Salvage Stereotactic Radiosurgery for Recurrent WHO Grade 2 and 3 Meningiomas: A Multicenter Study (STORM)

PURPOSE

The role of stereotactic radiosurgery (SRS) in the management of grade 2 and 3 meningiomas is not well elucidated. Unfortunately, local recurrence rates are high, and guidelines for management of recurrent disease are lacking. To address this knowledge gap, we conducted STORM, a multicenter retrospective cohort study of patients treated with primary SRS for recurrent grade 2 and 3 meningiomas.

METHODS AND MATERIALS

Data on patients with recurrent grade 2 and 3 meningioma treated with SRS at first recurrence were retrospectively collected from eight academic centers in the United States. Patients with multiple lesions at the time of initial diagnosis or more than two lesions at the time of first recurrence were excluded from this analysis. Patient demographics and treatment parameters were extracted at time of diagnosis, first recurrence, and second recurrence. Oncologic outcomes including progression-free survival (PFS) and overall survival (OS) as well as toxicity outcomes were reported at the patient level.

RESULTS

From 2000-2022, 108 patients were identified (94% grade 2, 6.0% grade 3). 106 patients (98%) had upfront surgical resection (60% gross-total resection) with 18% receiving adjuvant radiotherapy (RT). Median time to first progression was 2.5 years (IQR 1.34-4.30). At first recurrence, patients were treated with single or fractionated SRS to a median marginal dose of 16 Gy to a maximum of two lesions (87% received single fraction SRS). Median follow-up time after SRS was 2.6 years. 1-, 2-, and 3-year PFS was 90%, 75%, and 57%, respectively after treatment with SRS. 1-, 2-, and 3-year OS was 97%, 94%, and 92%, respectively. On multivariable analysis, grade 3 disease (HR 6.80; 95% CI 1.61-28.6), male sex (HR 3.48; 95% CI 1.47-8.26), and receipt of prior RT (HR 2.69; 95% CI 1.23-5.86) were associated with worse PFS. SRS dose and tumor volume were not correlated with progression. Treatment was well-tolerated, with a 3.0% incidence of grade 2+ radiation necrosis.

CONCLUSIONS

This is the largest multi-center study to evaluate salvage SRS in recurrent grade 2 and 3 meningiomas. In this select cohort of patients with primarily grade 2 meningioma with potentially more favorable natural history of delayed, localized first recurrence amenable to salvage SRS, local control rates and toxicity profiles were favorable, warranting further prospective validation.

Radiation-Induced Sensorineural Hearing Loss and Potential Management

The cochlear apparatus is one of the major organs at risk when considering radiation therapy (RT) for brain, head, and neck tumors. Radiation oncologists currently consider mean dose constraints of <35 Gy for conventionally fractioned radiation therapy (RT), <4 Gy for single fraction stereotactic radiosurgery, and <17.1 or 25 Gy for 3- or 5-fraction stereotactic radiosurgery, respectively, as the standard of care. Indeed, dose adjustments are made in the setting of concurrent platinum-based chemotherapy or when prioritizing tumor coverage during treatment planning. Despite guidelines, in many patients, RT to the cochlea may still cause sensorineural hearing loss through progressive degeneration and ossification of the inner ear. There are several audiologic and otolaryngologic interventions for incident RT-induced hearing loss, including hearing aids, cochlear implants, or, in the context of vestibular schwannoma due to neurofibromatosis type 2, auditory brain stem implantation. Cochlear implants are the most effective at restoring hearing and improving quality of life for those with an intact cochlear nerve. An early multidisciplinary approach is essential to optimally manage RT-induced hearing loss, and this topic discussion serves as a guide for radiation oncologists on cochlear dosimetric considerations as well as how to address potential RT-induced adverse effects.

MGMT Promoter Methylation Predicts Overall Survival after Chemotherapy for 1p/19q-Codeleted Gliomas

PURPOSE

While MGMT promoter methylation (mMGMT) is predictive of response to alkylating chemotherapy and guides treatment decisions in glioblastoma, its role in grade 2 and 3 glioma remains unclear. Recent data suggest that mMGMT is prognostic of progression-free survival in 1p/19q-codeleted oligodendrogliomas, but an effect on overall survival (OS) has not been demonstrated.

EXPERIMENTAL DESIGN

We identified patients with newly diagnosed 1p/19q-codeleted gliomas and known MGMT promoter status in the National Cancer Database from 2010 to 2019. Multivariable Cox proportional hazards regression modeling was used to assess the effect of mMGMT on OS after adjusting for age, sex, race, comorbidity, grade, extent of resection, chemotherapy, and radiotherapy.

RESULTS

We identified 1,297 eligible patients, 938 (72.3%) of whom received chemotherapy in their initial course of treatment. The MGMT promoter was methylated in 1,009 (77.8%) patients. Unmethylated MGMT (uMGMT) was associated with worse survival compared with mMGMT [70% {95% confidence interval (CI), 64%-77%} vs. 81% (95% CI, 78%-85%); P < 0.001; adjusted HR (aHR), 2.35 (95% CI, 1.77-3.14)]. uMGMT was associated with worse survival in patients who received chemotherapy [63% (95% CI, 55-73%) vs. 80% (95% CI, 76%-84%); P < 0.001; aHR, 2.61 (95% CI, 1.89-3.60)] but not in patients who did not receive chemotherapy [P = 0.38; HR, 1.31 (95% CI, 0.71-2.42)]. Similar results were observed regardless of World Health Organization grade and after single- or multiagent chemotherapy.

CONCLUSIONS

Our study demonstrates an association between mMGMT and OS in 1p/19q-codeleted gliomas. MGMT promoter status should be considered as a stratification factor in future clinical trials of 1p/19q-codeleted gliomas that use OS as an endpoint.

Spheno-Orbital Meningioma - Treatment Outcomes and Factors Influencing Recurrence

PURPOSE

To determine treatment outcomes, recurrence rates, and predictors of recurrence, to inform future therapeutic approaches for spheno-orbital meningiomas (SOM).

METHODS

A retrospective single-center study of SOM treated from 1990 to 2021 was conducted with comprehensive neuro-ophthalmologic follow-up at Columbia University Medical Center (CUMC). Recurrence requiring reintervention was defined clinically as worsening of visual acuity, visual field defect, or ocular motility after an initial period of stabilization or 6 months of improvement following treatment, or radiologically as either a regrowth with an increase in tumor size by 20% at the site of previous growth or a new region of tumor growth.

RESULTS

In total 46 patients met the inclusion criteria. The mean follow-up was 106 months (range 1-303). Dictated by the phenotype of the disease, patients underwent either gross- (50%), near- (17%), or subtotal resection (26%). Removal of the anterior clinoid process (ACP) was performed in 52% of patients. Nine patients (20%) required an enucleation or exenteration. Radiotherapy was employed at some point of treatment in 50% of cases. Inherited cases (24%) were referred to CUMC for treatment following 1 or more recurrences. The total recurrence rate, including inherited cases, was 54%, occurring at a mean interval of 43 months. The recurrence rate of patients treated solely at CUMC was 40%, occurring at a mean interval of 41 months. A subset of patients (32%) had 2 or more recurrences. Histopathology at the first surgery was WHO grade I (87%) and II (13%) and at the final surgery was WHO grade I (74%), II (21%), and III (4%). A subset of grade I tumors that received radiotherapy (35%) evolved to a higher grade or developed multiple recurrences without a change in histologic grade I. Grade II tumors and treatment with radiotherapy increased the odds of recurrence. Removal of the ACP and gross total resection decreased the odds of recurrence.

CONCLUSION

Due to the routinely long interval to tumor recurrence, lifelong surveillance of patients with SOM is prudent. ACP resection and gross total resection, where possible, reduce tumor recurrence and the need for further treatment. Radiotherapy should be reserved for higher-grade meningiomas and select grade I tumors.

MGMT Promoter Methylation Predicts Survival in 1p19q-Codeleted Gliomas after Chemotherapy

PURPOSE/OBJECTIVE(S)

MGMT promoter methylation (mMGMT) is predictive of response to alkylating chemotherapy in glioblastomas and used to guide treatment decisions. However, the role of MGMT promoter status in low-grade and anaplastic gliomas remains unclear due to molecular heterogeneity and the lack of sufficiently large datasets. We recently found that MGMT promoter methylation predicts progression-free survival in 1p19q-codeleted gliomas after alkylating chemotherapy in a meta-analysis of three prospective cohorts. There were not enough deaths to determine the effect on overall survival. Here, we query a large national database to determine the association between MGMT promoter methylation and overall survival in patients with 1p19q-codeleted gliomas.

MATERIALS/METHODS

We identified all patients with newly diagnosed gliomas in the National Cancer Database (NCDB) from 2010-2016 with 1p19q-codeletion and information on MGMT promoter methylation status. The cohort was stratified based on receipt of chemotherapy. Multivariable Cox proportional hazards regression modeling was used to assess the effect of MGMT promoter methylation status on overall survival after adjusting for age, sex, race, co-morbidity, grade, extent of resection, chemotherapy, and radiotherapy.

RESULTS

We identified 530 eligible patients, 373 (70.4%) of whom received chemotherapy in their initial course of treatment. The MGMT promoter was methylated in 400 (75.5%) patients. For all patients, unmethylated MGMT (uMGMT) was associated with poorer survival compared to mMGMT (75% survival time [75%ST] 45 months vs. not reached, P = .003, adjusted hazard ratio [aHR] 2.36 [95% confidence interval (95% CI) 1.53-3.62]). uMGMT was associated with poorer survival in patients who received chemotherapy (75%ST 22 vs. 66 months, P<.001, aHR 2.55 [95% CI 1.60-4.06]) but not in patients who did not receive chemotherapy (75%ST 110 months vs. not reached, P = 0.7, HR 1.24 [95% CI 0.40-3.81]).

