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Purpose: T2-FLAIR mismatch serves as a highly specific but insensitive marker for IDH-mutant (IDHm) astrocytoma with potential limitations in real-world application. We aimed to assess the utility of a broader definition of T2-FLAIR discordance across a cohort of adult-type diffuse lower-grade gliomas (LrGG) to see if specific patterns emerge and additionally examine factors determining deviation from the classic T2-FLAIR mismatch sign. Methods: Preoperative MRIs of non-enhancing adult-type diffuse LrGGs were reviewed. Relevant demographic, molecular, and MRI data were compared across tumor subgroups. Results: Eighty cases satisfied the inclusion criteria. Highest discordance prevalence and > 50% T2-FLAIR discordance volume were noted with IDHm astrocytomas (P < 0.001), while < 25% discordance volume was associated with oligodendrogliomas (P = 0.03) and IDH-wildtype (IDHw) LrGG (P = 0.004). "T2-FLAIR matched pattern" was associated with IDHw LrGG (P < 0.001) and small or minimal areas of discordance with oligodendrogliomas (P = 0.03). Sensitivity and specificity of classic mismatch sign for IDHm astrocytoma were 25.7% and 100%, respectively (P = 0.06). Retained ATRX expression and/or non-canonical IDH mutation (n = 10) emerged as a significant factor associated with absence of classic T2-FLAIR mismatch sign in IDHm astrocytomas (100%, P = 0.02) and instead had minimal discordance or matched pattern (40%, P = 0.04). Conclusion: T2-FLAIR discordance patterns in adult-type diffuse LrGGs exist on a diverging but distinct spectrum of classic mismatch to T2-FLAIR matched patterns. Specific molecular markers may play a role in deviations from classic mismatch sign. [ABSTRACT FROM AUTHOR]

Purpose: Recurrent high-grade glioma (rHGG) is a heterogeneous population, and the ideal patient selection for re-irradiation (re-RT) has yet to be established. This study aims to identify prognostic factors for rHGG patients treated with re-RT. Methods: We retrospectively reviewed consecutive adults with rHGG who underwent re-RT from 2009 to 2020 from our institutional database. The primary objective was overall survival (OS). Secondary endpoints included prognostic factors for early death (< 6 months after re-RT) and predictors of radiation necrosis (RN). Results: For the 79 patients identified, the median OS after re-RT was 9.9 months (95% CI 8.3–11.6). On multivariate analyses, re-resection at progression (HR 0.56, p = 0.027), interval from primary treatment to first progression ≥ 16.3 months (HR 0.61, p = 0.034), interval from primary treatment to re-RT ≥ 23.9 months (HR 0.35, p < 0.001), and re-RT PTV volume < 112 cc (HR 0.27, p < 0.001) were prognostic for improved OS. Patients who had unmethylated-MGMT tumours (OR 12.4, p = 0.034), ≥ 3 prior systemic treatment lines (OR 29.1, p = 0.022), interval to re-RT < 23.9 months (OR 9.0, p = 0.039), and re-RT PTV volume ≥ 112 cc (OR 17.8, p = 0.003) were more likely to die within 6 months of re-RT. The cumulative incidence of RN was 11.4% (95% CI 4.3–18.5) at 12 months. Concurrent bevacizumab use (HR < 0.001, p < 0.001) and cumulative equivalent dose in 2 Gy fractions (EQD2, α/β = 2) < 99 Gy2 (HR < 0.001, p < 0.001) were independent protective factors against RN. Re-RT allowed for less corticosteroid dependency. Sixty-six percent of failures after re-RT were in-field. Conclusion: We observe favorable OS rates following re-RT and identified prognostic factors, including methylation status, that can assist in patient selection and clinical trial design. Concurrent use of bevacizumab mitigated the risk of RN. [ABSTRACT FROM AUTHOR]

