Low-grade hemispheric gliomas in adults: a critical review of extent of resection as a factor influencing outcome

[Interdisciplinary neuro-oncology: part 1: diagnostics and operative therapy of primary brain tumors]

By combining the expertise of clinical neuroscience, the aim of neuro-oncology is to optimize diagnostic planning and therapy of primary brain tumors in an interdisciplinary setting together with radio-oncology and medical oncology. High-end imaging frequently allows brain tumors to be diagnosed preoperatively with respect to tumor entity and even tumor malignancy grade. Moreover, neuroimaging is indispensable for guidance of biopsy resection and monitoring of therapy. Surgical resection of intracranial lesions with preservation of neurological function is increasingly feasible. Tools to achieve this goal are, for example neuronavigation, functional magnetic resonance imaging (fMRI), tractography, intraoperative cortical stimulation and precise intraoperative definition of tumor margins by virtue of various techniques. In addition to classical histopathological diagnosis and tumor classification, modern neuropathology is supplemented by molecular characterization of brain tumors in order to provide clinicians with prognostic and predictive (of therapy) markers, such as codeletion of chromosomes 1p and 19q in anaplastic gliomas and O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation in glioblastomas. Although this is not yet individualized tumor therapy, the increasingly more detailed analysis of the molecular pathogenesis of an individual glioma will eventually lead to specific pharmacological blockade of disturbed intracellular pathways in individual patients. This article gives an overview of the state of the art of interdisciplinary neuro-oncology whereby part 1 deals with the diagnostics and surgical therapy of primary brain tumors and part 2 describes the medical therapy of primary brain tumors.

Suprasellar pilocytic astrocytoma: one national centre's experience

INTRODUCTION

Pilocytic astrocytomas in the supratentorial compartment make up 20 % of all brain tumours in children with only 5 % of these arising in the suprasellar region. Optic pathway gliomas or suprasellar gliomas are often seen in neurofibromatosis type 1 (NF1) patients. Given their location, suprasellar pilocytic astrocytomas are challenging to manage surgically with high morbidity rates from surgical resection. We assess our cohort of patients with suprasellar pilocytic astrocytoma and document our experience.

METHOD

A retrospective review of patients diagnosed with suprasellar glioma between 2000-October 2012. We included patients diagnosed with optic pathway glioma based on radiological features (with or without biopsy) and those who had a biopsy confirming pilocytic astrocytoma.

RESULTS

Fifty-three patients included (sporadic tumours 24 and NF1 related 29). Fifteen sporadic and four NF1 patients were biopsied. Twelve sporadic and 13 NF1 patients were initially treated with chemotherapy while only 1 patient had radiotherapy initially. Progression was noted in 58 % of the sporadic group and 24 % of the NF1 group. The only significant factor for progression was NF1 status (p = 0.026).

CONCLUSION

Management should be guided by individual patient circumstance. In our cohort, chemotherapy did not significantly improve progression free survival; however, NF1 status significantly correlated with the decreased progression.

CXCR7 and CXCR4 Expressions in Infiltrative Astrocytomas and Their Interactions with HIF1α Expression and IDH1 Mutation

The CXCR7, a new receptor for CXCL12 with higher affinity than CXCR4 has raised key issues on glioma cell migration. The aim of this study is to investigate the CXCR7 mRNA expression in diffuse astrocytomas tissues and to evaluate its interactions with CXCR4 and HIF1α expression and IDH1 mutation. CXCR7, CXCR4 and HIF1α mRNA expression were evaluated in 129 frozen samples of astrocytomas. IDH1 mutation status was analyzed with gene expressions, matched with clinicopathological parameters and overall survival time. Protein expression was analyzed by immunohistochemistry in different grades of astrocytoma and in glioma cell line (U87MG) by confocal microscopy. There was significant difference in the expression levels of the genes studied between astrocytomas and non-neoplasic (NN) controls (p < 0.001). AGII showed no significant correlation between CXCR7/HIF1α (p = 0.548); there was significant correlation between CXCR7/CXCR4 (p = 0.042) and CXCR7/IDH1 (p = 0.008). GBM showed significant correlations between CXCR7/CXCR4 (p = 0.002), CXCR7/IDH1 (p < 0.001) and CXCR7/HIF1α (p = 0.008). HIF1α overexpression was associated with higher expressions of CXCR7 (p = 0.01) and CXCR4 (p < 0.0001), while IDH1 mutation was associated with lower CXCR7 (p = 0.009) and CXCR4 (p = 0.0005) mRNA expressions. Protein expression increased with malignancy and in U87MG cell line was mainly localized in the cellular membrane. CXCR7 was overexpressed in astrocytoma and correlates with CXCR4 and IDH1 in AGII and CXCR4, IDH1 and HIF1α in GBM. Overexpression HIF1α was related with higher expressions of CXCR7 and CXCR4, otherwise IDH1 mutation related with lower expression of both genes. No association between CXCR7 and CXCR4 expression and survival data was related.

Updated therapeutic strategy for adult low-grade glioma stratified by resection and tumor subtype

The importance of surgical resection for patients with supratentorial low-grade glioma (LGG) remains controversial. This retrospective study of patients (n = 153) treated between 2000 to 2010 at a single institution assessed whether increasing the extent of resection (EOR) was associated with improved progression-free survival (PFS) and overall survival (OS). Histological subtypes of World Health Organization grade II tumors were as follows: diffuse astrocytoma in 49 patients (32.0%), oligoastrocytoma in 45 patients (29.4%), and oligodendroglioma in 59 patients (38.6%). Median pre- and postoperative tumor volumes and median EOR were 29.0 cm(3) (range 0.7-162 cm(3)) and 1.7 cm(3) (range 0-135.7 cm(3)) and 95%, respectively. Five- and 10-year OS for all LGG patients were 95.1% and 85.4%, respectively. Eight-year OS for diffuse astrocytoma, oligoastrocytoma, and oligodendroglioma were 70.7%, 91.2%, and 98.3%, respectively. Five-year PFS for diffuse astrocytoma, oligoastrocytoma, and oligodendroglioma were 42.6%, 71.3%, and 62.7%, respectively. Patients were divided into two groups by EOR ≥90% and <90%, and OS and PFS were analyzed. Both OS and PFS were significantly longer in patients with ≥90% EOR. Increased EOR resulted in better PFS for diffuse astrocytoma but not for oligodendroglioma. Multivariate analysis identified age and EOR as parameters significantly associated with OS. The only parameter associated with PFS was EOR. Based on these findings, we established updated therapeutic strategies for LGG. If surgery resulted in EOR <90%, patients with astrocytoma will require second-look surgery, whereas patients with oligodendroglioma or oligoastrocytoma, which are sensitive to chemotherapy, will be treated with chemotherapy.