CONCLUSION

To our knowledge, this is the first study to demonstrate an association between overall survival and MGMT promoter status in 1p19q-codeleted gliomas. MGMT promoter status should be used as a stratification factor in future clinical trials of 1p19q-codeleted gliomas that use overall survival as an endpoint.

Association of MGMT Promoter Methylation With Survival in Low-grade and Anaplastic Gliomas After Alkylating Chemotherapy

Importance

O6-methylguanine-DNA methyltransferase (MGMT [OMIM 156569]) promoter methylation (mMGMT) is predictive of response to alkylating chemotherapy for glioblastomas and is routinely used to guide treatment decisions. However, the utility of MGMT promoter status for low-grade and anaplastic gliomas remains unclear due to molecular heterogeneity and the lack of sufficiently large data sets.

Objective

To evaluate the association of mMGMT for low-grade and anaplastic gliomas with chemotherapy response.

Design, Setting, and Participants

This cohort study aggregated grade II and III primary glioma data from 3 prospective cohort studies with patient data collected from August 13, 1995, to August 3, 2022, comprising 411 patients: MSK-IMPACT, EORTC (European Organization of Research and Treatment of Cancer) 26951, and Columbia University. Statistical analysis was performed from April 2022 to January 2023.

Exposure

MGMT promoter methylation status.

Main Outcomes and Measures

Multivariable Cox proportional hazards regression modeling was used to assess the association of mMGMT status with progression-free survival (PFS) and overall survival (OS) after adjusting for age, sex, molecular class, grade, chemotherapy, and radiotherapy. Subgroups were stratified by treatment status and World Health Organization 2016 molecular classification.

Results

A total of 411 patients (mean [SD] age, 44.1 [14.5] years; 283 men [58%]) met the inclusion criteria, 288 of whom received alkylating chemotherapy. MGMT promoter methylation was observed in 42% of isocitrate dehydrogenase (IDH)-wild-type gliomas (56 of 135), 53% of IDH-mutant and non-codeleted gliomas (79 of 149), and 74% of IDH-mutant and 1p/19q-codeleted gliomas (94 of 127). Among patients who received chemotherapy, mMGMT was associated with improved PFS (median, 68 months [95% CI, 54-132 months] vs 30 months [95% CI, 15-54 months]; log-rank P < .001; adjusted hazard ratio [aHR] for unmethylated MGMT, 1.95 [95% CI, 1.39-2.75]; P < .001) and OS (median, 137 months [95% CI, 104 months to not reached] vs 61 months [95% CI, 47-97 months]; log-rank P < .001; aHR, 1.65 [95% CI, 1.11-2.46]; P = .01). After adjusting for clinical factors, MGMT promoter status was associated with chemotherapy response in IDH-wild-type gliomas (aHR for PFS, 2.15 [95% CI, 1.26-3.66]; P = .005; aHR for OS, 1.69 [95% CI, 0.98-2.91]; P = .06) and IDH-mutant and codeleted gliomas (aHR for PFS, 2.99 [95% CI, 1.44-6.21]; P = .003; aHR for OS, 4.21 [95% CI, 1.25-14.2]; P = .02), but not IDH-mutant and non-codeleted gliomas (aHR for PFS, 1.19 [95% CI, 0.67-2.12]; P = .56; aHR for OS, 1.07 [95% CI, 0.54-2.12]; P = .85). Among patients who did not receive chemotherapy, mMGMT status was not associated with PFS or OS.

Conclusions and Relevance

This study suggests that mMGMT is associated with response to alkylating chemotherapy for low-grade and anaplastic gliomas and may be considered as a stratification factor in future clinical trials of patients with IDH-wild-type and IDH-mutant and codeleted tumors.

A Transcriptome-Based Precision Oncology Platform for Patient-Therapy Alignment in a Diverse Set of Treatment-Resistant Malignancies

Predicting in vivo response to antineoplastics remains an elusive challenge. We performed a first-of-kind evaluation of two transcriptome-based precision cancer medicine methodologies to predict tumor sensitivity to a comprehensive repertoire of clinically relevant oncology drugs, whose mechanism of action we experimentally assessed in cognate cell lines. We enrolled patients with histologically distinct, poor-prognosis malignancies who had progressed on multiple therapies, and developed low-passage, patient-derived xenograft models that were used to validate 35 patient-specific drug predictions. Both OncoTarget, which identifies high-affinity inhibitors of individual master regulator (MR) proteins, and OncoTreat, which identifies drugs that invert the transcriptional activity of hyperconnected MR modules, produced highly significant 30-day disease control rates (68% and 91%, respectively). Moreover, of 18 OncoTreat-predicted drugs, 15 induced the predicted MR-module activity inversion in vivo. Predicted drugs significantly outperformed antineoplastic drugs selected as unpredicted controls, suggesting these methods may substantively complement existing precision cancer medicine approaches, as also illustrated by a case study.

SIGNIFICANCE

Complementary precision cancer medicine paradigms are needed to broaden the clinical benefit realized through genetic profiling and immunotherapy. In this first-in-class application, we introduce two transcriptome-based tumor-agnostic systems biology tools to predict drug response in vivo. OncoTarget and OncoTreat are scalable for the design of basket and umbrella clinical trials. This article is highlighted in the In This Issue feature, p. 1275.

Instrumented insoles for assessment of gait in patients with vestibular schwannoma

Background

Imbalance and gait disturbances are common in patients with vestibular schwannoma (VS) and can result in significant morbidity. Current methods for quantitative gait analysis are cumbersome and difficult to implement. Here, we use custom-engineered instrumented insoles to evaluate the gait of patients diagnosed with VS.

Methods

Twenty patients with VS were recruited from otology, neurosurgery, and radiation oncology clinics at a tertiary referral center. Functional gait assessment (FGA), 2-minute walk test (2MWT), and uneven surface walk test (USWT) were performed. Custom-engineered instrumented insoles, equipped with an 8-cell force sensitive resistor (FSR) and a 9-degree-of-freedom inertial measurement unit (IMU), were used to collect stride-by-stride spatiotemporal gait parameters, from which mean values and coefficients of variation (CV) were determined for each patient.

Results

FGA scores were significantly correlated with gait metrics obtained from the 2MWT and USWT, including stride length, stride velocity, normalized stride length, normalized stride velocity, stride length CV, and stride velocity CV. Tumor diameter was negatively associated with stride time and swing time on the 2MWT; no such association existed between tumor diameter and FGA or DHI.

Conclusions

Instrumented insoles may unveil associations between VS tumor size and gait dysfunction that cannot be captured by standardized clinical assessments and self-reported questionnaires.

Re-convolving the compositional landscape of primary and recurrent glioblastoma reveals prognostic and targetable tissue states

Glioblastoma (GBM) diffusely infiltrates the brain and intermingles with non-neoplastic brain cells, including astrocytes, neurons and microglia/myeloid cells. This complex mixture of cell types forms the biological context for therapeutic response and tumor recurrence. We used single-nucleus RNA sequencing and spatial transcriptomics to determine the cellular composition and transcriptional states in primary and recurrent glioma and identified three compositional 'tissue-states' defined by cohabitation patterns between specific subpopulations of neoplastic and non-neoplastic brain cells. These tissue-states correlated with radiographic, histopathologic, and prognostic features and were enriched in distinct metabolic pathways. Fatty acid biosynthesis was enriched in the tissue-state defined by the cohabitation of astrocyte-like/mesenchymal glioma cells, reactive astrocytes, and macrophages, and was associated with recurrent GBM and shorter survival. Treating acute slices of GBM with a fatty acid synthesis inhibitor depleted the transcriptional signature of this pernicious tissue-state. These findings point to therapies that target interdependencies in the GBM microenvironment.

Feasibility of fractionated gamma knife radiosurgery in the management of newly diagnosed Glioblastoma

BACKGROUND

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults, with overall survival remaining poor despite ongoing efforts to explore new treatment paradigms. Given these outcomes, efforts have been made to shorten treatment time. Recent data report on the safety of CyberKnife (CK) fractionated stereotactic radiosurgery (SRS) in the management of GBM using a five-fraction regimen. The latest Gamma Knife (GK) model also supports frameless SRS, and outcomes using GK SRS in the management of primary GBM have not yet been reported.

OBJECTIVE

To report on the feasibility of five-fraction SRS with the GammaKnife ICON in the management of newly diagnosed GBM.

METHODS

In this single institutional study, we retrospectively reviewed all patients from our medical center from January 2017 through December 2021 who received fractionated SRS with Gamma Knife ICON for newly diagnosed GBM. Patient demographics, upfront surgical margins, molecular subtyping, radiation treatment volumes, systemic therapies, and follow-up imaging findings were extracted to report on oncologic outcomes.

RESULTS

We identified six patients treated within the above time frame. Median age at diagnosis was 73.5 years, 66% were male, and had a median Karnofsky Performance Status (KPS) of 70. All tumors were IDH wild-type, and all but one were MGMT methylated and received concurrent temozolomide (TMZ). Within this group, progression free survival was comparable to that of historical data without significant radiation-induced toxicities.

CONCLUSION

Gamma Knife ICON may be discussed as a potential treatment option for select GBM patients and warrants further investigation in the prospective setting.

BOLD Asynchrony Elucidates Tumor Burden in IDH-Mutated Gliomas

BACKGROUND

Gliomas comprise the most common type of primary brain tumor, are highly invasive, and often fatal. IDH-mutated gliomas are particularly challenging to image and there is currently no clinically accepted method for identifying the extent of tumor burden in these neoplasms. This uncertainty poses a challenge to clinicians who must balance the need to treat the tumor while sparing healthy brain from iatrogenic damage. The purpose of this study was to investigate the feasibility of using resting-state blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) to detect glioma-related asynchrony in vascular dynamics for distinguishing tumor from healthy brain.

