Extended stereotactic brain biopsy in suspected primary central nervous system angiitis: good diagnostic accuracy and high safety

OBJECTIVE

To evaluate the diagnostic accuracy and safety of extended stereotactic brain biopsy (ESBB) in a single center cohort with suspected primary angiitis of the central nervous system (PACNS).

METHODS

A standardized stereotactic biopsy targeting MRI-positive lesions and collecting samples from the meninges and the cortex as well as from the white matter was performed in 23 patients with clinically suspected PACNS between 2010 and 2017. The relationship between biopsy yield and clinical characteristics, cerebrospinal fluid parameters, MR-imaging, time point of biopsy and exact localization of biopsy as well as number of tissue samples were examined.

RESULTS

PACNS was confirmed in 7 of 23 patients (30.4%). Alternative diagnoses were identified in 7 patients (30%). A shorter time period between the onset or worsening of symptoms (p = 0.018) and ESBB significantly increased the diagnostic yield. We observed only minor and transient postoperative complications in 3 patients (13.0%). ESBB led to a direct change of the therapeutic regime in 13 of 23 patients (56.5%). Careful neuropathological analysis furthermore revealed that cortical samples were crucial in obtaining a diagnosis.

CONCLUSION

ESBB is a safe approach with good feasibility, even in critically ill patients, and high diagnostic accuracy in patients with suspected PACNS changing future therapies in 13 of 23 patients (56.5%). Early biopsy after symptom onset/worsening is crucial and (sub)acute MRI-lesions should be targeted with a particular need for biopsy samples from the cortical layer.

CTNI-20. PCV CHEMOTHERAPY ALONE IS ASSOCIATED WITH BETTER CLINICAL COURSE IN OLIGODENDROGLIOMA WHO GRADE II

BACKGROUND

Current treatment guidelines for oligodendrogliomas (OD) recommend watch-and-wait strategies after gross total resection and radiation with subsequent chemotherapy (procarbazine, CCNU and vincristine (PCV)) after incomplete resection. The value of chemotherapy alone as an option to delay the risk of late cognitive deficits is not well defined yet. Here, we retrospectively investigated long-term outcome in OD WHO II with respect to initial therapy and tumor volume in magnetic resonance imaging (MRI).

METHODS

A total of 142 patients with OD WHO (World Health Organization) II according to WHO 2016 were retrospectively included. Patients either had watch and wait (W&W) after histological sampling through stereotactic biopsy (n=59) or tumor resection (n=27) or else stereotactic biopsy with subsequent temozolomide (TMZ) (n=26) or PCV (n=30). Pre- and post-therapeutic T2 tumor volumes were obtained. Progression-free survival (PFS), post-recurrence PFS (PR-PFS) and rate of secondary malignization after 10 years (MR-10yrs) were correlated with clinical and volumetric data.

RESULTS

PFS was significantly longer in the PCV cohort compared to TMZ (9.1 vs. 3.6 years, p = 0.04), even after matching patients according to age and initial tumor volume (9.1 vs 4.7 yrs, p = 0.03). PFS in the W&W cohort was 5.1 years and 4.4 years in those receiving tumor resection only. MR-10yrs was 4% in PCV cohort, 18% in the W&W cohort and 52% in the resection only cohort (p = 0.01). In the W&W cohort, patients treated with PCV at first relapse had a longer PR-PFS than those treated with TMZ (in years, 7.2 vs 4.0, p = 0.04). Multivariate analysis confirmed initial PCV therapy (p = 0.01) and initial T2 tumor volume (p = 0.02) to be prognostic.

CONCLUSION

In oligodendrogliomas WHO II PCV chemotherapy alone is superior in terms of PFS and rate of secondary malignization compared to TMZ chemotherapy alone or tumor resection only.

Dynamic 18F-FET PET is a powerful imaging biomarker in gadolinium-negative gliomas

BACKGROUND

We aimed to elucidate the place of dynamic O-(2-[18F]-fluoroethyl)-L-tyrosine (18F-FET) PET in prognostic models of gadolinium (Gd)-negative gliomas.

METHODS

In 98 patients with Gd-negative gliomas undergoing 18F-FET PET guided biopsy, time activity curves (TACs) of each tumor were qualitatively categorized as either increasing or decreasing. Additionally, post-hoc quantitative analyses were done using minimal time-to-peak (TTPmin) measurements. Prognostic factors were obtained from multivariate hazards models. The fit of the biospecimen- and imaging-derived models was compared.

RESULTS

A homogeneous increasing, mixed, and homogeneous decreasing TAC pattern was seen in 51, 19, and 28 tumors, respectively. Mixed TAC tumors exhibited both increasing and decreasing TACs. Corresponding adjusted 5-year survival was 85%, 47%, and 19%, respectively (P < 0.001). Qualitative and quantitative TAC measurements were highly intercorrelated (P < 0.0001). TTPmin was longest (shortest) in the homogeneous increasing (decreasing) TAC group and in between in the mixed TAC group. TTPmin was longer in isocitrate dehydrogenase (IDH)-mutant tumors (P < 0.001). Outcome was similarly precisely predicted by biospecimen- and imaging-derived models. In the biospecimen model, World Health Organization (WHO) grade (P < 0.0001) and IDH status (P < 0.001) were predictors for survival. Outcome of homogeneous increasing (homogeneous decreasing) TAC tumors was nearly identical, with both TTPmin > 25 min (TTPmin ≤ 12.5 min) tumors and IDH-mutant grade II (IDH-wildtype) gliomas. Outcome of mixed TAC tumors matched that of both intermediate TTPmin (>12.5 min and ≤25 min) and IDH-mutant, grade III gliomas. Each of the 3 prognostic clusters differed significantly from the other ones of the respective models (P < 0.001).

CONCLUSION

TAC measurements constitute a powerful biomarker independent from tumor grade and IDH status.

MicroRNA-93 acts as an "anti-inflammatory tumor suppressor" in glioblastoma

Background

Inflammation is an important driver of malignant glioma disease. Inflammatory mediators are not only produced by immune cells in the tumor microenvironment, but also by glioblastoma (GBM) cells themselves creating a mutually reinforcing loop. We here aimed at identifying an “anti-inflammatory switch” that allows to dampen inflammation in GBM.

Methods

We used human GBM specimens, primary cultures, and cell lines. The response of GBM cells toward inflammatory stimuli was tested by incubation with supernatant of stimulated human immune cells. Expression levels were measured by whole transcriptome microarrays and qRT-PCR, and protein was quantified by LUMINEX and SDS-PAGE. MicroRNA binding to 3′UTRs was analyzed by luciferase assays. Proliferation rates were determined by flow cytometry, and invasion and angiogenesis were studied using migration and endothelial tube formation assays.

Results

We demonstrated GBM cells to secrete high amounts of proinflammatory mediators in an inflammatory microenvironment. We found miR-93 as a potential “anti-inflammatory tumor suppressor” dramatically downregulated in GBM. Concordantly, cytokine secretion dropped after miR-93 re-expression. Transfection of miR-93 in GBM cells led to down-regulation of hubs of the inflammatory networks, namely, HIF-1α and MAP3K2 as well as IL-6, G-CSF, IL-8, LIF, IL-1β, COX2, and CXCL5. We showed only COX2 and CXCL5 to be indirectly regulated by miR-93 while all other genes are true targets. Phenotypically, re-expression of miR-93 in GBM cells substantially suppressed proliferation, migration, and angiogenesis.

