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BACKGROUND: Stereotactic radiosurgery has become a common treatment approach for small-to-medium size vestibular schwannomas. OBJECTIVE: To evaluate relationship between time (beam-on and treatment) and risk of hearing decline after stereotactic radiosurgery for vestibular schwannomas in patients with Gardner–Robertson (GR) baseline classes I and II. METHODS: This retrospective longitudinal single-center study included 213 patients with GR I and II treated between June 2010 and December 2019. Risk of passing from GR classes I and II (coded 0) to other classes III, IV, and V (coded 1) and the increase in pure tone average (continuous outcome) were evaluated using a mixed-effect regression model. Biologically effective dose (BED) was further assessed for an alpha/beta ratio of 2.47 (Gy2.47). RESULTS: Binary outcome analysis revealed sex, dose rate, integral dose, time [beam-on time odds ratio 1.03, P = .03, 95% CI 1.00-1.06; treatment time (P = .02) and BED (P = .001) as relevant. Fitted multivariable model included the sex, dose rate, and BED. Pure tone average analysis revealed age, integral dose received by tumor, isocenter number, time (beam-on time odds ratio 0.20, P = .001, 95% CI 0.083-0.33) and BED (P = .005) as relevant. CONCLUSION: Our analysis showed that risk of hearing decline was associated with male sex, higher radiation dose rate (cutoff 2.5 Gy/minute), higher integral dose received by the tumor, higher beam-on time ≥20 minutes, and lower BED. A BED between 55 and 61 was considered as optimal for hearing preservation. De tre sista författarna delar sistaförfattarskapet

Background and purpose: To minimize cognitive decline without increasing brain tumor recurrence (BTR) by reduced-dose whole-brain radiotherapy (RD-WBRT) (25 Gy, 10 fractions) + stereotactic radiosurgery (SRS) in patients with = 70. The primary endpoint was the non-inferiority of BTR at distant sites in the brain (BTR-distant)-free survival at 6 months compared to that of the standard dose (SD)-WBRT (30 Gy, 10 fractions) + SRS arm in a randomized clinical trial (JROSG99-1) of SRS with/without SD-WBRT. Secondary endpoints included BTR at any brain sites (BTR-all) and neurocognitive function assessed by a six-test standardized battery.Results: Forty patients from seven institutions were enrolled (median age 69 years). The primary tumor site was a lung in 28 patients; 20 patients had a solitary brain metastasis. The median survival time was 19.0 months (95 % CI: 13.8 %-27.5 %). The BTR-distant-free survival at 6 months was 76.9 % (59.5 %-87.7 %), which is compa-rable to that of historical control although predetermined non-inferiority (>71 %) could not be confirmed (p = 0.16). The cumulative incidence of BTR-all at 6 months accounting for the competing risk of death was 23.0 % (11.4-37.1), which was not worse than that of historical control (p = 0.774). The frequency of the cumulative incidence of persistent cognitive decline at 6 months was 48.6 % under the [>2.0 SD in >= 1 test] definition.Conclusions: RD-WBRT may yield comparable intracranial tumor control when combined with SRS, and may reduce the risk of neurocognitive decline compared to that after SD-WBRT.

In this study, the dose schedule efficacy, safety and late adverse effects of stereotactic radiosurgery (SRS) were evaluated for patients with symptomatic cavernomas who were not eligible for surgery and treated with SRS. Between January 2013 and December 2018, 53 patients with cavernomas were treated using SRS with the CyberKnife® system. Patients’ diseases were deeply located or were in subcortical functional brain regions. In addition to bleeding, 23 (43.4%) patients had epilepsy, 12 (22.6%) had neurologic symptoms and 16 patients (30.2%) had severe headaches. The median volume was 741 (range, 421–1351) mm3, and the median dose was 15 (range, 14–16) Gy in one fraction. After treatment, six (50%) of 12 patients with neurologic deficits still had deficits. Rebleeding after treatment developed in only two (3.8%) patients. The drug was completely stopped in 14 (60.9%) out of 23 patients who received epilepsy treatment, and the dose of levetiracetam decreased from 2000 mg to 1000 mg in four (17.3%) of nine patients. Radiologically, complete response (CR) was observed in 13 (24.5%) patients, and partial responses (PR) were observed in 32 (60.2%) patients. Clinical response of CR was observed in 30 (56.6%) patients, PR was observed in 16 (30.2%), stable disease (SD) was observed in three (5.7%) and four (7.5%) patients progressed. In conclusion, SRS applied in the appropriate dose schedule may be an effective and reliable method in terms of symptom control and prevention of rebleeding, especially in patients with inoperable cavernomas.

Hintergrund: Lebensqualität und Neurokognition rückt zunehmend in den klinischen und wissenschaftlichen Fokus in der Behandlung von Hirnmetastasen. Ziel: Die vorliegende Arbeit basiert auf einer selektiven Literaturrecherche in der Datenbank PubMed zum Thema neurokognitive Veränderungen und Lebensqualität nach zerebraler Radiotherapie. Es wird eine Übersicht über die aktuelle Datenlage gegeben. Ergebnisse und Schlussfolgerung: Die technischen Verbesserungen in der Radioonkologie führen zu schneller und effektiver Hochpräzisionsbestrahlung. Die potenziell geringere intrakranielle Kontrolle nach stereotaktischer Radiochirurgie („stereotactic radiosurgery“, SRS) scheint im Vergleich zur Ganzhirnbestrahlung („whole brain radiation therapy“, WBRT) keinen relevanten Einfluss auf das Überleben zu haben. Daher ist die Erhaltung der Neurokognition und der Lebensqualität zentrales Ziel der Behandlung und Gegenstand der aktuellen Forschung.

Brain metastases (BMs) represent advanced cancer, and so BM patients must be treated quickly and effectively while minimizing treatment toxicities. Stereotactic radiosurgery (SRS) uses conformal, ablative radiation doses to treat BMs, but with failure rates up to 30%. A predictive model of BM progression post-SRS would therefore aid in BM treatment selection and SRS planning. Previous studies have used pre-treatment T1-weighted contrast-enhanced magnetic resonance imaging (T1w-CE MRI) to predict SRS outcomes, through quantitative radiomic analysis with machine learning (ML) and qualitative appearance analysis. Comparison of these methods is not well understood, and ML methods have not been studied for sensitivity to relevant clinical factors, robust model interpretability, or multi-centre external validation. To meet these needs, a dataset of 123 BMs across 99 SRS patients was used to develop T1w-CE MRI radiomics-based ML models to understand their sensitivity to clinical factors. A ML model using radiomic and clinical features obtained the highest area-under-the-receiver-operating-characteristic-curve (AUC) of 0.77, and this model was sensitive to primary cancer site, BM volume, and MRI scanner model. BM volume sensitivity was reduced by removing volume-correlated radiomic features. An observer study of BM qualitative analysis revealed high interobserver variability that in turn limited outcome prediction, while ML models provided enhanced stratification of BMs into risk groups for post-SRS progression (Kaplan-Meier rank-sum p = 0.0003). BM qualitative appearance was useful for ML model interpretation, revealing the post-SRS progression radiomic signature is tied to necrotic or heterogeneous BM appearance, indicating a potentially less radiosensitive, hypoxic environment. An additional dataset of 117 BMs across 62 SRS patients was collected at a second centre for external validation. Transferring a locked model between centres revealed poor performance, but limiting the model to use radiomic features important at both centres increased the AUC to 0.70. Retraining a model with the second centre’s dataset using a locked methodology developed with the first centre’s dataset achieved a higher AUC of 0.80. In conclusion, this work successfully characterized radiomics-based ML model performance with respect to clinical factors and BM qualitative appearance, while also providing the ML model interpretability and external validation necessary to motivate future research and clinical translation.

Patients with brain metastases (BMETS) need information about the prognosis and potential value of treatment options to make informed therapeutic decisions, but tools to predict survival in contemporary practice are scarce. We propose an Updated Recursive Partitioning Analysis (U-RPA) instrument to predict survival and benefit from brain-directed treatment (BDT) of contemporary patients. This was a retrospective analysis of patients with BMETS treated between 2017 and 2019. With survival as the primary endpoint, we calculated the U-RPA and generated estimates using Kaplan–Meier curves and hazard ratios. Of 862 eligible patients, 752 received BDT and 110 received best supportive care (BSC). Median overall survival with BDT and BSC was 9.3 and 1.3 months, respectively. Patients in RPA class 1, 2A, 2B and 3 who underwent BDT had median survival of 28.1, 14.7, 7.6 and 3.3 months, respectively. The median survival for patients in RPA 3 who received BDT (n = 147), WBRT (n = 79) and SRS (n = 54) was 3.3, 2.9 and 4.1 months, respectively. The U-RPA defines prognosis estimates, independent of tumor type and treatment modality, which can assist to make value-based care treatment decisions. The prognosis for patients in U-RPA class 2B and 3 remains poor, with consideration for early palliative care involvement in these cases.