Extent of resection and survival in supratentorial infiltrative low-grade gliomas: analysis of and adjustment for treatment bias

BACKGROUND

Any correlation between the extent of resection and the prognosis of patients with supratentorial infiltrative low-grade gliomas may well be related to biased treatment allocation. Patients with an intrinsically better prognosis may undergo more aggressive resections, and better survival may then be falsely attributed to the surgery rather than the biology of the disease. The present study investigates the potential impact of this type of treatment bias on survival in a series of patients with low-grade gliomas treated at the authors' institution.

METHODS

We conducted a retrospective study of 148 patients with low-grade gliomas undergoing primary treatment at our institution from 1996-2011. Potential prognostic factors were studied in order to identify treatment bias and to adjust survival analyses accordingly.

RESULTS

Eloquence of tumor location proved the most powerful predictor of the extent of resection, i.e., the principal source of treatment bias. Univariate as well as multivariate Cox regression analyses identified the extent of resection and the presence of a preoperative neurodeficit as the most important predictors of overall survival, tumor recurrence and malignant progression. After stratification for eloquence of tumor location in order to correct for treatment bias, Kaplan-Meier estimates showed a consistent association between the degree of resection and improved survival.

CONCLUSION

Treatment bias was not responsible for the correlation between extent of resection and survival observed in the present series. Our data seem to provide further support for a strategy of maximum safe resections for low-grade gliomas.

Chemotherapy for low-grade gliomas

Low-grade gliomas pose a difficult problem for the neuro-oncologist. More needs to be known about their natural history. In addition, the role and timing of radiotherapy and chemotherapy in the management of low-grade tumors is highly controversial. Most agree that physicians should recommend treatment in symptomatic cases or in instances of radiologic tumor progression. This review discusses some of the recent advances with respect to chemotherapy for low-grade gliomas, with a special emphasis on low-grade astrocytomas and oligodendrogliomas.

Oligodendrogliomas: clinical significance of 1p and 19q chromosomal deletions

Oligodendrogliomas are a distinct subgroup of brain tumors with a fairly favorable clinical prognosis. However, these tumor exhibit varying degrees of heterogeneity and their clinical behavior is therefore not always the same. For this reason, genetic markers have been developed to further guide the clinical treatment. One such marker, the 1p and 19q chromosomal deletions, has been well documented in a subset of patients with oligodendrogliomas. Most importantly, patients who exhibit these chromosomal deletions respond favorably to chemotherapy. This article reviews the evidence describing the association of such deletions with a favorable response to chemotherapy and improved prognosis of patients with oligodendrogliomas. In addition, attempts to elucidate the molecular mechanisms behind the biologic behavior of these tumors are further explored.

Intraoperative cortico–subcortical stimulations in surgery of low-grade gliomas

In order to increase the impact of surgery on the natural history of low-grade glioma, resection should be of maximum importance. Nevertheless, since low-grade gliomas are frequently located in eloquent structures, function needs to be preserved. Therefore, studying the functional organization of the brain is mandatory for each patient due to the inter-individual anatomofunctional variability, increased in tumors due to cerebral plasticity. This strategy enables performance of a resection according to functional boundaries. However, preoperative neurofunctional imaging only allows the study of the gray matter. Consequently, since low-grade glioma invades cortical and subcortical structures and shows an infiltrative progression along the fibers, the goal of this review is to focus on the techniques able to map both cortical and subcortical regions. In addition to diffusion tensor imaging, which gives only anatomical information and still needs to be validated, intraoperative direct cortico-subcortical electrostimulation is the sole current method allowing a reliable study of the individual anatomofunctional connectivity, concerning sensorimotor, language and other cognitive functions. Its actual contribution is detailed, both in clinical issues, especially the improvement of the benefit/risk ratio of low-grade glioma resection, and in fundamental applications--namely, a new door to the connectionism and cerebral plasticity.

Surgical management of high-grade gliomas

High-grade gliomas, in particular anaplastic astrocytoma and glioblastoma multiforme, represent two of the most devastating forms of brain cancer. In spite of the poor prognosis, new treatments and emerging therapies are making an impact on this disease. This review discusses the role of the surgical management of high-grade gliomas and provides an overview of the currently available therapies which depend on surgical intervention. At the same time, cutting-edge clinical trials for patients with malignant brain tumors are reviewed to provide further insights into potential future therapies.

Radiotherapy in low-grade glioma adult patients: a retrospective survival and neurocognitive toxicity analysis

PURPOSE

The treatment of low-grade glioma is still debated. Surgery is the first-line approach, and the correct timing of radiation therapy has not yet been defined since "early" radiation therapy improves relapse-free survival but not overall survival. Since a longer progression-free survival is desirable, the main issue related to radiotherapy is the incidence of late neurocognitive toxicity.

MATERIALS AND METHODS

Ninety-five patients with low-grade glioma were consecutively treated with early (within 3 months) or late (at disease progression) post-surgical radiation therapy. Clinical and therapeutic factors were entered into the analysis overall (OS) and progression-free (PFS) survival, and the distribution in two accrual periods identified based on the evolution of imaging procedures and radiotherapy techniques were compared. For 6/18 long survivors (LS) without evidence of disease, neurocognitive evaluation was obtained and the dose to the hippocampus region was retrospectively calculated.

RESULTS

Univariate analysis of OS showed a statistically significant advantage for grade 1 and oligodendroglioma histology, better performance status [Karnofsky index (KI)], age <40 years, radical surgery, no steroid treatment; PFS was significantly related with younger age, better KI and "early" radiotherapy. Multivariate analysis of OS confirmed the significance of all variables except surgery; for PFS, only "early" radiotherapy and better KI retained significance. Memory impairment was evident in 4/6 of the LS tested; quality of life was good and executive functions were normal.

CONCLUSION

Radiotherapy remains an essential component in the treatment of low-grade glioma. Prospective studies are needed to evaluate the relative contributions of the disease itself and of surgery, radiation and chemotherapy to long-term neurocognitive damage.

Reoperations of patients with low-grade gliomas in eloquent or near eloquent brain areas

BACKGROUND AND PURPOSE

Reoperations of patients with recurrent low-grade gliomas (LGG) are not always recommended due to a higher risk of neurological deficits when compared to initial surgery. The purpose of the present study was to evaluate surgical outcomes of patients operated on for recurrent LGG.

MATERIAL AND METHODS

Sixteen patients who had surgery for recurrent LGG out of 68 LGG patients who underwent surgery at the Department of Neurosurgery in Sosnowiec, Poland between 2005 and 2011 were enrolled in the study.

RESULTS

A large tumour volume prior to the initial surgery was the most significant parameter influencing LGG progression (96.6 cm³ vs. 47.9 cm3, p = 0.01). Increased incidence of epileptic seizures and decreased mental ability according to Karnofsky score were the most common symptoms associated with tumour recurrence. In the group of patients with malignant transformation, the relative cerebral blood volume (rCBV) was considerably increased (1.21 vs. 2.41, p < 0.01). No statistically significant difference was found in terms of the extent of resection between initial surgery and reoperation. Similarly, no significant difference was found in the number of patients with a permanent neurological deficit after initial surgery and reoperation.

