The detrimental effect of biopsy preceding resection in surgically accessible glioblastoma: results from the national cancer database

PURPOSE

Aggressive resection in surgically-accessible glioblastoma (GBM) correlates with improved survival over less extensive resections. However, the clinical impact of performing a biopsy before definitive resection have not been previously evaluated.

METHODS

We analyzed 17,334 GBM patients from the NCDB from 2010-2014. We categorized them into: "upfront resection" and "biopsy followed by resection". The outcomes of interes included OS, 30-day readmission/mortality, 90-day mortality, and length of hospital stay (LOS). The Kaplan-Meier methods and accelerated failure time (AFT) models were applied for survival analysis. Multivariable binary logistic regression were performed to compare differences among groups. Multiple imputation and propensity score matching (PSM) were conducted for validation.

RESULTS

"Upfront resection" had superior OS over "biopsy followed by resection" (median OS:12.4 versus 11.1 months, log-rank p = 0.001). Similarly, multivariable AFT models favored "upfront resection" (time ratio[TR]:0.83, 95%CI: 0.75-0.93, p = 0.001). Patients undergoing "upfront gross-total resection (GTR)" had higher OS over "upfront subtotal resection (STR)", "GTR following STR", and "GTR or STR following initial biopsy" (14.4 vs. 10.3, 13.5, 13.3, and 9.1 months;TR: 1.00 [Ref.], 0.75, 0.82, 0.88, and 0.67). Recent years of diagnosis, higher income, facilities located in Southern regions, and treatment at academic facilities were significantly associated with the higher likelihood of undergoing upfront resection. Multivariable regression showed a decreased 30 and 90-day mortality for patients undergoing "upfront resection", 73% and 44%, respectively (p < 0.001).

CONCLUSIONS

Pre-operative biopsies for surgically accessible GBM are associated with worse survival despite subsequent resection compared to patients undergoing upfront resection.

Extent of Resection Thresholds in Molecular Subgroups of Newly Diagnosed Isocitrate Dehydrogenase-Wildtype Glioblastoma

BACKGROUND AND OBJECTIVES

Maximizing the extent of resection (EOR) improves outcomes in glioblastoma (GBM). However, previous GBM studies have not addressed the EOR impact in molecular subgroups beyond IDH1/IDH2 status. In the current article, we evaluate whether EOR confers a benefit in all GBM subtypes or only in particular molecular subgroups.

METHODS

A retrospective cohort of newly diagnosed GBM isocitrate dehydrogenase (IDH)-wildtype undergoing resection were prospectively included in a database (n = 138). EOR and residual tumor volume (RTV) were quantified with semiautomated software. Formalin-fixed paraffin-embedded tumor tissues were analyzed by targeted next-generation sequencing. The association between recurrent genomic alterations and EOR/RTV was evaluated using a recursive partitioning analysis to identify thresholds of EOR or RTV that may predict survival. The Kaplan-Meier methods and multivariable Cox proportional hazards regression methods were applied for survival analysis.

RESULTS

Patients with EOR ≥88% experienced 44% prolonged overall survival (OS) in multivariable analysis (hazard ratio: 0.56, P = .030). Patients with alterations in the TP53 pathway and EOR <89% showed reduced OS compared to TP53 pathway altered patients with EOR>89% (10.5 vs 18.8 months; HR: 2.78, P = .013); however, EOR/RTV was not associated with OS in patients without alterations in the TP53 pathway. Meanwhile, in all patients with EOR <88%, PTEN-altered had significantly worse OS than PTEN-wildtype (9.5 vs 15.4 months; HR: 4.53, P < .001).

CONCLUSION

Our results suggest that a subset of molecularly defined GBM IDH-wildtype may benefit more from aggressive resections. Re-resections to optimize EOR might be beneficial in a subset of molecularly defined GBMs. Molecular alterations should be taken into consideration for surgical treatment decisions in GBM IDH-wildtype.

The genomic alterations in glioblastoma influence the levels of CSF metabolites

Cerebrospinal fluid (CSF) analysis is underutilized in patients with glioblastoma (GBM), partly due to a lack of studies demonstrating the clinical utility of CSF biomarkers. While some studies show the utility of CSF cell-free DNA analysis, studies analyzing CSF metabolites in patients with glioblastoma are limited. Diffuse gliomas have altered cellular metabolism. For example, mutations in isocitrate dehydrogenase enzymes (e.g., IDH1 and IDH2) are common in diffuse gliomas and lead to increased levels of D-2-hydroxyglutarate in CSF. However, there is a poor understanding of changes CSF metabolites in GBM patients. In this study, we performed targeted metabolomic analysis of CSF from n = 31 patients with GBM and n = 13 individuals with non-neoplastic conditions (controls), by mass spectrometry. Hierarchical clustering and sparse partial least square-discriminant analysis (sPLS-DA) revealed differences in CSF metabolites between GBM and control CSF, including metabolites associated with fatty acid oxidation and the gut microbiome (i.e., carnitine, 2-methylbutyrylcarnitine, shikimate, aminobutanal, uridine, N-acetylputrescine, and farnesyl diphosphate). In addition, we identified differences in CSF metabolites in GBM patients based on the presence/absence of TP53 or PTEN mutations, consistent with the idea that different mutations have different effects on tumor metabolism. In summary, our results increase the understanding of CSF metabolites in patients with diffuse gliomas and highlight several metabolites that could be informative biomarkers in patients with GBM.

Surgical management and outcome of newly diagnosed glioblastoma without contrast enhancement (low-grade appearance): a report of the RANO resect group

BACKGROUND

Resection of the contrast-enhancing (CE) tumor represents the standard of care in newly diagnosed glioblastoma. However, some tumors ultimately diagnosed as glioblastoma lack contrast enhancement and have a 'low-grade appearance' on imaging (non-CE glioblastoma). We aimed to (a) volumetrically define the value of non-CE tumor resection in the absence of contrast enhancement, and to (b) delineate outcome differences between glioblastoma patients with and without contrast enhancement.

METHODS

The RANO resect group retrospectively compiled a global, eight-center cohort of patients with newly diagnosed glioblastoma per WHO 2021 classification. The associations between postoperative tumor volumes and outcome were analyzed. Propensity score-matched analyses were constructed to compare glioblastomas with and without contrast enhancement.

RESULTS

Among 1323 newly diagnosed IDH-wildtype glioblastomas, we identified 98 patients (7.4%) without contrast enhancement. In such patients, smaller postoperative tumor volumes were associated with more favorable outcome. There was an exponential increase in risk for death with larger residual non-CE tumor. Accordingly, extensive resection was associated with improved survival compared to lesion biopsy. These findings were retained on a multivariable analysis adjusting for demographic and clinical markers. Compared to CE glioblastoma, patients with non-CE glioblastoma had a more favorable clinical profile and superior outcome as confirmed in propensity score analyses by matching the patients with non-CE glioblastoma to patients with CE glioblastoma using a large set of clinical variables.

CONCLUSIONS

The absence of contrast enhancement characterizes a less aggressive clinical phenotype of IDH-wildtype glioblastomas. Maximal resection of non-CE tumors has prognostic implications and translates into favorable outcome.

Rapid detection of mutations in CSF-cfTNA with the Genexus Integrated Sequencer

PURPOSE

Genomic alterations are fundamental for molecular-guided therapy in patients with breast and lung cancer. However, the turn-around time of standard next-generation sequencing assays is a limiting factor in the timely delivery of genomic information for clinical decision-making.

METHODS

In this study, we evaluated genomic alterations in 54 cerebrospinal fluid samples from 33 patients with metastatic lung cancer and metastatic breast cancer to the brain using the Oncomine Precision Assay on the Genexus sequencer. There were nine patients with samples collected at multiple time points.

RESULTS

Cell-free total nucleic acids (cfTNA) were extracted from CSF (0.1-11.2 ng/μl). Median base coverage was 31,963× with cfDNA input ranging from 2 to 20 ng. Mutations were detected in 30/54 CSF samples. Nineteen (19/24) samples with no mutations detected had suboptimal DNA input (< 20 ng). The EGFR exon-19 deletion and PIK3CA mutations were detected in two patients with increasing mutant allele fraction over time, highlighting the potential of CSF-cfTNA analysis for monitoring patients. Moreover, the EGFR T790M mutation was detected in one patient with prior EGFR inhibitor treatment. Additionally, ESR1 D538G and ESR1::CCDC170 alterations, associated with endocrine therapy resistance, were detected in 2 mBC patients. The average TAT from cfTNA-to-results was < 24 h.

CONCLUSION

In summary, our results indicate that CSF-cfTNA analysis with the Genexus-OPA can provide clinically relevant information in patients with brain metastases with short TAT.

Survival outcomes and prognostic factors of infratentorial glioblastoma in the elderly

INTRODUCTION

Infratentorial glioblastoma(itGBM) is a rare and rapidly progressive form of GBM with poor prognosis. However, no studies have adequately examined itGBM outcomes in elderly patients (>65 years). Here, we used a national database to fill this knowledge gap.

METHODS

SEER 18 registries were utilized to identify adult itGBM patients diagnosed between 2000-2016. itGBM cases were further divided into cerebellar and brainstem GBM as cGBM and bGBM, respectively. Kaplan-Meier analysis and Cox hazards proportional regression models were performed to assess factors associated with overall survival (OS).

RESULTS

Among 137 (33%) elderly patients from the study cohort (N = 420), median age was 74 years, 38% were female, and 85% were white. Median OS in elderly itGBM patients was shorter than younger adults (10 vs. 5-months, p < 0.001). Multivariate analysis by tumor location revealed that older age was associated with poor survival for cGBM, but not for bGBM. Gross-total resection (GTR) was associated with better outcomes for both cGBM and bGBM. Radiotherapy had survival benefits for cGBM; meanwhile, chemotherapy prolonged OS in bGBM. In the elderly, advanced age (80 + years) was associated with poor outcomes, while GTR, CT and RT were all associated with improved survival.