INTRODUCTION: We evaluated real-world data on the patterns and outcomes of radiotherapy (RT) for brain metastases (BM) in a population-based cohort of patients with lung cancer (LC) in Victoria. METHODS: The Victorian Radiotherapy Minimum Data set (VRMDS) and the Victorian Cancer Registry (VCR) were linked to identify patients with LC who underwent RT for BM between 2013 and 2016. We determined: (i) proportion of patients treated with stereotactic radiosurgery (SRS); (ii) overall survival (OS); and (iii) 30-day mortality (30M) following RT for BM. RESULTS: Of the 1001 patients included in the study, 193 (19%) had SRS. There was no significant increase in SRS use over time - from 18% in 2013 to 21% in 2016 (P-trend = 0.8). In multivariate analyses, increased age (P = 0.03) and treatment in regional centres (P

Introduction: Traditionally, brain metastases have been treated with stereotactic radiosurgery (SRS), whole-brain radiation (WBRT), and/or surgical resection. Non-small cell lung cancers (NSCLC), over half of which carry EGFR mutations, are the leading cause of brain metastases. EGFR-directed tyrosine kinase inhibitors (TKI) have shown promise in NSCLC; but their utility in NSCLC brain metastases (NSCLCBM) remains unclear. This work sought to investigate whether combining EGFR-TKI with WBRT and/or SRS improves overall survival (OS) in NSCLCBM. Methods: A retrospective review of NSCLCBM patients diagnosed during 2010–2019 at a tertiary-care US center was performed and reported following the ‘strengthening the reporting of observational studies in epidemiology’ (STROBE) guidelines. Data regarding socio-demographic and histopathological characteristics, molecular attributes, treatment strategies, and clinical outcomes were collected. Concurrent therapy was defined as the combination of EGFR-TKI and radiotherapy given within 28 days of each other. Results: A total of 239 patients with EGFR mutations were included. Of these, 32 patients had been treated with WBRT only, 51 patients received SRS only, 36 patients received SRS and WBRT only, 18 were given EGFR-TKI and SRS, and 29 were given EGFR-TKI and WBRT. Median OS for the WBRT-only group was 3.23 months, for SRS + WBRT it was 3.17 months, for EGFR-TKI + WBRT 15.50 months, for SRS only 21.73 months, and for EGFR-TKI + SRS 23.63 months. Multivariable analysis demonstrated significantly higher OS in the SRS-only group (HR = 0.38, 95% CI 0.17–0.84, p = 0.017) compared to the WBRT reference group. There were no significant differences in overall survival for the SRS + WBRT combination cohort (HR = 1.30, 95% CI = 0.60, 2.82, p = 0.50), EGFR-TKIs and WBRT combination cohort (HR = 0.93, 95% CI = 0.41, 2.08, p = 0.85), or the EGFR-TKI + SRS cohort (HR = 0.46, 95% CI = 0.20, 1.09, p = 0.07). Conclusions: NSCLCBM patients treated with SRS had a significantly higher OS compared to patients treated with WBRT-only. While sample-size limitations and investigator-associated selection bias may limit the generalizability of these results, phase II/III clinicals trials are warranted to investigate synergistic efficacy of EGFR-TKI and SRS.

BACKGROUND: Stereotactic radiosurgery (SRS) is one of the main treatment options in the management of small to medium size vestibular schwannomas (VSs), because of high tumor control rate and low cranial nerves morbidity. Series reporting long-term hearing outcome (>3 years) are scarce.OBJECTIVE: To perform a systematic review of the literature and meta-analysis, with the aim of focusing on long-term hearing preservation after SRS.METHODS: Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we reviewed articles published between January 1990 and October 2020 and referenced in PubMed or Embase. Inclusion criteria were peer-reviewed clinical study or case series of VSs treated with SRS (single dose), reporting hearing outcome after SRS with a median or mean audiometric follow-up of at least 5 years. Hearing preservation, cranial nerves outcomes, and tumor control were evaluated.RESULTS: Twenty-three studies were included. Hearing preservation was found in 59.4% of cases (median follow-up 6.7 years, 1409 patients). Main favorable prognostic factors were young age, good hearing status, early treatment after diagnosis, small tumor volume, low marginal irradiation dose, and maximal dose to the cochlea. Tumor control was achieved in 96.1%. Facial nerve deficit and trigeminal neuropathy were found in 1.3% and 3.2% of patients, respectively, both significantly higher in Linear Accelerator series than Gamma Knife series (P < .05).CONCLUSION: Long-term hearing preservation remains one of the main issues after SRS, with a major impact on health related quality of life. Our meta-analysis suggests that hearing preservation can be achieved in almost 60% of patients after a median follow-up of 6.7 years, irrespective of the technique.

Refereed/Peer-reviewed Arteriovenous malformations (AVM) of the brain are congenital, high pressure vascular malformations, which are at risk of haemorrhage. Stereotactic radiosurgery (SRS) can obliterate the nidus by delivering a precise high dose of ionising radiation in a single fraction. This paper updates long term AVM obliteration rates, time to obliteration and retreatment outcomes in LINAC delivered SRS treatment at the Royal Adelaide Hospital. A retrospective review of a prospectively maintained AVM SRS database supplemented by clinical case notes, patient correspondence and electronic medical records was performed. 89 AVMs received primary SRS treatment for which the crude obliteration rate was 61% (68% for 79 patients with adequate follow up). Higher marginal dose, smaller nidus size and lower Pollock-Flickinger (PF) score were significantly associated with AVM obliteration. The crude obliteration rates for patients with adequate follow-up and AVM diameter < 3 cm vs ≥ 3 cm were 76% vs 48%, respectively, and 93% with PF score < 1.0. Median time to obliteration was 36 months. Higher dose and lower PF score were associated with earlier obliteration. The crude obliteration rate after second SRS was 56% (9/16 patients) and no significant associations were found. These obliteration rates after primary and retreatment LINAC SRS are comparable to other studies. Marginal dose and PF score were the main predictors of obliteration overall as well as early (

Meningiomas are the most common intracranial tumors. Most meningiomas are WHO grade 1 tumors whereas less than one-quarter of all meningiomas are classified as atypical (WHO grade 2) and anaplastic (WHO grade 3) tumors, based on local invasiveness and cellular features of atypia. Surgical resection remains the cornerstone of meningioma therapy and represents the definitive treatment for the majority of patients; however, grade 2 and grade 3 meningiomas display more aggressive behavior and are difficult to treat. Several retrospective series have shown the efficacy and safety of postoperative adjuvant external beam radiation therapy (RT) for patients with atypical and anaplastic meningiomas. More recently, two phase II prospective trials by the Radiation Therapy Oncology Group (RTOG 0539) and the European Organisation for Research and Treatment of Cancer (EORTC 2042) have confirmed the potential benefits of fractionated RT for patients with intermediate and high-risk meningiomas; however, several issues remain a matter of debate. Controversial topics include the timing of radiation treatment in patients with totally resected atypical meningiomas, the optimal radiation technique, dose and fractionation, and treatment planning/target delineation. Ongoing randomized trials are evaluating the efficacy of early adjuvant RT over observation in patients undergoing gross total resection.

Contains fulltext : 291966.pdf (Publisher’s version ) (Open Access) OBJECTIVE: Vestibular schwannoma (VS) growth of ≥2 mm during serial MRI observation, irrespective of size, is the benchmark for treatment initiation in almost all centers. Although the probability of less optimal outcomes significantly increases in VS closer to the brainstem, early intervention does not improve long-term quality of life. Moving beyond the recommendation of definitive treatment for all VS after detected growth, we subclassified Koos 2 tumors based on extrameatal extension and relation to the brainstem. The aim of the current study was to evaluate the Koos 2 subclassification's validity and the inter-and intra-rater reliability of the entire Koos classification. METHODS: Six experts, including neurosurgeons, otorhinolaryngologists and radiologists from two tertiary referral centers, classified 43 VS MRI scans. Validity of the Koos 2 subclassification was evaluated by the percentage agreement against the multidisciplinary skull base tumor board management advice. Inter- and intra-rater reliability were calculated using the intraclass correlation coefficient (ICC). RESULTS: Validity was almost perfect in Koos 2a VSs with a 100% agreement and 87.5% agreement for Koos 2b. Inter-rater reliability for all Koos grades was significantly excellent (ICC 0.91; 95%CI 0.866 to 0.944, p= 0.90; p=

ObjectivesThe objective of this study is to evaluate the user-defined optimization settings in the Fast Inverse Planning (FIP) optimizer in Leksell GammaPlan® and determine the parameters that result in the best stereotactic radiosurgery (SRS) plan quality for brain metastases, benign tumors, and arteriovenous malformations (AVMs).MethodsThirty patients with metastases and 30 with benign lesions-vestibular schwannoma, AVMs, pituitary adenoma, and meningioma-treated with SRS were evaluated. Each target was planned by varying the low dose (LD) and beam-on-time (BOT) penalties in increments of 0.1, from 0 to 1. The following plan quality metrics were recorded for each plan: Paddick conformity index (PCI), gradient index (GI), BOT, and maximum organ-at-risk (OAR) doses. A novel objective score matrix was calculated for each target using a linearly weighted combination of the aforementioned metrics. A histogram of optimal solutions containing the five best scores was extracted.ResultsA total of 7260 plans were analyzed with 121 plans per patient for the range of LD/BOT penalties. The ranges of PCI, GI, and BOT across all metastatic lesions were 0.58-0.97, 2.1-3.8, and 8.8-238 min, respectively, and were 0.13-0.97, 2.1-3.8, and 8.8-238 min, respectively, for benign lesions. The objective score matrix showed unique optimal solutions for metastatic lesions and benign lesions. Additionally, the plan metrics of the optimal solutions were significantly improved compared to the clinical plans for metastatic lesions with equivalent metrics for all other cases.ConclusionIn this study, FIP optimizer was evaluated to determine the optimal solution space to maximize PCI and minimize GI, BOT and OAR doses simultaneously for single metastatic/benign/non-neoplastic targets. The optimal solution chart was determined using a novel objective score which provides novice and expert planners a roadmap to generate the most optimal plans efficiently using FIP.