Conclusions

Alleviating GBM-derived inflammation by re-expression of miR-93 may be a powerful tool to mitigate these tumors’ aggressiveness and holds promise for new clinical approaches.

The IL-1 Antagonist Anakinra Attenuates Glioblastoma Aggressiveness by Dampening Tumor-Associated Inflammation

BACKGROUND

The recombinant IL-1 receptor antagonist anakinra-currently approved for the treatment of autoinflammatory diseases-blocks IL-1β-mediated inflammatory signaling. As inflammation is a major driver of cancer, we hypothesized that anakinra might be able to mitigate glioblastoma (GBM) aggressiveness.

METHODS

Primary GBM or T98G cells were incubated alone or with peripheral blood mononuclear cells (PBMCs) and were subsequently treated with IL-1β and/or anakinra. T cells were obtained by magnetic bead isolation. Protein and mRNA expression were quantified by SDS-PAGE, qRT-PCR, and ELISA, respectively. Cell proliferation and apoptosis were analyzed via flow cytometry. Chemotaxis was studied via time-lapse microscopy.

RESULTS

Upon IL-1β stimulation, anakinra attenuated proinflammatory gene expression in both GBM cells and PBMCs, and mitigated tumor migration and proliferation. In a more lifelike model replacing IL-1β stimulation by GBM-PBMC co-culture, sole presence of PBMCs proved sufficient to induce a proinflammatory phenotype in GBM cells with enhanced proliferation and migration rates and attenuated apoptosis. Anakinra antagonized these pro-tumorigenic effects and, moreover, reduced inflammatory signaling in T cells without compromising anti-tumor effector molecules.

CONCLUSION

By dampening the inflammatory crosstalk between GBM and immune cells, anakinra mitigated GBM aggressiveness. Hence, counteracting IL-1β-mediated inflammation might be a promising strategy to pursue.

TMIC-44. IL-1 ANTAGONIST ANAKINRA INHIBITS GLIOBLASTOMA PROLIFERATION BY ANTAGONIZING THE PROINFLAMMATORY MICROENVIRONMENT

INTRODUCTION

The recombinant IL-1 receptor antagonist anakinra prevents binding of IL-1 to its receptor and blocks IL-1β-mediated proinflammatory signaling. It is currently used in the treatment of autoinflammatory diseases. As inflammation is a major driver of malignancy, we hypothesized that anakinra – by ameliorating the inflammatory tumor environment – might be capable to mitigate glioblastoma (GBM) progression.

METHODS

T98G GBM cells were cultivated with PBMC, separated by cell culture inserts with or without anakinra and incubated 48h in 5% O2 mimicking the GBM microenvironment. T-cells were obtained by magnetic bead isolation. mRNA expression levels were measured by quantitative Real-Time-PCR (qRT-PCR). Cytokine production was assessed by ELISA. Cell proliferation was analyzed by flow cytometric quantification of Ki-67 protein expression. Anakinra has been provided by Swedish Orphan Biovitrum AB (Sweden). Results are presented as mean±SEM, p-Values were calculated using Student’s t-test.

RESULTS

After administration of anakinra, mRNA expression levels of the inflammatory and proangiogenic genes IL-1β, COX-2, CCL2 and IL-8 were reduced in T98G (-64%±19.1%, -56.2%±21.3%, -87.1%±28.8%, -91.7%±27.2%, n=7, p< 0.05). Surprisingly, no changes of these targets were detectable in PBMC. However, in T-cells, anakinra induced mRNA expression of Th2 transcription factor GATA3 and the antiinflammatory cytokines IL-4 and IL-10 (+6,7%±4,6%, +36,1%±22,9%, +69,1%32,8%, n=10, p< 0.05). The expression of the protumorigenic genes IL-22, IL-17 as well as IFNγ was dramatically repressed (-63.2%±21.9%, -88.1%±21.7%, -85.6%±45.2%, n=10, p< 0.05), protein secretion of IL-22 and IFNγ was strongly blocked (-36.3%±9.1%, -13.9%±0.5%, n=6, p< 0.05). Importantly, treatment with anakinra markedly attenuated GBM cell proliferation (-20.1%±5%, n=4, p< 0.05).

CONCLUSION

Anakinra indeed puts the brake on proinflammatory signaling pathways in GBM cells and simultaneously promotes a shift towards an anti-inflammatory T-cell phenotype. As a result, GBM proliferation is diminished. Hence, administration of anakinra might be an interesting and novel therapeutic approach to reduce Glioblastoma aggressiveness.

PATH-04. INFLUENCE OF INDIVIDUAL CpG METHYLATION STATUS OF THE MGMT PROMOTOR ON OUTCOME IN ADULT PATIENTS WITH GLIOBLASTOMA MULTIFORME RECEIVING ALKYLATING AGENT TREATMENT

BACKGROUND

Methylation of O-6-methylguanine-DNA-methyltransferase (MGMT) promotor causes gene silencing and has been associated with a favourable prognosis in patients with glioblastoma multiforme (GBM) receiving alkylating chemotherapy. However, analysis of MGMT promotor methylation is usually reported as a cut-off depending on the results of the correspondent CpG-site testing. This approach disregards a possible heterogeneity concerning the methylation status within the individual CpG-sites and its possible association with prognosis in GBM patients. The current study aimed at elucidating the association between methylation of CpG-sites 74–98 within the MGMT promotor region and outcome in GBM patients receiving alkylating agents.

METHODS

Individual methylation status of 230 patients with histologically proven GBM following concomitant radio-chemotherapy with TMZ after stereotactic biopsy or open tumor resection was assessed by the Sanger-sequencing approach. Methylation of CpG-sites 74–98 within the MGMT promotor region was defined according to a ratio of cytosine/thymine peak > 50%. The total number of methylated CpG-sites was correlated with outcome using proportional hazards models. In a subset of 34 patients, a correlation between individual CpG-site methylation and MGMT mRNA-expression was performed.

RESULTS

Median progression-free (PFS) and overall survival (OS) were 7.8 and 14.6months, respectively. The cumulative total number of methylated loci within the CpG-sites 74–98 was strongly associated with both PFS and OS and retained its prognostic influence on outcome in multivariate models (p< 0.001). Furthermore, a linear coherence between the total number of methylated CpG-sites 74–98 and survival parameters could be observed. Moreover, low number of methylated CpG-sites was observed in tumor specimen with a high mRNA-expression and vice versa (Spearman-correlation-coefficient: -0.62).

CONCLUSION

Our data suggest a strong linear coherence between outcome and the total number of methylated CpG-sites 74–98, thus an up-front analysis of the individual GpC-site methylation status prior to initiation of alkylating chemotherapy might help improving treatment response in GBM patients.

The surgical perspective in precision treatment of diffuse gliomas

Over the last decade, advances in molecular and imaging-based biomarkers have induced a more versatile diagnostic classification and prognostic evaluation of glioma patients. This, in combination with a growing therapeutic armamentarium, enables increasingly individualized, risk-benefit-optimized treatment strategies. This path to precision medicine in glioma patients requires surgical procedures to be reassessed within multidimensional management considerations. This article attempts to integrate the surgical intervention into a dynamic network of versatile diagnostic characterization, prognostic assessment, and multimodal treatment options in the light of the latest 2016 World Health Organization (WHO) classification of diffuse brain tumors, WHO grade II, III, and IV. Special focus is set on surgical aspects such as resectability, extent of resection, and targeted surgical strategies including minimal invasive stereotactic biopsy procedures, convection enhanced delivery, and photodynamic therapy. Moreover, the influence of recent advances in radiomics/radiogenimics on the process of surgical decision-making will be touched.