Introduction: Various treatment options exist to salvage stereotactic radiosurgery (SRS) failures for brain metastases, including repeat SRS and hypofractionated SRS (HSRS). Our objective was to report outcomes specific to salvage HSRS for brain metastases that failed prior HSRS/SRS. Methods: Patients treated with HSRS to salvage local failures (LF) following initial HSRS/SRS, between July 2010 and April 2020, were retrospectively reviewed. The primary outcomes were the rates of LF, radiation necrosis (RN), and symptomatic radiation necrosis (SRN). Univariable (UVA) and multivariable (MVA) analyses using competing risk regression were performed to identify predictive factors for each endpoint. Results: 120 Metastases in 91 patients were identified. The median clinical follow up was 13.4 months (range 1.1–111.1), and the median interval between SRS courses was 13.1 months (range 3.0–56.5). 115 metastases were salvaged with 20–35 Gy in 5 fractions and the remaining five with a total dose ranging from 20 to 24 Gy in 3-fractions. 67 targets (56%) were postoperative cavities. The median re-treatment target volume and biological effective dose (BED10) was 9.5 cc and 37.5 Gy, respectively. The 6- and 12- month LF rates were 18.9% and 27.7%, for RN 13% and 15.6%, and for SRN were 6.1% and 7.0%, respectively. MVA identified larger re-irradiation volume (hazard ratio [HR] 1.02, p = 0.04) and shorter interval between radiosurgery courses (HR 0.93, p < 0.001) as predictors of LF. Treatment of an intact target was associated with a higher risk of RN (HR 2.29, p = 0.04). Conclusion: Salvage HSRS results in high local control rates and toxicity rates that compare favorably to those single fraction SRS re-irradiation experiences reported in the literature. [ABSTRACT FROM AUTHOR]

Intracranial metastatic disease (IMD) complicates the course of nearly 2–4% of patients with systemic cancer. The prevalence of IMD has been increasing over the past few decades. Historically, definitive treatment for brain metastases (BM) has been limited to radiation therapy or surgical resection. Chemotherapies have not typically proven valuable in the treatment of IMD, with the exception of highly chemotherapy-sensitive lesions. Recent data have supported a role for systemic targeted therapies and immune checkpoint inhibitors (ICIs) in the treatment of select patients with IMD. There remains, however, a clear clinical need for further investigation to delineate the role of ICIs in patients with BM. In this review, we outline and describe recent and current efforts to identify the efficacy of ICI therapy in patients with IMD. [ABSTRACT FROM AUTHOR]

Purpose: The incidence of intracranial metastatic disease (IMD) in patients with gastrointestinal (GI) cancers is rising. Expression of the erythroblastic oncogene B-2 (ERBB2) is associated with an in increased risk of IMD in patients with breast cancer. The implications of ERBB2 expression for IMD risk in patients with GI cancers is less clear. The objective of this systematic review was to determine the incidence of IMD and OS in patients with ERBB2+ gastrointestinal cancers. Methods: A literature search of MEDLINE, EMBASE, CENTRAL, and grey literature sources was conducted from date of database inception to July 2021. Included studies reported outcomes on patients with IMD secondary to ERBB2 GI cancers. Results: Fourteen cohort studies met inclusion criteria, of which thirteen were retrospective. Eleven studies reported on gastric, esophageal, or gastroesophageal junction cancers. Three studies directly compared incidence of IMD based on ERBB2 status and among these, ERBB2+ patients had a higher incidence of IMD. One study indicated that ERBB2+ patients had significantly longer OS from the times of primary cancer (P =.015) and IMD diagnosis (P =.01), compared with patients with ERBB2− disease. Conclusions: In this systematic review, patients with ERBB2+ GI cancer were more likely to develop IMD. Future study is required on the prognostic and predictive value of ERBB2 status in patients with GI cancers. [ABSTRACT FROM AUTHOR]