Arun Kadamkulam Syriac,1 Nitish Singh Nandu,2 Jose Pablo Leone1 1Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA; 2Department of Hospice and Palliative Medicine, Montefiore Medical Center/ Albert Einstein College of Medicine, Bronx, NY, USACorrespondence: Jose Pablo LeoneDepartment of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, 02215, USAEmail JoseP_Leone@dfci.harvard.eduAbstract: It is estimated that approximately one-third of patients with triple-negative breast cancer (TNBC) will develop brain metastases. The prognosis for patients with breast cancer brain metastasis has improved in the recent past, especially for hormone receptor and human epidermal growth factor receptor 2 (HER) positive subtypes. However, the overall survival rate for patients with triple-negative subtype remains poor. The development of newer treatment options, including antibody-drug conjugates such as Sacituzumab govitecan, is particularly encouraging. This article reviews the clinical outcomes, challenges, and current approach to the treatment of brain metastasis in TNBC. We have also briefly discussed newer treatment options and ongoing clinical trials. The development of brain metastasis significantly decreases the quality of life of patients with TNBC, and newer treatment strategies and therapeutics are the need of the hour for this disease subgroup.Keywords: triple-negative breast cancer, metastatic disease, brain metastasis, prognosis clinical outcomes, immunotherapy, stereotactic radiosurgery, whole-brain radiation therapy, antibody–drug conjugate, oligometastatic brain metastasis, clinical outcomes, prediction, prognosis, personalization, multi-omics, machine learning, individualized treatment algorithms, patient benefits

Highlights • We performed a validity test of the Renal Graded Prognostic Assessment. • Therefore, we developed a new grading index. These results were validated using another dataset including 397 renal cancer patients with BMs. • This new grading system was clearly useful for predicting post-SRS outcomes of BM patients with renal cancer., Background and purpose The Renal Graded Prognostic Assessment (GPA) is relatively new and has not been sufficiently validated using a different dataset. We thus developed a new grading index, the Renal Brain Metastasis Score (Renal-BMS). Materials and methods Using our dataset including 262 renal cancer patients with brain metastases (BMs) undergoing stereotactic radiosurgery (SRS) (test series), we validity tested the Renal-GPA. Next, we applied clinical factor-survival analysis to the test series and thereby developed the Renal-BMS. This system was then validated using another series of 352 patients independently undergoing SRS at nine gamma knife facilities in Japan (verification series). Results Using the test series, with the Renal-GPA, 95% confidence intervals (CIs) of the post-SRS median survival times (MSTs) overlapped between pairs of neighboring subgroups. Among various pre-SRS clinical factors of the test series, six were highly associated with overall survival. Therefore, we assigned scores for six factors, i.e., “KPS ≥ 80%/

Arteriovenous malformations (AVMs) of the brain are quite rare vascular pathologies, but they are life-threatening, due to the risk of intracerebral hemorrhage. Stereotactic radiosurgical treatment of patients with cerebral AVM is performed in cases where surgical removal is impossible or embolization with a stable occlusive effect cannot be performed. Currently, for the diagnosis of AVM, magnetic resonance imaging (MRI) is increasingly used because of its noninvasiveness and minimal risks. When a malformation is located in a functionally significant area, then a non-invasive technique is used to assess its interposition and mapping - functional magnetic resonance imaging.We have presented the experience of radiosurgical treatment of a 43-year-old male patient with a ruptured AVM located in the left temporal lobe, near Wernicke’s area. The patient underwent stereotactic radiosurgical treatment with Elekta Leksell Gamma Knife Perfection device, taking into account the location of the AVM in a functionally significant area, preoperative mapping was performed. After two years, according to MR angiography, the arterial component in the projection of the irradiated AVM was not visualized, which was confirmed by the data of cerebral angiography. Thus, a clinical example has demonstrated the high efficiency of MRI in the diagnosis and assessment of the results of the performed stereotactic radiosurgical treatment of AVMs.

High-grade gliomas (HGGs) are presently managed via surgical resection, external beam radiation therapy (EBRT), and chemotherapy. Although Gamma Knife radiosurgery (GKRS) is currently used to manage HGGs, it has not been considered standard care. This paper aims to compare the contribution of GKRS to clinical outcomes in patients in which gross total resection (GTR) cannot be achieved. We retrospectively reviewed the data of 99 patients with HGG (World Health Organization (WHO) grade III and IV) from two groups: group 1 consisted of 68 patients for which only EBRT was administered, and group 2 consisted of 31 patients for which EBRT and GKRS were administered. Patient demographic data, the extent of resection, IDH mutation, radiation dosage, progression-free survival (PFS), overall survival (OS), and follow-up time were recorded and compared across groups. The grade III/IV tumor ratio was 10/58 and 10/21 in groups 1 and 2, respectively. In group 2, PFS and OS were higher than in group 1 (P = 0.030 and 0.021). The mean follow-up time was 15.02 +/- 11.8 (3-52) and 18.9 +/- 98.6 (7-43) months in groups 1 and 2, respectively. In addition to the standard management of HGGs in patients without GTR, boost GKRS during the early postoperative period is beneficial for increasing PFS and OS. (c) 2021 Published by Elsevier Ltd.

Purpose: Arteriovenous malformations with basal ganglia, brainstem, and thalamic locations represent complex vessel anomalies with critical areas. Treatment of these central lesions is related to high morbidity and mortality rates. This retrospective study aims to examine the results of our clinic's patients with basal ganglia, brainstem, and thalamic arteriovenous malformations remedied with gamma knife radiosurgery (GKS).Method: The results of patients with basal ganglia, thalamus, and brainstem located AVM who underwent GKS from May 2005-December 2020 were analyzed in the Gazi University Gamma Knife Unit.Results: A total of 859 patients with intracranial AVM were treated at the Gamma Knife Unit of the Gazi University Neurosurgery Clinic between May 2005-December 2020. Seventy-three patients with basal ganglia, brainstem, and thalamic locations were recorded. In a total of 73 patients who were included in the study, the lesion was located in the basal ganglia in 14 (19.2%), the brainstem in 13 (17.8%), and the thalamic region in 46 (63%) patients. The mean volume of AVMs was 4565,54 mm3. The patients who underwent embolization before gamma knife surgery treatment were found to be 19.2%. The mean of AVMs' obliteration time after SRS is 38.4 months. We detected that there was no significant statistical rate relationship between obliteration rate and AVMs volume, Spetzler - Martin Grading Scale, nidus type, gender, and prior embolization (p>0.05).Conclusions: GKS is one of the effective choice treatment methods used for cerebral AVMs today. Furthermore, it has been accepted as the first choice treatment method, especially in central AVMs, which are risky in terms of mortality and morbidity, and also with good outcomes., Amaç: Bazal gangliyon, beyin sapı ve talamik yerleşimli arteriovenöz malformasyonlar (AVM) kritik bölgede yerleşmiş kompleks damar anomalileridir. Bu santral yerleşimli lezyonların tedavisi yüksek morbidite ve mortalite riski taşır. Çalışmamızda bazal ganglion, beyin sapı ve talamik yerleşimli AVM nedeniyle kliniğimizde gamma knife radyocerrahi uygulanmış hastaların sonuçları retrospektif olarak incelenmesi amaçlandı.Gereç ve yöntem: Mayıs 2005-Aralık 2020 tarihleri arasında Gazi Üniversitesi Gamma Knife Ünitesinde tedavi edilmiş bazal gangliyon, talamus ve beyin sapı yerleşimli AVM hastalarının sonuçları incelendi.Bulgular: Mayıs 2005-Aralık 2020 tarihleri arasında Gazi Üniversitesi Gamma Knife Ünitesinde toplam 859 intrakraniyal AVM hastası tedavi edildi. Bazal ganglion, beyin sapı ve talamik lokalizasyonu olan 73 hasta çalışmaya dahil edildi. Çalışmamıza dahil edilen toplam 73 hastanın 14'ü (%19,2) bazal ganglionda, 13'ü (%17,8) beyin sapında ve 46'sı (%63) talamik bölgede yer alıyordu. Ortalama AVM hacmi 4565,54 mm3 olarak hesaplandı. Gamma knife cerrahisi tedavisinden önce embolizasyon uygulanan hastaların oranının %19.2’idi. SRS sonrası AVM'lerin ortalama tam kapanma sürelerinin 38,4 aydı. AVM hacmi, Spetzler Martin derecelendirme ölçeği, nidus tipi, cinsiyet ve önceki embolizasyon ile kapanma oranı arasında istatistiksel olarak anlamlı ilişkisi saptanmadı (p>0.05).Sonuç: GKS günümüzde serebral AVM tedavisinde kullanılan etkin bir tedavi yöntemidir. GKS özellikle tedavisi yüksek morbidite ve mortalite riski içeren santral yerleşimli AVM tedavisinde başarılı sonuçları ile öncelikli tercih edilen tedavi yöntemlerindendir.

