Prognostic factors to predict postoperative survival in patients with recurrent glioblastoma.

Background: There are no generally accepted criteria for selecting patients with recurrent glioblastoma for surgery. This retrospective study in a Danish population-based cohort aimed to identify prognostic factors affecting postoperative survival after repeated surgery for recurrent glioblastoma and to test if the preoperative New Scale for Recurrent Glioblastoma Surgery (NSGS) developed by Park CK et al could assist in the selection of patients for repeat glioblastoma surgery. Methods: Clinical data from 66 patients with recurrent glioblastoma and repeated surgery were analyzed. Kaplan-Meier plots were produced to illustrate survival in each of the three NSGS prognostic groups, and Cox proportional hazard regression was used to identify prognostic variables. Multivariable analysis was used to identify differences in survival in the three prognostic groups. Results: Six variables significantly affected postoperative survival: preoperative Karnofsky Performance Status (KPS) < 70 (p = 0.002), decreased KPS after second surgery (p = 0.012), ependymal involvement (p = 0.002), tumor volume â‰§ 50 cm3 (p = 0.021), age (p = 0.033) and Ki-67 (p = 0.005). Retrospective application of the criteria previously published by Park CK et al showed that median postoperative survival for the three prognostic groups was 390 days (0 points), 279 days (1 point), and 80 days (2 points), respectively. Conclusion: Several prognostic variables to predict postoperative survival in patients with recurrent glioblastoma were identified and should be considered when selecting patient for repeat surgery. The NSGS scoring system was useful as there were significant differences in postoperative survival between its three prognostic groups.

The Epigenetic Regulator Jumonji Domain-Containing Protein 6 (JMJD6) Is Highly Expressed but Not Prognostic in IDH-Wildtype Glioblastoma Patients.

Patients with IDH-wildtype glioblastoma (GBM) generally have a poor prognosis. However, there is an increasing need of novel robust biomarkers in the daily clinico-pathological setting to identify and support treatment in patients who become long-time survivors. Jumonji domain-containing protein 6 (JMJD6) is involved in epigenetic regulation of demethylation of histones and has been associated with GBM aggressiveness. We investigated the expression and prognostic potential of JMJD6 tumor fraction score in 184 IDH-wildtype GBMs. Whole-slides were double-stained with an antibody against JMJD6 and an exclusion-cocktail consisting of 4 antibodies (CD31, SMA, CD45, and Iba-1), enabling evaluation of tumor cells only. Stainings were quantified with a combined software- and scoring-based approach. For comparison, IDH-mutated WHO grade II, III and IV astrocytic gliomas were also stained, and the JMJD6 tumor fraction score increased with increasing WHO grade, although not significantly. In multivariate analysis including age, gender, performance status and post-surgical treatment high JMJD6 tumor fraction score was associated with longer overall survival in IDH-wildtype GBMs (p = 0.03), but the effect disappeared when MGMT promoter status was included (p = 0.34). We conclude that JMJD6 is highly expressed in IDH-wildtype GBM but it has no independent prognostic value.

Treatment plan comparison of proton vs photon radiotherapy for lower-grade gliomas.

BACKGROUND AND PURPOSE: Patients with lower-grade gliomas are long-term survivors after radiotherapy and may benefit from the reduced dose to normal tissue achievable with proton therapy. Here, we aimed to quantify differences in dose to the uninvolved brain and contralateral hippocampus and compare the risk of radiation-induced secondary cancer for photon and proton plans for lower-grade glioma patients. MATERIALS AND METHODS: Twenty-three patients were included in this in-silico planning comparative study and had photon and proton plans calculated (50.4 Gy(RBE = 1.1), 28 Fx) applying similar dose constraints to the target and organs at risk. Automatically calculated photon plans were generated with a 3 mm margin from clinical target volume (CTV) to planning target volume. Manual proton plans were generated using robust optimisation on the CTV. Dose metrics of organs at risk were compared using population mean dose-volume histograms and Wilcoxon signed-rank test. Secondary cancer risk per 10,000 persons per year (PPY) was estimated using dose-volume data and a risk model for secondary cancer induction. RESULTS: CTV coverage (V95%>98%) was similar for the two treatment modalities. Mean dose (Dmean) to the uninvolved brain was significantly reduced from 21.5 Gy (median, IQR 17.1-24.4 Gy) with photons compared to 10.3 Gy(RBE) (8.1-13.9 Gy(RBE)) with protons. Dmean to the contralateral hippocampus was significantly reduced from 6.5 Gy (5.4-11.7 Gy) with photons to 1.5 Gy(RBE) (0.4-6.8 Gy(RBE)) with protons. The estimated secondary cancer risk was reduced from 6.7 PPY (median, range 3.3-10.4 PPY) with photons to 3.0 PPY (1.3-7.5 PPY) with protons. CONCLUSION: A significant reduction in mean dose to uninvolved brain and contralateral hippocampus was found with proton planning. The estimated secondary cancer risk was reduced with proton therapy.