CONCLUSIONS

In our study, while elderly patients had worse survival compared to younger adults for both cGBM and bGBM, GTR improved OS in elderly itGBM, with CT and RT exhibiting a location-dependent survival benefit. Thus, elderly itGBM patients should undergo a combination of maximal resection and adjuvant treatment guided by infratentorial tumor location for maximal survival benefit.

Prognostic evaluation of re-resection for recurrent glioblastoma using the novel RANO classification for extent of resection: A report of the RANO resect group

BACKGROUND

The value of re-resection in recurrent glioblastoma remains controversial as a randomized trial that specifies intentional incomplete resection cannot be justified ethically. Here, we aimed to (1) explore the prognostic role of extent of re-resection using the previously proposed Response Assessment in Neuro-Oncology (RANO) classification (based upon residual contrast-enhancing (CE) and non-CE tumor), and to (2) define factors consolidating the surgical effects on outcome.

METHODS

The RANO resect group retrospectively compiled an 8-center cohort of patients with first recurrence from previously resected glioblastomas. The associations of re-resection and other clinical factors with outcome were analyzed. Propensity score-matched analyses were constructed to minimize confounding effects when comparing the different RANO classes.

RESULTS

We studied 681 patients with first recurrence of Isocitrate Dehydrogenase (IDH) wild-type glioblastomas, including 310 patients who underwent re-resection. Re-resection was associated with prolonged survival even when stratifying for molecular and clinical confounders on multivariate analysis; ≤1 cm3 residual CE tumor was associated with longer survival than non-surgical management. Accordingly, "maximal resection" (class 2) had superior survival compared to "submaximal resection" (class 3). Administration of (radio-)chemotherapy in the absence of postoperative deficits augmented the survival associations of smaller residual CE tumors. Conversely, "supramaximal resection" of non-CE tumor (class 1) was not associated with prolonged survival but was frequently accompanied by postoperative deficits. The prognostic role of residual CE tumor was confirmed in propensity score analyses.

CONCLUSIONS

The RANO resect classification serves to stratify patients with re-resection of glioblastoma. Complete resection according to RANO resect classes 1 and 2 is prognostic.

Novel Postoperative Serum Biomarkers in Atypical Meningiomas: A Multicenter Study

BACKGROUND

There has been no known serum biomarker to predict the prognosis of atypical meningioma.

OBJECTIVE

To investigate the prognostic impact of serum biomarkers in patients newly diagnosed with resected intracranial atypical meningiomas.

METHODS

This study enrolled 523 patients with atypical meningioma who underwent surgical resection between 1998 and 2018 from 5 Asian institutions. Serum laboratory data within 1 week after surgery were obtained for analysis. Optimal cutoffs were calculated for each serum marker using the maxstat package of R.

RESULTS

Of 523 patients, 19.5% underwent subtotal resection and 29.8% were treated with adjuvant radiation therapy (ART). Among the 523 patients, 454 were included in the multivariate analysis for the progression/recurrence (P/R) rate excluding patients with incomplete histopathologic or laboratory data. On multivariate analysis, tumor size >5 cm, subtotal resection, and postoperative aspartate aminotransferase/alanine transaminase (De Ritis) ratio >2 were associated with higher P/R rates, whereas ART and postoperative platelet count >137 × 10 3 /μL were associated with lower P/R rates. In the subgroup of patients treated with ART, tumor size >5 cm and postoperative neutrophil-to-lymphocyte ratio >21 were associated with higher P/R rates. By contrast, postoperative De Ritis ratio >2 remained an adverse prognosticator in patients not treated with ART.

CONCLUSION

Postoperative De Ritis ratio, platelet count, and neutrophil-to-lymphocyte ratio were revealed as a novel serum prognosticator in newly diagnosed atypical meningiomas. Additional studies are warranted to validate its clinical significance and biological background.

TERT Immunohistochemistry as a Surrogate Marker for TERT Promoter Mutations in Infiltrating Gliomas

Genomic alterations are critical for the diagnosis, prognostication, and treatment of patients with infiltrating gliomas. Telomerase reverse transcriptase promoter ( TERT p) mutations are among such crucial alterations. Although DNA sequencing is the preferred method for identifying TERT p mutations, it has limitations related to cost and accessibility. We tested telomerase reverse transcriptase (TERT) immunohistochemistry (IHC) as a surrogate for TERT p mutations in infiltrating gliomas. Thirty-one infiltrating gliomas were assessed by IHC using an anti-TERT Y182 antibody. IHC results were analyzed by a board-certified neuropathologist. Tumors were analyzed by targeted next-generation sequencing. A literature review of the use of TERT antibodies as a surrogate for TERT p mutations was performed. Eighteen gliomas harbored TERT p mutations. Overall, TERT IHC demonstrated a sensitivity of 61.1% and a specificity of 69.2% for identifying TERT p mutations. Among the 19 IDH1/IDH2 -wild-type gliomas, 16 (84%) harbored TERT p mutations, and TERT IHC had a sensitivity of 62.5% and a specificity of 33.3%. Among the 12 IDH1/IDH2 -mutant gliomas, 2 (17%) harbored TERT p mutations, and TERT IHC had a sensitivity of 50% and a specificity of 80%. TERT IHC had low positive and negative likelihood values in the identification of TERT p mutations. The literature review included 5 studies with 645 patients and 4 different TERT antibodies. The results consistently showed poor sensitivity and specificity of TERT IHC for identifying TERT p mutations. TERT IHC is a suboptimal surrogate marker for TERT p mutations in infiltrating gliomas. The need remains for cost-effective, efficient, and accessible alternatives to next-generation sequencing for the evaluation of TERT p mutations in gliomas.

Prediction of Brain Metastases Development in Patients With Lung Cancer by Explainable Artificial Intelligence From Electronic Health Records

PURPOSE

Early detection of brain metastases (BMs) is critical for prompt treatment and optimal control of the disease. In this study, we seek to predict the risk of developing BM among patients diagnosed with lung cancer on the basis of electronic health record (EHR) data and to understand what factors are important for the model to predict BM development through explainable artificial intelligence approaches accurately.

MATERIALS AND METHODS

We trained a recurrent neural network model, REverse Time AttentIoN (RETAIN), to predict the risk of developing BM using structured EHR data. To interpret the model's decision process, we analyzed the attention weights in the RETAIN model and the SHAP values from a feature attribution method, Kernel SHAP, to identify the factors contributing to BM prediction.

RESULTS

We developed a high-quality cohort with 4,466 patients with BM from the Cerner Health Fact database, which contains over 70 million patients from more than 600 hospitals. RETAIN uses this data set to achieve the best area under the receiver operating characteristic curve at 0.825, a significant improvement over the baseline model. We also extended a feature attribution method, Kernel SHAP, to structured EHR data for model interpretation. Both RETAIN and Kernel SHAP can identify important features related to BM prediction.

CONCLUSION

To the best of our knowledge, this is the first study to predict BM using structured EHR data. We achieved decent prediction performance for BM prediction and identified factors highly relevant to BM development. The sensitivity analysis demonstrated that both RETAIN and Kernel SHAP could discriminate unrelated features and put more weight on the features important to BM. Our study explored the potential of applying explainable artificial intelligence for future clinical applications.

Infiltrating gliomas with FGFR alterations: Histologic features, genetic alterations, and potential clinical implications

BACKGROUND

Fibroblast growth factor receptors (FGFRs) are frequently altered in cancers and present a potential therapeutic avenue. However, the type and prevalence of FGFR alterations in infiltrating gliomas (IGs) needs further investigation.

OBJECTIVE

To understand the prevalence/type of FGFR alterations in IGs.

METHODS

We reviewed clinicopathologic and genomic alterations of FGFR-mutant gliomas in a cohort of 387 patients. Tumors were examined by DNA next-generation sequencing for somatic mutations with a panel interrogating 205-genes. For comparison, cBioPortal databases were queried to identify FGFR-altered IGs.

RESULTS

Fourteen patients (3.6%) with FGFR-mutant tumors were identified including 11 glioblastomas, Isocitrate dehydrogenase (IDH) - wildtype (GBM-IDH-WT), 2 oligodendrogliomas, and 1 astrocytoma IDH-mutant. FGFR-altered IGs showed endocrinoid capillaries, microvascular proliferation, necrosis, oligodendroglioma-like cells, fibrin thrombi, microcalcifications, and nodular growth. FGFR3 was the most commonly altered FGFR gene (64.3%). The most common additional mutations in FGFR-altered IGs were TERTp, CDKN2A/B, PTEN, CDK4, MDM2, and TP53. FGFR3 alterations were only observed in GBM-IDH-WT. EGFR alterations were rarely identified in FGFR3-altered gliomas.

CONCLUSIONS

Histologic features correlate with FGFR alterations in IGs. FGFR3-TACC3 fusion and FGFR3 amplification are the most common FGFR alterations in IGs. FGFR alterations are a rare, but potentially viable, therapeutic target in asubset of IGs.

Early repeat resection for residual glioblastoma: decision-making among an international cohort of neurosurgeons

OBJECTIVE

The importance of extent of resection (EOR) in glioblastoma (GBM) has been thoroughly demonstrated. However, few studies have explored the practices and benefits of early repeat resection (ERR) when residual tumor deemed resectable is unintentionally left after an initial resection, and the survival benefit of ERR is still unknown. Herein, the authors aimed to internationally survey current practices regarding ERR and to analyze differences based on geographic location and practice setting.

METHODS

The authors distributed a survey to the American Association of Neurological Surgeons and Congress of Neurological Surgeons Tumor Section, Society of British Neurological Surgeons, European Association of Neurosurgical Society, and Latin American Federation of Neurosurgical Societies. Neurosurgeons responded to questions about their training, practice setting, and current ERR practices. They also reported the EOR threshold below which they would pursue ERR and their likelihood of performing ERR using a Likert scale of 1-5 (5 being the most likely) in two sets of 5 cases, the first set for a patient's initial hospitalization and the second for a referred patient who had undergone resection elsewhere. The resection likelihood index for each respondent was calculated as the mean Likert score across all cases.