CONCLUSIONS

Reoperations of the patients with recurrent LGG are not burdened with a higher risk of neurological sequelae when compared to initial surgery. The extent of resection during the surgery for LGG recurrence is comparable to initial surgery. The increase of rCBV seems to be a significant biomarker that indicates malignant transformation.

Usefulness of intraoperative computed tomography in surgery for low-grade gliomas: a comparative study between two series without and with intraoperative computed tomography

We have routinely used an intraoperative CT (i-CT) system in over 800 neurosurgical procedures since 1997. To investigate the utility of i-CT in low-grade glioma (LGG) surgery, we investigated whether i-CT improved the extent of tumor resection and prognosis in 46 patients with histologically confirmed LGG consisting of 27 patients with World Health Organization grade II astrocytoma, 12 with oligodendroglioma, and 7 with oligoastrocytoma. The patients were divided into two groups, 23 who underwent tumor resection without i-CT (non i-CT group) and 23 who underwent surgery using i-CT (i-CT group). We investigated the extent of tumor resection, pre- and postoperative Karnofsky performance status scores, and overall survival in each group. The extent of tumor resection was biopsy 26.1%, partial resection 60.9%, subtotal resection 13.0%, and gross total resection 0% in the non i-CT group, and 4.4%, 21.7%, 34.8%, and 39.1%, respectively, in the i-CT group. The i-CT group showed significantly longer overall survival than the non i-CT group among patients with astrocytoma (p < 0.05) and oligodendroglioma or oligoastrocytoma (p < 0.005). Prolonged survival was related to the extent of resection. There were no significant differences between pre- and postoperative Karnofsky performance status scores between the groups. Surgical resection using i-CT may improve the outcomes of patients with LGG. Additional resection or emergency treatment can be quickly performed as the surgical results are confirmed intraoperatively or immediately after the operation using i-CT.

Neurocognitive functioning in adult WHO grade II gliomas: impact of old and new treatment modalities

In the treatment of patients with low-grade glioma, there still is controversy on how surgical intervention, radiation therapy, and chemotherapy contribute to an ameliorated progression-free survival, overall survival, and treatment-related neurotoxicity. With the ongoing changes in treatment options for these patients, neurocognitive functioning is an increasingly important outcome measure, because neurocognitive impairments can have a large impact on self-care, social and professional functioning, and consequently, health-related quality of life. Many factors contribute to neurocognitive outcome, such as direct and indirect tumor effects, seizures, medication, and oncological treatment. Although the role of radiotherapy has been studied extensively, the adverse effects on neurocognitive function of other treatment-related factors remain elusive. This holds for both resective surgery, in which the use of intraoperative stimulation mapping has a high potential benefit concerning survival and patient functioning, and the use of chemotherapy that might have some interesting new applications, such as the facilitation of total resection for initially primary or recurrent diffuse low-grade glioma tumors. This article will discuss these treatment options in patients with low-grade glioma and their potential effects on neurocognitive functioning.

Spontaneous and therapeutic prognostic factors in adult hemispheric World Health Organization Grade II gliomas: a series of 1097 cases

Object

The spontaneous prognostic factors and optimal therapeutic strategy for WHO Grade II gliomas (GIIGs) have yet to be unanimously defined. Specifically, the role of resection is still debated, most notably because the actual amount of resection has seldom been assessed.

Methods

Cases of GIIGs treated before December 2007 were extracted from a multicenter database retrospectively collected since January 1985 and prospectively collected since 1996. Inclusion criteria were a patient age ≥ 18 years at diagnosis, histological diagnosis of WHO GIIG, and MRI evaluation of tumor volume at diagnosis and after initial surgery. One thousand ninety-seven lesions were included in the analysis. The mean follow-up was 7.4 years since radiological diagnosis. Factors significant in a univariate analysis (with a p value ≤ 0.1) were included in the multivariate Cox proportional hazard regression model analysis.

Results

At the time of radiological diagnosis, independent spontaneous factors of a poor prognosis were an age ≥ 55 years, an impaired functional status, a tumor location in a nonfrontal area, and, most of all, a larger tumor size. When the study starting point was set at the time of first treatment, independent favorable prognostic factors were limited to a smaller tumor size, an epileptic symptomatology, and a greater extent of resection.

Conclusions

This large series with its volumetric assessment refines the prognostic value of previously stressed clinical and radiological parameters and highlights the importance of tumor size and location. The results support additional arguments in favor of the predominant role of resection, in accordance with recently reported experiences.

Accumulation of 2-hydroxyglutarate is not a biomarker for malignant progression in IDH-mutated low-grade gliomas

OBJECTIVES

To determine whether accumulation of 2-hydroxyglutarate in IDH-mutated low-grade gliomas (LGG; WHO grade II) correlates with their malignant transformation and to evaluate changes in metabolite levels during malignant progression.

METHODS

Samples from 54 patients were screened for IDH mutations: 17 patients with LGG without malignant transformation, 18 patients with both LGG and their consecutive secondary glioblastomas (sGBM; n = 36), 2 additional patients with sGBM, 10 patients with primary glioblastomas (pGBM), and 7 patients without gliomas. The cellular tricarboxylic acid cycle metabolites, citrate, isocitrate, 2-hydroxyglutarate, α-ketoglutarate, fumarate, and succinate were profiled by liquid chromatography-tandem mass spectrometry. Ratios of 2-hydroxyglutarate/isocitrate were used to evaluate differences in 2-hydroxyglutarate accumulation in tumors from LGG and sGBM groups, compared with pGBM and nonglioma groups.

RESULTS

IDH1 mutations were detected in 27 (77.1%) of 37 patients with LGG. In addition, in patients with LGG with malignant progression (n = 18), 17 patients were IDH1 mutated with a stable mutation status during their malignant progression. None of the patients with pGBM or nonglioma tumors had an IDH mutation. Increased 2-hydroxyglutarate/isocitrate ratios were seen in patients with IDH1-mutated LGG and sGBM, in comparison with those with IDH1-nonmutated LGG, pGBM, and nonglioma groups. However, no differences in intratumoral 2-hydroxyglutarate/isocitrate ratios were found between patients with LGG with and without malignant transformation. Furthermore, in patients with paired samples of LGG and their consecutive sGBM, the 2-hydroxyglutarate/isocitrate ratios did not differ between both tumor stages.

CONCLUSION

Although intratumoral 2-hydroxyglutarate accumulation provides a marker for the presence of IDH mutations, the metabolite is not a useful biomarker for identifying malignant transformation or evaluating malignant progression.

