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Δευτέρα 5 Σεπτεμβρίου 2022

P18.11.A Active beam scanning proton therapy for large skull base benign meningiomas: long-term results

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Abstract
Purpose
To report long-term results of active beam scanning proton therapy (PT) for large skull base benign meningiomas
Material and Methods
Eighty-two patients (pts) with large skull base meningiomas were treated with PT between April 2015 and December 2021. Median age was 62 years (range, 48-82) while KPS ranged between 60 and 100 (median 90); 60 were female (73%), and 22 were male (27%). Thirty-two pts (39%) had histologically proven World Health Organization (WHO) Grade I tumors. In remaining pts diagnosis was based on the typical imaging appearance of benign meningioma. All patients received PT for residual, progressive or non-operable lesions. Newly diagnosed tumors received total dose of 50 GyRBE (RBE: relative biologic effectiveness) while progressing meningiomas 54 GyRBE. All the treatments were delivered at 2 GyRBE per fraction. All pts were treated with active beam scanning PT using 3 fields with single field optimiz ation technique. Treatment planning was based on morphological magnetic resonance imaging (MRI) with contrast enhancement medium administration. All pts received also 68-Ga-DOTATOC-PET. Gross tumor volume ranged from 21 to 64 cc. Toxicity was assessed according to Common Terminology Criteria for Adverse Events version 4.0. Median follow-up time was 40 months (range, 3-83).
Results
All pts completed the treatment without breaks. Registered acute side effects include grade 1 (19%) and grade 2 (8%) skin erythema, grade 1 (5%) and grade 2 (5%) alopecia, grade 1 (40%) fatigue, grade 1 (5%) and grade 2 (10%) conjunctivitis, grade 1 (10%) pain, grade 1 (5%) blurred vision, grade 1 (10%) headache, and grade 2 (5%) skin hyperpigmentation. One pts (1%) experienced grade 3 pain. There were no further grade 3 or higher acute toxicities. Registered late side effects include grade 1 (2%) and grade 2 (5%) alopecia, grade 1 (21%) fatigue, grade 1 (5%) and grade 2 (5%) headache, grade 1 (6% ) dizziness, grade 1 (3%) blurred vision, grade 1 (3%) and grade 2 (6%) pain, grade 1 (2%) dry eye, and grade 1 (5%) skin hyperpigmentation. Two pts (2%) experienced grade 3 pain. Two further pts (2%) experienced grade 3 optic neuropathy. There were no further grade 3 or higher late toxicities. During follow-up one pts (1%) with cavernous sinus meningioma experienced complete obstruction of intracavernous carotid artery with mild transient symptoms that resolved in few days and brain tissue ischemia detected at MRI (grade 2). Before irradiation this pts already had a meningioma-related near-complete obstruction of the intracavernous carotid artery and received a vascular surgery evaluation. Currently, absolute tumor control is 99%. Moreover, relief of symptoms recorded before irradiation occurred in 40% of pts.
Conclusion
PT is safe and effective treatment for pts with large skull base benign meningiomas.
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P03.05.A Radiation-induced leukoencephalopathy (RIL) in glioma: unique injury dynamics following proton vs photon beam radiotherapy