METHODS

Twenty-four stereotactically localized biopsies were obtained during open surgical resection from ten treatment-naïve patients with IDH-mutated gliomas who received standard of care preoperative imaging as well as echo-planar resting-state BOLD fMRI. Signal intensity for BOLD asynchrony and standard of care imaging was compared to cell counts of total cellularity (H&E), tumor density (IDH1 & Sox2), cellular proliferation (Ki67), and neuronal density (NeuN), for each corresponding sample.

RESULTS

BOLD asynchrony was directly related to total cellularity (H&E, p = 4 x 10 -5), tumor density (IDH1, p = 4 x 10 -5; Sox2, p = 3 x 10 -5), cellular proliferation (Ki67, p = 0.002), and as well as inversely related to neuronal density (NeuN, p = 1 x 10 -4).

CONCLUSIONS

Asynchrony in vascular dynamics, as measured by resting-state BOLD fMRI, correlates with tumor burden and provides a radiographic delineation of tumor boundaries in IDH-mutated gliomas.

Asynchrony in Peritumoral Resting-State Blood Oxygen Level-Dependent fMRI Predicts Meningioma Grade and Invasion

BACKGROUND AND PURPOSE

Meningioma grade is determined by histologic analysis, with detectable brain invasion resulting in a diagnosis of grade II or III tumor. However, tissue undersampling is a common problem, and invasive parts of the tumor can be missed, resulting in the incorrect assignment of a lower grade. Radiographic biomarkers may be able to improve the diagnosis of grade and identify targets for biopsy. Prior work in patients with gliomas has shown that the resting-state blood oxygen level-dependent fMRI signal within these tumors is not synchronous with normal brain. We hypothesized that blood oxygen level-dependent asynchrony, a functional marker of vascular dysregulation, could predict meningioma grade.

MATERIALS AND METHODS

We identified 25 patients with grade I and 11 patients with grade II or III meningiomas. Blood oxygen level-dependent time-series were extracted from the tumor and the radiographically normal control hemisphere and were included as predictors in a multiple linear regression to generate a blood oxygen level-dependent asynchrony map, in which negative values signify synchronous and positive values signify asynchronous activity relative to healthy brain. Masks of blood oxygen level-dependent asynchrony were created for each patient, and the fraction of the mask that extended beyond the contrast-enhancing tumor was computed.

RESULTS

The spatial extent of blood oxygen level-dependent asynchrony was greater in high (grades II and III) than in low (I) grade tumors (P < 0.001) and could discriminate grade with high accuracy (area under the curve = 0.88).

CONCLUSIONS

Blood oxygen level-dependent asynchrony radiographically discriminates meningioma grade and may provide targets for biopsy collection to aid in histologic diagnosis.

Deconvolution of cell type-specific drug responses in human tumor tissue with single-cell RNA-seq

BACKGROUND

Preclinical studies require models that recapitulate the cellular diversity of human tumors and provide insight into the drug sensitivities of specific cellular populations. The ideal platform would enable rapid screening of cell type-specific drug sensitivities directly in patient tumor tissue and reveal strategies to overcome intratumoral heterogeneity.

METHODS

We combine multiplexed drug perturbation in acute slice culture from freshly resected tumors with single-cell RNA sequencing (scRNA-seq) to profile transcriptome-wide drug responses in individual patients. We applied this approach to drug perturbations on slices derived from six glioblastoma (GBM) resections to identify conserved drug responses and to one additional GBM resection to identify patient-specific responses.

RESULTS

We used scRNA-seq to demonstrate that acute slice cultures recapitulate the cellular and molecular features of the originating tumor tissue and the feasibility of drug screening from an individual tumor. Detailed investigation of etoposide, a topoisomerase poison, and the histone deacetylase (HDAC) inhibitor panobinostat in acute slice cultures revealed cell type-specific responses across multiple patients. Etoposide has a conserved impact on proliferating tumor cells, while panobinostat treatment affects both tumor and non-tumor populations, including unexpected effects on the immune microenvironment.

CONCLUSIONS

Acute slice cultures recapitulate the major cellular and molecular features of GBM at the single-cell level. In combination with scRNA-seq, this approach enables cell type-specific analysis of sensitivity to multiple drugs in individual tumors. We anticipate that this approach will facilitate pre-clinical studies that identify effective therapies for solid tumors.

Extent of resection, molecular signature, and survival in 1p19q-codeleted gliomas

OBJECTIVE

Genomic analysis in neurooncology has underscored the importance of understanding the patterns of survival in different molecular subtypes within gliomas and their responses to treatment. In particular, diffuse gliomas are now principally characterized by their mutation status (IDH1 and 1p/19q codeletion), yet there remains a paucity of information regarding the prognostic value of molecular markers and extent of resection (EOR) on survival. Furthermore, given the modern emphasis on molecular rather than histological diagnosis, it is important to examine the effect of maximal resection on survival in all gliomas with 1p/q19 codeletions, as these will now be classified as oligodendrogliomas under the new WHO guidelines. The objectives of the present study were twofold: 1) to assess the association between EOR and survival for patients with oligodendrogliomas in the National Cancer Database (NCDB), which includes information on mutation status, and 2) to demonstrate the same effect for all patients with 1p/19q codeleted gliomas in the NCDB.

METHODS

The NCDB was queried for all cases of oligodendroglioma between 2004 and 2014, with follow-up dates through 2016. The authors found 2514 cases of histologically confirmed oligodendrogliomas for the final analysis of the effect of EOR on survival. Upon further query, 1067 1p/19q-codeleted tumors were identified in the NCDB. Patients who received subtotal resection (STR) or gross-total resection (GTR) were compared to those who received no tumor debulking surgery. Univariable and multivariable analyses of both overall survival and cause-specific survival were performed.

RESULTS

EOR was associated with increased overall survival for both histologically confirmed oligodendrogliomas and all 1p/19q-codeleted-defined tumors (p < 0.001 and p = 0.002, respectively). Tumor grade, location, and size covaried predictably with EOR. When evaluating tumors by each classification system for predictors of overall survival, facility setting, age, comorbidity index, grade, location, chemotherapy, and radiation therapy were all shown to be significantly associated with overall survival. STR and GTR were independent predictors of improved survival in historically classified oligodendrogliomas (HR 0.83, p = 0.18; HR 0.69, p = 0.01, respectively) and in 1p/19q-codeleted tumors (HR 0.49, p < 0.01; HR 0.43, p < 0.01, respectively).

CONCLUSIONS

By using the NCDB, the authors have demonstrated a side-by-side comparison of the survival benefits of greater EOR in 1p/19q-codeleted gliomas.

Craniotomy and Survival for Primary Central Nervous System Lymphoma

BACKGROUND

Cytoreductive surgery is considered controversial for primary central nervous system lymphoma (PCNSL).

OBJECTIVE

To investigate survival following craniotomy or biopsy for PCNSL.

METHODS

The National Cancer Database-Participant User File (NCDB, n = 8936), Surveillance, Epidemiology, and End Results Program (SEER, n = 4636), and an institutional series (IS, n = 132) were used. We retrospectively investigated the relationship between craniotomy, prognostic factors, and survival for PCNSL using case-control design.

RESULTS

In NCDB, craniotomy was associated with increased median survival over biopsy (19.5 vs 11.0 mo), independent of subsequent radiation and chemotherapy (hazard ratio [HR] 0.80, P < .001). We found a similar trend with survival for craniotomy vs biopsy in the IS (HR 0.68, P = .15). In SEER, gross total resection was associated with increased median survival over biopsy (29 vs 10 mo, HR 0.68, P < .001). The survival benefit associated with craniotomy was greater within recursive partitioning analysis (RPA) class 1 group in NCDB (95.1 vs 29.1 mo, HR 0.66, P < .001), but was smaller for RPA 2-3 (14.9 vs 10.0 mo, HR 0.86, P < .001). A surgical risk category (RC) considering lesion location and number, age, and frailty was developed. Craniotomy was associated with increased survival vs biopsy for patients with low RC (133.4 vs 41.0 mo, HR 0.33, P = .01), but not high RC in the IS.

CONCLUSION

Craniotomy is associated with increased survival over biopsy for PCNSL in 3 retrospective datasets. Prospective studies are necessary to adequately evaluate this relationship. Such studies should evaluate patients most likely to benefit from cytoreductive surgery, ie, those with favorable RPA and RC.

Surgery plus adjuvant radiotherapy for primary central nervous system lymphoma

Objective: Recent studies of primary central nervous system lymphoma (PCNSL) have found a positive association between cytoreductive surgery and survival, challenging the traditional notion that surgery is not beneficial and potentially harmful. However, no studies have examined the potential added benefits of adjuvant treatment in the post-operative setting. Here, we investigate survival in PCNSL patients treated with surgery plus radiation therapy (RT).Methods: The Surveillance, Epidemiology, and End-Results Program was used to identify patients with PCNSL from 1995-2013. We retrospectively analyzed the relationship between treatment, prognostic factors, and survival using case-control design. Treatment categories were compared to biopsy alone.Results: We identified 5417 cases. Median survival times for biopsy alone (n = 1824, 34%), biopsy + RT (n = 1460, 27%), surgery alone (n = 1222, 27%), and surgery + RT (n = 911, 17%) were 7, 8, 20, and 27 months, respectively. On multivariable analysis, surgery + RT was associated with improved survival over surgery alone (hazard ratio [HR] = 0.58 [95% confidence interval = 0.53-0.64] vs. HR = 0.71 [0.65-0.77]). Adjuvant RT was associated with improved survival, regardless of the extent of resection. HR's for subtotal resection, gross-total resection, subtotal resection + RT, and gross-total resection + RT were 0.77 (0.66-0.89), 0.66 (0.57-0.76), 0.62 (0.52-0.72), and 0.54 (0.46-0.63), respectively. Survival improved after adjuvant RT in patients under and over 60 years old. All findings were confirmed by multivariable analysis of cause-specific survival.Conclusion: Adjuvant RT was associated with improved survival in PCNSL patients who underwent surgery. Although these data are hypothesis-generating, additional information on neurotoxicity, dosing, and concurrent chemotherapy will be necessary to validate these findings. Cytoreductive surgery for PCNSL is common in the general population, and more studies are needed to assess optimal treatment in the post-operative setting.