Clinical application of motor pathway mapping using diffusion tensor imaging tractography and intraoperative direct subcortical stimulation in cerebral glioma surgery: a prospective cohort study

BACKGROUND

Glioma surgery in eloquent areas remains a challenge because of the risk of postoperative motor deficits.

OBJECTIVE

To prospectively evaluate the efficiency of using a combination of diffusion tensor imaging (DTI) tractography functional neuronavigation and direct subcortical stimulation (DsCS) to yield a maximally safe resection of cerebral glioma in eloquent areas.

METHODS

A prospective cohort study was conducted in 58 subjects with an initial diagnosis of primary cerebral glioma within or adjacent to the pyramidal tract (PT). The white matter beneath the resection cavity was stimulated along the PT, which was visualized with DTI tractography. The intercept between the PT border and DsCS site was measured. The sensitivity and specificity of DTI tractography for PT mapping were evaluated. The efficiency of the combined use of both techniques on motor function preservation was assessed.

RESULTS

Postoperative analysis showed gross total resection in 40 patients (69.0%). Seventeen patients (29.3%) experienced postoperative worsening; 1-month motor deficit was observed in 6 subjects (10.3%). DsCS verified a high concordance rate with DTI tractography for PT mapping. The sensitivity and specificity of DTI were 92.6% and 93.2%, respectively. The intercepts between positive DsCS sites and imaged PTs were 2.0 to 14.7 mm (5.2 ± 2.2 mm). The 6-month Karnofsky performance scale scores in 50 postoperative subjects were significantly increased compared with their preoperative scores.

CONCLUSION

DTI tractography is effective but not completely reliable in delineating the descending motor pathways. Integration of DTI and DsCS favors patient-specific surgery for cerebral glioma in eloquent areas.

Biopsy versus resection for the management of low-grade gliomas

BACKGROUND

Low-grade gliomas (LGG) constitute a class of slow-growing primary brain neoplasms. Patients with clinically and radiographically suspected LGG have two initial surgical options, biopsy or resection. Biopsy can provide a histological diagnosis with minimal risk but does not offer a direct treatment. Resection may have additional benefits such as increasing survival and delaying recurrence, but is associated with a higher risk for surgical morbidity. There remains controversy about the role of biopsy versus resection and the relative clinical outcomes for the management of LGG.

OBJECTIVES

To assess the clinical effectiveness of biopsy compared to surgical resection in patients with a new lesion suspected to be a LGG.

SEARCH METHODS

The following electronic databases were searched: Cochrane Central Register of Controlled Trials (CENTRAL) (2012, Issue 11), MEDLINE (1950 to week 3 November 2012), EMBASE (1980 to Week 46 2012). Unpublished and grey literature including Metaregister, Physicians Data Query, www.controlled-trials.com/rct, www.clinicaltrials.gov, and www.cancer.gov/clinicaltrials were also queried for ongoing trials.

SELECTION CRITERIA

Patients of any age with a suspected intracranial LGG receiving biopsy or resection within a randomized clinical trial (RCT) or controlled clinical trial (CCT) were included. Patients with prior resections, radiation therapy, or chemotherapy for LGG were excluded. Outcome measures included overall survival (OS), progression free survival (PFS), functionally independent survival (FIS), adverse events, symptom control, and quality of life (QoL).

DATA COLLECTION AND ANALYSIS

A total of 2764 citations were searched and critically analyzed for relevance. This effort was undertaken by three independent review authors.

MAIN RESULTS

No RCTs of biopsy or resection for LGG were identified. Twenty other studies were retrieved for analysis based on pre-specified selection criteria. Ten studies were retrospective or literature reviews. Three studies were prospective but were limited to tumor recurrence or the extent of resection. One study was a population-based parallel cohort and not an RCT. Four studies were RCTs, however patients were randomized with respect to varying radiotherapy regimens to assess timing and dose of radiation. One RCT was focused on high-grade gliomas and not LGG. One last RCT evaluated diffusion tensor imaging (DTI)-based neuro-navigation for surgical resection.

AUTHORS' CONCLUSIONS

Currently there are no randomized clinical trials or controlled clinical trials available on which to base clinical decisions. Therefore, physicians must approach each case individually and weigh the risks and benefits of each intervention until further evidence is available. Future research could focus on randomized clinical trials to determine outcomes benefits for biopsy versus resection.

Surgical resection of malignant gliomas-role in optimizing patient outcome

Malignant gliomas represent one of the most devastating human diseases. Primary treatment of these tumours involves surgery to achieve tumour debulking, followed by a multimodal regimen of radiotherapy and chemotherapy. Survival time in patients with malignant glioma has modestly increased in recent years owing to advances in surgical and intraoperative imaging techniques, as well as the systematic implementation of randomized trial-based protocols and biomarker-based stratification of patients. The role and importance of several clinical and molecular factors-such as age, Karnofsky score, and genetic and epigenetic status-that have predictive value with regard to postsurgical outcome has also been identified. By contrast, the effect of the extent of glioma resection on patient outcome has received little attention, with an 'all or nothing' approach to tumour removal still taken in surgical practice. Recent studies, however, reveal that maximal possible cytoreduction without incurring neurological deficits has critical prognostic value for patient outcome and survival. Here, we evaluate state-of-the-art surgical procedures that are used in management of malignant glioma, with a focus on assessment criteria and value of tumour reduction. We highlight key surgical factors that enable optimization of adjuvant treatment to enhance patient quality of life and improve life expectancy.

Low-grade astrocytoma: surgical outcomes in eloquent versus non-eloquent brain areas

A retrospective study of 81 patients with low-grade astrocytoma (LGA) comparing the efficacy of aggressive versus less aggressive surgery in eloquent and non-eloquent brain areas was conducted. Extent of surgical resection was analyzed to assess overall survival (OS) and progression- free survival (PFS). Degree of tumor resection was classified as gross total resection (GTR), subtotal resection (STR) or biopsy. GTR, STR and biopsy in patients with tumors in non-eloquent areas were performed in 31, 48 and 21% subjects, whereas in patients with tumors in eloquent areas resections were 22.5, 35 and 42.5%. Overall survival was 4.7 and 1.9 years in patients with tumors in non-eloquent brain areas submitted to GTR/STR and biopsy (p=0.013), whereas overall survival among patients with tumors in eloquent area was 4.5 and 2.1 years (p=0.33). Improved outcome for adult patients with LGA is predicted by more aggressive surgery in both eloquent and non-eloquent brain areas.

Low grade gliomas in eloquent locations - implications for surgical strategy, survival and long term quality of life

Background

Surgical management of suspected LGG remains controversial. A key factor when deciding a surgical strategy is often the tumors’ perceived relationship to eloquent brain regions

Objective

To study the association between tumor location, survival and long-term health related quality of life (HRQL) in patients with supratentorial low-grade gliomas (LGG).