Die Hochpräzisionsbestrahlung mittels stereotaktischer Radiochirurgie (SRS), fraktionierter stereotaktischer Radiotherapie (FSRT) und Körperstereotaxie (SBRT) stellt heutzutage eine unverzichtbare Therapiemodalität in der modernen Onkologie dar. Im Kontext dieser Habilitation wurden die klinischen bzw. radioonkologischen Ergebnisse der Stereotaxie für Foramen magnum Meningeome, intramedulläre Metastasen, Nebennierenmetastasen, spinale Ependymome und Prostatakarzinomlokalrezidive analysiert. Darüber hinaus erfolgte eine erstmalige Betrachtung der gyroskopischen Radiochirurgie (GRS). Die dargestellten Arbeiten und Daten zeigen, dass die Stereotaxie auch im Rahmen seltener Indikationen und Tumorlokalisationen meist effektiv und sicher eingesetzt werden kann. Durch weitere Fortschritte auf dem Gebiet der funktionellen und nicht-funktionellen Bildgebung, adaptiven Strahlentherapie sowie der molekularpathologischen Diagnostik und biologischen Charakterisierung von Tumoren wird sich zusätzliches Potenzial zur Therapieoptimierung ergeben. Darüber hinaus wird es Aufgabe zukünftiger radioonkologischer Forschung sein, die Patientenselektion für die SRS, FSRT und SBRT weiter zu verfeinern und die Stereotaxie sinnvoll in den Kontext multimodaler Therapiekonzepte zu implementieren. Hierfür werden eine standardisierte und prospektive Datenerhebung und Evaluation von zentraler Bedeutung sein. Weiterhin sind technische Innovationen – wie bei der GRS oder Magnetresonanztomographie-gestützten Linearbeschleunigern ersichtlich – von großer Relevanz, um die Verfügbarkeit, Effektivität und Sicherheit der Hochpräzisionsbestrahlung weiter voranzutreiben.

Background: This study aimed to assess the clinical outcomes of salvage surgical resection (SSR) after stereotactic radiosurgery and fractionated stereotactic radiotherapy (SRS/fSRT) for newly diagnosed brain metastasis. Methods: Between November 2009 and May 2020, 318 consecutive patients with 1114 brain metastases were treated with SRS/fSRT for newly diagnosed brain metastasis at our hospital. During this study period, 21 of 318 patients (6.6%) and 21 of 1114 brain metastases (1.9%) went on to receive SSR after SRS/fSRT. Three patients underwent multiple surgical resections. Twenty-one consecutive patients underwent twenty-four SSRs. Results: The median time from initial SRS/fSRT to SSR was 14 months (range: 2–96 months). The median follow-up after SSR was 17 months (range: 2–78 months). The range of tumor volume at initial SRS/fSRT was 0.12–21.46 cm3 (median: 1.02 cm3). Histopathological diagnosis after SSR was recurrence in 15 cases, and radiation necrosis (RN) or cyst formation in 6 cases. The time from SRS/fSRT to SSR was shorter in the recurrence than in the RNs and cyst formation, but these differences did not reach statistical significance (p = 0.067). The median survival time from SSR and from initial SRS/fSRT was 17 and 74 months, respectively. The cases with recurrence had a shorter survival time from initial SRS/fSRT than those without recurrence (p = 0.061). Conclusions: The patients treated with SRS/fSRT for brain metastasis need long-term follow-up. SSR is a safe and effective treatment for the recurrence, RN, and cyst formation after SRS/fSRT for brain metastasis.

Purpose/objective(s) To determine, for intact melanoma brain metastases (MBM) treated with single-fraction stereotactic radiosurgery (SRS), whether planning parameter peripheral dose per lesion diameter (PDLDm, Gy/mm) and lesion control (LC) differs with versus without immunotherapy (IO). Materials/methods We performed a retrospective analysis of patients with intact MBM treated with SRS from 2008 to 2019. Cox-frailty models were constructed to include confounders selected by penalized Cox regression models with a LASSO selector. Interaction effect testing was used to determine whether a significant effect between IO and PDLDm could be demonstrated with respect to LC. Results The study cohort comprised 67 patients with 244 MBMs treated with SRS (30 patients with 122 lesions treated with both SRS and IO) were included. The logarithm of PDLDm was selected as a predictor of LC (HR 0.307, 95% CI 0.098-0.441), adjusting for IO receipt (HR 0.363, 95% CI 0.108-1.224). Interaction effect testing demonstrated a differential effect of PDLDm by IO receipt, with respect to LC (p = 0.048). Twelve-month LC rates for a 7.5 mm lesion receiving SRS (18 Gy) with IO versus without IO were 87.8% (95% CI 69.0-98.3%) versus 79.8% (95% CI 55.1-93.8%) respectively. Conclusion PDLDm predicted LC in patients with small MBMs treated with single-fraction SRS. We found a differential effect of dose per lesion size and LC by immunotherapy receipt. Future studies are needed to determine whether lower doses of single-fraction SRS afford similarly effective LC for patients with small MBMs receiving immunotherapy.

As novel systemic therapies yield improved survival in metastatic cancer patients, the frequency of brain metastases continues to increase. Over the years, management strategies have continued to evolve. Historically, stereotactic radiosurgery has been used as a boost to whole-brain radiotherapy (WBRT) but is increasingly being used as a replacement for WBRT. Given its capacity to treat both macro- and micro-metastases in the brain, WBRT has been an important management strategy for years, and recent research has identified technologic and pharmacologic approaches to delivering WBRT more safely. In this review, we outline the current landscape of radiotherapeutic treatment options and discuss approaches to integrating radiotherapy advances in the contemporary management of brain metastases.

The development of breast cancer (BC) brain metastases (BrM) is a common complication of advanced disease, occurring in up to half of the patients with advanced disease depending on the subtype. The management of BCBrM requires complex multidisciplinary care including local therapy, surgical resection and/or radiotherapy, palliative care, and carefully selected systemic therapies. Significant progress has been made in the human epidermal growth factor receptor 2-positive (HER2+) BCBrM population due to novel brain penetrable systemic therapies. Increased inclusion of patients with BCBrM in clinical trials using brain-penetrant systemic therapies recently led to the first FDA approval of a HER2-directed therapy specifically in the BCBrM population in the last year. Advances for the treatment of HR+/HER2− and TNBC BCBrM subgroups continue to evolve. In this review, we will discuss the diagnosis and multidisciplinary care of BCBrM. We focus on recent advances in neurosurgery, radiation therapy, and systemic treatment therapies with intracranial activity. We also provide an overview of the current clinical trial landscape for patients with BCBrM.

Clinical outcomes were reviewed in 30 patients treated by gamma knife radiosurgery for skull base meningiomas with carotid artery encasement (SKBM‐CAE). The overall clinical improvement rate after treatment was 46%. At a median imaging follow‐up of 49 months, tumor volumes were unchanged, were larger, and were smaller or had resolved in 70%, 23%, and 7% of cases, respectively. The crude survival rate at 10 years was 20% and the complication (new cranial nerve deficit not accompanied by imaging‐shown tumor growth) rate was 10%. SKBM‐CAE is amenable to being effectively and safely controlled with the application of gamma knife radiosurgery.

A 13-year-old right-handed girl had operculoinsular refractory epilepsy with several seizures per week after temporal lobe epilepsy surgery despite appropriate anticonvulsant therapy. Instead of reoperation, she underwent stereotactic radiosurgery (SRS), which was performed using a linac-based Elekta Axesse SRS machine with a marginal dose of 24 Gy (gross target volume: 6.67 cm3) in one fraction. Post-radiosurgery, she had no clinical or radiological complications. She was maintained on two anti-seizure medications following treatment (valproate and levetiracetam) and was seizure free at the time of this report (during four weeks after SRS). Monthly follow-up was planned for the evaluation of long-term outcomes. SRS may be a safe option for treating intractable focal epilepsy or recurrent epilepsy after surgery failure in children.