Near real-time intraoperative brain tumor diagnosis using stimulated Raman histology and deep neural networks

Intraoperative diagnosis is essential for providing safe and effective care during cancer surgery1. The existing workflow for intraoperative diagnosis based on hematoxylin and eosin staining of processed tissue is time, resource and labor intensive2,3. Moreover, interpretation of intraoperative histologic images is dependent on a contracting, unevenly distributed, pathology workforce4. In the present study, we report a parallel workflow that combines stimulated Raman histology (SRH)5-7, a label-free optical imaging method and deep convolutional neural networks (CNNs) to predict diagnosis at the bedside in near real-time in an automated fashion. Specifically, our CNNs, trained on over 2.5 million SRH images, predict brain tumor diagnosis in the operating room in under 150 s, an order of magnitude faster than conventional techniques (for example, 20-30 min)2. In a multicenter, prospective clinical trial (n = 278), we demonstrated that CNN-based diagnosis of SRH images was noninferior to pathologist-based interpretation of conventional histologic images (overall accuracy, 94.6% versus 93.9%). Our CNNs learned a hierarchy of recognizable histologic feature representations to classify the major histopathologic classes of brain tumors. In addition, we implemented a semantic segmentation method to identify tumor-infiltrated diagnostic regions within SRH images. These results demonstrate how intraoperative cancer diagnosis can be streamlined, creating a complementary pathway for tissue diagnosis that is independent of a traditional pathology laboratory.

Treatment Outcomes and Dose Rate Effects Following Gamma Knife Stereotactic Radiosurgery for Vestibular Schwannomas

BACKGROUND

Gamma Knife radiosurgery (GKRS; Elekta AB) remains a well-established treatment modality for vestibular schwannomas. Despite highly effective tumor control, further research is needed toward optimizing long-term functional outcomes. Whereas dose-rate effects may impact post-treatment toxicities given tissue dose-response relationships, potential effects remain largely unexplored.

OBJECTIVE

To evaluate treatment outcomes and potential dose-rate effects following definitive GKRS for vestibular schwannomas.

METHODS

We retrospectively reviewed 419 patients treated at our institution between 1998 and 2015, characterizing baseline demographics, pretreatment symptoms, and GKRS parameters. The cohort was divided into 2 dose-rate groups based on the median value (2.675 Gy/min). Outcomes included clinical tumor control, radiographic progression-free survival, serviceable hearing preservation, hearing loss, and facial nerve dysfunction (FND). Prognostic factors were assessed using Cox regression.

RESULTS

The study cohort included 227 patients with available follow-up. Following GKRS 2-yr and 4-yr clinical tumor control rates were 98% (95% CI: 95.6%-100%) and 96% (95% CI: 91.4%-99.6%), respectively. Among 177 patients with available radiographic follow-up, 2-yr and 4-yr radiographic progression-free survival rates were 97% (95% CI: 94.0%-100.0%) and 88% (95% CI: 81.2%-95.0%). The serviceable hearing preservation rate was 72.2% among patients with baseline Gardner-Robertson class I/II hearing and post-treatment audiological evaluations. Most patients experienced effective relief from prior headaches (94.7%), tinnitus (83.7%), balance issues (62.7%), FND (90.0%), and trigeminal nerve dysfunction (79.2%), but not hearing loss (1.0%). Whereas GKRS provided effective tumor control independently of dose rate, GKRS patients exposed to lower dose rates experienced significantly better freedom from post-treatment hearing loss and FND (P = .044).

CONCLUSION

Whereas GKRS provides excellent tumor control and effective symptomatic relief for vestibular schwannomas, dose-rate effects may impact post-treatment functional outcomes. Further research remains warranted.

Extent of resection and survival for oligodendroglioma: a U.S. population-based study

BACKGROUND

National guidelines recommend maximal safe resection of low-grade and high-grade oligodendrogliomas. However, there is no level 1 evidence to support these guidelines, and recent retrospective studies on the topic have yielded mixed results.

OBJECTIVE

To assess the association between extent of resection (EOR) and survival for oligodendrogliomas in the general U.S.

POPULATION

METHODS

Cases diagnosed between 2004 and 2013 were selected from the Surveillance, Epidemiology, and End-Results (SEER) Program and retrospectively analyzed for treatment, prognostic factors, and survival times. Cases that did not undergo tumor de-bulking surgery (e.g. no surgery or biopsy alone) were compared to subtotal resection (resection) and gross-total resection (GTR). The primary end-points were overall survival (OS) and cause-specific survival (CSS). An external validation cohort with 1p/19q-codeleted tumors was creating using the TCGA and GSE16011 datasets.

RESULTS

3135 Cases were included in the final analysis. The 75% survival time (75ST) and 5-year survival rates were 47 months and 70.8%, respectively. Subtotal resection (STR, 75ST = 50 months) and GTR (75ST = 61 months) were associated with improved survival times compared to cases that did not undergo surgical debulking (75ST = 20 months, P < 0.001 for both), with reduced hazard ratios (HRs) after controlling for other factors (HR 0.81 [0.68-0.97] and HR 0.65 [0.54-0.79], respectively). GTR was associated with improved OS in both low-grade and anaplastic oligodendroglioma subgroups (HR 0.74 [0.58-0.95], HR 0.60 [0.44-0.82], respectively) while STR fell short of significance in the subgroup analysis. All findings were corroborated by multivariable analysis of CSS and externally validated in a cohort of patients with 1p19q-codeleted tumors.

CONCLUSION

Greater EOR is associated with improved survival in oligodendrogliomas. Our findings in this U.S. population-based cohort support national guidelines.

Frameless Stereotactic Radiosurgery on the Gamma Knife Icon: Early Experience From 100 Patients

BACKGROUND

The Gamma Knife (GK) Icon (Elekta AB) uses a cone-beam computed tomography (CBCT) scanner and an infrared camera system to support the delivery of frameless stereotactic radiosurgery (SRS). There are limited data on patients treated with frameless GK radiosurgery (GKRS).

OBJECTIVE

To describe the early experience, process, technical details, and short-term outcomes with frameless GKRS at our institution.

METHODS

We reviewed our patient selection and described the workflow in detail, including image acquisition, treatment planning, mask-based immobilization, stereotactic CBCT localization, registration, treatment, and intrafraction monitoring. Because of the short interval of follow-up, we provide crude rates of local control.

RESULTS

Data from 100 patients are reported. Median age is 67 yr old. 56 patients were treated definitively, 21 postoperatively, and 23 had salvage GKRS for recurrence after surgery. Forty-two patients had brain metastases, 26 meningiomas, 16 vestibular schwannomas, 9 high-grade gliomas, and 7 other histologies. Median doses to metastases were 20 Gy in 1 fraction (range: 14-21), 24 Gy in 3 fractions (range: 19.5-27), and 25 Gy in 5 fractions (range: 25-30 Gy). Thirteen patients underwent repeat SRS to the same area. Median treatment time was 17.7 min (range: 5.8-61.7). We found an improvement in our workflow and a greater number of patients eligible for GKRS because of the ability to fractionate treatments.

CONCLUSION

We report a large cohort of consecutive patients treated with frameless GKRS. We look forward to studies with longer follow-up to provide valuable data on clinical outcomes and to further our understanding of the radiobiology of hypofractionation in the brain.

Performance of the cone beam computed tomography-based patient positioning system on the Gamma Knife Icon™

PURPOSE

Cone beam computed tomography (CBCT) imaging has been implemented on the Leksell Gamma Knife^® Icon™ for assessing patient positioning in mask-based Gamma Knife radiosurgery. The purpose of this study was to evaluate the performance of the CBCT-based patient positioning system as a tool for frameless Gamma Knife radiosurgery.

METHODS

Daily quality assurance (QA) CBCT precision test results from a 12-month period were analyzed for the geometric accuracy and the stability of the imager. The performance of the image acquisition module and the image registration algorithm was evaluated using an anthropomorphic head phantom (CIRS Inc., Norfolk, VA) and a XYZR axis manual positioning stage (TOAUTO Inc., Guangdong, China). The head phantom was fixed on a mask adaptor and manually translated in the X, Y, Z directions or rotated around the X, Y, Z axes in the range of ±10 mm or ±10º. A CBCT scan was performed after each manual position setup followed by an image registration to the reference scan. To assess the overall setup uncertainties in fractionated treatment, two cylindrical Presage phantoms (Heuris Inc., Skillman, NJ) of 15 cm diameter and 10 cm height were irradiated with identical prescription dose and shot placement following standard mask-based treatment workflow according to two different fraction schedules: a single fraction treatment of 7.5 Gy and a 5-fraction treatment with 1.5 Gy per fraction.

RESULTS

The averaged vector deviations of the four marks from their preset values are 0.087, 0.085, 0.095, and 0.079 mm from the 212 daily QA tests. The averaged displacements in the X, Y, Z coordinates and the pitch, yaw, roll angles from the image registration tests are 0.23, 0.27, 0.14, 0.32º, 0.19º, 0.31º from the manual setup. The corresponding maximum differences are 0.41, 0.33, 0.29 mm, 0.45º, 0.31º, and 0.43º, respectively. Compared to the treatment plan using the 2% & 1 mm criteria, the averaged 2D Gamma passing rate is 98.25% for the measured dose distribution from the Presage phantom with 1-fraction irradiation and 95.12% for the 5-fraction irradiation. The averaged Gamma passing rates are 99.53% and 98.16% for the 1-fraction and 5-fraction irradiations using the 2% & 2 mm criteria.

CONCLUSIONS

The CBCT imager and the image registration algorithm can reproduce phantom position with <0.5 mm/0.5º uncertainty. A systematic contribution from the interfraction phantom repositioning procedure was observed in the Gamma analysis over the irradiated volumes of two end-to-end test phantoms.