Objective: Gamma Knife Icon-based hypofractionated stereotactic radiosurgery (GKI-HSRS) is a novel technical paradigm in the treatment of brain metastases that allows for both the dosimetric benefits of the GKI stereotactic radiosurgery (SRS) platform as well as the biologic benefits of fractionation. We report mature local control and adverse radiation effect (ARE) outcomes following 5 fraction GKI-HSRS for intact brain metastases. Methods: Patients with intact brain metastases treated with 5-fraction GKI-HSRS were retrospectively reviewed. Survival, local control, and adverse radiation effect rates were determined. Univariable and multivariable regression (MVA) were performed on potential predictive factors. Results: Two hundred and ninety-nine metastases in 146 patients were identified. The median clinical follow-up was 10.7 months (range 0.5–47.6). The median total dose and prescription isodose was 27.5 Gy (range, 20–27.5) in 5 daily fractions and 52% (range, 45–93), respectively. The median overall survival (OS) was 12.7 months, and the 1-year local failure rate was 15.2%. MVA identified a total dose of 27.5 Gy vs. ≤ 25 Gy (hazard ratio [HR] 0.59, p = 0.042), and prior chemotherapy exposure (HR 1.99, p = 0.015), as significant predictors of LC. The 1-year ARE rate was 10.8% and the symptomatic ARE rate was 1.8%. MVA identified a gross tumor volume of ≥ 4.5 cc (HR 7.29, p < 0.001) as a significant predictor of symptomatic ARE. Conclusion: Moderate total doses in 5 daily fractions of GKI-HSRS were associated with high rates of LC and a low incidence of symptomatic ARE. [ABSTRACT FROM AUTHOR]

Purpose: The concept of a radioresistant (RR) phenotype has been challenged with use of stereotactic body radiotherapy (SBRT). We compared outcomes following SBRT to RR spinal metastases to a radiosensitive cohort. Methods: Renal cell, melanoma, sarcoma, gastro-intestinal, and thyroid spinal metastases were identified as RR and prostate cancer (PCA) as radiosensitive. The primary endpoint was MRI-based local failure (LF). Secondary endpoints included overall survival (OS) and vertebral compression fracture (VCF). Results: From a prospectively maintained database of 1394 spinal segments in 605 patients treated with spine SBRT, 173 patients/395 RR spinal segments were compared to 94 patients/185 PCA segments. Most received 24–28 Gy in 2 fractions (68.9%) and median follow-up was 15.5 months (range, 1.4–84.2 months). 1- and 2-year LF rates were 19.2% and 22.4% for RR metastases, respectively, which were significantly greater (p < 0.001) than PCA (3.2% and 8.4%, respectively). Epidural disease (HR: 2.47, 95% CI 1.65–3.71, p < 0.001) and RR histology (HR: 2.41, 95% CI 1.45–3.99, p < 0.001) predicted for greater LF. Median OS was 17.4 and 61.0 months for RR and PCA cohorts, respectively. Lung/liver metastases, polymetastatic disease and epidural disease predicted for worse OS. 2-year VCF rates were ~ 13% in both cohorts. Coverage of the CTV V90 (clinical target volume receiving 90% of prescription dose) by ≥ 87% (HR: 2.32, 95% CI 1.29–4.18, p = 0.005), no prior spine radiotherapy (HR: 1.96, 95% CI 1.09–3.55, p = 0.025), and a greater Spinal Instability Neoplasia Score (p = 0.013) predicted for VCF. Conclusions: Higher rates of LF were observed after spine SBRT in RR metastases. Optimization strategies include dose escalation and aggressive management of epidural disease. [ABSTRACT FROM AUTHOR]