Canh Duy Phan,1 Anh Tuan Dang,2 Van Anh Ton-Nu,3 Huu Son Nguyen,4 Nhu Hiep Pham1 1Oncology Center, Hue Central Hospital, Hue City, Vietnam; 2Neurology Department, National Hospital of Pediatrics, Ha Noi, Vietnam; 3Pediatric Department, Hue University of Medicine and Pharmacy - Hue University, Hue City, Vietnam; 4Pediatric Center, Hue Central Hospital, Hue City, VietnamCorrespondence: Van Anh Ton-NuPediatric Department, Hue University of Medicine and Pharmacy - Hue University, 06 Ngo Quyen St, Hue City, VietnamTel +84982066063Email tonnuvananh@huemed-univ.edu.vnAbstract: A 13-year-old right-handed girl had operculoinsular refractory epilepsy with several seizures per week after temporal lobe epilepsy surgery despite appropriate anticonvulsant therapy. Instead of reoperation, she underwent stereotactic radiosurgery (SRS), which was performed using a linac-based Elekta Axesse SRS machine with a marginal dose of 24 Gy (gross target volume: 6.67 cm3) in one fraction. Post-radiosurgery, she had no clinical or radiological complications. She was maintained on two anti-seizure medications following treatment (valproate and levetiracetam) and was seizure free at the time of this report (during four weeks after SRS). Monthly follow-up was planned for the evaluation of long-term outcomes. SRS may be a safe option for treating intractable focal epilepsy or recurrent epilepsy after surgery failure in children.Keywords: stereotactic radiosurgery, epilepsy, refractory, epilepsy surgery

The Princess Alexandra Hospital (PAH) Gamma Knife® Centre of Queensland (GKCoQ) began operations in October of 2015 as a sub‐specialty located within a larger radiation oncology service at PAH. It is uniquely positioned as the only Leksell Gamma Knife® (LGK) treatment unit available in the public hospital system in Australia, and the first and only service in Queensland. The GKCoQ treated the 1000th patient on 23 January 2019. LGK is a non‐invasive alternative to neurosurgery which uses radioactive cobalt sources to treat a variety of intracranial conditions ranging from tumours and metastases to functional disorders. It is a platform for stereotactic radiosurgery, a highly precise form of radiotherapy utilising very high doses to the target while maximally sparing surrounding normal brain. LGK enables patient planning and treatment to be done in one day as an outpatient procedure. This paper will outline our LGK service and provide insight into the expanded role that radiation therapists have within the multidisciplinary team required to deliver radiosurgery in a timely manner. The training programme and radiation licensing pathway that have been established for radiation therapists will also be described.

Background: Peritumoral edema may be a prohibitive side effect in treating large incidental meningiomas with stereotactic radiosurgery. An approach that limits peritumoral edema and achieves tumor control with SRS would be an attractive management option for large incidental meningiomas. Methods: This is a retrospective cohort study of patients with large incidental meningiomas (≥2 mL in volume and/or 2 cm in diameter) treated with gamma knife radiosurgery (GKRS) between 2000 and 2019 in Taiwan and followed up for 5 years. The outcomes of a pathophysiological approach targeting the dural feeding artery site with a higher marginal dose (18–20 Gy) to enhance vascular damage and the parenchymal margin of the tumor with a lower dose (9–11 Gy) to reduce parenchymal damage were compared with those of a conventional approach targeting the tumor center with a higher dose and tumor margin with a lower dose (12–14 Gy). Results: A total of 53 incidental meningiomas were identified, of which 23 (43.4%) were treated with a pathophysiological approach (4 cases underwent a two-stage approach) and 30 (56.7%) were treated with a conventional approach. During a median follow-up of 3.5 (range 1–5) years, tumor control was achieved in 19 (100%) incidental meningiomas that underwent a single-stage pathophysiological approach compared with 29 (96.7%) incidental meningiomas that underwent a conventional approach (log-rank test: p = 0.426). Peritumoral edema developed in zero (0%) incidental meningiomas that underwent a single stage pathophysiological approach compared to seven (23.3%) incidental meningiomas that underwent a conventional approach (log-rank test: p = 0.023). Conclusions: Treatment of large incidental meningiomas with a pathophysiological approach with GKRS achieves similar rates of tumor control and reduces the risk of peritumoral edema. GKRS with a pathophysiological approach may be a reasonable management strategy for large incidental meningiomas.

Stereotactic radiosurgery (SRS) is a standard of care for many patients with brain metastases. To optimize post-SRS surveillance, this study aimed to validate a previously published nomogram predicting post-SRS intracranial progression (IP). We identified consecutive patients completing an initial course of SRS across two institutions between July 2017 and December 2020. Patients were classified as low- or high-risk for post-SRS IP per a previously published nomogram. Overall survival (OS) and freedom from IP (FFIP) were assessed via the Kaplan–Meier method. Assessment of parameters impacting FFIP was performed with univariable and multivariable Cox proportional hazard models. Among 890 patients, median follow-up was 9.8 months (95% CI 9.1–11.2 months). In total, 47% had NSCLC primary tumors, and 47% had oligometastatic disease (defined as ≤5 metastastic foci) at the time of SRS. Per the IP nomogram, 53% of patients were deemed high-risk. For low- and high-risk patients, median FFIP was 13.9 months (95% CI 11.1–17.1 months) and 7.6 months (95% CI 6.4–9.3 months), respectively, and FFIP was superior in low-risk patients (p < 0.0001). This large multisite BM cohort supports the use of an IP nomogram as a quick and simple means of stratifying patients into low- and high-risk groups for post-SRS IP.

ilustraciones, fotografías a blanco y negro, fotografías a color, gráficas En este trabajo final de maestría se realizó la implementación de tratamientos de radiocirugía intracraneal (SRS) en un hospital de mediana y alta complejidad. La primera parte fue el comisionamiento del CLINAC TrueBeam, para la validación del comisionamiento se aplicó el protocolo TG 119 usando los fantoma Octavius 4D, Ruby y el Portal Dosimetry. Para la técnica VMAT y las evaluaciones del índice gamma usando el Octavius 4D se encontraron valores del límite de confianza de 4.5, 4.7, 4.06, 5.30 y 4.5 para los haces de energía 6, 6 FFF, 10, 10 FFF y 16 MV, respectivamente, para esta misma técnica y la evaluación de dosis a punto se encontraron límites de confianza de 0.019, 0.026, 0.016, 0.026 y 0.018 para los haces de energía 6, 6 FFF, 10, 10 FFF y 16 MV, respectivamente. Posteriormente se desarrollo un protocolo para la implementación de radiocirugía intracraneal; desde las recomendaciones para la simulación hasta la evaluación de los planes de tratamiento. Para los controles de calidad usando el índice gamma se usaron las cantidades planteadas en el TG-218. La tercera parte se centró en la evaluación de la exactitud de la entrega de la dosis, se encontró que para las evaluaciones usando el Octavius 4D y para tratamientos de una única lesión con los criterios de diferencia de dosis y la distancia de 3%2mm se obtuvieron resultados con un promedio de 99.13 (IC 95%: 97.45-100). (Texto tomado de la fuente) In this final master's project, the implementation of intracranial radiosurgery (SRS) treatments was carried out in a medium and high complexity hospital. The first part was the commissioning of the CLINAC TrueBeam, for the validation of the commissioning the TG 119 protocol was applied using the Octavius ​​4D and Ruby phantoms and the Dosimetry Portal. For the VMAT technique and the gamma index evaluations using the Octavius ​​4D, confidence limit values ​​of 4.5, 4.7, 4.06, 5.30 and 4.5 were found for the energy beams 6, 6 FFF, 10, 10 FFF and 16 MV, respectively. , for this same technique and the point dose evaluation, confidence limits of 0.019, 0.026, 0.016, 0.026 and 0.018 were found for energy beams 6, 6 FFF, 10, 10 FFF and 16 MV, respectively. Subsequently, a protocol was developed for the implementation of intracranial radiosurgery; from recommendations for simulation to evaluation of treatment plans. For the quality controls using the gamma index, the amounts stated in the TG-218 were used. The third part focused on the evaluation of the accuracy of the dose delivery, it was found that for the evaluations using the Octavius ​​4D and for treatments of a single lesion with the criteria of dose difference and the distance of 3%2mm, obtained results with an average of 99.13 (95% CI: 97.45-100). Maestría Maestría en Física Médica

Purpose We investigated the immobilization accuracy of a new type of thermoplastic mask—the Double Shell Positioning System (DSPS)—in terms of geometry and dose delivery. Methods Thirty‐one consecutive patients with 1–5 brain metastases treated with stereotactic radiotherapy (SRT) were selected and divided into two groups. Patients were divided into two groups. One group of patients was immobilized by the DSPS (n = 9). Another group of patients was immobilized by a combination of the DSPS and a mouthpiece (n = 22). Patient repositioning was performed with cone beam computed tomography (CBCT) and six‐degree of freedom couch. Additionally, CBCT images were acquired before and after treatment. Registration errors were analyzed with off‐line review. The inter‐ and intrafractional setup errors, and planning target volume (PTV) margin were also calculated. Delivered doses were calculated by shifting the isocenter according to inter‐ and intrafractional setup errors. Dose differences of GTV D99% were compared between planned and delivered doses against the modified PTV margin of 1 mm. Results Interfractional setup errors associated with the mouthpiece group were significantly smaller than the translation errors in another group (p = 0.03). Intrafractional setup errors for the two groups were almost the same in all directions. PTV margins were 0.89 mm, 0.75 mm, and 0.90 mm for the DSPS combined with the mouthpiece in lateral, vertical, and longitudinal directions, respectively. Similarly, PTV margins were 1.20 mm, 0.72 mm, and 1.37 mm for the DSPS in the lateral, vertical, and longitudinal directions, respectively. Dose differences between planned and delivered doses were small enough to be within 1% for both groups. Conclusions The geometric and dosimetric assessments revealed that the DSPS provides sufficient immobilization accuracy. Higher accuracy can be expected when the immobilization is combined with the use of a mouthpiece.