Methods

Adults (≥18 years) operated due to newly diagnosed LGG from 1998 through 2009 included from two Norwegian university hospitals. After review of initial histopathology, 153 adults with supratentorial WHO grade II LGG were included in the study. Tumors’ anatomical location and the relationship to eloquent regions were graded. Survival analysis was adjusted for known prognostic factors and the initial surgical procedure (biopsy or resection). In long-term survivors, HRQL was assessed with disease specific questionnaires (EORTC QLQ-C30 and BN20) as well as a generic questionnaire (EuroQol 5D).

Results

There was a significant association between eloquence and survival (log-rank, p<0.001). The estimated 5-year survival was 77% in non-eloquent tumors, 71% in intermediate located tumors and 54% in eloquent tumors. In the adjusted analysis the hazard ratio of increasing eloquence was 1.5 (95% CI 1.1–2.0, p = 0.022). There were no differences in HRQL between patients with eloquent and non-eloquent tumors. The most frequent self-reported symptoms were related to fatigue, cognition, and future uncertainty.

Conclusion

Eloquently located LGGs are associated with impaired survival compared to non-eloquently located LGG, but in long-term survivors HRQL is similar. Although causal inference from observational data should be done with caution, the findings illuminate the delicate balance in surgical decision making in LGGs, and add support to the probable survival benefits of aggressive surgical strategies, perhaps also in eloquent locations.

Low-grade glioma surgery in eloquent areas: volumetric analysis of extent of resection and its impact on overall survival. A single-institution experience in 190 patients

Object

A growing number of published studies have recently demonstrated the role of resection in overall survival (OS) for patients with gliomas. In this retrospective study, the authors objectively investigated the role of the extent of resection (EOR) in OS in patients with low-grade gliomas (LGGs).

Methods

Between 1998 and 2011, 190 patients underwent surgery for LGGs. All surgical procedures were conducted under corticosubcortical stimulation. The EOR was established by analyzing the pre- and postoperative volumes of the gliomas on T2-weighted MRI studies. The difference between the preoperative tumor volumes was also investigated by measuring the volumetric difference between the T2- and T1-weighted MRI images (ΔVT2T1) to evaluate how the diffusive tumor-growing pattern affected the EOR achieved.

Results

The median preoperative tumor volume was 55 cm3, and in almost half of the patients the EOR was greater than 90%. In this study, patients with an EOR of 90% or greater had an estimated 5-year OS rate of 93%, those with EOR between 70% and 89% had a 5-year OS rate of 84%, and those with EOR less than 70% had a 5-year OS rate of 41% (p < 0.001). New postoperative deficits were noted in 43.7% of cases, while permanent deficits occurred in 3.16% of cases. There were 41 deaths (21.6%), and the median follow-up was 4.7 years.

A further volumetric analysis was also conducted to compare 2 different intraoperative protocols (Series 1 [intraoperative electrical stimulation alone] vs Series 2 [intraoperative stimulation plus overlap of functional MRI/fiber tracking diffusion tensor imaging data on a neuronavigation system]). Patients in Series 1 had a median EOR of 77%, while those in Series 2 had a median EOR of 90% (p = 0.0001). Multivariate analysis showed that OS is influenced not only by EOR (p = 0.001) but also by age (p = 0.003), histological subtype (p = 0.005), and the ΔVT2T1 value (p < 0.0001). Progression-free survival is similarly influenced by histological subtype (fibrillary astrocytoma, p = 0.003), EOR (p < 0.0001), and ΔVT2T1 value (p < 0.0001), as is malignant progression–free survival (p = 0.003, p < 0.0001, and p < 0.0001, respectively). Finally, the study shows that the higher the ΔVT2T1 value, the less extensive the currently possible resection, highlighting an apparent correlation between the ΔVT2T1 value itself and EOR (p < 0.0001).

Conclusions

The EOR and the ΔVT2T1 values are the strongest independent predictors in improving OS as well as in delaying tumor progression and malignant transformation. Furthermore, the ΔVT2T1 value may be useful as a predictive index for EOR. Finally, due to intraoperative corticosubcortical mapping and the overlap of functional data on the neuronavigation system, major resection is possible with an acceptable risk and a significant increase in expected OS.

Awake craniotomy and electrophysiological mapping for eloquent area tumours

OBJECTIVE

An awake craniotomy facilitates radical excision of eloquent area gliomas and ensures neural integrity during the excision. The study describes our experience with 67 consecutive awake craniotomies for the excision of such tumours.

METHODS

Sixty-seven patients with gliomas in or adjacent to eloquent areas were included in this study. The patient was awake during the procedure and intraoperative cortical and white matter stimulation was performed to safely maximize the extent of surgical resection.

RESULTS

Of the 883 patients who underwent craniotomies for supratentorial intraaxial tumours during the study period, 84 were chosen for an awake craniotomy. Sixty-seven with a histological diagnosis of glioma were included in this study. There were 55 men and 12 women with a median age of 34.6 years. Forty-two (62.6%) patients had positive localization on cortical stimulation. In 6 (8.9%) patients white matter stimulation was positive, five of whom had responses at the end of a radical excision. In 3 patients who developed a neurological deficit during tumour removal, white matter stimulation was negative and cessation of the surgery did not result in neurological improvement. Sixteen patients (24.6%) had intraoperative neurological deficits at the time of wound closure, 9 (13.4%) of whom had persistent mild neurological deficits at discharge, while the remaining 7 improved to normal. At a mean follow-up of 40.8 months, only 4 (5.9%) of these 9 patients had persistent neurological deficits.

CONCLUSION

Awake craniotomy for excision of eloquent area gliomas enable accurate mapping of motor and language areas as well as continuous neurological monitoring during tumour removal. Furthermore, positive responses on white matter stimulation indicate close proximity of eloquent cortex and projection fibres. This should alert the surgeon to the possibility of postoperative deficits to change the surgical strategy. Thus the surgeon can resect tumour safely, with the knowledge that he has not damaged neurological function up to that point in time thus maximizing the tumour resection and minimizing neurological deficits.

The role of intraoperative magnetic resonance imaging in glioma surgery

For patients with gliomas, the goal of surgery is to maximize the extent of tumor resection while avoiding injury to functional tissue. The hope is to improve patients' survival and maintain the highest quality of life as possible. However, because of the infiltrative nature of gliomas these two goals often oppose each other so a compromise must be met. Many tools have been developed to help with this challenge of glioma surgery. Over the past two decades, intraoperative-magnetic resonance imaging (iMRI) has emerged as an increasingly important modality to enhance surgical safety while providing the surgeon with updated information to guide their resection. Here the authors review the studies that demonstrate a positive correlation between extent of resection (EOR) and overall survival (OS), although the data is clearer in patients with low-grade gliomas (LGG) and still somewhat controversial in those with higher-grade tumors. We will then review some of the studies that support the role of iMRI and how it has impacted glioma surgery by increasing the EOR. The value of iMRI usage in regards to overall patient outcome can be extrapolated through its effect on EOR. Overall, available data support the safe use of iMRI and as an effective adjunct in glioma surgery.

