on molecular and pathological diagnostics, and the main treatment modalities of surgery, radiotherapy, and chemotherapy. In this guideline, we also integrated the results of some clinical trials of immune therapies and target therapies, which we think are ongoing future directions. The guideline should serve as an application for all professionals involved in the management of patients with adult diffuse glioma and also a source of knowledge for insurance companies and other institutions involved in the cost regulation of cancer care in China and other countries.

To treat or not to treat? A retrospective multicenter assessment of survival in patients with IDH-mutant low-grade glioma based on adjuvant treatment

OBJECTIVE

The level of evidence for adjuvant treatment of diffuse WHO grade II glioma (low-grade glioma, LGG) is low. In so-called "high-risk" patients most centers currently apply an early aggressive adjuvant treatment after surgery. The aim of this assessment was to compare progression-free survival (PFS) and overall survival (OS) in patients receiving radiation therapy (RT) alone, chemotherapy (CT) alone, or a combined/consecutive RT+CT, with patients receiving no primary adjuvant treatment after surgery.

METHODS

Based on a retrospective multicenter cohort of 288 patients (≥ 18 years old) with diffuse WHO grade II gliomas, a subgroup analysis of patients with a confirmed isocitrate dehydrogenase (IDH) mutation was performed. The influence of primary adjuvant treatment after surgery on PFS and OS was assessed using Kaplan-Meier estimates and multivariate Cox regression models, including age (≥ 40 years), complete tumor resection (CTR), recurrent surgery, and astrocytoma versus oligodendroglioma.

RESULTS

One hundred forty-four patients matched the inclusion criteria. Forty patients (27.8%) received adjuvant treatment. The median follow-up duration was 6 years (95% confidence interval 4.8-6.3 years). The median overall PFS was 3.9 years and OS 16.1 years. PFS and OS were significantly longer without adjuvant treatment (p = 0.003). A significant difference in favor of no adjuvant therapy was observed even in high-risk patients (age ≥ 40 years or residual tumor, 3.9 vs 3.1 years, p = 0.025). In the multivariate model (controlled for age, CTR, oligodendroglial diagnosis, and recurrent surgery), patients who received no adjuvant therapy showed a significantly positive influence on PFS (p = 0.030) and OS (p = 0.009) compared to any other adjuvant treatment regimen. This effect was most pronounced if RT+CT was applied (p = 0.004, hazard ratio [HR] 2.7 for PFS, and p = 0.001, HR 20.2 for OS). CTR was independently associated with longer PFS (p = 0.019). Age ≥ 40 years, histopathological diagnosis, and recurrence did not achieve statistical significance.

CONCLUSIONS

In this series of IDH-mutated LGGs, adjuvant treatment with RT, CT with temozolomide (TMZ), or the combination of both showed no significant advantage in terms of PFS and OS. Even in high-risk patients, the authors observed a similar significantly negative impact of adjuvant treatment on PFS and OS. These results underscore the importance of a CTR in LGG. Whether patients ≥ 40 years old should receive adjuvant treatment despite a CTR should be a matter of debate. A potential tumor dedifferentiation by administration of early TMZ, RT, or RT+CT in IDH-mutated LGG should be considered. However, these data are limited by the retrospective study design and the potentially heterogeneous indication for adjuvant treatment.

Neuro-Oncology Practice Clinical Debate: Early treatment or observation for patients with newly diagnosed oligodendroglioma and small-volume residual disease

Advances in treatment of oligodendroglioma represent arguably the most significant recent development in the treatment of brain tumors, with multiple clinical trials demonstrating that median survival is approximately doubled in patients with World Health Organization grade II and III 1p/19q codeleted gliomas (ie, oligodendrogliomas) treated with procarbazine, lomustine, vincristine chemotherapy and radiation vs radiation alone. However, chemoradiotherapy itself is not without morbidity, including both short-term toxicities primarily related to chemotherapy and longer-term cognitive issues likely due to radiation. Patients and physicians both desire maximally effective therapy with minimal toxicity, and it remains unclear whether some patients with macroscopic residual disease after surgery can safely delay therapy, to avoid or delay toxicity, while simultaneously preserving the full benefits of treatment. In this article, experts in the field discuss the rationale for the approaches of up-front treatment with chemoradiotherapy and initial observation, respectively.