Curative treatment for low-grade arteriovenous malformations

Background

Spetzler-Martin (SM) grade I-II (low-grade) arteriovenous malformations (AVMs) are often considered safe for microsurgery or radiosurgery. The adjunctive use of preoperative embolization to reduce surgical risk in these AVMs remains controversial.

Objective

To assess the safety of combined treatment of grade I-II AVMs with preoperative embolization followed by surgical resection or radiosurgery, and determine the long-term functional outcomes.

Methods

With institutional review board approval, a retrospective analysis was carried out on patients with ruptured and unruptured SM I-II AVMs between 2002 and 2017. Details of the endovascular procedures, including number of arteries supplying the AVM, number of branches embolized, embolic agent(s) used, and complications were studied. Baseline clinical and imaging characteristics were compared. Functional status using the modified Rankin Scale (mRS) before and after endovascular and microsurgical treatments was compared.

Results

258 SM I-II AVMs (36% SM I, 64% SM II) were identified in patients with a mean age of 38 ± 17 years. 48% presented with hemorrhage, 21% with seizure, 16% with headache, 10% with no symptoms, and 5% with clinical deficits. 90 patients (68%) in the unruptured group and 74 patients (59%) in the ruptured group underwent presurgical embolization (p = 0.0013). The mean number of arteries supplying the AVM was 1.44 and 1.41 in the unruptured and ruptured groups, respectively (p = 0.75). The mean number of arteries embolized was 2.51 in the unruptured group and 1.82 in the ruptured group (p = 0.003). n-Butyl cyanoacrylate and Onyx were the two most commonly used embolic agents. Four complications were seen in four patients (4/164 patients embolized): two peri-/postprocedural hemorrhage, one dissection, and one infarct. All patients undergoing surgery had a complete cure on postoperative angiography. Patients were followed up for a mean of 55 months. Good long-term outcomes (mRS score ≤ 2) were seen in 92.5% of patients with unruptured AVMs and 88.0% of those with ruptured AVMs. Permanent neurological morbidity occurred in 1.2%.

Conclusions

Curative treatment of SM I-II AVMs can be performed using endovascular embolization with microsurgical resection or radiosurgery in selected cases, with very low morbidity and high cure rates. Compared with other published series, these outcomes suggest that preoperative embolization is a safe and effective adjunct to definitive surgical treatment. Long-term follow-up showed that patients with low-grade AVMs undergoing surgical resection or radiosurgery have good functional outcomes.

Spinal location is prognostic of survival for solitary-fibrous tumor/hemangiopericytoma of the central nervous system

BACKGROUND

Prior studies have highlighted infratentorial tumor location as a prognostic factor for solitary fibrous tumor (SFT) and hemangiopericytoma (HPC) of the central nervous system (CNS), and spinal location is considered a positive prognostic factor for other tumors of the CNS. While SFT/HPC of the CNS is known to frequently arise from the spinal meninges, there are no case series that report outcomes for spinally located CNS tumors, and their prognosis in relation to intracranial and other CNS-located tumors is unknown.

OBJECTIVE

To investigate outcomes for patients with SFT/HPC of the spinal meninges.

METHODS

The Surveillance, Epidemiology, and End-Results Program was used to identify patients with SFT/HPC within the CNS from 1993-2015. We retrospectively analyzed the relationship between tumor location (spinal vs. Brain and other CNS) and survival.

RESULTS

We identified 551 cases of CNS SFT/HPC, 64 (11.6%) of which were primary tumors of the spinal meninges. Spinal tumors were more likely than brain and other CNS tumors to be SFT vs. HPC (37.5 vs. 12%, p < 0.001), benign (42.2 vs. 20.3%, p < 0.001), and less than 5 cm (53.1 vs. 35.7%, p < 0.001). The 10-year survival rates for spinal and brain/other CNS tumors were 85 and 58%, respectively. Median survival time was significantly longer for spinal tumors (median survival not reached vs. 138 months, p = 0.03, HR = 0.41 [95% CI 0.18-0.94]). On multivariable analysis, spinal tumor location was associated with improved survival over tumors located in the brain and other CNS (HR = 0.36 [95% CI 0.15-0.89], p = 0.03).

CONCLUSION

Spinal tumor location is associated with improved survival in patients with SFT/HPC of the CNS. Larger institutional studies are necessary to characterize the relationship between tumor location and other relevant factors such as presentation and amenability to gross-total resection and adjuvant radiotherapy. Future studies exploring optimal management of spinally located tumors are also needed.

Natural history, clinical course and predictors of interval time from initial diagnosis to development of subsequent NSCLC brain metastases

PURPOSE

Non-small cell lung cancer (NSCLC) brain metastases are associated with substantial morbidity and mortality. During recent years, accompanying dramatic improvements in systemic disease control, NSCLC brain metastases have emerged as an increasingly relevant clinical problem. However, optimal surveillance practices remain poorly defined. This purpose of this study was to further characterize the natural history, clinical course and risk factors associated with earlier development of subsequent NSCLC brain metastases to better inform clinical practice and help guide survivorship care.

METHODS

We retrospectively reviewed all institutional NSCLC brain metastasis cases treated with radiotherapy between 1997 and 2015. Exclusion criteria included presence of brain metastases at initial NSCLC diagnosis and incomplete staging information. Interval time to brain metastases and subsequent survival were characterized using Kaplan-Meier and multivariate Cox regression analyses.

RESULTS

Among 105 patients within this cohort, median interval time to development of brain metastases was 16 months. Median interval times were 29, 19, 16 and 13 months for Stage I-IV patients, respectively (P = 0.016). Additional independent predictors for earlier development of NSCLC brain metastases included non-adenocarcinomatous histopathology (HR 3.036, P < 0.001), no prior surgical resection (HR 1.609, P = 0.036) and no prior systemic therapy (HR 3.560, P = 0.004). Median survival following intracranial progression was 16 months. Delayed development of brain metastases was associated with better prognosis (HR 0.970, P < 0.001) but not survival following intracranial disease onset.

CONCLUSIONS

Collectively, our results provide valuable insights into the natural history of NSCLC brain metastases. NSCLC stage, histology, prior surgical resection and prior systemic therapy emerged as independent predictors for interval time to brain metastases.

Abstract 664: Surgery plus adjuvant radiation as a valid treatment option for primary central nervous system lymphoma (PCSNL)

Background: Recent studies of primary central nervous system lymphoma (PCNSL) have found an association between cytoreductive surgery and survival, challenging the traditional notion that surgery is not beneficial and potentially harmful. However, no studies have examined outcomes after surgery plus adjuvant treatment. We investigated treatment-related outcomes for surgery plus radiation using data from the Surveillance, Epidemiology, and End Results (SEER) Program.

Methods: The SEER database was queried to collect cases of histologically confirmed non-Hodgkin's lymphoma within the CNS diagnosed between 1995-2014. Median survival times were determined by the Kaplan-Meier method and compared using the log-rank test. Predictors of overall survival and cause-specific survival were determined using the Cox proportional hazards regression model. Treatment modalities were categorized as biopsy alone, biopsy plus radiation therapy (RT), surgery alone, and surgery + RT. Biopsy alone was used as the reference category. Subgroup analysis stratified patients by extent of surgical resection and recursive partition analysis (RPA) risk group.

Results: We identified 5,417 cases that met search criteria, 39% of which received surgical resection. Median survival times for biopsy alone (n=1,824, 34%), biopsy + RT (n=1,460, 27%), surgery alone (n=1,222, 23%), and surgery + RT (n=911, 17%) were 7, 8, 20, and 27 months, respectively (p&lt;0.0001). On multivariable analysis, RT after surgery was associated with a 13% incremental increase in overall survival (Hazard Ratio [HR]=0.71, p&lt;0.0001 vs. HR=0.58, p&lt;0.0001). When analyzing by extent of resection, median survival times for subtotal resection alone (n=111, 2%), gross-total resection alone (n=583, 11%), subtotal resection + RT (n=98, 2%), and gross-total resection + RT (n=459, 8.5%) were 10, 20, 20, and 27 months, respectively (p&lt;0.0001). RT after surgery was independently associated with increased survival in the gross-total resection subgroup (HR=0.85, p=0.046) and in all patients who received surgery (HR=0.87, p=0.017). RT after surgery was also associated with an incremental increase in survival in the RPA class I (HR=0.47, p&lt;0.0001 vs. 0.40, p&lt;0.0001) and class II-III (HR=0.77, p&lt;0.0001 vs. HR=0.66, p&lt;0.0001) subgroups. All findings were confirmed by multivariable analysis of cause-specific survival.

Conclusion: Surgical resection of PCNSL in the general population is more common than previously thought. Radiation therapy after surgery is associated with increased survival, regardless of the extent of surgical resection or the patient's RPA risk category. Neurotoxicity, dosing, and effects of concurrent chemotherapy should be addressed in future studies.

Citation Format: Connor J. Kinslow, Ali I. Rae, Alfred I. Neugut, Christopher M. Adams, Sameer A. Sheth, Guy M. McKhann, Michael B. Sisti, Jeffrey N. Bruce, Fabio M. Iwamoto, Adam M. Sonabend, Tony J. Wang. Surgery plus adjuvant radiation as a valid treatment option for primary central nervous system lymphoma (PCSNL) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 664.

Single institution validation of a modified graded prognostic assessment of patients with breast cancer brain metastases

Aim:

The number of breast cancer brain metastases is a prognostic clinical variable in the modified graded prognostic assessment (GPA) Index for breast cancer.

Patients & methods:

We retrospectively gathered data from 127 breast cancer patients who underwent radiation therapy for brain metastasis. Patients were stratified by both breast GPA and modified breast GPA scores, and survival was determined using the Kaplan–Meier curves and Cox proportional hazards model.

Results & Conclusion:

The Kaplan–Meier curve for patients under the breast GPA classification were not significant, but were significant under the modified breast GPA classification. The inclusion of number of brain metastases into the modified breast GPA index improved prognosis, thus validating the use of the modified breast GPA in prognosticating patient outcome.