Clinical applications of imaging biomarkers. Part 2. The neurosurgeon's perspective

Advances in imaging, including multivoxel spectroscopy, tractography, functional MRI and positron emission spectroscopy, are being used by neurosurgeons to target aggressive areas in gliomas, and to help identify tumour boundaries, functional areas and tracts. Neuro-oncological surgeons need to understand these techniques to help maximise tumour resection, while minimising morbidity in an attempt to improve the quality of patient outcome. This article reviews the evidence for the practical use of multimodal imaging in modern glioma surgery.

The assessment of prognostic factors in surgical treatment of low-grade gliomas: a prospective study

OBJECTIVE

A prospective volumetric analysis of extent of resection (EOR) was carried out to assess surgical outcomes in adults diagnosed with hemispheric low grade gliomas (LGGs).

MATERIALS AND METHODS

68 consecutive patients diagnosed with LGGs were enrolled in the study. Pre- and post-operative tumor volumes and EOR were measured based on FLAIR MRI. Dynamic susceptibility contrast perfusion magnetic resonance imaging (DSC MRI) was used for the assessment of relative cerebral blood volume (rCBV). Three outcome measures were assessed: overall survival (OS), progression-free survival (PFS), and malignant degeneration-free survival (MFS).

RESULTS

In 6 (9%) patients permanent neurologic deficits were observed. No statistically significant dependence between the EOR and the occurrence of permanent deficits was found. The eloquent or close to the eloquent location was statistically connected with lower EOR (p=0.023). The preoperative volume of tumors treated with gross total resection was significantly smaller than the volume of tumors in subtotal or partial resection groups (p=0.020, p<0.001, respectively). OS was predicted by age at diagnosis (p=0.032), and rCBV (p=0.002). Progression and malignant transformation occurred in 22 (32%) and 11 (16%) out of 68 patients. PFS was predicted by preoperative tumor volume (p=0.005), postoperative tumor volume (p=0.008), the EOR (p=0.001), and by the rCBV (p=0.033). MFS was predicted by preoperative tumor volume (p=0.034), the EOR (pp=0.020), and by rCBV (p=0.022). Postoperative tumor volume was associated with a trend of improved MFS (p=0.072). The univariate analysis shows the statistical trend for the relationship between histological subtype and PFS and MFS (p=0.079, p=0.078, respectively). Multivariate analysis selected preoperative tumor volume and rCBV as independently associated with PFS (p=0.009, p=0.019, respectively) and MFS (p=0.023, p=0.035, respectively). EOR was associated with a trend of improved PFS, and MFS (p=0.069, p=0.094, respectively).

CONCLUSIONS

Tumor resection of LGG with the use of intraoperative monitoring and neuronavigation is associated with a low risk of new permanent deficits, but EOR significantly decreases with the size of the tumor and/or its location in/close to the eloquent areas. Smaller preoperative tumor volume and greater EOR are significantly associated with longer OS, PFS and MFS. Preoperative rCBV is one of the important prognostic factors significantly connected with survival. Prognosis in LGGs is still under discussion. Other factors such as age, histopathological subtype and KPS should not be underestimated.

Magnetic resonance imaging volumetric assessment of the extent of contrast enhancement and resection in oligodendroglial tumors

OBJECT

Oligodendrogliomas that enhance on MR images are associated with poor prognosis. However, the importance of the volume of enhancing tumor tissue, and the extent of its resection, is uncertain. The authors examined the prognostic significance of preoperative and residual postoperative enhancing tissue volumes in a large single-center series of patients with oligodendroglioma. They also examined the relationship between enhancement and characteristic genetic signatures in oligodendroglial tumors, specifically deletion of 1p and 19q (del 1p/19q).

METHODS

The authors retrospectively analyzed 100 consecutive cases of oligodendroglioma involving patients who had undergone T1-weighted gadolinium-enhanced MRI at diagnosis and immediately after initial surgical intervention. The presence of preoperative enhancement was determined by consensus. Preoperative and residual postoperative volumes were measured using a quantitative, semiautomated method by a single blinded observer. Intrarater reliability for preoperative volumes was confirmed by remeasurement in a subset of patients 3 months later. Intrarater and interrater reliability for residual postoperative volumes was confirmed by remeasurement of these volumes by both the original and a second blinded observer. Multivariate analysis was used to assess the influence of contrast enhancement at diagnosis and the volume of pre- and postoperative contrast-enhancing tumor tissue on time to relapse (TTR) and overall survival (OS), while controlling for confounding clinical, pathological, and genetic factors.

RESULTS

Sixty-three of 100 patients had enhancing tumors at initial presentation. Presence of contrast enhancement at diagnosis was related to reduced TTR and OS on univariate analysis but was not significantly related on multivariate analysis. In enhancing tumors, however, greater initial volume of enhancing tissue correlated with shortened TTR (p = 0.00070). Reduced postoperative residual enhancing volume and a relatively greater resection of enhancing tissue correlated with longer OS (p = 0.0012 and 0.0041, respectively). Interestingly, patients in whom 100% of enhancing tumor was resected had significantly longer TTR (174 vs 64 weeks) and OS (392 vs 135 weeks) than those with any residual enhancing tumor postoperatively. This prognostic benefit was not consistently maintained with greater than 90% or even greater than 95% resection of enhancing tissue. There was no relationship between presence or volume of enhancement and del 1p/19q.

CONCLUSIONS

In enhancing oligodendrogliomas, completely resecting enhancing tissue independently improves outcome, irrespective of histological grade or genetic status. This finding supports aggressive resection and may impact treatment planning for patients with these tumors.

Long-term follow-up in adult patients with low-grade glioma (WHO II) postoperatively irradiated. Analysis of prognostic factors

AIM

To report the long-term follow-up of a cohort of adult patients with LGG post-operatively irradiated in one institution, and to identify prognostic factors for progression free survival.

BACKGROUND

There is little consensus about the optimal treatment for low-grade glioma (LGG), and the clinical management of LGG is one of the most controversial areas in neurooncology. Radiation therapy is one option for treatment of patients with LGG, whereas other options include postoperative observation.

MATERIALS AND METHODS

Between 1975 and 2005, 180 patients with LGG (WHO II) received postoperative irradiation after non radical (subtotal or partial) excision. Patients had to be 18 years of age or older, and have histologic proof of supratentorial fibrillary (FA), protoplasmic (PA) or gemistocytic astrocytoma (GA). Radiotherapy was given within 3-10 weeks after surgery. Treatment fields were localized and included the preoperative tumor volume, with a 1-2 cm margin, treated to a total dose of 50-60 Gy in 25-30 fractions over 5-6 weeks.