The biological and clinical basis for early referral of low grade glioma patients to a surgical neuro-oncologist

The discovery of IDH1/2 (isocitrate dehydrogenase) mutation in large scale, genomewide mutational analyses of gliomas has led to profound developments in understanding tumourigenesis, and restructuring of the classification of both high and low grade gliomas. Owing to this progress made in the recognition of molecular markers which predict tumour behavior and treatment response, the increasing importance of adjuvant treatments such as chemo- and radiotherapy, and the tremendous advances in surgical technique and intraoperative monitoring which have facilitated superior extents of resection whilst preserving neurological functioning and quality of life, contemporary management of low grade glioma (LGG) has switched from a passive, observant approach to a more active, interventional one. Furthermore, this has implications for the manner in which patients with incidentally discovered and/or asymptomatic LGG are managed, and this review of the biological behaviour of LGG, as well as its clinical investigation and management, should act as a timely reminder to all clinicians of the importance of referring LGG patients early to a surgical neuro-oncologist who is not only familiar and acquainted with the vagaries of this disease process, but who, in addition, is devoted to delivering care to these patients with the support of a multi-disciplinary clinical decision-making unit, comprising medical neuro-oncologists, radiation oncologists and allied health professionals.

Early versus delayed postoperative radiotherapy for treatment of low-grade gliomas

BACKGROUND

This is an update of the review originally published in 2011 and first updated in 2015. In most people with low-grade gliomas (LGG), the primary treatment regimen remains a combination of surgery followed by postoperative radiotherapy. However, the optimal timing of radiotherapy is controversial. It is unclear whether to use radiotherapy in the early postoperative period, or whether radiotherapy should be delayed until tumour progression occurs.

OBJECTIVES

To assess the effects of early postoperative radiotherapy versus radiotherapy delayed until tumour progression for low-grade intracranial gliomas in people who had initial biopsy or surgical resection.

SEARCH METHODS

Original searches were run up to September 2014. An updated literature search from September 2014 through November 2019 was performed on the following electronic databases: the Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 11), MEDLINE via Ovid (September 2014 to November week 2 2019), and Embase via Ovid (September 2014 to 2019 week 46) to identify trials for inclusion in this Cochrane review update.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared early versus delayed radiotherapy following biopsy or surgical resection for the treatment of people with newly diagnosed intracranial LGG (astrocytoma, oligodendroglioma, mixed oligoastrocytoma, astroblastoma, xanthoastrocytoma, or ganglioglioma). Radiotherapy may include conformal external beam radiotherapy (EBRT) with linear accelerator or cobalt-60 sources, intensity-modulated radiotherapy (IMRT), or stereotactic radiosurgery (SRS).

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed the trials for inclusion and risk of bias, and extracted study data. We resolved any differences between review authors by discussion. Adverse effects were also extracted from the study report. We performed meta-analyses using a random-effects model with inverse variance weighting.

MAIN RESULTS

We included one large, multi-institutional, prospective RCT, involving 311 participants; the risk of bias in this study was unclear. This study found that early postoperative radiotherapy was associated with an increase in time to progression compared to observation (and delayed radiotherapy upon disease progression) for people with LGG but did not significantly improve overall survival (OS). The median progression-free survival (PFS) was 5.3 years in the early radiotherapy group and 3.4 years in the delayed radiotherapy group (hazard ratio (HR) 0.59, 95% confidence interval (CI) 0.45 to 0.77; P < 0.0001; 311 participants; 1 trial; low-quality evidence). The median OS in the early radiotherapy group was 7.4 years, while the delayed radiotherapy group experienced a median overall survival of 7.2 years (HR 0.97, 95% CI 0.71 to 1.33; P = 0.872; 311 participants; 1 trial; low-quality evidence). The total dose of radiotherapy given was 54 Gy; five fractions of 1.8 Gy per week were given for six weeks. Adverse effects following radiotherapy consisted of skin reactions, otitis media, mild headache, nausea, and vomiting. Rescue therapy was provided to 65% of the participants randomised to delayed radiotherapy. People in both cohorts who were free from tumour progression showed no differences in cognitive deficit, focal deficit, performance status, and headache after one year. However, participants randomised to the early radiotherapy group experienced significantly fewer seizures than participants in the delayed postoperative radiotherapy group at one year (25% versus 41%, P = 0.0329, respectively).

AUTHORS' CONCLUSIONS

Given the high risk of bias in the included study, the results of this analysis must be interpreted with caution. Early radiation therapy was associated with the following adverse effects: skin reactions, otitis media, mild headache, nausea, and vomiting. People with LGG who underwent early radiotherapy showed an increase in time to progression compared with people who were observed and had radiotherapy at the time of progression. There was no significant difference in overall survival between people who had early versus delayed radiotherapy; however, this finding may be due to the effectiveness of rescue therapy with radiation in the control arm. People who underwent early radiation had better seizure control at one year than people who underwent delayed radiation. There were no cases of radiation-induced malignant transformation of LGG. However, it remained unclear whether there were differences in memory, executive function, cognitive function, or quality of life between the two groups since these measures were not evaluated.

Isocitrate Dehydrogenase Mutations in Low-Grade Gliomas Correlate With Prolonged Overall Survival in Older Patients

BACKGROUND

Older age has been associated with worse outcomes in low-grade gliomas (LGGs). Given their rarity in the older population, determining optimal treatment plans and patient outcomes remains difficult.