Clinical and molecular characteristics of gliosarcoma and modern prognostic significance relative to conventional glioblastoma

Gliosarcoma is a rare histopathologic variant of glioblastoma traditionally associated with a poor prognosis. While gliosarcoma may represent a distinct clinical entity given its unique histologic composition and molecular features, its relative prognostic significance remains uncertain. While treatment of gliosarcoma generally encompasses the same standardized approach used in glioblastoma, supporting evidence is limited given its rarity. Here, we characterized 32 cases of gliosarcoma and retrospectively evaluated survival relative to 451 glioblastoma patients diagnosed during the same era within the same institution. Overall, we identified 22 primary gliosarcomas, representing 4.7% of WHO Grade IV primary glioblastomas, and 10 secondary gliosarcomas. With median age of 62, patients were predominately Caucasian (87.5%) and male (65.6%). Tumors with available molecular profiling were primarily MGMT-unmethylated (87.5%), IDH-1-preserved (100%) and EGFR wild-type (100%). Interestingly, while no significant median survival difference between primary gliosarcoma and glioblastoma was observed across the entire cohort (11.0 vs. 14.8 months, p = 0.269), median survival was worse for gliosarcoma specifically among patients who received modern temozolomide-based (TMZ) chemoradiotherapy (11.0 vs. 17.3 months, p = 0.006). Matched-pair analysis also trended toward worse median survival among gliosarcomas (11.0 vs. 19.6 months, log-rank p = 0.177, Breslow p = 0.010). While adjuvant radiotherapy (HR 0.206, p = 0.035) and TMZ-based chemotherapy (HR 0.531, p = 0.000) appeared protective, gliosarcoma emerged as a significantly poor prognostic factor on multivariate analysis (HR 3.27, p = 0.012). Collectively, our results suggest that gliosarcoma may still portend worse prognosis even with modern trimodality therapy.

Defining Glioblastoma Resectability Through the Wisdom of the Crowd: A Proof-of-Principle Study

BACKGROUND

Extent of resection (EOR) correlates with glioblastoma outcomes. Resectability and EOR depend on anatomical, clinical, and surgeon factors. Resectability likely influences outcome in and of itself, but an accurate measurement of resectability remains elusive. An understanding of resectability and the factors that influence it may provide a means to control a confounder in clinical trials and provide reference for decision making.

OBJECTIVE

To provide proof of concept of the use of the collective wisdom of experienced brain tumor surgeons in assessing glioblastoma resectability.

METHODS

We surveyed 13 academic tumor neurosurgeons nationwide to assess the resectability of newly diagnosed glioblastoma. Participants reviewed 20 cases, including digital imaging and communications in medicine-formatted pre- and postoperative magnetic resonance images and clinical vignettes. The selected cases involved a variety of anatomical locations and a range of EOR. Participants were asked about surgical goal, eg, gross total resection, subtotal resection (STR), or biopsy, and rationale for their decision. We calculated a "resectability index" for each lesion by pooling responses from all 13 surgeons.

RESULTS

Neurosurgeons' individual surgical goals varied significantly ( P = .015), but the resectability index calculated from the surgeons' pooled responses was strongly correlated with the percentage of contrast-enhancing residual tumor ( R = 0.817, P < .001). The collective STR goal predicted intraoperative decision of intentional STR documented on operative notes ( P < .01) and nonresectable residual ( P < .01), but not resectable residual.

CONCLUSION

In this pilot study, we demonstrate the feasibility of measuring the resectability of glioblastoma through crowdsourcing. This tool could be used to quantify resectability, a potential confounder in neuro-oncology clinical trials.

Monitoring Radiation Treatment Effects in Glioblastoma: FLAIR Volume as Significant Predictor of Survival

Glioblastoma is the most common adult central nervous system malignancy and carries a poor prognosis. Disease progression and recurrence after chemoradiotherapy are assessed via serial magnetic resonance imaging sequences. T2-weighted fluid-attenuated inversion recovery (FLAIR) signal is presumed to represent edema containing microscopic cancer infiltration. Here we assessed the prognostic impact of computerized volumetry of FLAIR signal in the peri-treatment setting for glioblastoma. We analyzed pre- and posttreatment FLAIR sequences of 40 patients treated at the Columbia University Medical Center between 2011 and 2014, excluding those without high-quality FLAIR imaging within 2 weeks before treatment and 60 to 180 days afterward. We manually contoured regions of FLAIR hyperintensity as per Radiation Therapy Oncology Group guidelines and calculated the volumes of nonenhancing tumor burden. At the time of this study, all but 1 patient had died. Pre- and posttreatment FLAIR volumes were assessed for correlation to overall and progression-free survival. Larger post-treatment FLAIR volumes from sequences taken between 60 and 180 days after conclusion of chemoradiotherapy were negatively correlated with overall survival (P = .048 on Pearson's correlation and P = .017 and P = .043 on univariable and multivariable Cox regression analyses, respectively) and progression-free survival (P = .002 on Pearson's correlation and P = < .001 and P = < .001 on univariable and multivariable Cox regression analyses). This study suggests that higher FLAIR volumes in the 2- to 6-month posttreatment window are associated with worsened survival.

Subependymomas Are Low-Grade Heterogeneous Glial Neoplasms Defined by Subventricular Zone Lineage Markers

OBJECTIVE

Subependymomas are infrequent, low-grade gliomas associated with the ventricular system and the spinal cord. Little is known about the origin and natural history of these slow-growing lesions.

METHODS

We identified all patients with pathologically proven subependymomas presenting to our institution between 1998 and 2016. We retrospectively reviewed clinical, radiographic, histologic, and surgical outcomes data in all patients who underwent surgical resection. Immunohistochemical analyses for cell lineage markers were performed.

RESULTS

A total of 31 patients with pathologically proven subependymomas were identified. Of these, 7 asymptomatic lesions were discovered at autopsy and 24 symptomatic cases were treated surgically. There were 15 (48%) lateral ventricle tumors, 11 (35%) fourth ventricular tumors, and 5 (17%) spinal tumors. Symptomatic intracranial lesions most commonly presented with headaches and balance and gait abnormalities. Subependymomas had no distinguishing radiographic features that provided definitive preoperative diagnosis. At last follow-up, no patient treated surgically experienced recurrence. Immunohistochemical analyses demonstrated a diffusely GFAP-positive glial neoplasm with mixed populations of cells that were variably positive for Olig2, NHERF1, Sox2, and CD44. The Ki67 proliferation index was generally low (<1% in many of the tumors).

CONCLUSIONS

Subependymomas demonstrate mixed populations of cells expressing glial lineage markers as well as putative stem cell markers, suggesting these tumors may arise from multipotent glial progenitors that reside in the subventricular zone. Definitive diagnosis requires surgical sampling. Although the clinical course of subependymomas appears benign, the inability to radiographically diagnose these lesions, and the possibility of an alternative malignant lesion support a low threshold for early and safe maximal resection.

Breast cancer subtype and stage are prognostic of time from breast cancer diagnosis to brain metastasis development

Breast cancer brain metastasis (BCBM) is associated with high morbidity and mortality. Patients with breast cancer risk factors associated with rapid development of BCBM could potentially benefit from early brain metastasis screening. We retrospectively reviewed all BCBM patients treated with brain radiotherapy at our institution from 1997 to 2015. Interval time to BCBM was defined as date of pathologic breast cancer diagnosis to date of radiographic evidence of brain metastasis. Patients were stratified by breast cancer molecular subtype and stage at diagnosis. Kaplan Meier analysis was conducted on time to development of BCBM. Breast cancer risk factors were correlated with time to BCBM on Cox proportion hazard analysis. The study cohort comprised 121 BCBM patients, with median interval time to BCBM of 46 months. Times to BCBM for Her2+/2HR+, Her2+, Her2-/HR+, and triple-negative (TNBC) subtypes were 70, 44, 42, and 28 months respectively (p = 0.002). Time to BCBM for stages I, II, III, and IV were 70, 54, 29, and 24 months, respectively (p = 0.000). BCBM patients were further stratified by both molecular subtype (TNBC vs. non-TNBC) and stage (I, II vs. III, IV). Median times to BCBM for non-TNBC/stage I-II, TNBC/stage I-II, non-TNBC stage III-IV, and TNBC/stage III-IV were 68, 47, 29, and 6 months respectively (p = 0.000). Subtype and stage were associated with shorter time to BCBM on multivariate analysis. Subtype and initial stage are independently correlated with decreased time to development of BCBM. Patients with advanced high stage and triple negative breast cancer develop brain metastases significantly earlier.

Sodium Fluorescein Facilitates Guided Sampling of Diagnostic Tumor Tissue in Nonenhancing Gliomas

BACKGROUND

Accurate tissue sampling in nonenhancing (NE) gliomas is a unique surgical challenge due to their intratumoral histological heterogeneity and absence of contrast enhancement as a guide for intraoperative stereotactic guidance. Instead, T2/fluid-attenuated inversion-recovery (FLAIR) hyperintensity on MRI is commonly used as an imaging surrogate for pathological tissue, but sampling from this region can yield nondiagnostic or underdiagnostic brain tissue. Sodium fluorescein is an intraoperative fluorescent dye that has a high predictive value for tumor identification in areas of contrast enhancement and NE in glioblastomas. However, the underlying histopathological alterations in fluorescent regions of NE gliomas remain undefined.

OBJECTIVE

To evaluate whether fluorescein can identify diagnostic tissue and differentiate regions with higher malignant potential during surgery for NE gliomas, thus improving sampling accuracy.

METHODS

Thirteen patients who presented with NE, T2/FLAIR hyperintense lesions suspicious for glioma received fluorescein (10%, 3 mg/kg intravenously) during surgical resection.