Radiation dose and image quality in intraoperative CT (iCT) angiography of the brain with stereotactic head frames

OBJECTIVES

Intraoperative CT (iCT) angiography of the brain with stereotactic frames is an integral part of navigated neurosurgery. Validated data regarding radiation dose and image quality in these special examinations are not available. We therefore investigated two iCT protocols in this IRB-approved study.

METHODS

Retrospective analysis of patients, who received a cerebral stereotactic iCT angiography on a 128 slice CT scanner between February 2016 and December 2017. In group A, automated tube current modulation (ATCM; reference value 410 mAs) and automated tube voltage selection (reference value 120 kV) were enabled, and only examinations with a selected voltage of 120 kV were included. In group B, fixed parameters were applied (300 mAs, 120 kV). Radiation dose was measured by assessing the volumetric CT dose index (CTDI_vol), dose length product (DLP) and effective dose (ED). Signal-to-noise ratio (SNR) and image noise were assessed for objective image quality, visibility of arteries and grey-white differentiation for subjective image quality.

RESULTS

Two hundred patients (n = 100 in each group) were included. In group A, median selected tube current was 643 mAs (group B, 300 mAs; p < 0.001). Median values of CTDI_vol, DLP and ED were 91.54 mGy, 1561 mGy cm and 2.97 mSv in group A, and 43.15 mGy, 769 mGy cm and 1.46 mSv in group B (p < 0.001). Image quality did not significantly differ between groups (p > 0.05).

CONCLUSIONS

ATCM yielded disproportionally high radiation dose due to substantial tube current increase at the frame level, while image quality did not improve. Thus, ATCM should preferentially be disabled.

KEY POINTS

• Automated tube current modulation (ATCM) yields disproportionally high radiation dose in intraoperative CT angiography of the brain with stereotactic head frames. • ATCM does not improve overall image quality in these special examinations. • ATCM is not yet optimised for CT angiography of the brain with major extracorporeal foreign materials within the scan range.

Stereotactic Internal Shunt Placement in Congenital Intracranial Cysts

INTRODUCTION

Treatment of symptomatic intracranial cysts remains a controversial issue. We present a risk/benefit profile of a minimally invasive, not yet described, stereotactic internal shunt implantation technique. The provided data might serve as a reference against which other treatment modalities could be compared.

METHODS

From our prospective database, we identified a consecutive series of patients with symptomatic, untreated cysts who had undergone internal shunting from 2009 to 2017. We estimated the rates of clinical symptom improvement (RCSI), cyst reduction, total complications, and long-term complications. A minimal follow-up of 6 months was required. The prognostic factors were obtained from logistic regression models. Cyst recurrence-free survival was calculated using the Kaplan-Meier method. The outcomes data were compared with those from reported alternative treatment strategies using χ² statistics.

RESULTS

We included 38 patients. The cyst locations differed greatly and included the cerebellum (n = 2), brainstem (n = 5), and pineal area (n = 4). Cyst-associated hydrocephalus (n = 6) resolved after treatment. The 2-year cyst recurrence-free survival rate was 97%. The RCSI and rate of cyst reduction, total complications, and long-term complications was 91%, 97%, 11%, and 2.6%, respectively. We did not find any risk factors associated with the rate of total complications. The RCSI and rate of total and long-term complications compared favorably (P < 0.01) with the corresponding estimates of alternative treatments (P < 0.01).

CONCLUSIONS

The described stereotactic internal shunt implantation technique is safe and can be successfully applied for treatment of cystic formations in any location in the brain.

Biological tumour volumes of gliomas in early and standard 20-40 min 18F-FET PET images differ according to IDH mutation status

PURPOSE

For the clinical evaluation of O-(2-¹⁸F-fluoroethyl)-L-tyrosine (¹⁸F-FET) PET images, the use of standard summation images obtained 20-40 min after injection is recommended. However, early summation images obtained 5-15 min after injection have been reported to allow better differentiation between low-grade glioma (LGG) and high-grade glioma (HGG) by capturing the early ¹⁸F-FET uptake peak specific for HGG. We compared early and standard summation images with regard to delineation of the PET-derived biological tumour volume (BTV) in correlation with the molecular genetic profile according the updated 2016 WHO classification.

METHODS

The analysis included 245 patients with newly diagnosed, histologically verified glioma and a positive ¹⁸F-FET PET scan prior to any further treatment. BTVs were delineated during the early 5-15 min and standard 20-40 min time frames using a threshold of 1.6 × background activity and were compared intraindividually. Volume differences between early and late summation images of >20% were considered significant and were correlated with WHO grade and the molecular genetic profile (IDH mutation and 1p/19q codeletion status).

RESULTS

In 52.2% of the patients (128/245), a significant difference in BTV of >20% between early and standard summation images was found. While 44.3% of WHO grade II gliomas (31 of 70) showed a significantly smaller BTV in the early summation images, 35.0% of WHO grade III gliomas (28/80) and 37.9% of WHO grade IV gliomas (36/95) had a significantly larger BTVs. Among IDH-wildtype gliomas, an even higher portion (44.4%, 67/151) showed significantly larger BTVs in the early summation images, which was observed in 5.3% (5/94) of IDH-mutant gliomas only: most of the latter had significantly smaller BTVs in the early summation images, i.e. 51.2% of IDH-mutant gliomas without 1p/19q codeletion (21/41) and 39.6% with 1p/19q codeletion (21/53).

CONCLUSION

BTVs delineated in early and standard summation images differed significantly in more than half of gliomas. While the standard summation images seem appropriate for delineation of LGG as well as IDH-mutant gliomas, a remarkably high percentage of HGG and, particularly, IDH-wildtype gliomas were depicted with significantly larger volumes in early summation images. This finding might be of interest for optimization of treatment planning (e.g. radiotherapy) in accordance with the individual IDH mutation status.

Cystic Craniopharyngiomas: Microsurgical or Stereotactic Treatment?

BACKGROUND

Prognosis and treatment of cystic craniopharyngiomas are poorly defined.

OBJECTIVE

To analyze progression-free survival (PFS) and safety profile of cystic craniopharyngiomas undergoing resection or minimally invasive drainage procedures. We compared further outcome measurements for cystic and solid tumors undergoing resection to elucidate the impact of the initial tumor composition on both PFS and the toxicity profile.

METHODS

All patients with craniopharyngiomas consecutively treated between 1999 and 2014 were included. A treatment decision in favor of microsurgery or stereotactic treatment was made interdisciplinarily. For stereotactic drainage, a catheter was implanted, allowing both permanent upstream (into ventricular spaces) and downstream (into prepontine cistern) drainage. Study endpoints were tumor progression, functional outcome, and treatment toxicity. Functional endocrinological and visual outcome analyses referred to data obtained preoperatively and 6 weeks after treatment. The Kaplan-Meier method was used for survival analysis. Prognostic factors were obtained from proportional hazard models.

RESULTS

Seventy-nine patients were included. The distribution of clinical and tumor-related data was well balanced among patients with solid (n = 35) and cystic (n = 44) tumors and those undergoing microsurgical or stereotactic treatment. Cystic tumors had shorter PFS (5-year PFS: 53.6% vs 66.8%, P = .10) and needed significantly more therapeutic interventions, which was independent of the initial treatment mode. The endocrinological deterioration rate was high for both solid and cystic tumors after microsurgery (59.4% and 85.7%, respectively), whereas it was significantly lower for cystic tumors undergoing stereotactic treatment (23.1%, P < .001).