OBJECTIVE

To retrospectively study LGG survival outcomes in an older population stratified by molecular genetic profiles.

METHODS

We included patients age ≥40 yr with pathologically confirmed World Health Organization grade II gliomas treated at a single institution between 1995 and 2015. We collected tumor genomic information when available.

RESULTS

Median overall survival for the entire group (n = 111, median age 51 yr, range 40-77 yr) was 15.75 yr with 5- and 10-yr survival rates of 84.3% and 67.7%, respectively. On univariate analysis, patients with isocitrate dehydrogenase (IDH) mutation had significantly increased survival compared to IDH wildtype (hazard ratio [HR] 0.17 [0.07-0.45], P < .001). Older age, seizure at presentation, larger tumor size, IDH wildtype, biopsy only, chemotherapy, and radiation were significantly associated with shorter survival based on univariate analyses. In patients with known IDH status (n = 73), bivariate analysis of IDH mutation status and age showed only IDH status significantly influenced overall survival (HR 0.22 [0.07-0.68], P = .008). Greater surgical resection was predictive of survival, although extent of resection significantly correlated with IDH mutation status (odds ratio 7.5; P < .001).

CONCLUSION

We show that genomic alterations in LGG patients ≥40 occur at high rates like the younger population and predict a similar survival advantage. Maximizing surgical resection may have survival benefit, although feasibility of resection is often linked to IDH status. Given the importance of molecular genetics, a redefinition of prognostic factors associated with these tumors is likely to emerge.

Observation after surgery for low grade glioma: long-term outcome in the light of the 2016 WHO classification

PURPOSE

To provide detailed long-term data after initial observation for patients after histological confirmation of low grade (WHO II) gliomas according to molecular stratification.

METHODS

A series of 110 patients with watchful waiting strategy after initial surgery for LGG and re-surgery at tumor progression were analyzed. Progression-free survival, time to malignant transformation, post-recurrence survival, and overall survival were estimated with the Kaplan-Meier method. Prognostic factors were identified by the Log Rank test and Cox multivariate proportional hazards model.

RESULTS

The cohort comprised 18 IDH wild type (IDH^wt) and 53 IDH mutated (IDH^mut) astrocytomas, and 39 IDH mutated and 1p 19q co-deleted (IDH^mut/codel) patients. The median follow-up was 126 (95% CI 109-143) months. Surgery was gross total resection in 58, subtotal resection in 28, and biopsy in 24 patients. Progression-free survival rates at 5, 10 and 15 years was 38% 18% and 1%. The corresponding malignant transformation rates were 17%, 39% and 71%. The initial extent of resection influenced progression-free survival, time to malignant transformation and overall survival. Molecular subtype IDH^mut/codel was the strongest prognostic factor for overall survival and for time to malignant transformation.

CONCLUSION

The strongest determinant of the patients' course after initial watchful waiting was the molecular tumor status. Extensive resection may increase time to progression and malignant transformation. Observation may be justified in selected patients.

Quantifying effects of radiotherapy-induced microvascular injury; review of established and emerging brain MRI techniques

Microvascular changes are increasingly recognised not only as primary drivers of radiotherapy treatment response in brain tumours, but also as an important contributor to short- and long-term (cognitive) side effects arising from irradiation of otherwise healthy brain tissue. As overall survival of patients with brain tumours is increasing, monitoring long-term sequels of radiotherapy-induced microvascular changes in the context of their potential predictive power for outcome, such as cognitive disability, has become increasingly relevant. Ideally, radiotherapy-induced significant microvascular changes in otherwise healthy brain tissue should be identified as early as possible to facilitate adaptive radiotherapy and to proactively start treatment to minimise the influence on these side-effects on the final outcome. Although MRI is already known to be able to detect significant long-term radiotherapy induced microvascular effects, more recently advanced MR imaging biomarkers reflecting microvascular integrity and function have been reported and might provide a more accurate and earlier detection of microvascular changes. However, the use and validation of both established and new techniques in the context of monitoring early and late radiotherapy-induced microvascular changes in both target-tissue and healthy tissue currently are minimal at best. This review aims to summarise the performance and limitations of existing methods and future opportunities for detection and quantification of radiotherapy-induced microvascular changes, as well as the relation of these findings with key clinical parameters.

Impact of 1p/19q codeletion status on extent of resection in WHO grade II glioma: Insights from a national cancer registry

OBJECTIVE

Traditionally, extent of resection (EOR) has been seen as a surgical parameter that can predict survival outcomes of surgically managed WHO grade II gliomas. The aim of this study was to evaluate if such an influence was potentially affected by 1p/19q codeletion status based on a national cancer registry.