BackgroundImmune checkpoint inhibitors (ICI) have been a breakthrough for selected cancer patients, including those with brain metastases (BMs). Likewise, steroids have been an integral component of symptomatic management of BM patients. However, clinical evidence on the interaction between ICI and steroids in BM patients is conflicting and has not adequately been summarized thus far. Hence, the aim of this study was to perform a systematic literature review and meta-analysis on the association between steroid use and overall survival (OS) in BM patients receiving ICI.MethodsA systematic literature search was performed. Pooled effect estimates were calculated using random-effects models across included studies.ResultsAfter screening 1145 abstracts, 15 observational studies were included. Fourteen studies reported sufficient data for meta-analysis, comprising 1102 BM patients of which 32.1% received steroids. In the steroid group, median OS ranged from 2.9 to 10.2 months. In the nonsteroid group, median OS ranged from 4.9 to 25.1 months. Pooled results demonstrated significantly worse OS (HR = 1.84, 95% CI 1.22-2.77) and systemic progression-free survival (PFS; HR = 2.00, 95% CI 1.37-2.91) in the steroid group. Stratified analysis showed a consistent effect across the melanoma subgroup; not in the lung cancer subgroup. No significant association was shown between steroid use and intracranial PFS (HR = 1.31, 95% CI 0.42-4.07).ConclusionsAdministration of steroids was associated with significantly worse OS and PFS in BM patients receiving ICI. Further research on dose, timing, and duration of steroids is needed to elucidate the cause of this association and optimize outcomes in BM patients receiving ICI.

Purpose Intrafraction patient motion is a well‐documented phenomenon in radiation therapy. In stereotactic radiosurgery applications in which target sizes can be very small and dose gradients very steep, patient motion can significantly impact the magnitude and positional accuracy of the delivered dose. This work investigates the impact of intrafraction motion on dose metrics for small targets when treated with a virtual cone. Materials and Methods Monte Carlo simulations were performed to calculate dose kernels for treatment apertures ranging from 1 × 2.5 mm2 to 10 × 10 mm2. The phantom was an 8.2‐cm diameter sphere and isotropic voxels had lengths of 0.25 mm. Simulated treatments consisted of 3 arcs: 1 axial arc (360° gantry rotation, couch angle 0°) and 2 oblique arcs (180° gantry rotation, couch angle ±45°). Dose distributions were calculated via superposition of the rotated kernels. Two different collimator orientations were considered to create a virtual cone: (a) each treatment arc was delivered twice, once each with a static collimator angle of ±45°, and (b) each treatment arc was delivered once, with dynamic collimator rotation throughout the arc. Two different intrafraction motion patterns were considered: (a) constant linear motion and (b) sudden, persistent motion. The impact of motion on dose distributions for target sizes ranging from 1 to 10 mm diameter spheres was quantified as a function of the aperture size used to treat the lesions. Results The impact of motion on both the target and the surrounding tissue was a function of both aperture shape and target size. When a 0.5‐mm linear drift along each dimension occurred during treatment, targets ≥5 mm saw less than a 10% decrease in coverage by the prescription dose. Smaller apertures accrued larger penalties with respect to dosimetric hotspots seen in the tissues surrounding the target volume during intrafraction motion. For example, treating a 4‐mm‐sized target that undergoes 2.60 mm (3D vector) of continuous linear motion, the D5 in the concentric shells that extend 1, 2, and 3 mm from the surface of the target was 39%, 24%, and 14% smaller, respectively when comparing the delivery of a larger aperture (6 × 10 mm2) to a smaller aperture (2 × 5 mm2). Using a static collimator for shaping a virtual cone during treatment minimized the dosimetric impact of motion in the majority of cases. For example, the volume that is covered by 70% or more of the prescription dose is smaller in 60.4% of cases when using the static collimator. The volume covered by 50, and 30% or more of the prescription dose is also smaller when treating with a static collimator, but the clinical significance of this finding is unknown. Conclusions In this work, the dosimetric trade‐offs between aperture size and target size when irradiating with virtual cones has been demonstrated. These findings provide information about the tradeoffs between target coverage and normal tissue sparing that may help inform clinical decision making when treating smaller targets with virtual cones.

Objective ‒ the treatment result estimation of subtotally removed and recurrent pituitary adenomas using different algorithms of radiotherapy and radiosurgery.Materials and methods. The retrospective analysis of 21 cases of pituitary adenomas was performed. There were 11 women and 10 men included. The average age was 45 (from 18 to 72) years. All patients had relapse or residual tumor after incomplete surgical removal. The method of irradiation was chosen by a radiologist. Tumor size control was assessed by an independent radiologist in 3 months and 1 year after treatment. Endocrine function was estimated by an independent endocrinologist in 3 months and 1 year after treatment.Results. Following transsphenoidal removal ‒ 13 patients (4 were operated twice), 5 after cranial surgery and 3 were operated sequentially transnasally and transcranially. Irradiation of 14 cases of residual tumor was performed no later than 6 months after surgery. The mean term of treatment start of recurrent adenomas was 12 months (8‒17) after surgery. VARIAN Novalis was applied in 16 cases, VARIAN Clinac iX in 4 cases and VARIAN TrueBeam STx was used once. Single and total radiation doses were determined individually. None of patients had visual impairment after treatment. The hypopituitarism deterioration was not noted as well.Conclusions. Hypofractionated stereotactic radiosurgery allows to bring a high dose of radiation to the pituitary adenomas, minimizing damage to the visual pathways, the pituitary gland and infundibulum. As the sequence, it reduces the toxicity of the technique. The application of modern radiation technologies minimize the irradiation of healthy surrounding tissues and reduce the negative effects of treatment.

Survival prediction models may serve as decision-support tools for clinicians who have to assign the right treatment to each patient, in a manner whereby harmful over- or undertreatment is avoided as much as possible. Current models differ regarding their components, the overall number of components and the weighting of individual components. Some of the components are easy to assess, such as age or primary tumor type. Others carry the risk of inter-assessor inconsistency and time-dependent variation. The present publication focuses on issues related to assessment of extracranial metastases and potential surrogates, e.g. blood biomarkers. It identifies areas of controversy and provides recommendations for future research projects, which may contribute to prognostic models with improved accuracy. (c) 2021 Elsevier B.V. All rights reserved. Radiotherapy and Oncology 159 (2021) 17-20

Introduction: The clinical management of parasellar meningiomas (PM) is challenging due to their intimate association with critical neurovascular structures. Consensus regarding the recommended treatment protocol is lacking. This study will evaluate patients’ visual outcomes following endoscopic transnasal optic nerve decompression (ETOND) and will investigate the possibility of reducing the rate of complications associated with stereotactic radiosurgery (SRS). Methods: Retrospective analysis was conducted on all patients who underwent ETOND for PM between 2013 and 2020. The study comprised 12 patients (7 women and 5 men aged 36–75 years; mean, 55.2 years; median, 57.6 years) in which 14 optic nerve decompression procedures were carried out. Patients were followed up for 6 to 86 months (mean, 29.3 months; median, 25 months). There were five cases of spheno-orbital meningioma, four cases of cavernous sinus meningioma, and one case each of petro-clival meningioma, optic nerve sheath meningioma, and planum sphenoidale/tuberculum sellae meningioma. Visual outcome was evaluated and any postoperative complications noted. Results: Improvements in visual acuity were noted in 10 of 14 eyes (71.4%) 3 to 6 months postoperation. Visual acuity remained stable in the remaining four eyes. No deterioration of visual acuity was noted during the follow-up period. In total, 9 of the 12 patients underwent SRS. No tumor growth was determined, while reduction in tumor volume was noted in five patients following SRS. No complications associated with SRS or the surgical procedure were noted. Conclusions: ETOND appears to be a promising technique for increasing rates of improved visual function, while reducing the risk of post SRS-related complications. In combination with subsequent SRS, it is an ideal treatment modality in the management of parasellar meningiomas. Confirmation of our findings would require a larger, prospective multicenter study.

Pancreatic adenocarcinoma is an extremely aggressive cancer with a low survival rate. Common sites for metastases include the liver and lungs, while brain metastases are considered extremely rare, especially in elderly patients. We present an elderly female patient who developed brain metastases 51 months after the initial diagnosis of pancreatic cancer and was treated with gross tumor resection, chemotherapy, and stereotactic radiosurgery. The treatment completely resolved her neurological symptoms but did not result in improved survival for this patient. The patient developed generalized tonic-clonic seizures, was diagnosed with leptomeningeal carcinomatosis, and died 5.5 months after tumor resection. The literature on pancreatic cancer with brain metastases is scarce, with limited guidelines for treatment strategies in this patient population. Adding this case report to the existing literature may provide additional guidance to clinicians managing patients with similar presentations.