CONCLUSION

Stereotactic bidirectional drainage of cystic craniopharyngiomas is effective and provides a better endocrinological outcome than conventional microsurgery.

Brachytherapy of Intracranial Gliomas

Interstitial implantation of radioactive materials (brachytherapy [BT]) has been designed to protractedly deliver a high radiation dose to a well-defined target volume, while minimizing irradiation of the adjacent normal tissues. Even though promising results have been reported over time, the role of this treatment modality in the management of brain tumors is still poorly defined, and only a few centers worldwide apply it in clinical practice. Nevertheless, temporary or permanent interstitial implantation of low activity (<20 mCi) and low dose rate (≤10 cGy/h) iodine-125 (125I) seeds as possible therapy of intracranial gliomas is currently undergoing a definite revival, and several indications for its use have been identified. Generally, 125I-BT may be considered a reasonable option in cases of unresectable, well-circumscribed, either newly diagnosed or recurrent tumors with a diameter of ≤4 cm, virtually in any location within the brain. Importantly, this treatment does not narrow down the spectrum of the possible subsequent salvage therapeutic options, since neither repeated interstitial nor additional external beam irradiation at the time of tumor progression after BT is associated with a significantly increased risk of radiogenic complications. Using correct patient selection criteria, appropriate surgical technique, and established treatment parameters, would make BT a truly minimally invasive procedure with a low risk of complications and reasonable efficacy.

The role of surgery for brain metastases from solid tumors

Surgery, stereotactic radiosurgery, radiotherapy, and chemotherapy including novel targeted therapy strategies and any combination thereof as well as supportive care are the key elements for treatment of brain metastases. Goals of microsurgery are to obtain tissue samples for histologic diagnosis (particularly in case of uncertainty about the unknown primary tumor but also in the context of future targeted therapies), to relieve burden from space-occupying effects, to improve local tumor control, and to prolong overall survival. Complete surgical resection improves local tumor control and may even affect overall survival. Stereotactic radiosurgery is an equal effective alternative for metastases up to 3 cm in diameter, especially in highly eloquent or deep seated location. Gross total resection (as defined by immediate postoperative MRI) does not necessarily have to be combined with whole brain radiotherapy (WBRT), at least for patients with good performance status and controlled systemic disease. Particularly in cases of incomplete resections, focal irradiation or radiosurgery of the resection cavity or tumor remnant rather than WBRT may be attempted.

Suspected recurrence of brain metastases after focused high dose radiotherapy: can [18F]FET- PET overcome diagnostic uncertainties?

Background

After focused high dose radiotherapy of brain metastases, differentiation between tumor recurrence and radiation-induced lesions by conventional MRI is challenging. This study investigates the usefulness of dynamic O-(2-¹⁸F-Fluoroethyl)-L-Tyrosine positron emission tomography (¹⁸F-FET PET) in patients with MRI-based suspicion of tumor recurrence after focused high dose radiotherapy of brain metastases.

Methods

Twenty-two patients with 34 brain metastases (median age 61.9 years) were included. Due to follow-up scan evaluations after repeated treatment in a subset of patients, a total of 50 lesions with MRI-based suspicion of tumor recurrence after focused high dose radiotherapy could be evaluated. ¹⁸F-FET PET analysis included the assessment of maximum and mean tumor-to-background ratio (TBR_max and TBR_mean) and analysis of time-activity-curves (TAC; increasing vs. decreasing) including minimal time-to-peak (TTP_min). PET parameters were correlated with histological findings and radiological-clinical follow-up evaluation.

Results

Tumor recurrence was found in 21/50 cases (15/21 verified by histology, 6/21 by radiological-clinical follow-up) and radiation-induced changes in 29/50 cases (5/29 verified by histology, 24/29 by radiological-clinical follow-up). Median clinical-radiological follow-up was 28.3 months (range 4.2–99.1 months). ¹⁸F-FET uptake was higher in tumor recurrence compared to radiation-induced changes (TBR_max 2.9 vs. 2.0, p < 0.001; TBR_mean 2.2 vs. 1.7, p < 0.001). Receiver-operating-characteristic (ROC) curve analysis revealed optimal cut-off values of 2.15 for TBR_max and 1.95 for TBR_mean (sensitivity 86 %, specificity 79 %). Increasing TACs and long TTP_min were associated with radiation-induced changes, decreasing TACs with tumor recurrence (p = 0.01). By combination of TBR and TACs, sensitivity and specificity could be increased to 93 and 84 %.

Conclusions

In patients with MRI-suspected tumor recurrence after focused high dose radiotherapy, ¹⁸F-FET PET has a high sensitivity and specificity for the differentiation of vital tumor tissue and radiation-induced lesions.

The role of surgery in grade II/III oligodendroglial tumors

Supratentorial gliomas WHO grade II and III with an oligodendroglial phenotype are highly infiltrative lesions that preferentially originate in lobar location. Open tumor resection represents one of the mainstays of management as beneficial decompressive effects for large space-occupying lesions and oncologically relevant cytoreductive effects from complete resection can be expected. In patients not eligible for safe tumor resection meticulous histological and molecular-genetic evaluation can be obtained from advanced stereotactic biopsy techniques. In this perspective, important aspects of open tumor surgery and stereotactic biopsy are discussed within the context of diagnosis, prognosis and treatment of oligodendrogliomas and oligoastrocytomas WHO grade II and III. Practical considerations are provided in order to integrate the place of surgery into an increasingly personalized management concept. For highly selected patients interstitial brachytherapy is introduced as an alternative surgically performed treatment option.

Outcome and toxicity profile of salvage low-dose-rate iodine-125 stereotactic brachytherapy in recurrent high-grade gliomas

BACKGROUND

The aim of this study was to provide an outcome and toxicity profile of salvage low-dose-rate iodine-125 (I-125) stereotactic brachytherapy (SBT) in patients with small, circumscribed malignant glioma recurrences.

METHODS

Patients with malignant glioma recurrences consecutively undergoing salvage SBT from 2003 to 2011 were identified from our prospective tumor database. SBT was considered a potentially suitable treatment strategy for adult mostly multimodally pretreated patients (Karnofsky score of ≥ 70) with biopsy-proven, circumscribed, small (diameter ≤ 3.5 cm) recurrences. Exclusively temporary I-125 seeds were used (reference dose: 50 Gy, dose rate: < 15 cGy/h). Study endpoints were time-to-treatment failure (TTF) after SBT, postrecurrence survival (PRS), and toxicity. Survival was assessed with the Kaplan-Meier method. Adverse events were categorized according to the RTOG/EORTC classification. Prognostic factors were obtained from proportional hazards models.

RESULTS

Sixty-eight patients (28 WHO grade III, 40 WHO grade IV gliomas) were included. Fifty-nine patients had previously received external beam radiation. Median TTF and PRS were 8.3 months and 13.4 months, respectively. TTF and PRS were longer for grade III gliomas than for glioblastomas (15.0 vs. 6.2 months and 28.1 vs. 9.3 months, respectively). Patients with grade III tumors were younger (p = 0.002). Favorable factors for TTF and PRS were age ≤ 50 years and a methylated O(6)-methylguanine-DNA methyltransferase (MGMT)-promoter. Alternative models including tumor grade instead of age reached a similar good fit. Three patients suffered from grade I, one from grade II, and two from grade IV toxicity.

CONCLUSIONS

Salvage SBT is feasible and safe even after previously performed external beam radiation. Favorable outcome measurements in particular for grade III recurrences deserve further prospective evaluation.