Purpose: Quantitative MRI (qMRI) was performed using a 1.5T protocol that includes a novel chemical exchange saturation transfer/magnetization transfer (CEST/MT) approach. The purpose of this prospective study was to determine if qMRI metrics at baseline, at the 10th and 20th fraction during a 30 fraction/6 week standard chemoradiation (CRT) schedule, and at 1 month following treatment could be an early indicator of response for glioblastoma (GBM). Methods: The study included 51 newly diagnosed GBM patients. Four regions-of-interest (ROI) were analyzed: (i) the radiation defined clinical target volume (CTV), (ii) radiation defined gross tumor volume (GTV), (iii) enhancing-tumor regions, and (iv) FLAIR-hyperintense regions. Quantitative CEST, MT, T1 and T2 parameters were compared between those patients progressing within 6.9 months (early), and those progressing after CRT (late), using mixed modelling. Exploratory predictive modelling was performed to identify significant predictors of early progression using a multivariable LASSO model. Results: Results were dependent on the specific tumor ROI analyzed and the imaging time point. The baseline CEST asymmetry within the CTV was significantly higher in the early progression cohort. Other significant predictors included the T2 of the MT pools (for semi-solid at fraction 20 and water at 1 month after CRT), the exchange rate (at fraction 20) and the MGMT methylation status. Conclusions: We observe the potential for multiparametric qMRI, including a novel pulsed CEST/MT approach, to show potential in distinguishing early from late progression GBM cohorts. Ultimately, the goal is to personalize therapeutic decisions and treatment adaptation based on non-invasive imaging-based biomarkers. [ABSTRACT FROM AUTHOR]

Introduction: This study proposes contouring recommendations for radiation treatment planning target volumes and organs-at-risk (OARs) for both low grade and high grade gliomas. Methods: Ten cases consisting of 5 glioblastomas and 5 grade II or III gliomas, including their respective gross tumor volume (GTV), clinical target volume (CTV), and OARs were each contoured by 6 experienced neuro-radiation oncologists from 5 international institutions. Each case was first contoured using only MRI sequences (MRI-only), and then re-contoured with the addition of a fused planning CT (CT-MRI). The level of agreement among all contours was assessed using simultaneous truth and performance level estimation (STAPLE) with the kappa statistic and Dice similarity coefficient. Results: A high level of agreement was observed between the GTV and CTV contours in the MRI-only workflow with a mean kappa of 0.88 and 0.89, respectively, with no statistically significant differences compared to the CT-MRI workflow (p = 0.88 and p = 0.82 for GTV and CTV, respectively). Agreement in cochlea contours improved from a mean kappa of 0.39 to 0.41, to 0.69 to 0.71 with the addition of CT information (p < 0.0001 for both cochleae). Substantial to near perfect level of agreement was observed in all other contoured OARs with a mean kappa range of 0.60 to 0.90 in both MRI-only and CT-MRI workflows. Conclusions: Consensus contouring recommendations for low grade and high grade gliomas were established using the results from the consensus STAPLE contours, which will serve as a basis for further study and clinical trials by the MR-Linac Consortium. [ABSTRACT FROM AUTHOR]

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Purpose: Radiation-induced pseudoprogression is a subacute clinical entity that is distinct from radiation necrosis and mimics tumor progression. Bevacizumab is a well-described treatment option for radiation necrosis, but its role in pseudoprogression is not clearly defined. Methods: We report a case of radiation-induced pseudoprogression rescued with bevacizumab in a 20-year-old man with a biopsy-proven low-grade astrocytoma of the tectum. A review of the literature was also conducted specific to bevacizumab as a treatment for symptomatic pseudoprogression after radiotherapy for CNS tumors. Results: This patient was treated with definitive intensity modulated stereotactic radiotherapy at a total dose of 54 Gy delivered in 30 daily fractions. Six weeks after radiotherapy the patient developed progressive headache, weakness and a documented deterioration in vision, which was accompanied by worsening of radiographic findings. A diagnosis of pseudoprogression was made and after limited benefit from a trial of dexamethasone, four cycles of bevacizumab were administered which resulted in rapid clinical and radiographic improvement. Conclusions: Our findings support the potential use of bevacizumab as a rescue agent for symptomatic pseudoprogression. [ABSTRACT FROM AUTHOR]