RESULTS

Actuarial ten-year progression free survival (APFS) in the whole group was 19%. The worse prognosis was observed in patients with GA. Ten-year APFS rates for GA, PA and FA were 10%, 18% and 22%, respectively.

CONCLUSION

The findings from our long-term cohort of 180 patients with LGG confirmed by uni- and multivariate analysis demonstrated that only astrocytoma histology significantly determined the prognosis. The best survival was observed in patients with the fibrillary variant, and the worst for the gemistocytic one.

Improving the time-machine: estimating date of birth of grade II gliomas

OBJECTIVES

Here we present a model aiming to provide an estimate of time from tumour genesis, for grade II gliomas. The model is based on a differential equation describing the diffusion-proliferation process. We have applied our model to situations where tumour diameter was shown to increase linearly with time, with characteristic diametric velocity.

MATERIALS AND METHODS

We have performed numerical simulations to analyse data, on patients with grade II gliomas and to extract information concerning time of tumour biological onset, as well as radiology and distribution of model parameters.

RESULTS AND CONCLUSIONS

We show that the estimate of tumour onset obtained from extrapolation using a constant velocity assumption, always underestimates biological tumour age, and that the correction one should add to this estimate is given roughly by 20/v (year), where v is the diametric velocity of expansion of the tumour (expressed in mm/year). Within the assumptions of the model, we have identified two types of tumour: the first corresponds to very slowly growing tumours that appear during adolescence, and the second type corresponds to slowly growing tumours that appear later, during early adulthood. That all these tumours become detectable around a mean patient age of 30 years could be interesting for formulation of strategies for early detection of tumours.

Use of intraoperative MRI for resection of gliomas

Literature has shown that extent of tumor resection has an impact on quality of life and survival of patients with gliomas. Intraoperative MRI has been used to increase resection while preserving procedure's safety. METHOD: The first five patients with gliomas operated on at the University of São Paulo using intraoperative MRI are reported. All but one patient had Karnofsky Performance Status of 100% before surgery. Presentation symptoms were progressive headache, seizures, behavior disturbance, one instance of hemianopsia, and another of hemiparesis. RESULTS: Gross total removal was achieved in two patients. Surgical resection was limited by tumor invasion of critical areas like the internal capsule or the mesencephalon in the remaining patients. CONCLUSION: Intra-operative MRI is an important tool that helps surgeons to remove glial tumors, however, knowledge of physiology and functional anatomy is still fundamental to avoid morbidity.

Role of diffusion tensor magnetic resonance tractography in predicting the extent of resection in glioma surgery

Diffusion tensor imaging (DTI) tractography enables the in vivo visualization of the course of white matter tracts inside or around a tumor, and it provides the surgeon with important information in resection planning. This study is aimed at assessing the ability of preoperative DTI tractography in predicting the extent of the resection achievable in surgical removal of gliomas. Patients with low-grade gliomas (LGGs; 46) and high-grade gliomas (HGGs; 27) were studied using a 3T scanner according to a protocol including a morphological study (T2, fluid-attenuated inversion-recovery, T1 sequences) and DTI acquisitions (b = 1000 s/mm(2), 32 gradient directions). Preoperative tractography was performed off-line on the basis of a streamline algorithm, by reconstructing the inferior fronto-occipital (IFO), the superior longitudinal fascicle (SLF), and the corticospinal tract (CST). For each patient, the relationship between each bundle reconstructed and the lesion was analyzed. Initial and residual tumor volumes were measured on preoperative and postoperative 3D fluid-attenuated inversion-recovery images for LGGs and postcontrast T1-weighted scans for HGGs. The presence of intact fascicles was predictive of a better surgical outcome, because these cases showed a higher probability of total resection than did subtotal and partial resection. The presence of infiltrated or displaced CST or infiltrated IFO was predictive of a lower probability of total resection, especially for tumors with preoperative volume <100 cm(3). DTI tractography can thus be considered to be a promising tool for estimating preoperatively the degree of radicality to be reached by surgical resection. This information will aid clinicians in identifying patients who will mostly benefit from surgery.

A critical evaluation of cystic features in primary glioblastoma as a prognostic factor for survival

Object

The presence of cystic features in glioblastoma (GBM) has been described as a favorable prognostic factor. The aim of this study was to determine the survival outcome in patients undergoing surgery for newly diagnosed primary GBM with a large cystic component as compared with a large cohort of patients with noncystic GBM, while controlling for well-characterized prognostic factors.

Methods

A retrospective review of 354 consecutive patients treated with resection of primary GBM was performed using medical records and imaging information obtained at the University of California, San Francisco from 2005 to 2009. Within this cohort, 37 patients with large cysts (≥ 50% of tumor) were identified. Clinical presentations and surgical outcomes were statistically compared between the cystic and noncystic patients.

Results

There were no statistically significant differences in clinical presentation between groups, including differences in age, sex, presenting symptoms, tumor location, or preoperative functional status, with the exception of tumor size, which was marginally larger in the cystic group. Surgical outcomes, including extent of resection and postoperative functional status, were equivalent. The median actuarial survival for the patients with cystic GBM was 17.0 months (95% CI 12.6–21.3 months), and the median survival for patients with noncystic GBM was 15.9 months (95% CI 14.6–17.2 months). There was no significant between-groups difference in survival (p = 0.99, log-rank test). A Cox multivariate regression model was constructed, which identified only age and extent of resection as independent predictors of survival. The presence of a cyst was not a statistically significant prognostic factor.

Conclusions

This study, comprising the largest series of cases of primary cystic GBM reported in the literature to date, demonstrates that the presence of a large cyst in patients with GBM does not significantly affect overall survival as compared with survival in patients without a cyst. Preoperative discussions with patients with GBM should focus on validated prognostic factors. The presence of cystic features does not confer a survival advantage.

Combination of neoadjuvant chemotherapy followed by surgical resection as a new strategy for WHO grade II gliomas: a study of cognitive status and quality of life

Diffuse WHO grade II (GIIG) may be unresectable when involving critical structures. To assess the feasibility and functional tolerance (cognition and quality of life) of an original therapeutic strategy combining neoadjuvant chemotherapy followed by surgical resection for initially inoperable GIIG. Ten patients underwent Temozolomide for unresectable GIIG, as initial treatment or at recurrence after previous partial resection, due to invasion of eloquent areas or bi-hemispheric diffusion preventing a total/subtotal removal. Functional outcome after both treatments was assessed, with evaluation of seven cognitive domains. Chemotherapy induced tumor shrinkage (median volume decrease 38.9%) in ipsilateral functional areas in six patients and in the contralateral hemisphere in four. Only four patients had a 1p19q codeletion. The tumor shrinkage made possible the resection (mean extent of resection 93.3%, 9 total or subtotal removals) of initially inoperable tumors. Postoperatively, three patients had no deficits, while verbal episodic memory and executive functions were slightly impaired in seven patients. However, global quality of life was roughly preserved on the EORTC QLQ C30 + BN 20 (median score: 66.7%). Role functioning score was relatively reduced (median score: 66.7%) whereas KPS was preserved (median score: 90, range 80-100). Seven patients became seizure-free while three improved. This combined treatment is feasible, efficient (surgery made possible by neoadjuvant chemotherapy) and well-tolerated (preservation of quality of life, no serious cognitive disturbances). Cognitive deficits seem mostly related to tumor location. Because KPS is not reliable enough, a detailed neuropsychological assessment should be systematically performed in GIIG.