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Abstract
Background
White matter injury after brain-directed radiotherapy (RT), aka radiation-induced leukoencephalopathy (RIL), is common in brain tumor patients. Differentiation from progressive disease can be challenging. Dosimetric advantages of protons (PRT) over photons (XRT) minimize radiation to healthy brain tissue, potentially limiting radiotoxic sequelae including RIL. We characterized RIL during periods of progression-free survival (PFS) in glioma patients irradiated with either PRT or XRT, hypothesizing that PRT would result in reduced RIL outside of the target field.
Material and Methods
34 patients (19 male; mean age = 40.10y) with grade 2/3 gliomas and a history of partial cranial RT were stratified by RT modality [XRT (n=17) vs PRT (n=17)] and matched on 11 criteria [age, sex, tumor type/location/laterality, mutational status (IDH; 1p19q deletion), concurrent/adjuvant chemotherapy, radiation dose/fractions] for retrospe ctive analysis. RIL development was characterized longitudinally for up to 3 years post-RT via analysis of serial MRI T2/FLAIR sequences. A novel RIL scoring system with embedded Fazekas scale was designed to quantify injury severity at both global (whole brain) and hemispheric levels.
Results
Matched groups did not differ significantly on any demographic or clinical characteristics. Median PFS post-RT was 4.7 (XRT) and 5.1 (PRT) years. The novel RIL scoring system was reliable (intraclass correlation coefficient >0.9). There was a significant increase in global RIL in both XRT [F(3, 57)=8.63, p< .001] and PRT [F(3, 61)=4.69, p< .005] groups over time, relative to baseline (1-month post-RT). A majority [62% (XRT) and 72% (PRT)] developed moderate or severe RIL within 3 years, with the ipsilesional hemisphere more severely affected. Analysis of RIL injury dynamics (i.e., average % change between 1 and 3 years post-RT) at hemispheric level identified radiation modality-specific differences: XRT resulted in greater contralesional hemispheric injury than PRT [F(1, 31)=4.32, p<.05]. This effect was not observed in ipsilesional hemispheres.
Conclusion
RIL is common in glioma patients and quantifiable by characteristic imaging features, including early onset post-RT, greater ipsilesional injury burden, and progression over time. RIL injury dynamics appear to be radiation modality-specific, whereby XRT causes greater delayed injury in the remote, contralesional hemisphere. These findings may reflect dosimetric differences between protons and photons. The impact of such sequelae on cognitive function is subject of current investigation.
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KS04.6.A Epidemiology of adult meningioma in the Netherlands: a population-based study

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Abstract
Background
Meningiomas are the most common primary tumours of the central nervous system. As the majority of meningiomas are benign, initial management often consists of observation only. Consequently, estimates on meningioma incidence are generally considered too low, with many registries mainly depending on pathology notifications. With additional notification sources, this study provides more complete population-based estimates on the incidence, prevalence, and prognostic impact of meningioma diagnosis in the Netherlands.
Material and Methods
Data on patients diagnosed with meningioma during 2000-2019 were obtained from the Netherlands Cancer Registry (NCR), which was expanded to the Dutch Brain Tumour Registry (DBTR) for meningiomas as of 2016. In addition to histological confirmations, the NCR/DBTR receives case notifications from hospital administrative registrations on cost reimbursement and outpatient care. In addition, a data linkage was performed with a clinical database maintained by one of the Dutch neuro-oncology centres to evaluate local completeness of the NCR/DBTR. Time trends of the age-adjusted incidence rates were evaluated by calculating the estimated annual percentage change (EAPC). Relative survival rates were calculated using the Pohar-Perme estimator.
Results
From 2000 to 2019, a total of 22,605 cases of meningioma were registered; 11,423 (50.5%) were histologically confirmed, while 11,182 (49.5%) had a radiological diagnosis. Over time, incidence increased from 4.7 per 100,000 inhabitants (European Standardized Rate, ESR) to 10.7 (EAPC 4.6%, p<0.01); the incidence of radiological diagnosis increased from 1.2 to 6.9 per 100,000 ESR (EAPC 9.6%, p<0.01). Local data completeness was estimated at 98% for histologically confirmed meningiomas and 87% for radiological diagnoses. On the basis of these incidence estimates, the prevalence of meningioma is estimated at 105/100, 000 on January 1st of 2020, with over 17,500 individuals having had a diagnosis of meningioma at that moment. Relative survival rate at 5 years for grade I meningiomas was 94.8% (95%-confidence interval: 94.0%-95.4%), 84.0% (95%CI: 81.0%-86.5%) for grade II meningiomas, and 47.3% (95%CI: 38.2%-55.8%) for grade III meningiomas.
Conclusion
As the incidence estimates in this study may be considered most complete, the results obtained should approximate the true incidence, prevalence, and prognostic impact of meningioma diagnosis in the Netherlands.
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P12.09.B Extracellular vesicle derived-miR-146a increases melanoma brain metastasis progression via Notch signalling pathway dysregulation