With emerging innovations in artificial intelligence (AI) poised to substantially impact medical practice, interest in training current and future physicians about the technology is growing. Alongside comes the question of what, precisely, should medical students be taught. While competencies for the clinical usage of AI are broadly similar to those for any other novel technology, there are qualitative differences of critical importance to concerns regarding explainability, health equity, and data security. Drawing on experiences at the University of Toronto Faculty of Medicine and MIT Critical Data's "datathons", the authors advocate for a dual-focused approach: combining robust data science-focused additions to baseline health research curricula and extracurricular programs to cultivate leadership in this space. [ABSTRACT FROM AUTHOR]

Purpose: Anesthetic and surgical considerations for awake craniotomy (AC) include airway patency, patient comfort, and optimization of real-time brain mapping. The purpose of this study is to report our experience of using dexmedetomidine and scalp blocks, without airway intervention, as a means to facilitate and optimize intraoperative brain mapping and brain tumour resection during AC.Methods: We conducted a retrospective cohort study of 55 patients who underwent AC from March 2012 to September 2016. The incidence of critical airway outcomes, perioperative complications, and successful intraoperative mapping was determined. The primary outcome was the incidence of a failed AC anesthetic technique as defined by the need to convert to general anesthesia with a secured airway prior to (or during) brain mapping and brain tumour resection. Secondary outcomes were the intraoperative incidence of: 1) altered surgical management due to information acquired through real-time brain mapping, 2) interventions to restore airway patency or rescue the airway, 3) hemodynamic instability (> 20% from baseline), 4) nausea and vomiting, 5) new onset neurologic deficits, and 6) seizure activity.Results: There were no anesthesia-related critical events and no patients required airway manipulation or conversion to a general anesthetic. Multimodal language, motor, and sensory assessment with direct cortical electrical stimulation was successfully performed in 100% of cases. In 24% (13/55) of patients, data acquired during intraoperative brain mapping influenced surgical decision-making regarding the extent of tumour resection. Nine (16%) patients had intraoperative seizures.Conclusions: Dexmedetomidine-based anesthesia and scalp block facilitated AC surgery without any requirement for urgent airway intervention or unplanned conversion to a full general anesthetic. This approach can enable physiologic testing before and during tumour resection facilitating real-time surgical decision-making based on intraoperative brain mapping with patients awake thereby minimizing the risk of neurologic deficit and increasing the opportunity for optimal surgical resection. [ABSTRACT FROM AUTHOR]

Driving is a complex task that requires integration of various skills that may be impaired in patients with brain tumours. Determining fitness to drive is a responsibility of all physicians in Canada; however, it is an inconsistent practice based on few objective guidelines. The primary purpose of the study is to determine the consistency of driving recommendations amongst health care professionals in Ontario. Secondary aims include evaluation of physician awareness of driving regulations and determination of whether physicians would benefit from more specific driving guidelines. An 18-item questionnaire was sent to 126 health care professionals who take care of patients with brain tumours in Ontario. Seventy-five health care professionals responded to the survey. Less than 10% said they could reliably determine fitness to drive and almost an equal percentage of respondents indicated that determining fitness to drive should be a shared responsibility. The factors deemed important in determining driving safety were highly variable; 70% indicated that cognitive and emotional deficits were important. Over a third of respondents never heard of the CMA guidelines and of those who were familiar with it, 12.5% felt they were sufficient to inform clinical decisions. 90% of respondents wanted more specific and detailed driving guidelines for patients with brain tumours. The current guidelines for physicians are not specific enough for physicians to confidently determine fitness to drive in this population. These findings suggest the need for more detailed guidelines for driving safety that are based on empirical studies on driving habits and performance in patients with a variety of brain tumours. [ABSTRACT FROM AUTHOR]