RESULTS

Overall, 180 neurosurgeons from 25 countries responded to the survey. Neurosurgeons performed ERRs very rarely in their practices (< 1% of all GBM cases), with an EOR threshold of 80.2% (75%-95%). When presented with 10 cases, the case context (initial hospitalization vs referred patient) did not significantly change the surgeon ERR likelihood, although ERR likelihood did vary significantly on the basis of tumor location (p < 0.0001). Latin American neurosurgeons were more likely to pursue ERR in the provided cases. Neurosurgeons were more likely to pursue ERR when the tumor was MGMT methylated versus unmethylated, with a resection likelihood index of 3.78 and 3.21, respectively (p = 0.004); however, there was no significant difference between IDH mutant and IDH wild-type tumors.

CONCLUSIONS

Results of this survey reveal current practices regarding ERR, but they also demonstrate the variability in how neurosurgeons approach ERR. Standardized guidelines based on future studies incorporating tumor molecular characteristics are needed to guide neurosurgeons in their decision-making on this complicated issue.

SURG-19. PROGNOSTIC VALIDATION OF A NEW CLASSIFICATION SYSTEM FOR EXTENT OF RESECTION IN GLIOBLASTOMA: A REPORT OF THE RANO RESECT GROUP

BACKGROUND

Terminology to describe extent of resection in glioblastoma is inconsistent across clinical trials. A surgical classification system was previously proposed based upon residual contrast-enhancing (CE) tumor. We aimed to (I) explore the prognostic utility of the classification system and (II) define how much removed non-CE tumor translates into a survival benefit.

METHODS

The international RANO resect group retrospectively searched the databases from seven neuro-oncological centers in the USA and Europe for patients with newly diagnosed glioblastoma per WHO 2021 classification. Clinical and volumetric information from pre- and post-operative MRI were collected.

RESULTS

We collected 1021 patients with newly diagnosed glioblastoma, including 1008 IDHwt patients. 744 IDHwt glioblastomas were treated with radiochemotherapy per EORTC 26981/22981 (TMZ/RT→TMZ) following surgery. Among such homogenously treated patients, lower absolute residual tumor volumes (in cm3) were favorably associated with outcome: patients with ‘maximal CE resection’ (class 2) had superior outcome compared to patients with ‘submaximal CE resection’ (class 3) or ‘biopsy’ (class 4) (median OS: 19 versus 15 versus 10 months; p=0.001). Extensive resection of non-CE tumor (≤ 5 cm3 residual non-CE tumor) provided an additional survival benefit in patients with complete CE resection, thus defining class 1 (‘supramaximal CE resection’) (median OS: 24 versus 19 months; p=0.008). The prognostic value of the resection classes was retained on multivariate analysis when adjusting for molecular and clinical markers including MGMT promotor status. Relative tumor reduction (in percentage) was not prognostic for outcome on multivariate analysis, and inter-rater agreement for CE and non-CE tumor on post-operative MRI was sufficient.

CONCLUSION

The proposed “RANO categories for extent of resection in glioblastoma” are highly prognostic and may serve for stratification of clinical trials. Removal of non-CE tumor beyond the CE tumor borders translates into additional survival benefit, providing a rationale to explicitly denominate such a ‘supramaximal CE resection’.

BRAF/MEK Dual Inhibitors Therapy in Progressive and Anaplastic Pleomorphic Xanthoastrocytoma: Case Series and Literature Review

Recurrent and anaplastic pleomorphic xanthoastrocytoma (r&aPXA) is a rare primary brain tumor that is challenging to treat. Two-thirds of PXA tumors harbor a BRAF gene mutation. BRAF inhibitors have been shown to improve tumor control. However, resistance to BRAF inhibition develops in most cases. Concurrent therapy with MEK inhibitors may improve tumor control and patient survival. In this study, we identified 5 patients diagnosed with BRAF-mutated PXA who received BRAF and MEK inhibitors over a 10-year interval at our institution. Patient records were evaluated, including treatments, adverse effects (AEs), outcomes, pathology, next-generation sequencing, and MRI. The median age was 22 years (range, 14-66 years), 60% male, and 60% anaplastic PXA. Median overall survival was 72 months (range, 19-112 months); 1 patient died of tumor-related hemorrhage while off therapy, and the other 4 experienced long-term disease control (21, 72, 98, and 112 months, respectively). Dual BRAF/MEK inhibitors were well tolerated, with only grade 1-2 AEs, including rash, neutropenia, fatigue, abdominal discomfort, and diarrhea. No grade 3-5 AEs were detected. A literature review was also performed of patients diagnosed with BRAF-mutated PXA and treated with BRAF and/or MEK inhibitors through August 2021, with a total of 32 cases identified. The median age was 29 years (range, 8-57 years) and the median PFS and OS were 8.5 months (range, 2-35 months) and 35 months (range, 10-80 months), respectively. The most common AEs were grade 1-2 fatigue and skin rash. Results of this case series and literature review indicate that dual-drug therapy with BRAF and MEK inhibitors for r&aPXA with BRAF V600E mutation may delay tumor progression without unexpected AEs.

IDH1 p.R132H ctDNA and D-2-hydroxyglutarate as CSF biomarkers in patients with IDH-mutant gliomas

INTRODUCTION

We aimed to evaluate IDH1 p.R132H mutation and 2-hydroxyglutarate (2HG) in cerebrospinal fluid (CSF) as biomarkers for patients with IDH-mutant gliomas.

METHODS

CSF was collected from patients with infiltrating glioma, and 2HG levels were measured by liquid chromatography-mass spectrometry. IDH1 p.R132H mutant allele frequency (MAF) in CSF-ctDNA was measured by digital droplet PCR (ddPCR). Tumor volume was measured from standard-of-care magnetic resonance images.

RESULTS

The study included 48 patients, 6 with IDH-mutant and 42 with IDH-wildtype gliomas, and 57 samples, 9 from the patients with IDH-mutant and 48 from the patients with IDH-wildtype gliomas. ctDNA was detected in 7 of the 9 samples from patients with IDH-mutant glioma, and IDH1 p.R132H mutation was detected in 5 of the 7 samples. The MAF ranged from 0.3 to 39.95%. Total 2HG level, D-2HG level, and D/L-2HG ratio in CSF were significantly higher in patients with IDH-mutant gliomas than in patients with IDH-wildtype gliomas. D-2HG level and D/L-2HG ratio correlated with total tumor volume in patients with IDH-mutant gliomas but not in patients with IDH-wildtype gliomas.

CONCLUSION

Our results suggest that detection of IDH1 p.R132H mutation by ddPCR and increased D-2HG level in CSF may help identify IDH-mutant gliomas. Our results also suggest that D-2HG level and D/L-2HG ratio correlate with tumor volume in patients with IDH-mutant gliomas. Further prospective studies with larger cohorts are needed to validate these findings.

Prognostic validation of a new classification system for extent of resection in glioblastoma: a report of the RANO resect group

BACKGROUND

Terminology to describe extent of resection in glioblastoma is inconsistent across clinical trials. A surgical classification system was previously proposed based upon residual contrast-enhancing (CE) tumor. We aimed to (I) explore the prognostic utility of the classification system and (II) define how much removed non-CE tumor translates into a survival benefit.

METHODS

The international RANO resect group retrospectively searched previously compiled databases from seven neuro-oncological centers in the USA and Europe for patients with newly diagnosed glioblastoma per WHO 2021 classification. Clinical and volumetric information from pre- and post-operative MRI were collected.

RESULTS

We collected 1008 patients with newly diagnosed IDHwt glioblastoma. 744 IDHwt glioblastomas were treated with radiochemotherapy per EORTC 26981/22981 (TMZ/RT→TMZ) following surgery. Among these homogenously treated patients, lower absolute residual tumor volumes (in cm 3) were favorably associated with outcome: patients with 'maximal CE resection' (class 2) had superior outcome compared to patients with 'submaximal CE resection' (class 3) or 'biopsy' (class 4). Extensive resection of non-CE tumor (≤5 cm 3 residual non-CE tumor) was associated with better survival among patients with complete CE resection, thus defining class 1 ('supramaximal CE resection'). The prognostic value of the resection classes was retained on multivariate analysis when adjusting for molecular and clinical markers.

CONCLUSIONS

The proposed "RANO categories for extent of resection in glioblastoma" are highly prognostic and may serve for stratification within clinical trials. Removal of non-CE tumor beyond the CE tumor borders may translate into additional survival benefit, providing a rationale to explicitly denominate such 'supramaximal CE resection'.

Concordance between Ki‑67 index in invasive breast cancer and molecular signatures: EndoPredict and MammaPrint

Identifying patients with hormone receptor-positive (HR+) early invasive breast cancer (EIBC) who benefit from adjuvant chemotherapy has improved with molecular signature tests. However, due to high cost and limited availability, alternative tests are used. The present study sought to evaluate the performance of the proliferation marker Ki-67 to identify these patients and explore its association with molecular signatures and risk stratification markers. From the San José TecSalud Hospital in Monterrey México, patients with HR+ EIBC as tested with EndoPredict or MammaPrint and Ki-67 index were identified. They were categorized into two groups: Group 1 (June 2016-August 2018) was evaluated using EndoPredict and Group 2 (June 2016-August 2018) with MammaPrint. A ≥20% Ki67 index cutoff was utilized to identify highly proliferative EIBC and an area under the receiver-operating characteristic curve and κ concordance were utilized to evaluate the performance of Ki-67 index compared to molecular signature tests. In the EndoPredict group, 54/96 patients were considered high-risk based on their EPclin score, while 57/96 patients had Ki-67 index ≥20%. However, there was no significant overall concordance between them (59.37%, κ=0.168, P=0.09), while the given risk of distant recurrence given in percentage by EPclin had a positive association with the Ki67 index (P=0.04). In the MammaPrint group, 21/70 patients were considered high-risk and 36/70 patients presented with a Ki-67 index ≥20% with a significant overall concordance (67.14%, κ=0.35, P<0.001). In addition, high Ki-67 index was associated with the Nottingham histological grade in both groups. In conclusion, there was a concordance between Ki-67 and MammaPrint risk stratification of HR+ EIBC and no concordance with the EndoPredict molecular signature, but a positive association with the given percentage of recurrence and the median Ki-67 index as the cutoff at our center. Cost-effectiveness analyses of these tests in developing countries are required; until then, the use of Ki-67 appears reasonable to aid clinical decisions, together with the other established clinicopathological variables.