Prognostic significance of dynamic 18F-FET PET in newly diagnosed astrocytic high-grade glioma

Despite advances in diagnosis and the use of different therapeutic regimens in astrocytic high-grade glioma (HGG), the prognosis for patients remains grim. Additional pretherapeutic information is needed to tailor management. To gain additional prognostic information at primary diagnosis, we investigated the value of dynamic O-(2-(18)F-fluoroethyl)-L-tyrosine ((18)F-FET) PET.

METHODS

We retrospectively evaluated 121 patients who had a primary diagnosis of astrocytic HGG (51 World Health Organization [WHO] grade III; 70 WHO IV) and underwent dynamic (18)F-FET PET before histopathologic assessment. We assessed static parameters (maximal and mean tumoral standardized uptake value corrected for mean background activity in the contralateral hemisphere [SUV(max)/BG and SUV(mean)/BG, respectively], biologic tumor volume) and dynamic time-activity curves, including minimal time to peak (TTP(min)). The prognostic influence of PET parameters and other clinical parameters on progression-free and overall survival was evaluated using uni- and multivariate Cox regression and Kaplan-Meier survival estimates.

RESULTS

In the group overall, median progression-free survival and overall survival were 12.2 and 21.9 mo. SUV(max)/BG, SUV(mean)/BG, and biologic tumor volume were significantly higher in WHO IV than in WHO III gliomas; median TTP(min) was 12.5 min in both groups. On univariate analysis, the factors age, WHO grade, O6-methylguanine-DNA methyltransferase promoter methylation status, contrast enhancement, initial treatment, and TTP(min) showed prognostic significance, with WHO grade, O6-methylguanine-DNA methyltransferase status, age, and TTP(min) remaining significant in the multivariate analysis. WHO grade and TTP(min) reached a similar fit for the prognostic evaluation. The prognosis of WHO III astrocytoma with an early TTP(min) of 12.5 min or less did not differ significantly from that of glioblastoma.

CONCLUSION

Early TTP(min) is associated with worse outcome in patients with newly diagnosed astrocytic HGG. In the preoperative setting, TTP(min) can be a valuable noninvasive prognostic marker with comparable significance to WHO grade. Additionally, TTP(min) can help identify highly aggressive WHO III astrocytoma tumors and may help in adjusting standard treatment toward an individualized, risk-adapted therapy regime.

Dynamic 18F-FET PET in suspected WHO grade II gliomas defines distinct biological subgroups with different clinical courses

In suspected grade II gliomas, three distinct patterns of time-activity curves (TAC) on O-(2-[(18)F]fluoroethyl)-1-tyrosine ((18)F-FET) positron emission tomography (PET) have been delineated (i) increasing TAC homogeneously throughout the tumor, and decreasing TAC, (ii) either homogeneously throughout the tumor or (iii) only focally within otherwise increasing TAC patterns. Increasing TAC was associated with low-grade histology and decreasing TAC with high-grade histology. This prospective study analyzed whether these patterns correlate with distinct biological tumor subtypes and differential outcome. (18)F-FET PET-guided biopsies were used for stepwise histopathological evaluation. Molecular-genetic evaluation included O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation, isocitrate dehydrogenase (IDH1/2) mutational and 1p/19q codeletion status. Progression-free survival (PFS) was estimated with the Kaplan-Meier method. Prognostic factors were obtained from multivariate regression models. 98 adult patients were included. Homogeneous increasing, focal decreasing and homogeneous decreasing TAC were seen in 51, 19 and 28 patients. The corresponding 1-year (2-years) PFS were 92% (85%), 89% (51%) and 50% (28%; p = 0.002). IDH1/2 mutations were more frequent in tumors with homogeneous increasing (90%) and focal decreasing (79%) TAC, but were rare in those exhibiting homogeneous decreasing TAC (25%; p < 0.001). Overall, TAC patterns, IDH1/2 mutational and 1p/19q codeletion status were powerful and independent prognostic factors. Dynamic (18)F-FET PET might be an important and independent imaging biomarker for patients with suspected WHO grade II gliomas and offers perspectives for stratified diagnostic and therapeutic strategies. Tumors with focal decreasing TAC need highly targeted surgical interventions to avoid undergrading and undertreatment.

Male sex as a risk factor for the clinical course of skull base chordomas

Object

Chordomas of the skull base are rare and locally invasive and have a poor prognosis. The aim of this retrospective multicenter study was to evaluate the current pattern of care and clinical course and to identify prognostic factors.

Methods

A total of 47 patients (26 men; mean age 48.5 years) treated in 5 centers were included. Histology was centrally reviewed; additionally, semiquantitative N- and E-cadherin expression analysis was performed. Prognostic factors were obtained from multivariate regression models. For survival analysis the Kaplan-Meier method was used.

Results

The median follow-up period was 5.2 years. Complete resection, incomplete resection, and extended biopsy were performed in 14.9%, 80.9%, and 4.3% of patients, respectively. Surgical morbidity was not associated with extent of resection. Adjuvant radiation therapy was performed in 30 (63.8%) of 47 patients. The median progression-free survival (PFS) was 7.3 years. Complete resection prolonged median overall survival (OS) (p = 0.04). Male patients presented with worse PFS (4.8 years vs 9.8 years; p = 0.04) and OS (8.3 years vs not reached; p = 0.03) even though complete resection was exclusively achieved in the male subpopulation. Multivariate analysis confirmed male sex as the most important risk factor for tumor progression (p = 0.04) and death (p = 0.02). Age, duration of symptoms, initial Karnofsky Performance Scale score, brainstem compression, involvement of the petrous bone, infiltration of the dura mater, modality and dose of radiation therapy, and the E- and N-cadherin expression patterns did not gain prognostic relevance.

Conclusions

In skull base chordomas, male patients bear a higher risk of progressive disease and death. Male patients might benefit from more aggressive adjuvant therapy and/or from a closer follow-up schedule.

Re-irradiation and bevacizumab in recurrent high-grade glioma: an effective treatment option

Re-irradiation has been shown to be a meaningful option for recurrent high-grade glioma (HGG) patients. Furthermore, bevacizumab exerts certain activity in combination with chemotherapy/as monotherapy and was safely tested in combination with radiotherapy in several previous studies. To our knowledge, this is the largest cohort of patients treated with both re-irradiation and bevacizumab to date. After receiving standard radiotherapy (with or without TMZ) patients with recurrent HGG were treated with bevacizumab (10 mg/kg intravenously at d1 and d15) during re-irradiation. Median prescribed radiation dose during re-treatment was 36 Gy, conventionally fractionated. Datasets of 71 re-irradiated patients were retrospectively analyzed. Patients either received bevacizumab (N = 57) or not (N = 14; other substances (N = 4) and sole radiation (N = 10)). In patients receiving bevacizumab, both post-recurrence survival (PRS) (median 8.6 vs. 5.7 months; p = 0.003, log-rank test) and post-recurrence progression-free survival (PR-PFS, 5.6 vs. 2.5 months; p = 0.005, log-rank test; PFS-6 42.1 % for the bevacizumab group) were significantly increased which was confirmed by multivariate analysis. KPS, re-surgery, MGMT methylation status, sex, WHO grade, tumor volume and age were no significant predictors for neither PR-PFS nor PRS (univariate analysis). Re-irradiation with bevacizumab remains a feasible and highly effective treatment schedule. Studies on further salvage strategies and timing of sequential treatment options versus observation are warranted.