Recurrence rates of meningiomas have been widely reported in the literature, but it remains challenging for clinicians to predict recurrence rate depending on treatment, patient demographics and tumor characteristics. To address these needs, we performed a systematic analysis of the literature to determine the recurrence rate ranges of meningiomas following surgery or radiation. Our search yielded 13 studies that met all criteria for inclusion, allowing us to include 1539 patients in the assessment. Recurrence rates ranged from 0.00 to 2.36 per 100-person-years for WHO grade I meningiomas; and from 7.35 to 11.46 per 100-person-years for WHO grade II meningiomas. Our findings suggest that (1) reported recurrence rates are variable and complicated by the heterogeneity of study populations; (2) as expected, WHO grade II meningiomas generally have a higher recurrence rate than WHO grade I, when controlling for time of diagnosis (by employing person-years); and (3) there is a need for more rigorous reporting of recurrence rates, WHO grade, and Simpson grading for individual patients in order to determine a robust mean of recurrence across WHO grades. [ABSTRACT FROM AUTHOR]

Opinion Statement: Newly diagnosed elderly patients (age > 65-70 years) with glioblastoma should be treated with a patient-centred approach by a multi-disciplinary team. Chronological age alone should not be considered as a contraindication to treatment with maximal safe surgical resection. A 3-week course of adjuvant radiation and chemotherapy is appropriate in selected elderly patients with favourable Karnofsky performance status (KPS) who cannot tolerate a longer 6-week course of fractionated radiotherapy. The presence or absence of 06-methylguanine-DNA methyltransferase (MGMT) promoter methylation can be used to guide clinical decision-making as both prognostic and predictive biomarkers. This review provides an update and summary of the available evidence for treating newly diagnosed elderly patients with glioblastoma. [ABSTRACT FROM AUTHOR]

Seizures have considerable impact on a patient's quality of life. While guidelines have been articulated to direct clinicians in their management of patients with IMD who suffer from seizure, there have been few attempts to identify the seizure rate in IMD and to determine which primary cancers may be associated with an increased seizure incidence. To determine the incidence of seizure in patients with IMD. A systematic review on seizure incidence in patients with IMD from the magnetic resonance imaging (MRI) era was performed. Articles published between January 2000 and July 2014 with thirty or more consecutive adult patients were included in this study. Seizure rate was calculated using a pooled data analysis. Differences between observed and expected seizure rates between primary tumour sites were examined using the Chi square statistic and adjusted standardized residuals. The systematic search produced 18 relevant studies, with a total study population of 2012 patients. 14.6% (n = 294) had seizures. There was a significant association between primary tumour site and seizure rates. The seizure rate in patients with primary melanoma tumours was significantly greater than expected ( z = 2.7; p = .006). The seizure rate in patients with primary prostate tumours was significantly lower than expected ( z = −2.6; p = .008). Patients with intracranial metastasis are at significant risk for developing seizure, though at a significantly lower incidence than was estimated by studies performed during the CT era. Seizure rates appear to be greater in certain primary tumours, such as melanoma. [ABSTRACT FROM AUTHOR]

The Sundarbans is the world's largest contiguous mangrove ecosystem. Recent changes in the region have been reported due to a rise in relative sea level along with increased salinity intrusion. Intertidal benthic foraminifera are widely used as indicators of relative sea level change. The taxonomic diversity of foraminifera in the Sundarbans remains relatively understudied due to the remoteness of this ecoregion. The present study documented modern intertidal benthic foraminiferal assemblages across eight sites from previously unexplored eastern parts of the Indian Sundarbans. We also analyzed sediment texture from the study sites, which is essential for sea level reconstructions. Our study recorded an assemblage dominated by agglutinated genera that are characteristic of mangroves globally. However, we also recorded calcareous genera characteristic of higher-salinity zones, indicating saline intrusion further upstream in the region. In total, we recorded 15 species, representing ten different foraminiferal families. Total organic carbon (TOC) content and sediment composition showed variation across the studied sites. Canonical correspondence analysis (CCA) of the biological and environmental data confirmed its usefulness for understanding shifts in hydrological conditions across this region. [ABSTRACT FROM AUTHOR]