Gut microbiome and neurocritically ill patients

Since the times of Rokitansky and Cushing, we have been fascinated by the connections between the gut and the brain. Recent advances in next-generation sequencing techniques have shown that this relationship is even more complex and integral to our sense of self than previously imagined. As these techniques refine our understanding of the abundance and diversity of the gut bacterial microbiome, the relationship between the gut and the brain has been redefined. Now, this is understood as a complex symbiotic network with bidirectional communication, the gut-brain axis. The implication of this communication involves an intense focus of research on a variety of chronic psychiatric, neurological, neurodegenerative, and neuro-oncological diseases. Recently, the gut-brain axis has been studied in neurologically ill patients requiring intensive care. Preliminary studies have shown that acute brain injury changes the bacterial phenotype from one that is symbiotic with the host human to one that is pathologic, termed the “pathobiome.” This can contribute to nosocomial pneumonia and sepsis. The first studies in neurologically ill patients in the neurointensive care unit (NeuroICU) demonstrated changes in the gut microbiome between neuroICU patients and healthy matched subjects. Specifically, a decrease in short-chain fatty acid-producing bacteria and increase in harmful gut microbes have been associated with mortality and decreased function at discharge. Although these preliminary findings are exciting and have opened a new field of research in the complex NeuroICU population, there are several limitations and challenges. Further investigation is needed to confirm these correlations and understand their implications on patients in a complex intensive care environment.

Prognostic validation and refinement of a classification system for extent of resection in glioblastoma: A report of the RANO resect group

2003

Background: Terminology to describe extent of resection in glioblastoma is inconsistent across clinical trials. A surgical classification system for glioblastoma was previously proposed based upon the absolute residual contrast-enhancing (CE) tumor (in cm3) and the relative reduction of CE tumor (in percentage) on postoperative MRI. Class 0 was defined as ‘supramaximal CE resection’ (also including removal of non-CE tumor), class 1 as ‘maximal CE resection’, class 2 as ‘submaximal CE resection’, and class 3 as ‘biopsy’. We aimed to (I) explore the prognostic utility of the proposed classification system and (II) define how much non-CE tumor needs to be removed to translate into a survival benefit. Methods: An international Response Assessment in Neuro-Oncology (RANO) group was formed, entitled RANO resect. The members of the RANO resect group retrospectively searched the databases from seven neuro-oncological centers in the USA and Europe for patients with newly diagnosed glioblastoma. Clinical characteristics, volumetric information from pre- and postoperative MRI, and outcome were collected. Kaplan-Meier survival analysis and log-rank test were applied to calculate survival, and Cox’s proportional hazard regression model to adjust for multiple variables. Significance level was set at p ≤ 0.05. Results: We encountered 1021 patients with newly diagnosed glioblastoma, including 1008 IDHwt patients. 744 IDHwt patients were treated with radiochemotherapy per EORTC 26981/22981 following surgery. Among such homogenously treated patients, higher extent of resection was favorably associated with outcome: patients with ‘maximal CE resection’ (class 1) had superior outcome compared to patients with ‘submaximal CE resection’ (class 2) or ‘biopsy’ (class 3) (median OS: 20 versus 16 versus 10 months; p = 0.001). Similar findings were made when assessing progression (median PFS: 9 versus 8 versus 5 months; p = 0.001). Extensive resection of non-CE tumor (≥60% of non-CE tumor removed and ≤5 cm3 residual non-CE tumor) provided an additional survival benefit in patients with complete CE resection (class 1), thus defining class 0 (‘supramaximal CE resection’) (median OS: 29 versus 20 months; p = 0.003). Smaller pre-operative tumor volumes were associated with larger extent of resection. The favorable prognostic effect of CE resection was conserved in a multivariate analysis when stratifying for molecular and clinical markers including pre-operative tumor volume and MGMT promotor status ( p = 0.001). Conclusions: The proposed classification system for extent of surgery in glioblastoma is highly prognostic and may serve for stratification and design of clinical trials. Removal of non-CE tumor beyond the CE tumor borders translates into additional survival benefit in glioblastomas, providing a rationale to explicitly denominate such a 'supramaximal CE resection.'

Molecular, Histological, and Clinical Characteristics of Oligodendrogliomas: A Multi-Institutional Retrospective Study

BACKGROUND

Reports suggest that phosphatidylinositol 3-kinase pathway alterations confer increased risk of progression and poor prognosis in oligodendroglioma, IDH-mutant, and 1p/19q-codeleted molecular oligodendrogliomas (mODG). However, factors that affect prognosis in mODG have not been thoroughly studied. In addition, the benefits of adjuvant radiation and temozolomide (TMZ) in mODGs remain to be determined.

OBJECTIVE

To evaluate the role of PIK3CA mutations in mODGs.

METHODS

One hundred seven mODGs (2008-2019) diagnosed at 2 institutions were included. A retrospective review of clinical characteristics, molecular alterations, treatments, and outcomes was performed.

RESULTS

The median age was 37 years, and 61 patients (57%) were male. There were 64 (60%) World Health Organization (WHO) grade 2 and 43 (40%) WHO grade 3 tumors. Eighty-two patients (77%) were stratified as high risk (age 40 years or older and/or subtotal resection per Radiation Treatment Oncology Group-9802). Gross-total resection was achieved in 47 patients (45%). Treatment strategies included observation (n = 15), TMZ (n = 11), radiation (n = 13), radiation/TMZ (n = 62), and others (n = 6). Our results show a benefit of TMZ vs observation in progression-free survival (PFS). No difference in PFS or overall survival (OS) was observed between radiation and radiation/TMZ. PIK3CA mutations were detected in 15 (14%) mODG, and shorter OS was observed in PIK3CA-mutant compared with PIK3CA wild-type mODGs (10.7 years vs 15.1 years, P = .009). WHO grade 3 tumors showed a shorter PFS, but no significant difference in OS was observed between WHO grades.

CONCLUSION

Our findings suggest that mODGs harboring PIK3CA mutations have worse OS. Except for an advantage in PFS with TMZ treatment, adjuvant TMZ, radiation, or a combination of the two showed no significant improvement in OS.

Glioma and the Gut-Brain Axis: Opportunities and Future Perspectives

The gut–brain axis has presented a valuable new dynamic in the treatment of cancer and central nervous system (CNS) diseases. However, little is known about the potential role of this axis in neuro-oncology. The goal of this review is to highlight potential implications of the gut–brain axis in neuro-oncology, in particular gliomas, and future areas of research. The gut–brain axis is a well-established biochemical signaling axis that has been associated with various CNS diseases. In neuro-oncology, recent studies have described gut microbiome differences in tumor-bearing mice and glioma patients compared to controls. These differences in the composition of the microbiome are expected to impact the metabolic functionality of each microbiome. The effects of antibiotics on the microbiome may affect tumor growth and modulate the immune system in tumor-bearing mice. Preliminary studies have shown that the gut microbiome might influence PD-L1 response in glioma-bearing mice, as previously observed in other non-CNS cancers. Groundbreaking studies have identified intratumoral bacterial DNA in several cancers including high-grade glioma. The gut microbiome and its manipulation represent a new and relatively unexplored area that could be utilized to enhance the effectiveness of therapy in glioma. Further mechanistic studies of this therapeutic strategy are needed to assess its clinical relevance.

Impacts of genotypic variants on survival following reoperation for recurrent glioblastoma

INTRODUCTION

Recurrent glioblastoma (rGBM) prognosis is dismal. In the absence of effective adjuvant treatments for rGBM, re-resections remain prominent in our arsenal. This study evaluates the impact of reoperation on post-progression survival (PPS) considering rGBM genetic makeup.

METHODS

To assess the genetic heterogeneity and treatment-related changes (TRC) roles in re-operated or medically managed rGBMs, we compiled demographic, clinical, histopathological, and next-generation genetic sequencing (NGS) characteristics of these tumors from 01/2005 to 10/2019. Survival data and reoperation were analyzed using conventional and random survival forest analysis (RSF).

RESULTS

Patients harboring CDKN2A/B loss (p = 0.017) and KDR mutations (p = 0.031) had notably shorter survival. Reoperation or bevacizumab were associated with longer PPS (11.2 vs. 7.4-months, p = 0.006; 13.1 vs 6.2, p < 0.001). Reoperated patients were younger, had better performance status and greater initial resection. In 136/273 (49%) rGBMs undergoing re-operation, CDKN2A/B loss (p = 0.03) and KDR mutations (p = 0.02) were associated with shorter survival. In IDH-WT rGBMs with NGS data (n = 166), reoperation resulted in 7.0-month longer survival (p = 0.004) than those managed medically. This reoperation benefit was independently identified by RSF analysis. Stratification analysis revealed that EGFR-mutant, CDKN2A/B-mutant, NF1-WT, and TP53-WT rGBM IDH-WT subgroups benefit most from reoperation (p = 0.03). Lastly, whether or not TRC was prominent at re-operation does not have any significant impact on PPS (10.5 vs. 11.5-months, p = 0.77).

CONCLUSIONS

Maximal safe re-resection significantly lengthens PPS regardless of genetic makeup, but reoperations are especially beneficial for IDH-WT rGBMs with EGFR and CDKN2A/B mutations with TP53-WT, and NF1-WT. Histopathology at recurrence may be an imperfect gauge of disease severity at progression and the imaging progression may be more reflective of the prognosis.