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Abstract
Background
Melanoma has the highest tropism of any cancer to metastasize to the brain, and 40% of late-stage patients develop brain metastasis. Invasion, survival, and progression of tumors is dependent on the support of the surrounding microenvironment; therefore, modulation of neighboring cells is a key factor in metastasis. Extracellular vesicles (EVs) are important in cell-to-cell signalling, shuttling proteins, RNA and DNA to alter the surroundings into a favorable tumor microenvironment. Our aims were to investigate the role of melanoma brain metastasis (MBM) derived EVs in MBM development to find possible contributing mechanisms to cancer progression for eventual therapeutic targeting.
Material and Methods
MBM-EVs isolated via sequential ultracentrifugation were injected into mice as a pre-treatment prior to intracardial injection of MBM cells. EVs were co-cultured with normal human astrocytes (NHA) to investigate phenot ypic changes. MiRNA sequencing was performed on EVs collected from MBM cells and compared to NHA and melanocytes to determine a candidate miRNA for targeting. In situ hybridization was utilized to evaluate the level of miRNA in clinical patient MBM samples. Functional in vivo validation was performed by injecting miRNA knockout MBM cells into mice. Sequencing of NHA in the presence or absence of target miRNA mimic was used to determine downstream targets.
Results
Mice primed with EVs had a significant increase in MBM tumor burden, compared to non-primed mice. Co-culture with MBM-EVs resulted in NHA activation in vitro, with increased proliferation, invasion, cytokine production, and upregulation of GFAP. MiR-146a was highly upregulated in MBM EVs, and miR-146a mimics activated NHA. Patient samples had a significant increase in miR-146a expression, compared to healthy brain controls. MiR-146a knockdown in MBM mice models reduced MBM burden and prolonged animal survival. Sequ encing of NHA determined NUMB, an inhibitor of the Notch signalling pathway, as a target of miR-146a. Numb and other downstream Notch proteins expression was significantly altered in NHA in the presence of both MBM-EVs and miR-146a.
Conclusion
In conclusion, EVs are important regulators of MBM and establish tumor-supporting reactive astrocytes by delivery of miR-146a. MiR-146a alters Notch signalling in astrocytes via inhibition of the tumor suppressor gene NUMB. Elevated miR-146a levels in patients suggests a potential clinical intervention is possible via miR-146a targeting.
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P11.29.B Risk factors associated with the presence of brain metastasis at the moment of diagnosis in non-small cell lung cancer patients. Retrospective case series

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Abstract
Background
Lung cancer is the second most frequent neoplasm worldwide and the leading cause of cancer death in both sexes. Furthermore, it is the most common origin of brain metastases. The aim of this study is to identify clinical, histological, and molecular variables associated with a higher risk of presenting brain metastases at the moment of diagnosis in patients with lung cancer.
Material and Methods
A single-center retrospective case series analysis of patients with a new diagnosis of lung cancer (from January 2015 to December 2018) was performed. A total of 723 total patients with a new diagnosis of non-small cell lung cancer (NSCLC) were identified. Only patients with a brain imaging study at the time of diagnosis were included in the analysis. Non-parametric statistical tests were used to compare patients with or without metastases at the moment of diagnosis. A uni- and multivariate analysis were performed to identify risk factors associated with the presence of brain metastases at NSCLC diagnosis. Statistical significance was considered when p<0.05.
Results
We included 135 patients with a new diagnosis of lung cancer and with brain imaging study at the time of diagnosis (mean age at diagnosis of 64.69 years [SD= 10.34]; 71.9% men). The most common histology was adenocarcinoma (67.1%) followed by squamous carcinoma (25.2%). Brain metastases were present in 40% of patients at diagnosis. No significant differences in clinical, histological and molecular variables was identified between patients with or without brain metastases. In any case, as expected, the survival analysis showed that brain metastasis at diagnosis was associated with a worse overall survival (Log-Rank test, p<0.01).The univariate analysis showed that presenting neurological symptoms (OR=19.5, p<0.0001 CI [7.895-47.65]), histology of adenocarcinoma (OR= 2.113, p<0.014 CI [1.160-3.849]) and the presence of vis ceral metastases (OR= 14.444, p<0.0001 CI [6.161-33.86]) were associated to the presence of brain metastases at diagnosis. The presence of metastases limited to the thorax (OR= 0.019, p<0.001 CI [0.003-0.146] was associated to be free of brain metastasis at NSCLC diagnosis. However, only neurological symptoms (OR= 20.290, p<0.0001 CI [4.953-83.118]), presenting visceral metastases (OR= 4.451, p<0.010 CI [1.458-13.777]) and/or metastases limited to the thorax (OR= 0.066, p<0.024 CI [0.006-0.010]) reached statistical significance in the multivariate analysis.
Conclusion
Neurological symptoms and the presence of visceral metastases are independent predictors or presenting brain metastasis at the moment of diagnosis in lung cancer patients. On the other hand, the presence of lung cancer disease confined in the thoracic cavity is associated with a lower risk to present brain metastasis
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P11.75.B Survival benefit of radiotherapy and surgery in patients with lung cancer brain metastases with poor prognosis factors