Dynamic 18F-FET PET in newly diagnosed astrocytic low-grade glioma identifies high-risk patients

Because the clinical course of low-grade gliomas in the individual adult patient varies considerably and is unpredictable, we investigated the prognostic value of dynamic (18)F-fluorethyltyrosine ((18)F-FET) PET in the early diagnosis of astrocytic low-grade glioma (World Health Organization grade II).

METHODS

Fifty-nine patients with newly diagnosed low-grade glioma and dynamic (18)F-FET PET before histopathologic assessment were retrospectively investigated. (18)F-FET PET analysis comprised a qualitative visual classification of lesions; assessment of the semiquantitative parameters maximal, mean, and total standardized uptake value as ratio to background and biologic tumor volume; and dynamic analysis of intratumoral (18)F-FET uptake over time (increasing vs. decreasing time-activity curves). The correlation between PET parameters and progression-free survival, overall survival, and time to malignant transformation was investigated.

RESULTS

(18)F-FET uptake greater than the background level was found in 34 of 59 tumors. Dynamic (18)F-FET uptake analysis was available for 30 of these 34 patients. Increasing and decreasing time-activity curves were found in 18 and 12 patients, respectively. Neither the qualitative factor presence or absence of (18)F-FET uptake nor any of the semiquantitative uptake parameters significantly influenced clinical outcome. In contrast, decreasing time-activity curves in the kinetic analysis were highly prognostic for shorter progression-free survival and time to malignant transformation (P < 0.001).

CONCLUSION

Absence of (18)F-FET uptake in newly diagnosed astrocytic low-grade glioma does not generally indicate an indolent disease course. Among the (18)F-FET-positive gliomas, decreasing time-activity curves in dynamic (18)F-FET PET constitute an unfavorable prognostic factor in astrocytic low-grade glioma and, by identifying high-risk patients, may ease treatment decisions.

Personalized treatment strategies in glioblastoma: MGMT promoter methylation status

The identification of molecular genetic biomarkers considerably increased our current understanding of glioma genesis, prognostic evaluation, and treatment planning. In glioblastoma, the most malignant intrinsic brain tumor entity in adults, the promoter methylation status of the gene encoding for the repair enzyme O6-methylguanine-DNA methyltransferase (MGMT) indicates increased efficacy of current standard of care, which is concomitant and adjuvant chemoradiotherapy with the alkylating agent temozolomide. In the elderly, MGMT promoter methylation status has recently been introduced to be a predictive biomarker that can be used for stratification of treatment regimes. This review gives a short summery of epidemiological, clinical, diagnostic, and treatment aspects of patients who are currently diagnosed with glioblastoma. The most important molecular genetic markers and epigenetic alterations in glioblastoma are summarized. Special focus is given to the physiological function of DNA methylation-in particular, of the MGMT gene promoter, its clinical relevance, technical aspects of status assessment, its correlation with MGMT mRNA and protein expressions, and its place within the management cascade of glioblastoma patients.

Personalized surgical therapy

Gliomas are more or less diffuse tumours with the ability to infiltrate surrounding functional brain tissue. Thus, curative surgical treatment generally cannot be achieved. Despite these limitations, open tumour resection represents one of the mainstays in glioma treatment settings. Beyond tissue sampling for accurate histological and molecular genetic evaluation, decompressive effects in the case of space occupying tumours and oncologically relevant cytoreductive effects of microsurgery have been reported in selected patients with glioma of different grades. This paper provides practical considerations in order to integrate the concept of a personalized surgical therapy into the prognostic network of low- and high-grade gliomas, covering both microsurgery and stereotactic biopsy techniques.

Protoporphyrin IX fluorescence and photobleaching during interstitial photodynamic therapy of malignant gliomas for early treatment prognosis

BACKGROUND AND OBJECTIVE

Interstitial photodynamic therapy (iPDT) of non-resectable recurrent glioblastoma using 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) has shown a promising outcome. It remained unclear, however, to what extent inter- and intra-tumoural differences of PpIX concentrations influence the efficacy of iPDT. In the current pilot study, we analysed PpIX concentrations quantitatively and assessed PpIX induced fluorescence and photobleaching intraoperatively.

MATERIALS AND METHODS

Five patients harbouring non-resectable glioblastomas were included. ALA (20 or 30 mg/kg body weight) was given 5-8 hours before treatment. Stereotactic biopsies were taken throughout the tumour volume for both histological analysis and determination of PpIX concentrations, which were measured by chemical extraction. Cylindrical light diffusors were stereotactically implanted. Prior to and after irradiation, fluorescence measurements were performed. Outcome measurement was based on clinical and neuro-radiological follow up.

RESULTS

In three patients, a strong PpIX fluorescence was seen before treatment, which was completely photobleached after iPDT. High concentrations of PpIX could be detected in viable tumour parts of these patients (mean PpIX uptake per tumour: 1.4-3.0 µM). In the other two patients, however, no or only low PpIX uptake (0-0.6 µM) could be detected. The patients with strong PpIX uptake showed treatment response and long-term clinical stabilisation (no progression in 29, 30 and 36 months), early treatment failure was seen in the remaining two patients (death after 3 and 9 months).

CONCLUSIONS

Intra-tumoural PpIX concentrations exhibited pronounced inter- and intra-tumoural variations in glioblastoma, which are directly linked to variable degrees of fluorescence intensity. High intra-tumoural PpIX concentrations with strong fluorescence intensity and complete photobleaching after iPDT seem to be associated with favourable outcome. Real-time monitoring of PpIX fluorescence intensity and photobleaching turned out to be feasible and safe and might be employed for early treatment prognosis of iPDT.

Optical needle endoscope for safe and precise stereotactically guided biopsy sampling in neurosurgery

Proper treatment of deep seated brain tumors requires correct histological diagnosis which unambiguously necessitates biopsy sampling. Stereotactically guided sampling of biopsies is widely used but bears the danger of incorrect sampling locations and damage to intracerebral blood vessels. Here, we present a minimally invasive contact endoscopic probe that can be inserted into the tissue inside a standard biopsy needle and allows for fluorescence detection of both tumorous tissue and intracerebral blood vessels. Outer diameter of our contact probe is smaller than 1.5 mm, field-of-view in the range of several hundred microns; the optical design allows for simultaneous detection and visualization of tissue autofluorescence and selective fluorescence signals from deep seated brain tumors and vasculature as shown on in vivo animal models. We demonstrate the tumor detection capability during stereotactic needle insertion in a clinical pilot trial. Using our probe, we expect stereotactic interventions to become safer and more precise and the technology might ultimately be used also for various other kinds of applications.

Prediction of oligodendroglial histology and LOH 1p/19q using dynamic [(18)F]FET-PET imaging in intracranial WHO grade II and III gliomas

Oligodendroglial components (OC) and loss of heterozygosity on chromosomes 1p and 19q (LOH 1p/19q) are associated with better outcome in patients with glioma. We aimed to assess the fitness of [(18)F]fluoroethyltyrosine positron-emission-tomography (FET-PET) for noninvasively identifying these important prognostic/predictive factors. One hundred forty-four patients with MRI-suspected WHO grade II and III glioma underwent FET-PET scans prior to histological diagnosis. FET-PET analyses included maximal tumoral uptake (SUV(max)/BG), biological tumor volume (BTV), mean tumoral uptake (SUV(mean)/BG), total tumoral uptake (SUV(total)/BG), and kinetic analysis. Suspicion of OC was based on static and dynamic FET-uptake parameters. PET results were correlated with histology and 1p/19q status. OC tumors exhibited significantly higher uptake values, compared with astrocytomas (AC) (SUV(max)/BG 3.1 vs 2.3, BTV 15.5 mL vs 7.2 mL, SUV(total)/BG 38.5 vs 17.4, P < .01 each; SUV(mean)/BG 2.2 vs 2.1, P < .05). These differences were more pronounced in WHO grade II gliomas. Comparable results were found with respect to 1p/19q status. Kinetic analysis misclassified 18 of 34 low-grade OC tumors as high-grade glioma but misclassified only 5 of 45 of the low-grade ACs. FET-based suspicion of OC resulted in concordance rates of both 76% for the prediction of OC and LOH 1p/19q. FET-uptake was significantly higher in gliomas with OC, compared with AC, and likewise in 1p/19q codeleted, compared with noncodeleted tumors. However, FET-PET analysis did not reliably predict the presence of OC/LOH 1p/19q in the individual patient, mostly because of an overlap in PET characteristics of OC tumors and high-grade AC. Histological examination is still required for an accurate diagnosis.