RESULTS

Patchy fluorescence was identified within the T2/FLAIR hyperintense area in 10 of 13 (77%) patients. Samples taken from fluorescent regions were more likely to demonstrate diagnostic glioma tissue and cytologic atypia (P &lt; .05). Fluorescein demonstrated a 95% positive predictive value for the presence of diagnostic tissue. Samples from areas of fluorescence also demonstrated greater total cell density and higher Ki-67 labeling than nonfluorescent biopsies (P &lt; .05).

CONCLUSION

Fluorescence in NE gliomas is highly predictive of diagnostic tumor tissue and regions of higher cell density and proliferative activity.

Outcomes of melanoma brain metastases treated with stereotactic radiosurgery with and without concurrent immune checkpoint therapy

e21026

Background: Evidence supports a synergistic effect between immunotherapy and radiotherapy. In this single-institution study, we compared outcomes of patients (pts) with melanoma brain metastases (BMs) who received Gamma Knife Radiosurgery (GKRS) with and without concurrent immune checkpoint blockade (ICB). Methods: Using an IRB-approved protocol, we identified pts with melanoma BMs who received GKRS from 5/2000 to 8/2016. Treatment was deemed concurrent if patients had GKRS within 4 weeks of ICB. Irradiated lesion control, tumor growth rate (TGR; percent change in product diameters per month), distant brain control, overall response rate (ORR) by modified WHO criteria, best response, and overall survival (OS) were compared. Results: 28 pts were identified: 17 (34 BMs total) received GKRS alone; 11 (23 BMs total) received concurrent GKRS/ICB. ICB included: ipilimumab (n = 3), anti-programmed death-1 (anti-PD-1) therapy (n = 4), and combined ipilimumab + nivolumab (n = 4). In comparing baseline characteristics between the GKRS alone and GKRS/ICB groups: median age was 65 v. 59 years, proportion of males was 53% v. 73%, 41% v. 45% had prior neurosurgery, and median number of prior systemic therapies was 1 v. 0. There was no difference in irradiated lesion control (6-month control rate 86% v. 96%; n = 57; p = 0.65), median TGR (-14% [range -100% to +61%] v. -20% [range -71% to 0%]; n = 42 lesions, p = 0.38), or distant brain control (6-month control rate 68% v. 60%; p = 0.51; median follow-up 8.6 months v. 8.0 months) with GKRS/ICB v. GKRS alone. The ORR with GKRS alone v. GKRS/ICB was 61% v. 47% (p = 0.33), and the median maximum reduction in BM bidimensional measurement was -69% v. -45% (p = 0.43). Median OS from the date of GKRS was not reached for the GKRS/ICB group and was 16.6 months for the GKRS alone group (p = 0.03). Conclusions: There was no difference in local lesion control, TGR, or distant brain control with concurrent GKRS/ICB compared to GKRS alone, but the study was limited by small patient numbers and biased by closer follow-up in the GKRS/ICB group. OS was longer with concurrent ICB, likely reflecting the survival improvement with immune checkpoint inhibitors.

A Multiparametric Model for Mapping Cellularity in Glioblastoma Using Radiographically Localized Biopsies

BACKGROUND AND PURPOSE

The complex MR imaging appearance of glioblastoma is a function of underlying histopathologic heterogeneity. A better understanding of these correlations, particularly the influence of infiltrating glioma cells and vasogenic edema on T2 and diffusivity signal in nonenhancing areas, has important implications in the management of these patients. With localized biopsies, the objective of this study was to generate a model capable of predicting cellularity at each voxel within an entire tumor volume as a function of signal intensity, thus providing a means of quantifying tumor infiltration into surrounding brain tissue.

MATERIALS AND METHODS

Ninety-one localized biopsies were obtained from 36 patients with glioblastoma. Signal intensities corresponding to these samples were derived from T1-postcontrast subtraction, T2-FLAIR, and ADC sequences by using an automated coregistration algorithm. Cell density was calculated for each specimen by using an automated cell-counting algorithm. Signal intensity was plotted against cell density for each MR image.

RESULTS

T2-FLAIR (r = -0.61) and ADC (r = -0.63) sequences were inversely correlated with cell density. T1-postcontrast (r = 0.69) subtraction was directly correlated with cell density. Combining these relationships yielded a multiparametric model with improved correlation (r = 0.74), suggesting that each sequence offers different and complementary information.

CONCLUSIONS

Using localized biopsies, we have generated a model that illustrates a quantitative and significant relationship between MR signal and cell density. Projecting this relationship over the entire tumor volume allows mapping of the intratumoral heterogeneity in both the contrast-enhancing tumor core and nonenhancing margins of glioblastoma and may be used to guide extended surgical resection, localized biopsies, and radiation field mapping.

Efficacy and outcomes of facial nerve-sparing treatment approach to cerebellopontine angle meningiomas

OBJECTIVE Advanced microsurgical techniques contribute to reduced morbidity and improved surgical management of meningiomas arising within the cerebellopontine angle (CPA). However, the goal of surgery has evolved to preserve the quality of the patient's life, even if it means leaving residual tumor. Concurrently, Gamma Knife radiosurgery (GKRS) has become an acceptable and effective treatment modality for newly diagnosed, recurrent, or progressive meningiomas of the CPA. The authors review their institutional experience with CPA meningiomas treated with GKRS, surgery, or a combination of surgery and GKRS. They specifically focus on rates of facial nerve preservation and characterize specific anatomical features of tumor location with respect to the internal auditory canal (IAC). METHODS Medical records of 76 patients with radiographic evidence or a postoperative diagnosis of CPA meningioma, treated by a single surgeon between 1992 and 2016, were retrospectively reviewed. Patients with CPA meningiomas smaller than 2.5 cm in greatest dimension were treated with GKRS, while patients with tumors 2.5 cm or larger underwent facial nerve-sparing microsurgical resection where appropriate. Various patient, clinical, and tumor data were gathered. Anatomical features of the tumor origin as seen on preoperative imaging confirmed by intraoperative investigation were evaluated for prognostic significance. Facial nerve preservation rates were evaluated. RESULTS According to our treatment paradigm, 51 (67.1%) patients underwent microsurgical resection and 25 (32.9%) patients underwent GKRS. Gross-total resection (GTR) was achieved in 34 (66.7%) patients, and subtotal resection (STR) in 17 (33.3%) patients. Tumors recurred in 12 (23.5%) patients initially treated surgically, requiring additional surgery and/or GKRS. Facial nerve function was unchanged or improved in 68 (89.5%) patients. Worsening facial nerve function occurred in 8 (10.5%) patients, all of whom had undergone microsurgical resection. Upfront treatment with GKRS for CPA meningiomas smaller than 2.5 cm was associated with preservation of facial nerve function in all patients over a median follow-up of 46 months, regardless of IAC invasion and tumor origin. Anatomical origin was associated with extent of resection but did not correlate with postoperative facial nerve function. Tumor size, extent of resection, and the presence of an arachnoid plane separating the tumor and the contents of the IAC were associated with postoperative facial nerve outcomes. CONCLUSIONS CPA meningiomas remain challenging lesions to treat, given their proximity to critical neurovascular structures. GKRS is a safe and effective option for managing CPA meningiomas smaller than 2.5 cm without associated mass effect or acute neurological symptoms. Maximal safe resection with preservation of neurological function can be performed for tumors 2.5 cm or larger without significant risk of facial nerve dysfunction, and, when combined with GKRS for recurrence and/or progression, provides excellent disease control. Anatomical features of the tumor origin offer critical insights for optimizing facial nerve preservation in this cohort.

Timing of Adjuvant Radiotherapy in Glioblastoma Patients: A Single-Institution Experience With More Than 400 Patients

BACKGROUND

The standard of care for patients with newly diagnosed glioblastoma (GBM) is maximal safe resection followed by adjuvant radiation therapy (RT) and temozolomide (TMZ).

OBJECTIVE

To investigate whether the timing of adjuvant RT after surgery affected outcome in patients with GBM.

METHODS

We retrospectively reviewed all patients with a diagnosis of GBM at our institution. A total of 447 patients were included in our analysis. Patients were divided into 3 equal groups based on the interval between surgery and RT. The primary outcome was overall survival (OS).

RESULTS

Patients who began RT less than 21 days after surgery tended to be older, have a lower a Karnofsky Performance Status score, and higher recursive partitioning analysis class. These patients were more likely to have undergone biopsy only and received 3-dimensional conformal RT or 2-dimensional RT. The median OS for patients who started RT less than 21 days after surgery, between 21 and 32 days after surgery, and more than 32 days after surgery was 374, 465, and 478 days, respectively (P = .004). On multivariate Cox regression analysis, Karnofsky Performance Status score lower than 70, undergoing biopsy only, recursive partitioning analysis classes IV and V/VI, use of less than 36 Gy RT, and lack of TMZ chemotherapy were predictors of worse OS. The interval between surgery and RT was not significantly associated with OS on multivariate analysis.

CONCLUSION

Patients who begin RT less than 21 days after surgery tend to have worse prognostic factors than those who begin RT later. When accounting for significant covariates, the effect of timing between surgery and RT is not significant.