Prognostic role of Ki-67 in glioblastomas excluding contribution from non-neoplastic cells.

Survival of glioblastoma patients varies and prognostic markers are important in the clinical setting. With digital pathology and improved immunohistochemical multiplexing becoming a part of daily diagnostics, we investigated the prognostic value of the Ki-67 labelling index (LI) in glioblastomas more precisely than previously by excluding proliferation in non-tumor cells from the analysis. We investigated the Ki-67 LI in a well-annotated population-based glioblastoma patient cohort (178 IDH-wildtype, 3 IDH-mutated). Ki-67 was identified in full tumor sections with automated digital image analysis and the contribution from non-tumor cells was excluded using quantitative double-immunohistochemistry. For comparison of the Ki-67 LI between WHO grades (II-IV), 9 IDH-mutated diffuse astrocytomas and 9 IDH-mutated anaplastic astrocytomas were stained. Median Ki-67 LI increased with increasing WHO grade (median 2.7%, 6.4% and 27.5%). There was no difference in median Ki-67 LI between IDH-mutated and IDH-wildtype glioblastomas (p = 0.9) and Ki-67 LI was not associated with survival in glioblastomas in neither univariate (p = 0.9) nor multivariate analysis including MGMT promoter methylation status and excluding IDH-mutated glioblastomas (p = 0.2). Ki-67 may be of value in the differential diagnostic setting, but it must not be over-interpreted in the clinico-pathological context.

Quality of life in patients with cancer during the COVID-19 pandemic - a Danish cross-sectional study (COPICADS).

BACKGROUND: The COVID-19 pandemic is an international public health crisis. The risk of getting an infection with COVID-19 might impact the emotional well-being in patients with cancer. The aim of this study was to investigate quality of life (QoL) for patients with cancer during the COVID-19 pandemic. PATIENTS AND METHODS: A cross-sectional survey, including questions about demographics, concerns of COVID-19 impact on cancer treatment and outpatient clinic visits, and the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 questionnaire was sent to patients with cancer at the Department of Oncology, Odense University Hospital, Denmark. The survey was open from 15th May to 29th May 2020, and 4.571 responded. Results were compared to the Danish 'Barometer Study' conducted by the Danish Cancer Society to elucidate experiences with the Danish healthcare system prior to COVID-19 pandemic. RESULTS: In total, 9% of patients with cancer had refrained from consulting a doctor or the hospital due to fear of COVID-19 infection, and 80% were concerned about contracting COVID-19 to some extent. Seventeen patients were tested positive for COVID-19. The mean global QoL and emotional functioning (EF) scores were 71.3 and 82.8, respectively. In comparison to the 'Barometer Study', no clinical significant differences in QoL and EF scores were observed. Multivariate analysis demonstrated that being 'Concerned about contracting corona-virus' was correlated with lower QoL and EF scores. Factors associated with being concerned of contracting COVID-19 were comorbid conditions, incurable cancer, receiving medical cancer treatment and female gender. CONCLUSION: Danish patients with cancer during the COVID-19 pandemic did not have lower scores of QoL and emotional functioning compared to the Danish 'Barometer Study'. However, the study suggests that concerns of contracting COVID-19 was correlated with lower scores of QoL.

Posttreatment Effect of MGMT Methylation Level on Glioblastoma Survival.

The DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) removes temozolomide-induced alkylation, thereby preventing DNA damage and cytotoxicity. We investigated the prognostic effect of different MGMT methylation levels on overall and progression-free survival in 327 patients with primary glioblastoma undergoing standard treatment. We obtained MGMT methylation level in 4 CpG sites using pyrosequencing. The association between MGMT methylation level and survival was investigated using Cox proportional hazards model and an extension to detect time-varying effects. We found an association between MGMT methylation level and overall survival (OS) from around 9 months after the diagnosis, with no association between MGMT methylation level and OS before that. For patients surviving at least 9 months even small increases in MGMT methylation level are significantly beneficial (HR = 0.97, 95% CI [0.96, 0.98]). The predictive ability of MGMT methylation level on OS from 9 months after diagnosis has a Harrel's C of 66%. We conclude that the MGMT methylation level is strongly associated with survival only for patients surviving beyond 9 months with considerable effects for levels much lower than previously reported. Prognostic evaluation of cut-points of MGMT methylation levels and of CpG island site selection should take the time-varying effect on overall survival into account.

Evaluation of the proliferation marker Ki-67 in gliomas: Interobserver variability and digital quantification.

BACKGROUND: The Ki-67 Labelling Index (LI) is used as an ancillary tool in glioma diagnostics. Interobserver variability has been reported and no precise guidelines are available. Nor is it known whether novel digital approaches would be an advantage. Our aim was to evaluate the inter- and intraobserver variability of the Ki-67 LI between two pathologists and between pathologists and digital quantification both in whole tumour slides and in hot spots using narrow but diagnostically relevant intervals. METHODS: In samples of 235 low and high grade gliomas, two pathologists (A and B) estimated the Ki-67 LI (5-10% intervals) for whole tumour slides and for hot spots. In 20 of the cases intraobserver variability was evaluated. For digital quantification (C) slides were scanned with subsequent systematic random sampling of viable tumour areas. A software classifier trained to identify positive and negative nuclei calculated the Ki-67 LI. The interobserver agreements were evaluated using kappa (κ) statistics. RESULTS: The observed proportions of agreement and κ values for Ki-67 LI for whole tumour slides were: A/B: 46% (κ = 0.32); A/C: 37% (κ = 0.26); B/C: 37% (κ = 0.26). For hot spots equivalent values were: A/B: 14% (κ = 0.04); A/C: 18% (κ = 0.09); B/C: 31% (κ = 0.21). CONCLUSIONS: Interobserver variability was pronounced between pathologists and for pathologists versus digital quantification when attempting to estimate a precise value of the Ki-67 LI. Ki-67 LI should therefore be used with caution and should not be over interpreted in the grading of gliomas. Digital quantification of Ki-67 LI in gliomas was feasible, but intra- and interlaboratory robustness need to be determined.

Transferrin receptor-1 and ferritin heavy and light chains in astrocytic brain tumors: Expression and prognostic value.

Astrocytic brain tumors are the most frequent primary brain tumors. Treatment with radio- and chemotherapy has increased survival making prognostic biomarkers increasingly important. The aim of the present study was to investigate the expression and prognostic value of transferrin receptor-1 (TfR1) as well as ferritin heavy (FTH) and light (FTL) chain in astrocytic brain tumors. A cohort of 111 astrocytic brain tumors (grade II-IV) was stained immunohistochemically with antibodies against TfR1, FTH, and FTL and scored semi-quantitatively. Double-immunofluorescence stainings were established to determine the phenotype of cells expressing these markers. We found that TfR1, FTH, and FTL were expressed by tumor cells in all grades. TfR1 increased with grade (p<0.001), but was not associated with prognosis in the individual grades. FTH and FTL were expressed by tumor cells and cells with microglial/macrophage morphology. Neither FTH nor FTL increased with malignancy grade, but low FTH expression by both tumor cells (p = 0.03) and microglia/macrophages (p = 0.01) correlated with shorter survival in patients anaplastic astrocytoma. FTL-positive microglia/macrophages were frequent in glioblastomas, and high FTL levels correlated with shorter survival in the whole cohort (p = 0.01) and in patients with anaplastic astrocytoma (p = 0.02). Double-immunofluorescence showed that TfR1, FTH, and FTL were co-expressed to a limited extent with the stem cell-related marker CD133. FTH and FTL were also co-expressed by IBA-1-positive microglia/macrophages. In conclusion, TfR1 was highly expressed in glioblastomas and associated with shorter survival in the whole cohort, but not in the individual malignancy grades. Low levels of FTH-positive tumor cells and microglia/macrophages were associated with poor survival in anaplastic astrocytomas, while high amounts of FTL-positive microglia/macrophages had a negative prognostic value. The results suggest that regulation of the iron metabolism in astrocytic brain tumors is complex involving both autocrine and paracrine signaling.

Expression and prognostic value of JAM-A in gliomas.