FET-PET assessed recurrence pattern after radio-chemotherapy in newly diagnosed patients with glioblastoma is influenced by MGMT methylation status

BACKGROUND AND PURPOSE

The aim of the present study was to evaluate factors predicting the recurrence pattern determined by [(18)F]FET-PET imaging in patients with newly diagnosed glioblastoma after combined radio-chemotherapy treated according to the EORTC/NCIC trial.

MATERIAL AND METHODS

Seventy-nine patients with newly diagnosed GBM treated with radiotherapy plus temozolomide (75 mg/m(2)/d) followed by adjuvant cyclic (5/28 days) temozolomide (150-200 mg/m(2)) were retrospectively analysed. Recurrence patterns were assessed by means of positron-emission-tomography with [(18)F]FET and additional MRI; in 54 patients MGMT methylation status was evaluated.

RESULTS

Whilst 49.4% of the patients had an in-field recurrence, 12.6% an ex-field recurrence and 3.8% a recurrence at the field margin, 34.2% of the patients did not relapse during follow-up (median 595 days). Considering all patients included in this study, 41.5% (12/29) of the MGMT methylated population had no relapse, 37.9% (11/29) had an in-field-recurrence and 20.7% (6/29) an ex-field/marginal recurrence, whilst 28.0% (7/25) of the MGMT unmethylated population had no relapse, 64.0% (16/25) had an in-field-recurrence and 8.0% (2/25) an ex-field/marginal recurrence (p=0.15).

CONCLUSIONS

After the administration of temozolomide concomitant with and adjuvant to radiotherapy in patients with glioblastoma, the pattern determined by [(18)F]FET-PET seems to be associated with MGMT methylation status.

Iodine-125 brachytherapy for brain tumours--a review

Iodine-125 brachytherapy has been applied to brain tumours since 1979. Even though the physical and biological characteristics make these implants particularly attractive for minimal invasive treatment, the place for stereotactic brachytherapy is still poorly defined.An extensive review of the literature has been performed, especially concerning indications, results and complications. Iodine-125 seeds have been implanted in astrocytomas I-III, glioblastomas, metastases and several other tumour entities. Outcome data given in the literature are summarized. Complications are rare in carefully selected patients.All in all, for highly selected patients with newly diagnosed or recurrent primary or metastatic tumours, this method provides encouraging survival rates with relatively low complication rates and a good quality of life.

Molecular imaging of gliomas with PET: opportunities and limitations

Neuroimaging enables the noninvasive evaluation of glioma and is considered to be one of the key factors for individualized therapy and patient management, since accurate diagnosis and demarcation of viable tumor tissue is required for treatment planning as well as assessment of treatment response. Conventional imaging techniques like MRI and CT reveal morphological information but are of limited value for the assessment of more specific and reproducible information about biology and activity of the tumor. Molecular imaging with PET is increasingly implemented in neuro-oncology, since it provides additional metabolic information of the tumor, both for patient management as well as for evaluation of newly developed therapeutics. Different molecular processes have been proposed to be useful, like glucose consumption, expression of amino acid transporters, proliferation rate, membrane biosynthesis, and hypoxia. Thus, PET might help neuro-oncologists gain further insights into tumor biology by "true molecular imaging" as well as understand treatment-related phenomena. This review describes the method of PET acquisition as well as the tracers used to image biological processes in gliomas. Furthermore, it considers the clinical impact of PET on the use of currently available radiotracers, which were shown to be potentially valuable for discrimination between neoplastic and nonneoplastic tissue, as well as on tumor grading, determinination of treatment response, and providing an outlook toward further developments.

IDH1 mutations in grade II astrocytomas are associated with unfavorable progression-free survival and prolonged postrecurrence survival

BACKGROUND

The favorable prognostic impact of mutations in the IDH1 gene is well documented for malignant gliomas; its influence on World Health Organization (WHO) grade II astrocytomas, however, is still under debate.

METHODS

A previously published database of 127 predominantly surgically treated patients harboring WHO grade II astrocytomas was revisited. Patients were screened for TP53 mutations (sequencing analysis), IDH1 mutations (pyrosequencing), and MGMT promoter methylation (methylation-specific polymerase chain reaction and bisulfite sequencing). Endpoints were overall survival, progression-free survival (PFS), time to malignant transformation, and postrecurrence survival. Radiotherapy was usually withheld until tumor progression/malignant transformation occurred.

RESULTS

IDH1 mutations, TP53 mutations, and methylated MGMT promoters were seen in 78.1%, 51.2%, and 80.0% of the analyzed tumors, respectively. IDH1 mutations, which were significantly associated with TP53 mutations and/or MGMT promoter methylation (P < .001), resulted in shortened PFS (median, 47 vs 84 months; P = .004); postrecurrence survival, however, was significantly increased in those patients undergoing malignant transformation (median, 49 vs 13.5 months; P = .006). Overall survival was not affected by IDH1. A similar pattern of influence was seen for MGMT promoter methylation. Methylated tumors did significantly worse (better) in terms of PFS (postrecurrence survival); a low number of unmethylated tumors, however, limited the power of this analysis. Conversely, TP53 mutations were stringently associated with a worse prognosis throughout the course of the disease.

CONCLUSIONS

IDH1 mutations are associated with a Janus headlike phenomenon; unfavorable prognostic influence on PFS turns into favorable impact on postrecurrence survival. A similar pattern of influence might exist for MGMT methylation.

FET-PET for malignant glioma treatment planning

BACKGROUND AND PURPOSE

The aim of this study was to compare MRI-based morphological gross tumour volumes (GTVs) to biological tumour volumes (BTVs), defined by the pathological radiotracer uptake in positron emission tomography (PET) imaging with (18)F-fluoroethyltyrosine (FET), subsequently clinical target volumes (CTVs) and finally planning target volumes (PTVs) for radiotherapy planning of glioblastoma.

PATIENTS AND METHODS

Seventeen patients with glioblastoma were included into a retrospective protocol. Treatment-planning was performed using clinical target volume (CTV=BTV+20mm or CTV=GTV+20mm+inclusion of the edema) and planning target volume (PTV=CTV+5mm). Image fusion and target volume delineation were performed with OTP-Masterplan®. Initial gross tumour volume (GTV) definition was based on MRI data only or FET-PET data only (BTV), secondarily both data sets were used to define a common CTV.

RESULTS

FET based BTVs (median 43.9 cm(3)) were larger than corresponding GTVs (median 34.1cm(3), p=0.028), in 11 of 17 cases there were major differences between GTV/BTV. To evaluate the conformity of both planning methods, the index (CTV(MRT)∩CTV(FET))/(CTV(MRT)∪CTV(FET)) was quantified which was significantly different from 1 (0.73 ± 0.03, p<0.001).