Hormone exposure and its suppressive effect on risk of high-grade gliomas among patients with breast cancer

BACKGROUND

Prior reports demonstrate the expression of estrogen and progesterone receptors in high-grade gliomas (HGGs), but the relationship between hormone receptor-positive disease and risk of HHGs in patients with breast cancer (BC) remains uncharacterized.

METHODS

Using the SEER 18 registries (2000-2017), we examined the temporal trend of the incidence of HGGs and BC. The standardized incidence ratio was calculated to assess the risk of subsequent HGG in BC patients.

RESULTS

During the study period, the incidence of BC and HGGs remained comparable for men and women. Among 976,134 patients with BC, we found a decreased incidence of HGGs in females, but not in males. Female BC patients with hormone receptor-positive disease were at a lower risk of developing glioblastoma and anaplastic astrocytoma.

CONCLUSION

Our study findings allude to the protective role of hormone exposure in the development of HGGs, which may lead to the development of therapies targeting hormonal pathways.

INNV-06. BRAF AND MEK DUAL INHIBITORS THERAPY IN RECURRENT OR ANAPLASTIC PLEOMORPHIC XANTHOASTROCYTOMA (PXA)

BACKGROUND AND OBJECTIVE

Recurrent and anaplastic pleomorphic xanthoastrocytoma (PXA) tumors are challenging to treat due to their rarity and lack of management consensus. About 80% of PXAs harbor BRAF gene mutation. Although the development of BRAF inhibitors has dramatically improved the outcomes for patients with BRAF V600E mutant tumors, resistance develops in the majority of cases. We hypothesize that dual BRAF/MEK inhibitors therapy can improve tumor control and patient survival without added toxicity.

METHODS

Medical records from 2010 to 2021 in Memorial Hermann Texas Medical Center were reviewed. Patients diagnosed with PXA who received BRAF and/or MEK inhibitors therapies were identified. The data evaluated included age, sex, treatment received, side effects, and outcomes, as well as results from blood tests, pathology, next generation sequencing and MRI. Side effects were evaluated according to the CTCAE Version 5.0.

RESULTS

Five patients with recurrent or anaplastic PXA were identified. The median age at diagnosis was 22 years old (range 14-66 years old), with 60% male, and 60% grade III. All patients received BRAF/MEK dual inhibitors therapy at various stages of PXA treatment. The median follow-up was 72 months (range 17-108 months). One patient (66 years old) experienced short-term disease stability for 5 months and who died from tumor related brain hemorrhage while off therapy for 9 months. Four patients experienced long-term disease control (17, 22, 94, 108 months, respectively) while three of them remain on dual therapy and one patient died from systemic PXA progression. Dual BRAF/MEK inhibitors were well tolerated with only grade 1-2 adverse effects (AE) including skin rash, fatigue, mild abdominal discomfort, diarrhea. No grade III-V AE were detected.

CONCLUSION

BRAF/MEK dual inhibitor can provide potential clinical benefit to PXA patients with BRAF mutations. Our study supports the concurrent use of BRAF/MEK inhibitors for best tumor control without unexpected AE.

TERT Immunohistochemistry Expression as a Surrogate of TERT Promoter Mutations in Infiltrating Gliomas

Introduction/Objective

Genomic alterations are critical for the diagnosis of infiltrating gliomas. Mutations in the telomerase reverse transcriptase promoter (TERTp) are sufficient for a diagnosis of glioblastoma in some cases, independent of histologic features. Although DNA sequencing is the preferred method for evaluating TERTp mutations, there are limitations with regards to turn-around-time, accessibility, and cost. In this study, we evaluated the efficacy of using TERT immunohistochemistry (IHC) as a surrogate marker for the identification of TERTp mutations in infiltrating gliomas.

Methods/Case Report

The study cohort consisted of 31 infiltrating gliomas diagnosed following the 2016 WHO classification of CNS tumors by a board-certified neuropathologist. Each case was evaluated by immunohistochemistry (anti-TERT monoclonal antibody) and with a targeted next-generation sequencing (NGS) panel. A systemic literature search was conducted to examine reports of TERT antibody as a surrogate marker of TERTp mutations. TERTp mutation detected by sequencing was considered the gold standard.

Results (if a Case Study enter NA)

TERT immunohistochemistry demonstrated a sensitivity of 61.1% and specificity of 69.2%. Cases were divided into IDH-WT and IDH-mutant infiltrating gliomas. Among the IDH-WT group, 84% contained the TERTp mutation with a sensitivity of 62.5% and specificity of 33.3% for the TERTp IHC. IDH-mutant gliomas showed a 16.2% TERTp mutation rate, and immunohistochemistry had a sensitivity of 50% and 80% specificity. The probability of TERT immunohistochemistry in diagnosing TERTp mutations exhibited a poor likelihood ratio for both the positive and negative test. Literature review included 5 studies with an overall sensitivity and specificity remaining consistently low (&lt;80%), with 2 of these studies evaluating CNS related tumors giving rise to similar diagnostic performance.

Conclusion

TERT IHC has suboptimal sensitivity and specificity for identifying TERTp mutations in IDH-WT and IDH- mutant infiltrating gliomas.

Molecular Alterations in Meningioangiomatosis Causing Epilepsy

Meningioangiomatosis (MA) is a rare process at the intersection of cerebral developmental and neoplastic disorders that often results in epilepsy. We evaluated molecular alterations in MA to characterize its biology and pathogenesis. We searched a comprehensive institutional database for patients with MA treated between 2004 and 2019. Demographic, clinical, surgical, and radiographical data were collected. MA and associated meningioma tissues were evaluated using a next-generation sequencing assay interrogating 1425 cancer-related genes. We studied 5 cases: 3 with MA and 2 with MA associated with a meningioma. Of the MAs associated with a meningioma, 1 had deletions in the NF2 gene in both the MA and the meningioma components, whereas the other had an NF2 deletion in only the MA component. Additional mutations were identified in the MA components, suggesting that MA arises from the meningioma rather than the meningioma resulting from a transformation of the MA. The 3 cases of pure MA showed variants of unknown significance with no alterations in known oncogenic drivers. Our findings provide a starting point to a better understanding of the pathogenesis of this rare lesion. Our study indicates that MA-meningiomas have a neoplastic nature that differs from the hamartomatous/developmental nature of pure MA.

RADI-05. Metastatic Neoplasm Volume Kinetics Following Two-Staged Stereotactic Radiosurgery

Introduction

Multisession staged stereotactic radiosurgery (2-SSRS) represents an alternative approach for management of large brain metastases (LBMs), with potential theoretical advantages over fractionated SRS and represents an alternative to surgery in poor surgical candidates. We aimed to investigate the clinical efficacy and safety of 2-SSRS in patients with LBMs.

Methods

LBMs of patients treated with 2-SSRS between 2014 and 2020 were evaluated. Demographic, clinical, and radiologic information was obtained. Volumetric measurements at first SSRS, second SSRS, and follow-up imaging studies were obtained.

Results

Twenty-six patients with 28 LBMs were included in the study. Fifteen patients (58%) were male. Median age at 2-SSRS was 61 years (range: 31–84). Median marginal doses for first and second SSRS were 15 Gy (range: 12–18 Gy) and 15 Gy (range: 12–16 Gy), respectively. Median duration between sessions was 32 days. Two patients (8%) failed to receive their second SSRS due to local progression. Median tumor volumes at first SSRS, second SSRS, 3-month follow-up, and 6-month follow-up were 8.7 cm3 (range: 1.5–34.7 cm3), 3.3 cm3 (range: 0.8–26.1 cm3), 1.7 cm3 (range: 0.2–10.1 cm3), and 1.4 cm3 (range: .04–20.7 cm3), respectively. The median absolute and relative decrement between S-SRS sessions was 3.7 cm3 (range: 2.8–16.5 cm3) and 49.5% (range: 17.1- 87.1%), respectively. Overall, 26 of the 28 lesions (93%) demonstrated early local control following the first SSRS with 18 lesions (69%) demonstrating a decrease in volume of >30% and 3 lesions (12%) remaining stable. Six lesions (23%) showed disease progression. There were no grade 3 adverse events.

Conclusions

Our study supports the effectiveness and safety of 2-SSRS as a treatment modality for patients with large, symptomatic brain metastases, especially in non-surgical candidates. The local failure rate and low occurrence of adverse effects are comparable to other staged radiosurgery series.

Endoscopic Third Ventriculostomy for Hydrocephalus Secondary to Extraventricular Obstruction in Thalamic Hemorrhage: A Case Series

BACKGROUND

Intracranial hemorrhage carries significant morbidity and mortality, particularly if associated with hydrocephalus. Management of hydrocephalus includes temporary external ventricular drainage, with or without shunting. Thalamic location is an independent predictor of mortality and increases the likelihood of shunt dependence.

OBJECTIVE

To determine whether endoscopic third ventriculostomy (ETV) can avoid the need for shunt placement and expedite recovery.

METHODS

We prospectively identified thalamic intracranial hemorrhage patients who developed acute hydrocephalus requiring cerebrospinal fluid diversion by extraventricular drain placement from November 2017 to February 2019. Patients who failed an extraventricular drain clamping trial were then evaluated for eligibility for an ETV procedure. Patients who underwent ETV were then followed up for the development of hydrocephalus, need for shunting, and length of stay in the intensive care unit.

RESULTS

Eight patients (7 males, 1 female) were prospectively enrolled. All patients underwent an ETV successfully. None of the patients required shunting. ETV was performed despite the presence of other factors that would have prevented shunt placement, including fever, leukocytosis, and gastrostomy tube placement. Seven patients who underwent ETV were evaluated at 3-mo follow-up and did not require shunting.

CONCLUSION

ETV is a safe and effective technique for the management of hydrocephalus resulting from an extraventricular obstruction in thalamic hemorrhage. It can avoid the need for permanent shunting in this patient population. Larger studies should be conducted to validate and further analyze this intervention.