Gliomas are among the most lethal cancers, being highly resistant to both chemo- and radiotherapy. The expression of junctional adhesion molecule-A (JAM-A) was recently identified on the surface of stem cell-like brain tumor-initiating cells and suggested to function as a unique glioblastoma niche adhesion factor influencing the tumorigenic potential of brain tumor-initiating cells. We have recently identified high JAM-A expression to be associated with poor outcome in glioblastomas, and our aim was to further investigate the expression of JAM-A in gliomas focusing especially on the prognostic value in WHO grade II and III gliomas. JAM-A protein expression was evaluated by immunohistochemistry and advanced quantitative image analysis with continuous estimates of staining intensity. The JAM-A antibody stained tumor cell membranes and cytoplasm to various extent in different glioma subtypes, and the intensity was higher in glioblastomas than low-grade gliomas. We could not detect an association with overall survival in patients with grade II and III tumors. Double-immunofluorescence stainings in glioblastomas revealed co-expression of JAM-A with CD133, SOX2, nestin, and GFAP in tumor cells as well as some co-expression with the microglial/macrophage marker IBA-1. In conclusion, JAM-A expression was higher in glioblastomas compared to low-grade gliomas and co-localized with recognized stem cell markers suggesting an association of JAM-A with glioma aggressiveness. No significant association between JAM-A expression and overall survival was found in grade II and III gliomas. Further research is needed to determine the function and clinical impact of JAM-A in gliomas.

APNG as a prognostic marker in patients with glioblastoma.

AIM: Expression of the base excision repair enzyme alkylpurine-DNA-N-glycosylase (APNG) has been correlated to temozolomide resistance. Our aim was to evaluate the prognostic value of APNG in a population-based cohort with 242 gliomas including 185 glioblastomas (GBMs). Cellular heterogeneity of GBMs was taken into account by excluding APNG expression in non-tumor cells from the analysis. METHODS: APNG expression was evaluated using automated image analysis and a novel quantitative immunohistochemical (IHC) assay (qIHC), where APNG protein expression was evaluated through countable dots. Non-tumor cells were excluded using an IHC/qIHC double-staining. For verification, APNG was measured by a quantitative double-immunofluorescence (IF) assay. As validation APNG mRNA expression was evaluated using independent TCGA data. RESULTS: Using qIHC, high levels of APNG were associated with better overall survival (OS) in univariate (HR = 0.50; P < 0.001) and multivariate analysis (HR = 0.53; P = 0.001). Patients with methylated MGMT promoters and high APNG expression demonstrated better OS, than patients with methylated MGMT promoters and low APNG expression (HR = 0.59; P = 0.08). Retesting the cohort using IF showed similar results in both univariate (HR = 0.61; P = 0.002) and multivariate analysis (HR = 0.81; P = 0.2). The results were supported by data from the TCGA database. CONCLUSIONS: Using two different assays combined with quantitative image analysis excluding non-tumour cells, APNG was an independent prognostic factor among patients with a methylated MGMT promoter. We expect that APNG qIHC can potentially identify GBM patients who will not benefit from treatment with temozolomide.

Trends in tumors in the central nervous system in elderly in Denmark, 2008-2012.

BACKGROUND: Tumors in the central nervous system (CNS) comprise a heterogeneous group of tumors with different treatment strategies and prognoses. Current treatment regimens are based on studies on patients mainly younger than 70 years. The aim of the present study was to analyze and describe trends in incidence, mortality, prevalence, and relative survival in Denmark from 1980 to 2012 focusing on patients older than 70 years. MATERIAL AND METHODS: Tumors in the CNS were defined as ICD-10 codes C70-72, D32-33 and D42-43. Data with comparable data on cancer incidence, mortality, prevalence and relative survival derived from the NORDCAN database were delivered from the Danish Cancer Registry and the Danish Cause of Death Registry with follow-up for death or emigration until the end of 2013. RESULTS: During the period 1980-2012 the number of patients with CNS tumors increased from 603 to 1378 patients. The increase is seen mainly in the elderly patients, and especially in women aged 84-89 and 90 + at the time of diagnosis. During the same time period, the mortality rates increased within all age groups, most significantly in patients aged 70 years or older. This may reflect an increased focus on and identification of these patients. Noteworthy; the number of patients living with a CNS tumor increased from 2952 in 1980 to 12 147 patients in 2010. CONCLUSION: This study suggests that the current treatment strategies in general may have improved survival in patients with CNS tumors, but in order to improve survival further in the increasing group of elderly patients more knowledge about treatment of these patients is needed.