CONCLUSION

With FET-PET-CT planning, the size and geometrical location of GTVs/BTVs differed in a majority of patients. It remains open whether FET-PET-based target definition has a relevant clinical impact for treatment planning.

Hot spots in dynamic (18)FET-PET delineate malignant tumor parts within suspected WHO grade II gliomas

Molecular imaging studies have recently found inter- and intratumoral heterogeneity in World Health Organization (WHO) grade II gliomas. A correlative analysis with tumor histology, however, is still lacking. For elucidation we conducted the current prospective study. Fifty-five adult patients with an MRI-based suspicion of a WHO grade II glioma were included. [F-18]Fluoroethyltyrosine ((18)FET) uptake kinetic studies were combined with frame-based stereotactic localization techniques and used as a guide for stepwise (1-mm steps) histopathological evaluation throughout the tumor space. In tumors with heterogeneous PET findings, the O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation status and expression of mutated protein isocitrate dehydrogenase variant R132H (IDH1) were determined inside and outside of hot spot volumes. Metabolic imaging revealed 3 subgroups: the homogeneous WHO grade II glioma group (30 patients), the homogeneous malignant glioma group (10 patients), and the heterogeneous group exhibiting both low- and high-grade characteristics at different sites (15 patients). Stepwise evaluation of 373 biopsy samples indicated a strong correlation with analyses of uptake kinetics (p < 0.0001). A homogeneous pattern of uptake kinetics was linked to homogeneous histopathological findings, whereas a heterogeneous pattern was associated with histopathological heterogeneity; hot spots exhibiting malignant glioma characteristics covered 4-44% of the entire tumor volumes. Both MGMT and IDH1 status were identical at different tumor sites and not influenced by heterogeneity. Maps of (18)FET uptake kinetics strongly correlated with histopathology in suspected grade II gliomas. Anaplastic foci can be accurately identified, and this finding has implications for prognostic evaluation and treatment planning.

Therapeutic options for recurrent malignant glioma

BACKGROUND AND PURPOSE

Despite the given advances in neuro-oncology most patients with high grade malignant glioma ultimately fail locally or locoregionally. In parallel with improvements of initial treatment options, several salvage strategies have been elucidated and already entered clinical practice. Aim of this article is to review the current status of salvage strategies in recurrent high grade glioma.

MATERIAL AND METHODS

Using the following MESH headings and combinations of these terms the pubmed database was searched: "Glioma", "Recurrence", "Neoplasm Recurrence, Local", "Radiosurgery", "Brachytherapy", "Neurosurgical Procedures" and "Drug Therapy". For citation crosscheck the ISI web of science database was used employing the same search terms. In parallel, the abstracts of ASCO 2008-2009 were analyzed accordingly.

RESULTS

Currently the following options for salvage entered clinical practice: re-resection, re-irradiation (stereotactic radiosurgery, (hypo-)fractionated (stereotactic) radiotherapy, interstitial brachytherapy) or single/poly-chemotherapy schedules including new dose-intensified or alternative treatment protocols employing targeted drugs. Re-operation is associated with high morbidity and mortality, however, is an option in a highly selected patient cohort. Since toxicity has been overestimated, re-irradiation is an increasingly used option with precise fractionated radiotherapy being the most optimal technique. On average, time to secondary progression is in the range of several months. Conventional chemotherapy regimens also improve time to secondary progression; however the efficacy is only modest and treatment-related toxicities like myelo-suppression occur very frequently. Molecular targeted agents/kinases are undergoing clinical testing; however no final recommendations can be made.

CONCLUSIONS

Currently, several re-treatment options with only modest efficacy exist. The relative value of each approach compared to other options is unknown as well as it remains open which sequence of modalities should be chosen.

Serial stereotactic biopsy of brainstem lesions in adults improves diagnostic accuracy compared with MRI only

OBJECTIVE

The aim of the current prospective study was to analyse the validity of MRI based diagnosis of brainstem gliomas which was verified by stereotactic biopsy and follow-up evaluation as well as to assess prognostic factors and risk profile.

METHODS

Between 1998 and 2007, all consecutive adult patients with radiologically suspected brainstem glioma were included. The MRI based diagnosis of the lesions was made independently by an experienced neuroradiologist. Histopathological evaluation was performed in all patients from paraffin embedded specimens obtained by multimodal image guided stereotactic serial biopsy technique. Histopathological results were compared with prior radiological assessment. Length of survival was estimated with the Kaplan-Meier method and prognostic factors were calculated using the Cox model.

RESULTS

46 adult patients were included. Histological evaluation revealed pilocytic astrocytoma (n = 2), WHO grade II glioma (n = 14), malignant glioma (n = 12), metastasis (n = 7), lymphoma (n = 5), cavernoma (n = 1), inflammatory disease (n = 2) or no tumour/gliosis (n = 3). Perioperative morbidity was 2.5% (n = 1). There was no permanent morbidity and no mortality. All patients with "no tumour" or "inflammatory disease" survived. Patients with low grade glioma and malignant glioma showed a 1 year survival rate of 75% and 25%, respectively; the 1 year survival rate for patients with lymphoma or metastasis was 30%. In the subgroup with a verified brainstem glioma, negative predictors for length of survival were higher tumour grade (p = 0.002) and Karnofsky performance score < or =70 (p = 0.004).

CONCLUSION

Intra-axial brainstem lesions with a radiological pattern of glioma represent a very heterogeneous tumour group with completely different outcomes. Radiological features alone are not reliable for diagnostic classification. Stereotactic biopsy is a safe method to obtain a valid tissue diagnosis, which is indispensible for treatment decision.

Intraoperative mapping of language functions: a longitudinal neurolinguistic analysis

Object

This prospective longitudinally designed study was conducted to evaluate language functions pre- and postoperatively in patients who underwent microsurgical treatment of tumors in close proximity to or within language areas and to detect those patients at risk for a postoperative aphasic disturbance.

Methods

Between 1991 and 2005, 153 awake craniotomies with subsequent cortical mapping of language functions were performed in 149 patients. Language functions were assessed using a standardized test battery. Risk factors were obtained from multivariate logistic regression models.

Results

Language mapping was able to be performed in all patients, and complete tumor resection was achieved in 48.4%. Within 21 days after surgery a new language deficit (aphasic disturbance) was observed in 41 (32%) of the 128 cases without preoperative deficits. There were a total of 60 cases involving postoperative aphasic disturbances, including cases both with and without preoperative disturbances. Risk factors for postoperative aphasic disturbance were preoperative aphasia (p < 0.0002), intraoperative complications (p < 0.02), language-positive sites within the tumor (p < 0.001), and nonfrontal lesion location (p < 0.001). In patients without a preoperative deficit, a normal (yet submaximal) naming performance was a powerful predictor for an early postoperative aphasic disturbance (p < 0.0003). Seven months after treatment 10.9% of the 128 cases without preoperative aphasic disturbances continued to demonstrate new postoperative language disturbances. A total of 17.6% of all cases demonstrated new postoperative language disturbances after 7 months. Risk factors for persistent aphasic disturbance were increased age (> 40 years, p < 0.02) and preoperative aphasia (p < 0.001).

Conclusions

Every attempt should be undertaken to preserve language-relevant areas intraoperatively, even when they are located within the tumor. New postoperative deficits resolve in the majority of patients, which may be a result of cortical mapping as well as functional reorganization.