PATIENT AND METHODS

All adults diagnosed with grade II gliomas between the years 2004 to 2014 were queried from the National Cancer Database (NCDB). The population was then divided based on 1p/19q codeletion status, and then Kaplan-Meier, univariate and multivariate Cox regression analyses were utilized to evaluate the prognostic effect of EOR.

RESULTS

In total, 1,498 grade II gliomas satisfied inclusion for analysis, with the 1p/19q non-codeleted in 705 (47%) cases, and codeletion in 793 (53%) cases. When the cohort was divided based on codeletion status, Kaplan-Meier modelling and univariate regression analyses indicated that gross total resection (GTR) was significantly associated with greater 5-overall survival (OS) in both 1p/19q non-codeleted and codeletion groups. Upon multivariate analysis which incorporated adjuvant therapy status, the significance of GTR was only retained in the 1p/19q non-codeletion group after post-hoc adjustment.

CONCLUSION

Our findings indicate that the survival impact of GTR in grade II gliomas may be affected by 1p/19q codeletion status within the first five years after surgery based on overall survival. Therefore, molecular diagnostics have potential clinical application in surgery outcomes, and validation of the reported findings will assist in surgical planning if such an association can be thoroughly established.

Comprehensive Analysis Reveals a 4-Gene Signature in Predicting Response to Temozolomide in Low-Grade Glioma Patients

Low-grade gliomas (LGGs) are a highly heterogeneous group of slow-growing, lethal, diffusive brain tumors. Temozolomide (TMZ) is a frequently used primary chemotherapeutic agent for LGGs. Currently there is no consensus as to the optimal biomarkers to predict the efficacy of TMZ, which calls for decision-making for each patient while considering molecular profiles. Low-grade glioma data sets were retrieved from The Cancer Genome Atlas. Cox regression and survival analyses were applied to identify clinical features significantly associated with survival. Subsequently, Ordinal logistic regression, co-expression, and Cox regression analyses were applied to identify genes that correlate significantly with response rate, disease-free survival, and overall survival of patients receiving TMZ as primary therapy. Finally, gene expression and methylation analyses were exploited to explain the mechanism between these gene expression and TMZ efficacy in LGG patients. Overall survival was significantly correlated with age, Karnofsky Performance Status score, and histological grade, but not with IDH1 mutation status. Using 3 distinct efficacy end points, regression and co-expression analyses further identified a novel 4-gene signature of ASPM, CCNB1, EXO1, and KIF23 which negatively correlated with response to TMZ therapy. In addition, expression of the 4-gene signature was associated with those of genes involved in homologous recombination. Finally, expression and methylation profiling identified a largely unknown olfactory receptor OR51F2 as potential mediator of the roles of the 4-gene signature in reducing TMZ efficacy. Taken together, these findings propose the 4-gene signature as a novel panel of efficacy predictors of TMZ therapy, as well as potential downstream mechanisms, including homologous recombination, OR51F2, and DNA methylation independent of MGMT.

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.

IDH wild-type WHO grade II diffuse low-grade gliomas. A heterogeneous family with different outcomes. Systematic review and meta-analysis

WHO grade II diffuse low-grade gliomas (DLGGs) were recently divided into sub-groups on the basis of their molecular profiles. IDH wild-type (IDH-wt) tumors seem to be associated with unfavorable prognoses due to biological similarities to glioblastomas. The authors performed a systematic review and meta-analysis of literature examining epidemiology, clinical characteristics, management, and the outcome of IDH-wt grade II DLGGs. According to PRISMA guidelines, a comprehensive review of studies published from January 2009 to October 2017 was carried out. The authors identified series that examined the prevalence rate, clinical and radiological characteristics, treatment, and outcome of IDH-wt DLGGs. Variables influencing outcomes were analyzed using a random-effects meta-analysis model. Finally, a meta-regression analysis was performed to examine the impact of therapeutic strategies on the effect-size. Twenty-two studies were included in this systematic review. The IDH-wt prevalence rate was 22.9% (95% CI 18.4-27.4%). The hazard ratio for this molecular subgroup in the DLGGs population was 3.46 (95% CI 2.24-5.36; p < 0.001), and the heterogeneity was significant (I² = 85%, τ² = 0.88) (HR range 1.28-376). Nonetheless, publication bias did not affect the analysis (p = 0.176). The meta-regression revealed that the extent of resection and post-operative chemotherapy affected the outcome in the IDH-wt subgroup (p < 0.001 and 0.015, respectively), with no significant association of the HR with the rate of RT or RT + CHT. The prevalence of IDH-wt tumors is approximately 23% of DLGGs. The absence of IDH mutation is associated with a heterogeneous outcome, and its therapeutic relevance for postoperative management remains unclear. Maximal surgical resection improves the overall survival in the DLGGs population, beyond molecular status. Further molecular stratification is needed to better understand IDH-wt behavior and therapeutic response.