Differences in Genomic Alterations Between Brain Metastases and Primary Tumors

BACKGROUND

Brain metastases (BMs) occur in ∼1/3 of cancer patients and are associated with poor prognosis. Genomic alterations contribute to BM development; however, mutations that predispose and promote BM development are poorly understood.

OBJECTIVE

To identify differences in genomic alterations between BM and primary tumors.

METHODS

A retrospective cohort of 144 BM patients were tested for genomic alterations (85 lung, 21 breast, 14 melanoma, 4 renal, 4 colon, 3 prostate, 4 others, and 9 unknown carcinomas) by a next-generation sequencing assay interrogating 315 genes. The differences in genomic alterations between BM and primary tumors from COSMIC and TCGA were evaluated by chi-square or Fisher's exact test. Overall survival curves were plotted using the Kaplan-Meier method.

RESULTS

The comparison of BM and primary tumors revealed genes that were mutated in BM with increased frequency: TP53, ATR, and APC (lung adenocarcinoma); ARID1A and FGF10 (lung small-cell); PIK3CG, NOTCH3, and TET2 (lung squamous); ERBB2, BRCA2, and AXL1 (breast carcinoma); CDKN2A/B, PTEN, RUNX1T1, AXL, and FLT4 (melanoma); and ATM, AR, CDKN2A/B, TERT, and TSC1 (renal clear-cell carcinoma). Moreover, our results indicate that lung adenocarcinoma BM patients with CREBBP, GPR124, or SPTA1 mutations have a worse prognosis. Similarly, ERBB2, CDK12, or TP53 mutations are associated with worse prognosis in breast cancer BM patients.

CONCLUSION

The present study demonstrates significant differences in the frequency of mutations between primary tumors and BM and identifies targetable alterations and genes that correlate with prognosis. Identifying the genomic alterations that are enriched in metastatic central nervous system tumors could help our understanding of BM development and improve patient management.

PTEN mutations predict benefit from tumor treating fields (TTFields) therapy in patients with recurrent glioblastoma

INTRODUCTION

Optimal treatment for recurrent glioblastoma isocitrate dehydrogenase 1 and 2 wild-type (rGBM IDH-WT) is not standardized, resulting in multiple therapeutic approaches. A phase III clinical trial showed that tumor treating fields (TTFields) monotherapy provided comparable survival benefits to physician's chemotherapy choice in rGBM. However, patients did not equally benefit from TTFields, highlighting the importance of identifying predictive biomarkers of TTFields efficacy.

METHODS

A retrospective review of an institutional database with 530 patients with infiltrating gliomas was performed. Patients with IDH-WT rGBM receiving TTFields at first recurrence were included. Tumors were evaluated by next-generation sequencing for mutations in 205 cancer-related genes. Post-progression survival (PPS) was examined using the log-rank test and multivariate Cox-regression analysis.

RESULTS

149 rGBM patients were identified of which 29 (19%) were treated with TTFields. No significant difference in median PPS was observed between rGBM patients who received versus did not receive TTFields (13.9 versus 10.9 months, p = 0.068). However, within the TTFields-treated group (n = 29), PPS was improved in PTEN-mutant (n = 14) versus PTEN-WT (n = 15) rGBM, (22.2 versus 11.6 months, p = 0.017). Within the PTEN-mutant group (n = 70, 47%), patients treated with TTFields (n = 14) had longer median PPS (22.2 versus 9.3 months, p = 0.005). No PPS benefit was observed in PTEN-WT patients receiving TTFields (n = 79, 53%).

CONCLUSIONS

TTFields therapy conferred a significant PPS benefit in PTEN-mutant rGBM. Understanding the molecular mechanisms underpinning the differences in response to TTFields therapy could help elucidate the mechanism of action of TTFields and identify the rGBM patients most likely to benefit from this therapeutic option.

Genomic alterations predictive of response to radiosurgery in recurrent IDH-WT glioblastoma

INTRODUCTION

Despite aggressive treatment, glioblastoma invariably recurs. The optimal treatment for recurrent glioblastoma (rGBM) is not well defined. Stereotactic radiosurgery (SRS) for rGBM has demonstrated favorable outcomes for selected patients; however, its efficacy in molecular GBM subtypes is unknown. We sought to identify genetic alterations that predict response/outcomes from SRS in rGBM-IDH-wild-type (IDH-WT).

METHODS

rGBM-IDH-WT patients undergoing SRS at first recurrence and tested by next-generation sequencing (NGS) were reviewed (2009-2018). Demographic, clinical, and molecular characteristics were evaluated. NGS interrogating 205-genes was performed. Primary outcome was survival from GK-SRS assessed by Kaplan-Meier method and multivariable Cox proportional-hazards.

RESULTS

Sixty-three lesions (43-patients) were treated at 1st recurrence. Median age was 61-years. All patients were treated with resection and chemoradiotherapy. Median time from diagnosis to 1st recurrence was 8.7-months. Median cumulative volume was 2.895 cm3 and SRS median marginal dose was 18 Gy (median isodose-54%). Bevacizumab was administered in 81.4% patients. PFS from SRS was 12.9-months. Survival from SRS was 18.2-months. PTEN-mutant patients had a longer PFS (p = 0.049) and survival from SRS (p = 0.013) in multivariable analysis. Although no statistically significant PTEN-mutants patients had higher frequency of radiation necrosis (21.4% vs. 3.4%) and lower in-field recurrence (28.6% vs. 37.9%) compared to PTEN-WT patients.

CONCLUSIONS

SRS is a safe and effective treatment option for selected rGBM-IDH-WT patients following first recurrence. rGBM-IDH-WT harboring PTEN-mutation have improved survival with salvage SRS compared to PTEN-WT patients. PTEN may be used as a molecular biomarker to identify a subset of rGBM patients who may benefit the most from SRS.

IDH-Mutant Low-grade Glioma: Advances in Molecular Diagnosis, Management, and Future Directions

PURPOSE OF REVIEW

IDH-mutant low-grade gliomas (LGG) have emerged as a distinct clinical and molecular entity with unique treatment considerations. Here, we review updates in IDH-mutant LGG diagnosis and classification, imaging biomarkers, therapies, and neurocognitive and patient-reported outcomes.

RECENT FINDINGS

CDKN2A/B homozygous deletion in IDH-mutant astrocytoma is associated with shorter survival, similar to WHO grade 4. The T2-FLAIR mismatch, a highly specific but insensitive sign, is diagnostic of IDH-mutant astrocytoma. Maximal safe resection is currently indicated in all LGG cases. Radiotherapy with subsequent PCV (procarbazine, lomustine, vincristine) provides longer overall survival compared to radiotherapy alone. Temozolomide in place of PCV is reasonable, but high-level evidence is still lacking. LGG adjuvant treatment has important quality of life and neurocognitive side effects that should be considered. Although incurable, IDH-mutant LGG have a favorable survival compared to IDH-WT glioma. Recent advances in molecular-based classification, imaging, and targeted therapies will hopefully improve survival and quality of life.

Tumor recurrence or treatment-related changes following chemoradiation in patients with glioblastoma: does pathology predict outcomes?

BACKGROUND

Despite surgical resection and chemoradiation, all patients with GBM invariably recur. Radiological imaging is limited in differentiating tumor recurrence (TR) from treatment-related changes (TRC); therefore, re-resection is often needed. Few studies have assessed the relationship between re-resection histopathology and overall survival (OS). We performed a large retrospective study to analyze the clinical significance of histopathology following re-resection and its influence on genomic sequencing results.

METHODS

Clinical, radiographic, and histological information was compiled from 675 patients with GBM (2005-2017). 137-patients met the inclusion criteria. IDH1 p.R132H immunohistochemistry was performed in all patients. Next-generation sequencing interrogating 205 tumor-related genes was performed in 68-patients. Molecular alterations from initial and subsequent resections were compared in a subset of cases.

RESULTS

There were no differences in OS (17.3-months TRC vs. 21-months TR, p = 0.881) and survival from progression (9.0 vs. 11.7-months, p = 0.778) between patients with TR and TRC on re-resection. TR patients were more likely to receive salvage radiotherapy (26% vs. 0%) and tumor-treating fields (25% vs. 5%,) after the 2nd surgery than the TRC group (p = < 0.045). There was no correlation between mutations and TRC. IDH status was not predictive of TRC. Fifteen-patients had sequencing results from multiple surgeries without evident differences in genomic alterations.

CONCLUSIONS

Histopathologic findings following chemoradiation do not correlate with clinical outcomes. Such findings should be considered during patient management and clinical trial enrollment. Standardization of tissue sampling and interpretation following reoperation is urgently needed. Future work is required to understand the relationship between the mutation profile following TRC and outcomes.

Extent of resection and survival outcomes of geriatric patients with glioblastoma: Is there benefit from aggressive surgery?

OBJECTIVE

We examine the impact of age and extent of resection (EOR) on overall survival (OS) in geriatric patients with Glioblastoma (GBM).

METHODS

The SEER 18 Registries was used to identify patients aged 65 and above with GBM from 2000-2016. Patients were categorized into 4 groups based on EOR: Biopsy/Local Excision (B/LE), Subtotal Resection (STR), Gross Total Resection (GTR), and Supratotal Resection (SpTR). Primary endpoint was OS, which was calculated using the Kaplan-Meier method and analyzed by the Log-rank and Wilcoxon-Breslow-Gehan test. Multivariable Cox proportional hazards regression model was utilized to identify factors associated with OS. Likelihood of undergoing SpTR was explored using a multivariable logistic regression model. Results are given as median [IQR] and HR [95 % CI].