Purpose: A phase II study carried out to assess the efficacy of a risk-adapted strategy of stereotactic radiosurgery (SRS) for lung cancer. The primary endpoint was 3-year local recurrence, and the secondary endpoints were overall survival (OS), disease-free survival (DFS), rate of start of systemic therapy or best supportive care (SST-BSC), and toxicity. Materials and Methods: Eligible patients fulfilled the following criteria: performance status of 2 or less, forced expiratory volume in 1 s of 700 mL or more, and tumor not located in central or attached to the chest wall. Twenty-eight Gy was prescribed for primary lung cancers with diameters of 3 cm or less and 30 Gy was prescribed for primary lung cancers with diameters of 3.1–5.0 cm or solitary metastatic lung cancer diameters of 5 cm or less. Results: Twenty-one patients were analyzed. The patients included 7 patients with adenocarcinoma, 2 patients with squamous cell carcinoma, 1 patient with metastasis, and 11 patients with clinical diagnosis. The median tumor diameter was 1.9 cm. SRS was prescribed at 28 Gy for 18 tumors and 30 Gy for 3 tumors. During the median follow-up period of 38.9 months for survivors, 1 patient had local recurrence, 7 patients had regional or distant metastasis, and 5 patients died. The 3-year local recurrence, SST-BSC, DFS, and OS rates were 5.3% (95% confidence interval [CI]: 0.3–22.2%), 20.1% (95% CI: 6.0–40.2%), 59.2% (95% CI: 34.4–77.3%), and 78.2% (95% CI: 51.4–91.3%), respectively. The 95% CI upper value of local recurrence was lower than the null local recurrence probability. There was no severe toxicity, and grade 2 radiation pneumonitis occurred in 1 patient. Conclusions: Patients who received SRS for lung cancer had a low rate of 3-year local recurrence and tolerable toxicity.

Purpose Automated treatment planning systems are available for linear accelerator (linac)-based single-isocenter multi-target (SIMT) stereotactic radiosurgery (SRS) of brain metastases. In this study, we compared plan quality between Brainlab Elements Multiple Brain Metastases (Elements MBM) software which utilizes dynamic conformal arc therapy (DCAT) and Varian HyperArc (HA) software using a volumetric modulated arc therapy (VMAT) technique. Patients and methods Between July 2018 and April 2021, 36 consecutive patients ≥ 18 years old with 367 metastases who received SIMT SRS at UPMC Hillman Cancer San Pietro Hospital, Rome, were retrospectively evaluated. SRS plans were created using the commercial software Elements MBM SRS (Version 1.5 and 2.0). Median cumulative gross tumor volume (GTV) and planning tumor volume (PTV) were 1.33 cm3 and 3.42 cm3, respectively. All patients were replanned using HA automated software. Extracted dosimetric parameters included mean dose (Dmean) to the healthy brain, volumes of the healthy brain receiving more than 5, 8,10, and 12 Gy (V5Gy, V8Gy, V10Gy and V12Gy), and doses to hippocampi. Results Both techniques resulted in high-quality treatment plans, although Element MBM DCAT plans performed significantly better than HA VMAT plans, especially in cases of more than 10 lesions). Median V12Gy was 13.6 (range, 1.87–45.9) cm3 for DCAT plans and 18.5 (2.2–62,3) cm3 for VMAT plans (p 10Gy, V8Gy, V5Gy (p p = 0.0001) were favorable for DCAT plans. Conclusions Both Elements MBM and HA systems were able to generate high-quality plans in patients with up to 25 brain metastases. DCAT plans performed better in terms of normal brain sparing, especially in patients with more than ten lesions and limited total tumor volume.

Traballo Fin de Grao en Medicina. Curso 2021-2022 OBXECTIVOS: A radiocirurxía estereotáctica é unha das opcións de tratamento para as malformacións arteriovenosas cerebrais (MAVc). A literatura publicada ata o momento describe fundamentalmente os resultados en adultos, polo que o obxectivo deste traballo é determinar a eficacia, medida pola porcentaxe de obliteración, e seguridade, representada polas complicacións sintomáticas, radiolóxicas e o resangrado da lesión, desta técnica para o tratamento de MAVc en nenos. MÉTODOS: Preséntase o caso dunha paciente de tres anos tratada dunha MAVc con radiocirurxía estereotáctica no noso centro. Realízase unha revisión sistemática, de acordo coa guía PRISMA, da literatura publicada nas bases de datos de PubMed, Scopus e Web of Science ata decembro de 2021, incluíndo estudos que reportaron pacientes pediátricos con MAVc tratadas con radiocirurxía. A calidade dos estudos incluídos avaliouse coa ferramenta do JBI. Calculouse a media global dos estudos incluídos para cada variable cuantitativa. RESULTADOS: A MAVc da paciente presentada foi obliterada completamente nun período inferior a dous anos tras unha sesión de radiocirurxía, deixando unicamente unha área de gliose postradiocirurxía non sintomática. A revisión sistemática identificou 1760 artigos, dos cales se incluíron 34. Todos foron series de casos, cun total de 3044 pacientes e unha idade media de 12,6 anos. Reportaron unha taxa de obliteración media do 68%. A porcentaxe de complicacións sintomáticas media foi do 5,7%, a de complicacións radiolóxicas do 26% e a de resangrado do 6,2%. CONCLUSIÓN: A radiocirurxía estereotáctica pode ser unha terapia eficaz e segura para o tratamento de casos seleccionados de pacientes pediátricos con MAVc, aínda que a planificación do mesmo deberá facerse por un equipo multidisciplinar que domine as distintas técnicas dispoñibles. Precísase avaliar con estudos cunha evidencia máis robusta o verdadeiro grado de efectividade da técnica e as características individuais que condicionan mellores resultados OBJETIVOS: La radiocirugía estereotáctica es una de las opciones de tratamiento para las malformaciones arteriovenosas cerebrales (MAVc). La literatura publicada hasta la fecha describe fundamentalmente los resultados en adultos, por lo que el objetivo de este trabajo es determinar la eficacia, medida con el porcentaje de obliteración, y seguridad, representada por complicaciones sintomáticas, radiológicas y resangrado de la lesión, de esta técnica para el tratamiento de las MAVc en niños. MÉTODOS: Se presenta el caso de una paciente de tres años tratada de una MAVc con radiocirugía estereotáctica en nuestro centro. Se realiza una revisión sistemática, siguiendo la guía PRISMA, de la literatura publicada en PubMed, Scopus e Web of Science hasta diciembre de 2021, incluyendo estudios que reportaron pacientes pediátricos con MAVc tratadas con radiocirugía. La calidad se evaluó con la herramienta del JBI. Se calculó la media global de los estudios incluidos para cada variable cuantitativa. RESULTADOS: La MAVc del caso presentado fue obliterada completamente en menos de dos años tras una sesión de radiocirugía, dejando únicamente un área de gliosis postradiocirugía asintomática. La revisión sistemática identificó 1760 artículos, incluyéndose finalmente 34. Todos fueron series de casos, con 3044 pacientes en total y una edad media de 12,6 años. La tasa de obliteración media fue del 68%. El porcentaje de complicaciones sintomáticas medio fue del 5,7%, de complicaciones radiológicas del 26% y de resangrado del 6,2%. CONCLUSIÓN: La radiocirugía estereotáctica puede ser una terapia eficaz y segura para el tratamiento de casos seleccionados de pacientes pediátricos con MAVc, aunque la planificación deberá hacerse por un equipo multidisciplinar que domine las técnicas disponibles. Se necesita evaluar con estudios con evidencia más robusta el verdadero grado de eficacia de la radiocirugía y características individuales que condicionan mejores resultados BACKGROUND: Stereotactic radiosurgery is one of the current treatment options for brain arteriovenous malformations (bAVM). The literature published up to this date mainly describes the results of this treatment in adults. Hence, the objective of this study is to determine the efficacy, measured with the percentage of obliteration, and safety, represented by symptomatic, radiological complications and the rebleeding of the lesion, of this technique fo the treatment of bAVM in children. METHODS: We present the case of a three-year-old patient treated for a bAVM with stereotactic radiosurgery at our hospital. A systematic review of the literature published in PubMed, Scopus and Web of Science up to December 2021 is also carried out, following the PRISMA guidelines and including studies that reported pediatric patients with bAVM treated with radiosurgery. The quality of the studies was evaluated with the JBI tool. The overall mean of the included studies was calculated for each quantitative variable. RESULTS: Our patient’s bAVM was completely obliterated in less than two years after a single radiosurgery session, just leaving an area of asymptomatic post-radiosurgery gliosis. The systematic review identified 1760 articles, of which we included 34 for analysis. All the studies were case series, with a total of 3044 patients and a mean age of 12.6 years old. The mean obliteration rate was 68%. The mean percentage of symptomatic complications was 5.7%, of radiological complications, 26% and of rebleeding, 6.2%. CONCLUSIONS: Stereotactic radiosurgery can be considered an effective and safe treatment option for selected cases of pediatric patients with bAVM, although planning should be done by a multidisciplinary team that masters all the available techniques. Further studies, with more robust evidence, are required in order to evaluate the true degree of efficacy of radiosurgery and individual characteristics that determine a better outcome