Aggressive resection at the infiltrative margins of glioblastoma facilitated by intraoperative fluorescein guidance

OBJECTIVE Extent of resection is an important prognostic factor in patients undergoing surgery for glioblastoma (GBM). Recent evidence suggests that intravenously administered fluorescein sodium associates with tumor tissue, facilitating safe maximal resection of GBM. In this study, the authors evaluate the safety and utility of intraoperative fluorescein guidance for the prediction of histopathological alteration both in the contrast-enhancing (CE) regions, where this relationship has been established, and into the non-CE (NCE), diffusely infiltrated margins. METHODS Thirty-two patients received fluorescein sodium (3 mg/kg) intravenously prior to resection. Fluorescence was intraoperatively visualized using a Zeiss Pentero surgical microscope equipped with a YELLOW 560 filter. Stereotactically localized biopsy specimens were acquired from CE and NCE regions based on preoperative MRI in conjunction with neuronavigation. The fluorescence intensity of these specimens was subjectively classified in real time with subsequent quantitative image analysis, histopathological evaluation of localized biopsy specimens, and radiological volumetric assessment of the extent of resection. RESULTS Bright fluorescence was observed in all GBMs and localized to the CE regions and portions of the NCE margins of the tumors, thus serving as a visual guide during resection. Gross-total resection (GTR) was achieved in 84% of the patients with an average resected volume of 95%, and this rate was higher among patients for whom GTR was the surgical goal (GTR achieved in 93.1% of patients, average resected volume of 99.7%). Intraoperative fluorescein staining correlated with histopathological alteration in both CE and NCE regions, with positive predictive values by subjective fluorescence evaluation greater than 96% in NCE regions. CONCLUSIONS Intraoperative administration of fluorescein provides an easily visualized marker for glioma pathology in both CE and NCE regions of GBM. These findings support the use of fluorescein as a microsurgical adjunct for guiding GBM resection to facilitate safe maximal removal.

The Energy Index Does Not Affect Local Control of Brain Metastases Treated by Gamma Knife Stereotactic Radiosurgery

BACKGROUND

The energy index (EI) is a measure of dose homogeneity within a target volume calculated by the integral dose divided by the product of prescription dose and tumor volume.

OBJECTIVE

To assess whether a higher EI is associated with greater local control for brain metastases (BMs) treated by Gamma Knife radiosurgery (GKRS).

METHODS

We reviewed all patients treated with GKRS for BM at our institution between January 2009 and February 2014. Data on the prescription dose, prescription isodose line, minimum dose, mean dose, integral dose, tumor volume, and EI were collected. Tumor response was assessed by reviewing follow-up brain imaging studies and classified according to the Response Evaluation Criteria in Solid Tumors. Local control per lesion and dosimetric prognostic factors for local control were assessed by univariate and multivariate Cox proportional hazards regression analyses.

RESULTS

Of 213 patients treated, 126 had follow-up imaging available with a median follow-up of 6 months. Three hundred seventy-three individual tumors were analyzed. Of these, 133 showed a complete response, 157 showed a partial response, 46 remained stable, and 37 developed local failure. Tumors with EI ≥1.6 mJ·mL(-1)·Gy(-1) showed a higher rate of complete response. Local control rates at 6, 11, and 17 months were 95.4%, 86.5%, and 81.5%, respectively. On univariate analysis, the following factors were associated with higher rates of local failure: prescription doses of 16 and 18 Gy compared with a prescription dose of 20 Gy. The following factors were associated with a greater rate of local control: maximum dose and mean dose. On multivariate analysis, the only statistically significant factor associated with a greater rate of local failure was prescription dose of 16 Gy compared with 20 Gy.

CONCLUSION

GKRS for BM results in a high rate of local control with an 11-month rate of 86.5%. A higher EI was not significantly associated with a higher rate of local control on multivariate analysis. Prescription dose was found to be the only significant predictor of local control on multivariate analysis.

A Modern Radiotherapy Series of Survival in Hispanic Patients with Glioblastoma

BACKGROUND

Studies have shown racial differences in cancer outcomes. We investigate whether survival differences existed in Hispanic patients with glioblastoma (GBM) compared with other ethnicities from our modern radiotherapy series, because no study to date has focused on outcomes in this group after radiation therapy.

METHODS

We retrospectively evaluated 428 patients diagnosed with GBM from 1996 to 2014 at our institution, divided into 4 groups based on self-report: white, black, Hispanic, and Asian/Indian. The primary outcome was overall survival. We analyzed differences in prognostic factors among the whole cohort compared with the Hispanic cohort alone.

RESULTS

Baseline characteristics of the 4 racial groups were comparable. With a median follow-up of 387 days, no survival differences were seen by Kaplan-Meier analysis. Median overall survival for Hispanic patients was 355 days versus 450 days for the entire cohort. Factors significant for patient outcomes in the entire cohort differed slightly from those specific to Hispanic patients. Low Karnofsky Performance Status was significant on multivariate analysis in the whole population, but not in Hispanic patients. Extent of resection, recursive partitioning analysis class, and radiation therapy total dose were significant on multivariate analysis in both the whole population and Hispanic patients.

CONCLUSIONS

We found that Hispanic patients with GBM had no difference in survival compared with other ethnicities in our cohort. Differences exist in factors associated with outcomes on single and multivariate analysis for Hispanic patients with GBM compared with the entire cohort. Additional studies focusing on Hispanic patients will aid in more personalized treatment approaches in this group.

Hypofractionated radiation therapy versus standard fractionated radiation therapy with concurrent temozolomide in elderly patients with newly diagnosed glioblastoma

PURPOSE

Adjuvant hypofractionated radiation therapy (HRT) for elderly patients with newly diagnosed glioblastoma (GBM) is a reasonable option compared with standard fractionation radiation therapy (SFRT). Outcomes in patients receiving HRT in the presence of temozolomide (TMZ) compared with SFRT with TMZ are unclear. We examined HRT for GBM with TMZ in comparison to SFRT with TMZ.

METHODS AND MATERIALS

We conducted a retrospective analysis of patients ≥60 years of age with newly diagnosed GBM who received SFRT or HRT from 1994 to 2014 in the postoperative setting. Inclusion criteria included SFRT (60 Gy/30 fractions or 59.4 Gy/33 fractions) versus HRT (40 Gy/15 fractions).

RESULTS

In this cohort, 158 patients were treated with SFRT versus 26 with HRT. Median survival in patients receiving SFRT compared with HRT was 430 and 475 days (P = .550), respectively. Ninety-five percent of the SFRT patients received TMZ versus 100% of those treated with HRT. Patients receiving HRT were older (median, 72 vs 66 years). All HRT patients were treated with the intensity modulated radiation therapy (IMRT) technique versus SFRT, in which 57% had IMRT. Multivariate Cox regression showed decreased overall survival (OS) associated with patient age >70 (hazard ratio [HR], 1.84), lower Karnofsky performance status (HR, 5.25), biopsy versus surgical resection (HR, 4.18), radiation therapy planning technique 3- or 2-dimensional planning versus IMRT (HR, 1.91; HR, 3.40, respectively). Analysis restricted to patients receiving IMRT-based planning showed no difference in OS between HRT and SFRT. For patients receiving TMZ, there was no survival difference between those treated with HRT and those treated with SFRT.

CONCLUSIONS

Elderly GBM patients receiving HRT and those receiving SFRT had similar OS. Subset analysis patients receiving concurrent TMZ showed no difference in OS between the HRT and SFRT groups.

Breast cancer subtype as a predictor for outcomes and control in the setting of brain metastases treated with stereotactic radiosurgery

We investigated effects of breast cancer subtype on overall survival (OS), local and distant control, and time from initial diagnosis to brain metastases (BM). We also investigated advances in graded prognostic assessment (GPA) scores. A cohort of 72 patients treated for BM from breast cancer with Gamma Knife stereotactic radiosurgery at our institution from 2000 to 2014 had subtyping available and were used for this study. Median follow up for OS was 12 months and for control was 6 months. OS for luminal, HER2, and triple negative subtypes were 26, 20, and 22 months. OS when stratified by Sperduto et al. (J Clin Oncol 30(4):419-425, 2012) and Subbiah et al. (J Clin Oncol 33(20):2239-2245, 2015) GPAs were similar (p = 0.087 and p = 0.063). KPS and treatment modality were significant for OS (p = 0.002; p = 0.034). On univariate analysis, triple negative subtype and >3 BM were trending and significant for decreased OS (p = 0.084; p = 0.047). On multivariable analysis HER2, triple negative, and >3 BM were significant for OS (p = 0.022; p = 0.040; p = 0.009). Subtype was significant for response on a per lesion basis (p = 0.007). Subtype was trending towards significance when analyzing time from initial diagnosis to BM treatment (p = 0.064). Breast cancer subtype is an important prognostic factor when stratifying breast cancer patients with BM. The addition of number of BM to the GPA is a useful addition and should be further investigated. Subtype has an effect on lesion response, and also on rate of development BM after initial diagnosis.

Control of brain metastases from radioresistant tumors treated by stereotactic radiosurgery

Renal cell carcinoma, sarcoma, and melanoma are considered to be "radioresistant" tumor histologies. Brain metastases (BM) from these tumors are considered unlikely to be controlled using the relatively low doses used in whole brain radiotherapy (WBRT). Our objective was to analyze the efficacy of stereotactic radiosurgery (SRS) on local control and overall survival of BM from radioresistant primary tumors. We reviewed all patients who received Gamma Knife Radiosurgery (GKRS) for BM at Columbia University Medical Center between January 2009 and April 2014. All patients were treated using the Gamma Knife Perfexion System. Dosimetric data was collected from treatment plans and metastases were categorized as radioresistant or not. Response was assessed by reviewing follow-up brain imaging studies and classified according to RECIST. Local control and median overall survival were calculated using the Kaplan-Meier method. In total, 373 tumors were analyzed from 126 patients. Of these tumors, 49 (13.1 %) originated from radioresistant cancers. The overall local control rate in the radioresistant cohort was 89.8 and 90.1 % in the non-radioresistant cohort. Univariate and multivariate analyses demonstrated that radioresistance status of the primary tumor had no statistically significant effect on local control with hazard ratios of 1.0 (p = 1.0, 95 % CI 0.388-2.576) and 0.954 (p = 0.926, 95 % CI 0.349-2.603) respectively. Median overall survival for both radioresistant and non-radioresistant cohorts was 20.0 months, with a p value of 0.926. There was no significant difference in local control of BM from radioresistant and non-radioresistant primary tumors treated with GKRS. Both cohorts showed excellent response and local control, suggesting that SRS upfront or in addition to WBRT may be an appropriate strategy in the treatment of BM from radioresistant cancers. Median overall survival for both cohorts was equal, suggesting that improved local control may be associated with an improvement in long-term survival.