Glioblastoma is the most common and deadly type of brain cancer. Over the past decade, several divergent genetic pathways have been implicated in the initiation, progression and clinical outcome of this disease. As our understanding of GBM expands and identifies actionable targets specific to individual tumors, there will be a pressing need for the development of new tools that will maximize the use of limited clinical samples to enable the employment of personalized care paradigms. We used PrimePCR validated assays to generate a custom real-time PCR screening panel, containing 74 previously published mRNA targets showing gene expression changes in glioblastoma, and five house-keeping genes. A cohort of 19 frozen brain specimens were analyzed, including WHO Grade II oligodendroglioma (n = 3), WHO Grade II astrocytoma (n = 2), WHO Grade III astrocytoma (n = 1), and glioblastoma (n = 13). Four normal brain samples were also analyzed. We performed RNA extraction, followed by cDNA synthesis, multiplexed pre-amplification and SYBR-based qPCR, to generate expression profiles on all samples. We demonstrated that the workflow shows high tolerance to variation in RNA quality (RIN 8.5-4) and high sensitivity in detection. cDNA input that is equivalent to 3 ng of starting RNA was sufficient to conduct accurate semiquantitative analysis of the panel of 79 assays. Using principal component analysis, we were able to accurately separate glioblastoma from low-grade glioma. The two WHO Grade III tumors analyzed clustered with glioblastoma, but showed more similarity to Grade II gliomas. In this study, we have shown the feasibility of consolidating high-throughput data into a single functional panel capable of accurately classifying glioma specimens based solely on semiquantitative gene expression profiling. [ABSTRACT FROM AUTHOR]

Glioblastoma is the most common primary brain tumour in adults. While many patients achieve disease remission following treatment with surgical resection, radiation therapy and chemotherapy, this remission is brief and invariably followed by tumour recurrence and progression. Recent work using mouse models of the disease, coupled with data generated by The Cancer Genome Atlas, have given us new insights into the mechanisms that underlie gliomagenesis and result in glioblastoma heterogeneity. These findings suggest that the treatment of glioblastoma will require a more nuanced understanding of their biology and the employment of targeted therapeutic approaches. In this review, we will summarize the current state of mouse modeling in glioma, with a focus on how these models may inform our understanding of this disease and its treatment. [ABSTRACT FROM AUTHOR]

Opinion Statement: Primary brain tumors account for a minor fraction of cancer diagnoses made worldwide and remain one of the most difficult to treat. Despite ongoing efforts to improve the quality of life and overall survival of these patients, current multimodality therapy has achieved only modest gains; the median survival is approximately 14 months among patients with the deadliest form of primary brain tumor, glioblastoma multiforme. Although the brain has been long considered an immunologically privileged organ, there is increased awareness of and appreciation for the complex interplay between the nervous system and the immune system in the setting of many disease states, including neoplastic. Although the concept of harnessing the specificity, activity, and memory of the immune system toward the treatment of brain tumors has been in existence for several decades and the neuro-oncology literature holds many publications that once promised of a breakthrough, only recently has a strategy emerged that addresses many of the limitations identified through past failures. It is with cautious optimism that the authors review the past and discuss the present status of immunotherapy and its role in the management of patients with primary brain tumors. [ABSTRACT FROM AUTHOR]

Despite advances in therapy, glioblastoma remains an incurable disease with a dismal prognosis. Recent studies have implicated cancer stem cells within glioblastoma (glioma stem cells, GSCs) as mediators of therapeutic resistance and tumor progression. In this study, we investigated the role of the transforming growth factor-β (TGF-β) superfamily, which has been found to play an integral role in the maintenance of stem cell homeostasis within multiple stem cell systems, as a mediator of stem-like cells in glioblastoma. We find that BMP and TGF-β signaling define divergent molecular and functional identities in glioblastoma, and mark relatively quiescent and proliferative GSCs, respectively. Treatment of GSCs with BMP inhibits cell proliferation, but does not abrogate their stem-ness, as measured by self-renewal and tumorigencity. Further, BMP pathway activation confers relative resistance to radiation and temozolomide chemotherapy. Our findings define a quiescent cancer stem cell population in glioblastoma that may be a cellular reservoir for tumor recurrence following cytotoxic therapy. [ABSTRACT FROM AUTHOR]