Novel approaches for quantifying protein biomarkers in gliomas: benefits and pitfalls.

The therapeutic paradigm of gliomas is changing from a general approach towards an individualized and targeted approach. Accordingly, the search for prognostic and predictive biomarkers, as well as the demand for quantitative, feasible and robust methods for biomarker analysis increases. We find that software classifiers can identify and quantify the expression of a given biomarker within different subcellular compartments and that such classifiers can exclude frequently occurring nontumor cells, thereby avoiding potential bias. The use of a quantitative approach provides a continuous measurement of the expression, allowing establishment of new cut-points and identification of patients with specific prognoses. However, some pitfalls must be noted. This article focuses on benefits and pitfalls of novel approaches for quantifying protein biomarkers in gliomas.

Clinical value of CD133 and nestin in patients with glioma: a population-based study.

Cancer stem cell-related (CSC) markers have been suggested to have promising potentials as novel types of prognostic and predictive markers in gliomas. However no single CSC-related marker is currently used in clinical decisions. The aim of this study was to investigate the prognostic value of CD133 and nestin separately and in combination using a novel quantitative approach in a well-characterized population-based cohort of glioma patients. The expression of CD133 and nestin was measured by systematic random sampling in stained paraffin sections from 239 glioma patients diagnosed between 2005 and 2009. We found that the expression of CD133 did not correlate with WHO grade, and there was no association with overall survival (OS). The level of nestin correlated positively with WHO grade. In patients with WHO grade II tumors, a high level of nestin was associated with short progression-free survival (PFS) in multivariate analysis. High levels of co-localization were associated with poor PFS in patients with WHO grade II tumors, but not with OS. We conclude that CD133 was not an independent prognostic factor, but a high level of nestin was associated with poor PFS in patients with WHO grade II tumors. The combination of double-immunofluorescence and automated analysis seems to be a feasible and reproducible approach for investigation of the prognostic potential of biomarkers.

High-throughput flow cytometry screening reveals a role for junctional adhesion molecule a as a cancer stem cell maintenance factor.

Stem cells reside in niches that regulate the balance between self-renewal and differentiation. The identity of a stem cell is linked with the ability to interact with its niche through adhesion mechanisms. To identify targets that disrupt cancer stem cell (CSC) adhesion, we performed a flow cytometry screen on patient-derived glioblastoma (GBM) cells and identified junctional adhesion molecule A (JAM-A) as a CSC adhesion mechanism essential for self-renewal and tumor growth. JAM-A was dispensable for normal neural stem/progenitor cell (NPC) function, and JAM-A expression was reduced in normal brain versus GBM. Targeting JAM-A compromised the self-renewal of CSCs. JAM-A expression negatively correlated to GBM patient prognosis. Our results demonstrate that GBM-targeting strategies can be identified through screening adhesion receptors and JAM-A represents a mechanism for niche-driven CSC maintenance.

Prognostic value of Musashi-1 in gliomas.

The aim of this study was to investigate the prognostic value of the RNA-binding protein Musashi-1 in adult patients with primary gliomas. Musashi-1 has been suggested to be a cancer stem cell-related marker in gliomas, and high levels of Musashi-1 have been associated with high tumor grades and hence poor prognosis. Samples of 241 gliomas diagnosed between 2005 and 2009 were stained with an anti-Musashi-1 antibody using a fluorescent staining protocol followed by automated image acquisition and processing. Musashi-1 area fraction and intensity in cytoplasm and in nuclei were quantified by systematic random sampling in 2 % of the vital tumor area. In WHO grade III tumors high levels of Musashi-1 were associated with poor survival in multivariate analysis (HR 3.39, p = 0.02). We identified a sub-population of glioblastoma (GBM) patients with high levels of Musashi-1 and a superior prognosis (HR 0.65, p = 0.038). In addition patients with high levels of Musashi-1 benefitted most from post-surgical treatment, indicating that Musashi-1 may be a predictive marker in GBMs. In conclusion, our results suggest that high levels of Musashi-1 are associated with poor survival in patients with WHO grade III tumors and that Musashi-1 may be a predictive marker in GBMs, although further validation is needed. We find the combination of immunofluorescence and automated quantitation to be a feasible, robust, and reproducible approach for quantitative biomarker studies.