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Abstract
Background
Radiotherapy and surgery are the standard treatments for lung cancer brain metastases (BMs). However, limitted studies focused on the treatments for patients with lung cancer BMs with poor prognosis factors. The purpose of this study was to investigate the effects of radiotherapy and surgery in patients with lung cancer BMs with poor prognosis factors, providing reference for clinical strategies.
Material and Methods
We analyzed retrospectively 714 patients with lung cancer BMs. A 1:1 propensity score matching (PSM) was performed to balance potential confounders. Analyses of overall survival (OS) and risk factors for OS were assessed by log-rank test and Cox proportional hazard model.
Results
Age ≥65 years, Karnofsky Performance Scale (KPS) score ≤70, anaplastic large-cell lymphoma kinase (ALK)/epidermal growth factor receptor (EGFR) wild type, extracranial metastases, non-surgery and non-radiotherapy le d to poor prognosis. Patients were stratified according to these factors. Radiotherapy and surgery showed no survival benefit in patients with aged ≥65 years or pretreatment KPS score ≤70 before and after PSM. Before PSM, whole brain radiotherapy (WBRT) improved the OS and predicted good prognosis in patients with ALK/EGFR wild type or extracranial metastases. WBRT also predicted good prognosis in patients with non-surgery. Stereotactic radiosurgery (SRS) improved the OS and predicted good prognosis in patients with ALK/EGFR wild type or non-surgery. WBRT plus SRS improved the OS and predicted good prognosis in patients with extracranial metastases or non-surgery. WBRT plus SRS also predicted good prognosis in patients with ALK/EGFR wild type. Surgery improved the OS and predicted good prognosis in patients with non-radiotherapy. After PSM, SRS improved the OS and predicted good prognosis in patients with non-surgery. WBRT plus SRS improved the OS and predicted good prognosis in patients with non-surgery or extracranial metastases. WBRT plus SRS also predicted good prognosis in patients with ALK/EGFR wild type. Surgery improved the OS of patients with non-radiotherapy. We defined that the treatment would provide significant survival benefit if it both prolonged the OS and predicted good prognosis. Meanwhile, the results after PSM were more convincing than the results before PSM.
Conclusion
Radiotherapy has significant survival benefit in patients with lung cancer BMs with poor prognosis factors, including patients with ALK/EGFR wild type or extracranial metastases or non-surgery. Surgery only has significant survival benefit in patients with non-radiotherapy.
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P11.74.A Plexiform Neurofibromas prevalence and treatment modalities in a referral comprehensive cancer center

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Abstract
Background
Neurofibromatosis type 1 (NF1) is the most common tumor predisposition syndrome, with an incidence of 1/3500. Plexiform neurofibromas (PN) are benign tumors that can occur along the nerve sheath throughout the body, with unpredictable growth and with risk of malignant transformation. Symptoms will depend on their size and location, and include pain, deformity and functional impairment. There is a great variability in the PN severity and impact on quality-of-life (QOL). An unknown percentage of NF1 patients may need treatment, either medical and/or surgical.
Objectives
To assess the frequency of PN in a NF1 population followed in a comprehensive cancer center.
Material and Methods
Retrospective study. All patients with NF1 and PN followed in our center, between 31/12/2000 and 31/12/2021.
Results
Of 438 NF1 patients, 185 had PN (42%). 52 NF1 patients with PN were children (≤ 18). The most common sym ptoms were pain in 71 people (38,4%), deformity in 70 (37,8%) and functional impairment in 69 (37,3%). Several patients had a combination of these symptoms. Different treatment modalities were used for PN: medical, surgical or both. In this study, 54 patients (29,1%) were treated with MEK inhibitors (selumetinib), 74 patients (40%) were treated surgically and 12,4% (23) needed a combined approach (medical and surgical treatment).
Conclusion
PN are frequent in NF1 patients. A significant percentage is symptomatic and will require treatment, surgical, medical or both. There is no standard of care for PN NF1. The timing and sequence of medical and surgical treatment is yet to be defined.
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P11.73.B The diagnostic value of frame-based stereotactic biopsies in the age of precision oncology: A cross-sectional study