RESULTS

Among 17,820 geriatric patients with GBM, median age was 73 years [68-78], 44 % were female, 91 % White, and 8% Hispanic. SpTR was performed in 2907 (16 %), GTR was performed in 2451 (14 %) patients, STR in 4879 (28 %), and B/LE in 7396 (42 %). There was a decline in the proportion of patients treated with SpTR with advancing age (65-69 years, 17 % vs 95+ years, 0%; p < 0.0001), and older age corresponded with a decrease in the odds of undergoing SpTR. In survival analysis, GTR (HR 0.61 [0.58-0.65]) and SpTR (HR 0.65 [0.62-0.68]) were associated with improved survival, even in octogenarian patients.

CONCLUSIONS

These findings suggest that aggressive surgical resection is associated with improvement in OS in geriatric patients. These results emphasize that age should not influence surgical strategy, as there is a survival benefit from maximal resection in geriatric patients.

The role of RB1 alteration and 4q12 amplification in IDH-WT glioblastoma

BACKGROUND

Recent studies have identified that glioblastoma IDH-wildtype (GBM IDH-WT) might be comprised of molecular subgroups with distinct prognoses. Therefore, we investigated the correlation between genetic alterations and survival in 282 GBM IDH-WT patients, to identify subgroups with distinct outcomes.

METHODS

We reviewed characteristics of GBM IDH-WT (2009-2019) patients analyzed by next-generation sequencing interrogating 205 genes and 26 rearrangements. Progression-free survival (PFS) and overall survival (OS) were evaluated with the log-rank test and Cox regression models. We validated our results utilizing data from cBioPortal (MSK-IMPACT dataset).

RESULTS

Multivariable analysis of GBM IDH-WT revealed that treatment with chemoradiation and RB1-mutant status correlated with improved PFS (hazard ratio [HR] 0.25, P < .001 and HR 0.47, P = .002) and OS (HR 0.24, P < .001 and HR 0.49, P = .016). In addition, younger age (<55 years) was associated with improved OS. Karnofsky performance status less than 80 (HR 1.44, P = .024) and KDR amplification (HR 2.51, P = .008) were predictors of worse OS. KDR-amplified patients harbored coexisting PDGFRA and KIT amplification (P < .001) and TP53 mutations (P = .04). RB1-mutant patients had less frequent CDKN2A/B and EGFR alterations (P < .001). Conversely, RB1-mutant patients had more frequent TP53 (P < .001) and SETD2 (P = .006) mutations. Analysis of the MSK-IMPACT dataset (n = 551) validated the association between RB1 mutations and improved PFS (11.0 vs 8.7 months, P = .009) and OS (34.7 vs 21.7 months, P = .016).

CONCLUSIONS

RB1-mutant GBM IDH-WT is a molecular subgroup with improved PFS and OS. Meanwhile, 4q12 amplification (KDR/PDGFRA/KIT) denoted patients with worse OS. Identifying subgroups of GBM IDH-WT with distinct survival is important for optimal clinical trial design, incorporation of targeted therapies, and personalized neuro-oncological care.

Glioma and temozolomide induced alterations in gut microbiome

The gut microbiome is fundamental in neurogenesis processes. Alterations in microbial constituents promote inflammation and immunosuppression. Recently, in immune-oncology, specific microbial taxa have been described to enhance the effects of therapeutic modalities. However, the effects of microbial dysbiosis on glioma are still unknown. The aim of this study was to explore the effects of glioma development and Temozolomide (TMZ) on fecal microbiome in mice and humans. C57BL/6 mice were implanted with GL261/Sham and given TMZ/Saline. Fecal samples were collected longitudinally and analyzed by 16S rRNA sequencing. Fecal samples were collected from healthy controls as well as glioma patients at diagnosis, before and after chemoradiation. Compared to healthy controls, mice and glioma patients demonstrated significant differences in beta diversity, Firmicutes/Bacteroides (F/B) ratio, and increase of Verrucomicrobia phylum and Akkermansia genus. These changes were not observed following TMZ in mice. TMZ treatment in the non-tumor bearing mouse-model diminished the F/B ratio, increase Muribaculaceae family and decrease Ruminococcaceae family. Nevertheless, there were no changes in Verrucomicrobia/Akkermansia. Glioma development leads to gut dysbiosis in a mouse-model, which was not observed in the setting of TMZ. These findings seem translational to humans and warrant further study.

Predictors of outcome in pleomorphic xanthoastrocytoma

Background

Pleomorphic xanthoastrocytomas (PXA) are circumscribed gliomas that typically have a favorable prognosis. Limited studies have revealed factors affecting survival outcomes in PXA. Here, we analyzed the largest PXA dataset in the literature and identify factors associated with outcomes.

Methods

Using the Surveillance, Epidemiology, and End Results (SEER) 18 Registries database, we identified histologically confirmed PXA patients between 1994 and 2016. Overall survival (OS) was analyzed using Kaplan-Meier survival and multivariable Cox proportional hazard models.

Results

In total, 470 patients were diagnosed with PXA (males = 53%; median age = 23 years [14-39 years]), the majority were Caucasian (n = 367; 78%). The estimated mean OS was 193 months [95% CI: 179-206]. Multivariate analysis revealed that greater age at diagnosis (≥39 years) (3.78 [2.16-6.59], P < .0001), larger tumor size (≥30 mm) (1.97 [1.05-3.71], P = .034), and postoperative radiotherapy (RT) (2.20 [1.31-3.69], P = .003) were independent predictors of poor OS. Pediatric PXA patients had improved survival outcomes compared to their adult counterparts, in which chemotherapy (CT) was associated with worse OS. Meanwhile, in adults, females and patients with temporal lobe tumors had an improved survival; conversely, tumor size ≥30 mm and postoperative RT were associated with poor OS.

Conclusions

In PXA, older age and larger tumor size at diagnosis are risk factors for poor OS, while pediatric patients have remarkably improved survival. Postoperative RT and CT appear to be ineffective treatment strategies while achieving GTR confer an improved survival in male patients and remains the cornerstone of treatment. These findings can help optimize PXA treatment while minimizing side effects. However, further studies of PXAs with molecular characterization are needed.

PATH-05. A RETROSPECTIVE STUDY OF TREATMENT STRATEGIES AND OUTCOMES IN WHO GRADE II AND III ISOCITRATE DEHYDROGENASE (IDH) WILD-TYPE ASTROCYTOMA

BACKGROUND

WHO grade II and III IDH wild-type astrocytomas behave more aggressively than their IDH mutated counterparts. A subpopulation shares molecular features with the novel entity proposed in cIMPACT-NOW Update 3 “Diffuse astrocytic glioma, IDH wild-type, with molecular features of glioblastoma (GBM), WHO IV”.

METHODS

We performed a retrospective analysis of clinical and molecular features, management and survival of 134 adult patients treated for grade II and III IDH wild-type astrocytoma between 06/2012 and 12/2018 at MD Anderson Cancer Center (MDACC - 112) and UT Health Science Center at Houston (UTHSC - 22). All patients had IDH1 sequenced, all but 2 had IDH2 sequenced, and 73 had further next generation sequencing.

RESULTS

Median age at diagnosis was 53 (interquartile range 18-83). 82 patients (61%) were male. 31 patients were histologically diagnosed with grade II astrocytoma, 102 with grade III astrocytoma, and one with diffuse glioma (insufficient tissue to render histologic grade or perform sequencing). EGFR alterations were found in 31 patients and TERT promoter mutations in 22. 84 (63%) received concurrent chemoradiation and adjuvant temozolomide (grade II, n=9; grade III, n=74; NOS, n=1). PFS overall was 12.0 months (grade II = 17.9; grade III = 10.7). OS in patients treated with concurrent chemoradiation and adjuvant temozolomide was 17.1 months versus 17.7 in patients treated with sequential radiation and temozolomide (p = NS), and 10.6 in patients treated with RT alone or surveillance (p&lt; 0.016). The highest 2-year OS was seen in grade II patients treated with concurrent chemoradiation and adjuvant temozolomide (60%).

CONCLUSIONS

WHO grade II and III IDHwt astrocytoma survival is similar to historical GBM cohorts. The proportion meeting molecular criteria for GBM is yet undefined. Groups who received chemotherapy may perform better than those who do not. Further analysis of MGMT methylation and other molecular factors is ongoing.

SURG-23. REOPERATION IN MOLECULAR SUBTYPES OF RECURRENT GLIOBLASTOMA

BACKGROUND

Recurrent glioblastoma (rGBM) treatment is not well defined and multiple therapeutic approaches have been proposed, none of which has shown to prolong survival in randomized trials. The role of reoperation for rGBM is still unclear. While most studies demonstrate improve overall survival (OS) and post-progression survival (PPS), recent studies employing time-dependent analysis appear to undermine the OS benefit in reoperated patients. Moreover, the relevance of rGBM molecular subtypes that benefit from reoperation is an important question that may guide clinical decision-making.

METHODS

A retrospective review of rGBM demographics, clinical, molecular, and outcome characteristics was performed for all cases managed by us between 01/2005 to 10/2019 at our institution. IDH1/IDH2 status was determined by immunohistochemistry and/or next-generation sequencing (NGS). A genetic subanalysis was conducted for most rGBM IDH-wildtype (IDH-WT) by NGS. The primary outcome was PPS. Kaplan-Meier method, multivariable Cox proportional-hazards model, and accelerated failure time model were performed in survival analysis. Random survival forest was applied to identify variable importance.

RESULTS

284 rGBM patients fulfill inclusion criteria, 145 (51.1%) had reoperation at their 1st recurrence. Reoperated patients were significantly younger, had better performance status, and had a higher extent of resection at initial surgery; meanwhile, they were less likely to receive bevacizumab. Patients undergoing reoperation experienced superior PPS (11.5 vs. 7.4, months, log-rank test: p= 0.002), which kept consistent in multivariable Cox model (HR: 0.62, p= 0.001). Moreover, reoperated rGBM IDH-WT (N= 238) had 37% reduced risk of post-progression death compared to non-reoperated patients. A subanalysis of rGBM IDH-WT molecular subtypes identified that EGFR mutant, NF1 wildtype, and TP53 wildtype subgroups could benefit from reoperation (all p&lt; 0.008).