Intraoperative confocal microscopy in the visualization of 5-aminolevulinic acid fluorescence in low-grade gliomas

OBJECT

Greater extent of resection (EOR) for patients with low-grade glioma (LGG) corresponds with improved clinical outcome, yet remains a central challenge to the neurosurgical oncologist. Although 5-aminolevulinic acid (5-ALA)-induced tumor fluorescence is a strategy that can improve EOR in gliomas, only glioblastomas routinely fluoresce following 5-ALA administration. Intraoperative confocal microscopy adapts conventional confocal technology to a handheld probe that provides real-time fluorescent imaging at up to 1000× magnification. The authors report a combined approach in which intraoperative confocal microscopy is used to visualize 5-ALA tumor fluorescence in LGGs during the course of microsurgical resection.

METHODS

Following 5-ALA administration, patients with newly diagnosed LGG underwent microsurgical resection. Intraoperative confocal microscopy was conducted at the following points: 1) initial encounter with the tumor; 2) the midpoint of tumor resection; and 3) the presumed brain-tumor interface. Histopathological analysis of these sites correlated tumor infiltration with intraoperative cellular tumor fluorescence.

RESULTS

Ten consecutive patients with WHO Grades I and II gliomas underwent microsurgical resection with 5-ALA and intraoperative confocal microscopy. Macroscopic tumor fluorescence was not evident in any patient. However, in each case, intraoperative confocal microscopy identified tumor fluorescence at a cellular level, a finding that corresponded to tumor infiltration on matched histological analyses.

CONCLUSIONS

Intraoperative confocal microscopy can visualize cellular 5-ALA-induced tumor fluorescence within LGGs and at the brain-tumor interface. To assess the clinical value of 5-ALA for high-grade gliomas in conjunction with neuronavigation, and for LGGs in combination with intraoperative confocal microscopy and neuronavigation, a Phase IIIa randomized placebo-controlled trial (BALANCE) is underway at the authors' institution.

Low-grade gliomas in adults

Making treatment decisions for patients with infiltrating low-grade gliomas (LGGs) is challenging. Patients frequently present with seizures and usually have little or no neurologic deficit. In this younger and relatively well patient population, despite the potential for significant morbidity, we believe that surgical resection, radiation therapy, and chemotherapy each play an important role in the optimal management of these tumors. Randomized clinical trials have begun to address some of the many questions about prognosis, natural history, and treatment, but most questions have yet to be answered. We believe that, when possible, a maximal surgical resection consistent with preservation of neurologic function should be performed, even though it is likely that no randomized clinical trial will ever be done to demonstrate a survival advantage for this approach. External beam radiation therapy is most often given to a total dose of 50.4 or 54 Gy in 1.8-Gy fractions. The role of chemotherapy is less certain, but a growing body of evidence suggests that temozolomide, a generally well-tolerated drug, is active in the treatment of LGGs. In recent years, loss of heterozygosity of chromosome 1p and 19q, as well as silencing of the MGMT gene, have been identified as promising predictors of response to adjuvant therapy in gliomas. Although randomized trials have not yet shown a survival benefit for early radiation therapy or chemotherapy, one study by the European Organisation for Research and Treatment of Cancer did show an improvement in time to tumor progression with the earlier use of radiation therapy. In addition, a trial by the Radiation Therapy Oncology Group (soon to be analyzed and reported) is comparing radiation alone with radiation followed by a year (six cycles) of standard-dose PCV chemotherapy (procarbazine, CCNU, and vincristine); this trial may shed light on the use of chemotherapy in conjunction with radiation therapy for the initial treatment of LGGs. Because patients remain at risk for tumor progression for the remainder of their lives, we recommend lifelong follow-up with MRI scans, even for patients without documented tumor regrowth over long intervals. To give clinicians a more solid basis for guiding therapy recommendations, we encourage participation in large cooperative group clinical trials.

Analysis of DNA repair gene polymorphisms and survival in low-grade and anaplastic gliomas

The purpose of this study was to explore the variation in DNA repair genes in adults with WHO grade II and III gliomas and their relationship to patient survival. We analysed a total of 1,458 tagging single-nucleotide polymorphisms (SNPs) that were selected to cover DNA repair genes, in 81 grade II and grade III gliomas samples, collected in Sweden and Denmark. The statistically significant genetic variants from the first dataset (P < 0.05) were taken forward for confirmation in a second dataset of 72 grade II and III gliomas from northern UK. In this dataset, eight gene variants mapping to five different DNA repair genes (ATM, NEIL1, NEIL2, ERCC6 and RPA4) which were associated with survival. Finally, these eight genetic variants were adjusted for treatment, malignancy grade, patient age and gender, leaving one variant, rs4253079, mapped to ERCC6, with a significant association to survival (OR 0.184, 95% CI 0.054-0.63, P = 0.007). We suggest a possible novel association between rs4253079 and survival in this group of patients with low-grade and anaplastic gliomas that needs confirmation in larger datasets.

PROX1 is a predictor of survival for gliomas WHO grade II

Background:

The clinical course of World Health Organisation grade II gliomas remains variable and their time point of transformation into a more malignant phenotype is unpredictable. Identification of biological markers that can predict prognosis in individual patients is of great clinical value. PROX1 is a transcription factor that has a critical role in the development of various organs. PROX1 has been ascribed both oncogenic and tumour suppressive functions in human cancers. We have recently shown that PROX1 may act as a diagnostic marker for high-grade gliomas. The aim of this study was to address the prognostic value of PROX1 in grade II gliomas.

Methods:

A total of 116 samples were evaluated for the presence of PROX1 protein. The number of immunopositive cells was used as a variable in survival analysis, together with established prognostic factors for this patient group.

Results:

Higher PROX1 protein was associated with poor outcome. In the multivariate analysis, PROX1 was identified as an independent factor for survival (P=0.024), together with the presence of mutated isocitrate dehydrogenase 1 R132H protein, and with combined losses of chromosomal arms 1p/19q in oligodendrocytic tumours.

Conclusion:

PROX1 is a novel predictor of survival for grade II gliomas.