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Abstract
Background
For non-resectable, eloquent, multifocal and deep-seated intracranial lesions, stereotactic frame-based biopsies can deliver a finite amount of tissue for neuropathology studies. With the increasing role of molecular genetics in the diagnostics of intracranial tumors, sufficient tissue for sequencing studies is of paramount importance. This study explored the rate of successful diagnosis after stereotactic frame-based biopsies of intracranial lesions in a high-throughput neurooncology center
Material and Methods
145 consecutive patients undergoing frame-based stereotactic biopsies in 2020 and 2021 at our neurosurgical department were included in this retrospective analysis. Aspects of histological and molecular (methylomics, panel-sequencing) neuropathology analysis in addition to clinical and radiological variables were analyzed. Cases were classified as conclusive, likely-conclusive (sufficient diagnosis with non-s atisfying sequencing information), and inconclusive neuropathological diagnosis.
Results
Of 145 cases analyzed, astrocytic tumors were suspected in n= 94 (67%) of patients. In n= 122 cases (84%), a conclusive diagnosis was possible. For 14 (11%) cases, a likely-conclusive diagnosis was established Diagnoses comprised mainly WHO 4 glioblastomas (56%), WHO 3 gliomas (2%) in addition to WHO 1 and 2 gliomas (n=7, 5%), CNS lymphomas (n=23, 16%), inflammatory diseases (n=10, 7%) and normal or reactive tissue (n=4, 3%). Methylomics were pivotal in providing an integrated diagnosis in 30% of the cases (panel sequencing in 14%). In n= 12 (8%) of the cases further testing was hindered by insufficient tissue sample DNA. Only in 3 out of 12 cases this resulted in a final inconclusive diagnosis.
Conclusion
Although stereotactic frame-based biopsies deliver a limited amount of tissue, they bear an excellent histopathological and molecular genetic diagnostic yield, with rare case s of missing molecular data or rarely insufficient diagnosis. Optimizing the number and representativeness of cell and DNA-rich stereotactic biopsy specimen might enhance the diagnostic and therapeutic potential of precision oncology even further.
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P02.10.A CRISPR/Cas9 deletion of SOX2 Regulatory Region 2 (SRR2) decreases SOX2 malignant activity in glioblastoma

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Abstract
Background
SOX2 is a transcription factor associated with stem cell activity in several tissues. SOX2 expression is elevated in a large proportion of cancers, such as glioblastoma (GB), the most common malignant primary brain tumor in adults. SOX2 acts as a relevant driver of GB progression and high levels are associated with the population of tumor initiating cells and poor patient outcome. Transcriptional regulation of SOX2 is complex and not fully understood. The SOX2 regulatory region 2 (SRR2) is located downstream of the SOX2 coding region and mediates SOX2 expression by the association of p21CIP1 and p27KIP1 to SRR2. In this study we dissected the role of SRR2 on SOX2 activity in GB.
Material and Methods
We deleted SRR2 (SRR2del) by CRISPR/Cas9 technology in U373 GB cells. We analyzed the expression of SOX2 and performed in vitro functional experiments. We accomplished rescue experiments overexpressing SOX2 in SRR2del cells and we studied the link between SOX2, p21CIP1 and p27KIP1. Finally, we carried out an in vivo carcinogenesis assay by the injection of SRR2del cells in immunodeficient mice.
Results
We report that the deletion of SRR2 in GB cells leads to a reduction of SOX2 expression, which was accompanied with an impairment of cell growth and proliferation as well as with a reduction of self-renewal capacity in vitro. These data reveal that SRR2 is required for SOX2 expression and that its deletion results in impaired tumorigenic capacity of GB cells. These effects correlated with an increased expression of p21CIP1 and p27KIP1 together with high levels of p53 in SRR2del cells. On the contrary, SRR2del cells presented decreased levels of stem cell markers, supporting the idea that SRR2 is necessary for the SOX2-mediated regulation of stemness pathways. Furthermore, ectopic overexpression of SOX2 in SRR2del cells restored SOX2 expression as well as proliferation and stem cell properties, indicating that the expression and the oncogenic activity of SOX2 is regulated by SRR2. Additionally, our xenograft models re vealed that the lack of SRR2 impairs tumor initiation and growth in vivo. Tumors derived from SRR2del cells were significantly smaller compared to controls and exhibit low levels of SOX2, Ki67 and BMI1 but high levels of p21CIP1 and p27KIP1.
Conclusion
Our data confirm that the SRR2 regulates SOX2 expression and reveal that SRR2 deletion reduces SOX2 levels and halts malignant activity driven by SOX2 in GB.
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