CONCLUSIONS

Maximal safe re-resection improved the PPS of rGBM regardless of their IDH status. Reoperation for 1st recurrence was especially beneficial for GBM IDH-WT harboring EGFR alteration, TP53 WT, and NF1-WT.

BIOM-48. PTEN MUTATIONS PREDICT BENEFIT FROM TUMOR-TREATING FIELDS THERAPY IN PATIENTS WITH RECURRENT GLIOBLASTOMA

BACKGROUND

Glioblastoma IDH-wildtype (GBM-IDH-WT) recurs despite the standard of care which includes surgical resection and concurrent chemoradiotherapy. Optimal treatment for recurrent GBM-IDH-WT (rGBM) is not standardized and multiple therapeutic approaches are utilized. Clinical trials have shown that Tumor-Treating Fields (TTF) provide equal benefits compared to physician’s chemotherapy choice for patients with rGBM. However, not all rGBM patients respond equally to TTF and understanding which patients will benefit from TTF therapy is critical.

METHODS

We reviewed clinical, molecular, and outcome characteristics of rGBM patients between 09/2009 to 2/2019 in our institution. Patients who received TTF-treatment at the time of 1st recurrence were selected for analysis. Tumors were analyzed for mutations in 315 cancer-related genes by next-generation sequencing. Post-progression survival (PPS) defined as the interval from 1st recurrence to death or the time of analysis, was examined using the Log-rank test and multivariable Cox-regression model.

RESULTS

149 rGBM patients were identified of which 29 (19%) were treated with TTF. Overall, no significant difference in survival was observed in rGBM patients who received TTF therapy (13.9-months vs 10.9-months, p= 0.06). However, among TTF-treated patients (n= 29), there was improved survival in PTEN-mutant (n= 14) patients compared to PTEN-wt (n= 15), (22.2-months vs 11.6- months, p= 0.017). No differences in TTF usage were observed between groups. Within the PTEN-mutant patients (70/149, 47%), those treated with TTF (n= 14) had longer PPS (22.2-months vs 9.3-months, p= 0.005). No survival benefit with TTF-treatment was observed in PTEN-wt patients (79/149, 53%).

CONCLUSIONS

Patients with GBM-PTEN-mutant tumors show a significant improvement in survival when treated with TTF at recurrence. Understanding the molecular mechanism underpinning the differences in response to TTF therapy could help elucidate the mechanism of action of TTF and identify patients that will benefit the most from this therapeutic option.

PATH-19. MOLECULAR, HISTOLOGIC AND CLINICAL CHARACTERISTICS OF OLIGODENDROGLIOMAS: A MULTI-INSTITUTIONAL RETROSPECTIVE STUDY

In the 2016 WHO classification of CNS tumors, oligodendrogliomas are molecularly defined by IDH1 or IDH2 mutations and 1p/19q co-deletion. Some reports suggest that PI3K pathway alterations may confer increased risk of progression and poor prognosis in oligodendroglioma. However, factors that influence prognosis in molecularly defined oligodendroglioma (mOGD) have not been thoroughly studied. Also, the benefits of adjuvant radiation and temozolomide in mOGDs remain to be determined. 107 mOGDs diagnosed between 2008-2018 at the University of Texas Health Science Center at Houston (n= 39) and MD Anderson Cancer Center (n= 68) were included. A retrospective review of the demographic, clinical, histologic, molecular, and outcomes were performed. Median age at diagnosis was 37 years and 61 (57%) patients were male. There were 64 (60%) WHO Grade 2 and 43 (40%) WHO Grade 3 tumors. Ninety-five (88.8%) tumors were IDH1-mutant and 12 (11.2%) were IDH2-mutant. Eighty-two (77%) patients were stratified as high-risk: older than 40-years and/or subtotal resection (RTOG 9802). Gross-total resection was achieved in 47 (45%) patients. Treatment strategies included observation (n= 15), temozolomide (n= 11), radiation (n= 13), radiation with temozolomide (n= 62) and other (n= 6). Our results show a benefit of temozolomide vs. observation in progression-free survival (PFS). However, no benefit in PFS or overall survival (OS) was observed when comparing radiation vs. radiation with temozolomide. PIK3CA mutations were detected in 15 (14%) cases, and patients with PIK3CA-mutant mOGDs showed worse OS (10.7-years vs 15.1-years, p= 0.009). Patients with WHO Grade 3 tumors had shorter PFS but no significant difference in OS was observed compared to grade 2. Our findings suggest that mOGDs harboring PIK3CA mutations have worse OS. Except for an advantage in PFS in temozolomide treated patients, adjuvant treatment with radiation or the combination of both, showed no significant advantage in terms of OS.

EPID-17. THE RELATIONSHIP OF HORMONE EXPOSURE IN BREAST CANCER AND SUBSEQUENT RISK OF HIGH GRADE GLIOMAS

BACKGROUND

Women have a lower incidence of high grade gliomas (HGGs), which is thought to be related to sex differences and hormone exposure. The association between hormone dependent tumors in women and HGGs remains poorly investigated.

METHODS

The Surveillance, Epidemiology, and End Results (SEER) database of 18 Registries (2000–2017) was used to assess age-adjusted incidence rates and temporal trends of breast cancer (BC) and HGG. Female BC patients 18 years of age or older and with ductal or lobular BC were then assessed for the risk of subsequent HGG, calculated as the standardized incidence ratio (SIR).

RESULTS

A total of 976,134 patients diagnosed with BC between 2000–2017 were identified. The temporal trend of BC and HGG incidence rates remained comparable throughout the study, with a higher incidence of BC and lower incidence of HGGs in females. Female BC patients had a 22% lower risk of developing a HGG (SIR 0.78 [0.69–0.87], p&lt; 0.05) compared to general population. HGG risk by age groups in BC females was significant, with a lower risk found in pre-menopausal women (Ages 18–50, SIR 0.66 [0.45–0.94] vs Ages 50+ SIR 0.79 [0.70–0.89], p&lt; 0.05 for both). Among HGG tumors, a decreased risk of developing glioblastoma (SIR 0.83 [0.75–0.93], p&lt; 0.05) and anaplastic astrocytoma (SIR 0.58 [0.35–90, p&lt; 0.05), was found, but not for anaplastic oligodendrogliomas.

CONCLUSIONS

The findings of our study allude to the protective effect of hormone exposure in the development of HGGs, as shown by the lower risk in female patients with BC compared to the general population.

Comparative Analysis of Survival Outcomes and Prognostic Factors of Supratentorial versus Cerebellar Glioblastoma in the Elderly: Does Location Really Matter?

BACKGROUND

Cerebellar glioblastomas (cGBMs) are rare tumors that are uncommon in the elderly. In this study, we compare survival outcomes and identify prognostic factors of cGBM compared with the supratentorial (stGBM) counterpart in the elderly.

METHODS

Data from the SEER 18 registries were used to identify patients with a glioblastoma (GBM) diagnosis between 2000 and 2016. The log-rank method and a multivariable Cox proportional hazards regression model were used for analysis.

RESULTS

Among 110 elderly patients with cGBM, the median age was 74 years (interquartile range [IQR], 69-79 years), 39% were female and 83% were white. Of these patients, 32% underwent gross total resection, 73% radiotherapy, and 39% chemotherapy. Multivariable analysis of the unmatched and matched cohort showed that tumor location was not associated with survival; in the unmatched cohort, insurance status (hazard ratio [HR], 0.11; IQR, 0.02-0.49; P = 0.004), gross total resection (HR, 0.53; IQR, 0.30-0.91; P = 0.022), and radiotherapy (HR, 0.33; IQR, 0.18-0.61; P < 0.0001) were associated with better survival. Patients with cGBM and stGBM undergoing radiotherapy (7 months vs. 2 months; P < 0.001) and chemotherapy (10 months vs. 3 months; P < 0.0001) had improved survival. Long-term mortality was lower for cGBM in the elderly at 24 months compared with the stGBM cohort (P = 0.007).

CONCLUSIONS

In our study, elderly patients with cGBM and stGBM have similar outcomes in overall survival, and those undergoing maximal resection with adjuvant therapies, independent of tumor location, have improved outcomes. Thus, aggressive treatment should be encouraged for cGBM in geriatric patients to confer the same survival benefits seen in stGBM. Single-institutional and multi-institutional studies to identify patient-level prognostic factors are warranted to triage the best surgical candidates.

Real-time intracranial pressure monitoring during high-dose methotrexate treatment for primary central nervous system lymphoma

BACKGROUND

Primary central nervous system lymphoma (PCNSL) is an aggressive non-Hodgkin lymphoma with exclusive central nervous system (CNS) and/or ocular involvement. Increased intracranial pressure (ICP) from cerebral edema can commonly presents secondary to the mass effect of PCNSL. Methotrexate-based induction chemotherapy is the gold standard for treatment, however, several neurotoxic complications have been associated with high-dose methotrexate (HD-MTX) treatment. Tumor lysis and other biochemical disruptions following administration of HD-MTX are postulated to increase cerebral edema and ICP in predisposed patients, therefore, in the setting of ring-enhancing lesions with significant mass effect, monitoring of ICP to prevent cerebral herniation may be necessary.

PRESENTATION OF CASE

We present the case of a patient with diffuse cerebral edema secondary to PCNSL, who was treated with methotrexate-based induction chemotherapy and underwent real-time ICP monitoring to allow for early recognition, and management with aggressive medical therapy to prevent worsening cerebral edema and potential fatal herniation.

DISCUSSION AND CONCLUSIONS

Treatment of patients with high tumor burden PCNSL can prove to be challenging, particularly at the time of initiation of methotrexate based induction chemotherapy in the setting of impending cerebral herniation, as in the case presented. Close monitoring of the patient's ICP proved advantageous in rapidly recognizing, and successfully treating elevations in ICP that could have worsened mass effect and lead to fatal herniation.