A population-based study of low-grade gliomas and mutated isocitrate dehydrogenase 1 (IDH1).

Low-grade gliomas (LGG) have a slow growth rate, but transformations into malignant gliomas with a rapid deterioration occur in many patients. The aim of this study was to evaluate clinical prognostic factors in a population-based cohort of patients with LGG. In addition we investigated the expression and prognostic value of the isocitrate dehydrogenase 1 (IDH1) R132H mutation. Seventy-four patients diagnosed between 2005 and 2009 in the Region of Southern Denmark were identified using the Danish Cancer Register and The Danish Pathology Databank. Survival analysis using Cox regression was performed in 52 patients with tumor samples useable for immunohistochemical evaluation of IDH1 status. Patients with a contrast enhancing tumor, neurological deficits, headache, an astrocytic tumor and PS 2-4 had an increased risk of recurrence. In univariate analysis age > 50 years (HR 2.14, 95 % CI 1.08-4.24), having neurological deficit (HR 2.28, 95 % CI 1.15-4.52), receiving post-surgical treatment (HR 2.52, 95 % CI 1.19-5.32), being in performance status 2-4 (HR 1.44, 95 % CI 1.15-1.81), and having an astrocytic tumor (HR 3.79, 95 % CI 1.64-8.73) were associated with poor survival. Mutated IDH1 (mIDH1) was identified in 46 % of the patients and was significantly correlated to a good survival in both univariate (HR 0.24, 95 % CI 0.11-0.53) and in multivariate analysis (HR 0.40, 95 % CI 0.17-0.91). The other clinical variables were not significant when adjusted for the effect of mIDH1 status. We find that young age, the absence of neurologic deficit, PS 0-1 and oligodendroglial histology were associated with better survival. IDH1 status showed independent prognostic information when adjusting for classical prognostic factors, and should be validated in a larger patient population.

Small cell glioblastoma or small cell carcinoma: a case report and review of the literature.

It is often easy to distinguish between primary brain tumors and metastases based on morphology alone. However, in some cases immunohistochemistry (IHC) is necessary to obtain a diagnosis, but, as the present case report illustrates, this is not always straightforward. A 75-year old man was admitted to the hospital with left-sided loss of motor function. A MRI revealed a 6 cm tumor in the right temporoparietal area. The histology was consistent with both glioblastoma multiforme (GBM) and small cell lung carcinoma (SCLC) but IHC was suggestive of a SCLC metastasis. PET-CT revealed no enhancement in the lung, so the tumor was treated as a GBM. Eight months after the primary diagnosis a new MRI revealed metastases in the spinal cord, but there was still no enhancement in the lungs. We reviewed the literature concerning markers used to differentiate between GBM and SCLC and found that most of these markers showed limited specificity. It is further discussed whether the case illustrates an example of spontaneous regression of primary SCLC or might be an example of a GMB metastasizing to the spinal cord. Although immunohistochemical markers are of great help in many situations, the case illustrates important limitations and the need for better diagnostic markers.

A population-based study of high-grade gliomas and mutated isocitrate dehydrogenase 1.

UNLABELLED: High-grade gliomas have a dismal prognosis, and prognostic factors are needed to optimize treatment algorithms. In this study we identified clinical prognostic factors as well as the prognostic value of isocitrate dehydrogenase 1 (IDH1) status in a population-based group of patients with high-grade gliomas. Using the Danish Cancer Registry and the Danish Pathology Databank we identified 359 patients: 234 had WHO grade IV gliomas, 58 had WHO grade III gliomas, and 67 were diagnosed clinically. Mutated IDH1 was predominantly observed in oligodendroglial tumors (WHO grade III). Patients with mutated IDH1 had a significantly better outcome than patients with wildtype IDH1: 2-year OS 59% and 18%, respectively (HR 0.38, 95% CI 0.21-0.68). However, when adjusting for other prognostic factors, IDH1 status was not a significant independent prognostic factor (HR=0.58, 95% CI 0.32-1.07). Young age, absence of neurological deficit, performance status 0-1, tumor not crossing the midline, and receiving post-surgical treatment were significant independent indicators of a good prognosis in multivariate analysis. IN CONCLUSION: This population-based study could not demonstrate IDH1 status to be an independent prognostic factor in high-grade gliomas when adjusting for the effect of classic prognostic factors.