Brain tumors, which are among the most common solid tumors in childhood, remain a leading cause of cancer-related mortality in pediatric population. Gliomas, which may be broadly categorized as low grade glioma and high grade glioma, account for the majority of brain tumors in children. Expectant management, surgery, radiation therapy (RT), chemotherapy, targeted therapy or combinations of these modalities may be used for management of pediatric gliomas. Several patient, tumor and treatment-related characteristics including age, lesion size, grade, location, phenotypic and genotypic features, symptomatology, predicted outcomes and toxicity profile of available therapeutic options should be considered in decision making for optimal treatment. Management of pediatric gliomas poses a formidable challenge to the physicians due to concerns about treatment induced toxicity. Adverse effects of therapy may include neurological deficits, hemiparesis, dysphagia, ataxia, spasticity, endocrine sequelae, neurocognitive and communication impairment, deterioration in quality of life, adverse socioeconomic consequences, and secondary cancers. Nevertheless, improved understanding of molecular pathology and technological advancements may pave the way for progress in management of pediatric glial neoplasms. Multidisciplinary management with close collaboration of disciplines including pediatric oncology, surgery, and radiation oncology is warranted to achieve optimal therapeutic outcomes. In the context of RT, stereotactic irradiation is a viable treatment modality for several central nervous system disorders and brain tumors. Considering the importance of minimizing adverse effects of irradiation, radiosurgery has attracted great attention for clinical applications in both adults and children. Radiosurgical applications offer great potential for improving the toxicity profile of radiation delivery by focused and precise targeting of well-defined tumors under stereotactic immobilization and image guidance. Herein, we provide a concise review of stereotactic irradiation for pediatric glial neoplasms in light of the literature.

Stereotactic radiosurgery (SRS) is a proven treatment modality for inoperable arteriovenous malformations (AVMs). However, the rate of radiation-induced necrosis (RIN) is as high as 10%. A 6-year-old female patient presented with severe headache, emesis, and syncope, and workup revealed a Spetzler-Martin grade 4 AVM with intraventricular hemorrhage and hydrocephalus. The patient underwent a right frontal ventriculostomy followed by a linear accelerator-based SRS of 16.9 Gy. At 19 years, she developed progressive neurological symptoms. Diagnostic magnetic resonance imaging (MRI) revealed a recurrent parietal AVM nidus. We delivered the linear accelerator-based SRS of 18.5 Gy to the AVM nidus. Within 9 months, she experienced episodic headaches and left-sided weakness and spasticity; symptoms were initially managed with dexamethasone. Follow-up MRI was notable for edema and nondetectable blood flow, consistent with RIN and AVM obliteration. The second course of steroids did not provide the symptom control. Persistent RIN was noted on MRI, and she had stigmata of steroid toxicity (centripetal obesity, depression, and sleep disorder). Two infusions of bevacizumab (5 mg/kg) were administered concurrently with a tapering dose of dexamethasone. The patient noted a near immediate improvement in her headaches, and 2 months following the second bevacizumab infusion, she reported a near-complete resolution of her symptoms and displayed improved ambulation. The development of RIN remains a noteworthy concern post-SRS of AVMs. While steroids aid with initial management of RIN, for persistent and recurrent symptoms, bevacizumab infusions serve as a viable treatment course, with the added benefit of reducing the likelihood of adverse effects resulting from prolonged steroid therapy.

Background/aim: Few previous studies have evaluated the effectiveness of single-isocenter multitarget (SIMT) stereotactic radiosurgery (SRS) in clinical practice., Patients and methods:Gross tumor volumes of 113 metastases in 13 patients were measured by contrast-enhanced magnetic resonance imaging. Prescribed doses were set at 20-24 Gy. Based on tumor reduction rates (TRRs) measured before and after SIMT SRS, tumor shrinkage effect was categorized into four grades; almost disappeared: TRR=1, decreased: 0.3≤TRR, Results:Median survival time was 17 months, with 63.7%, 11.5% and 12.4% of metastases corresponded to almost disappeared, decreased and stable, respectively. No significant difference was found in the distribution for TRRs among 3 groups., Conclusion:Good local control of multiple brain metastases was demonstrated by SIMT SRS, irrespective of distance from the isocenter.

BACKGROUND Structural damage to the brain substance in adults is one of the most common causes of epilepsy. Currently, such patients are prescribed drug therapy and/or surgery. With this approach, epileptic symptoms can persist in a significant proportion of patients (up to 30%, depending on the disease).AIM OF STUDY To clarify the efficacy of stereotactic radiosurgery (STS) as part of the complex treatment of patients suffering from pharmacoresistant symptomatic epilepsy with hippocampal sclerosis, vascular malformations, and some benign tumors of the brain and its membranes.MATERIAl AND METHODS Examination and radiosurgical treatment were carried out in 45 patients with various brain diseases accompanied by symptomatic epilepsy, provided that the previous conservative or surgical treatment was insufficiently effective. During the observation period, the frequency of seizures was assessed and the presence and nature of postoperative complications were recorded.RESUlTS With a median follow-up of 30 months, good outcomes (class I–II according to J. Engel’s scale) were observed in 5 out of 8 patients with hippocampal sclerosis who underwent STS after amygdaloghippocamplobectomy; seizure frequency decreased in all patients. Complications of STS were noted in 2 patients and had a transient nature. In the group of patients with meningiomas, in 4 out of 8 patients, seizures completely stopped, in 3 patients the frequency of seizures decreased by more than 90%, in another 1 the frequency of seizures decreased by 60%. There were no complications of STS during the observation period. Inintracerebral tumors (diffuse astrocytoma), Engel Ia outcome was observed in both patients. In the group of patients with cavernous angiomas, there were good outcomes (class I–II according to J. Engel’s scale) in 17 patients (85%). Deterioration (Engel IVc outcome) was observed in 1 patient (5%), 2 patients (10%) had complications of STS. In the group of patients with arteriovenous malformations, good outcomes (classes I–II according to J. Engel’s scale) were found in all 7 patients. The complication after STS was revealed in 1 patient.CONClUSION The presented results confirm the high efficiency and low risk of side effects when using stereotactic radiosurgery in the complex treatment of patients with epilepsy associated with common structural brain lesions.

Brain metastases are common in stage IV malignant melanoma, carrying a prognosis traditionally regarded as severe, with a median survival of few months. Recently introduced systemic therapies as targeted therapy or immunotherapy have significantly improved the prognosis of metastatic melanoma. The optimal association of radiotherapy to such novel treatments has to be clarified. We report on a 43-year-old woman with 10 brain metastases. Three of them were treated with stereotactic radiosurgery (SRS) with complete response even of the untreated lesions. As the patient was BRAF-mutated, she was started on dabrafenib/trametinib. After 8 months she developed new brain metastases, which again responded to a new treatment with SRS. As after 7 months additional lesions appeared, she was treated with whole brain radiotherapy and was started on nivolumab. Twenty months after the first diagnosis of brain metastases the patient is fit without significant clinical and radiological signs of toxicity.

External beam radiotherapy (EBR) remained for a long time the only method of treatment in children with recurrent and resistant retinoblastoma (RB). This method often leads to serious complications, including the occurrence of secondary malignant tumors. Currently, EBR is used as second-line (salvage) therapy. There is no data in the literature of using Gamma Knife stereotactic radiosurgery (GKRS) in RB treatment. Purpose. To present 5-year experience of using GKRS in patients with RB. Material and methods. 16 children (17 eyes) were treated using GKRS in the period from 2015 to 2019. Mean patient age was 34.7 months (range, 12–114 months). The eyes were classified as group B (n=4), C (n=1), D (n=12). 3 children had the last eye. All patients received systemic and local chemotherapy, all types of local treatment modalities before using GKRS. Recurrent and resistant RB was the indication for GKRS. Marginal 50% mean dose was 22 Gу (range, 20–24 Gу), depending on tumour type and location. Radiation doses were evaluated accounting critical eye structures and the orbit bones. Results. Complete regression was achieved in 11 patients, partial in 2. Four patients underwent enucleation after GKRS. Indications for enucleation were retinoblastoma recurrence (n=2) and vitreous hemorrhage with total retinal detachment (n=2). 13 eyes were salvaged with no signs of keratopathy, uveitis or damage of orbital and surrounding tissues during mean follow-up 30.6 months (range, 7–60 months). Сomplications of different severity occurred in 13 patients, including vitreous hemorrhage in 6 patients, which was successfully treated both conservative (n=3) and using pars plana vitrectomy with simultaneous melphalan irrigation (n=3). Conclusion. The first experience of GKRS as an alternative to enucleation in patients with RB was proved to be reasonable and successful. Key words: retinoblastoma, gamma-knife, stereotactic radiosurgery.

Purpose This study investigated the intra‐fractional motion (IM) of patients immobilized using the QFix Encompass Immobilization System during HyperArc (HA) treatment. Method HA treatment was performed on 89 patients immobilized using the Encompass. The IM during treatment (including megavoltage (MV) registration) was analyzed for six degrees of freedom including three axes of translation (anterior‐posterior, superior‐inferior (SI) and left‐right (LR)) and three axes of rotation (pitch, roll, and yaw). Then, the no corrected IM (IMNC) was retrospectively simulated (excluding MV registration) in three directions (SI, LR, and yaw). Finally, the correlation between the treatment time and the IM of the 3D vector was assessed. Results The average IM in terms of the absolute displacement were 0.3 mm (SI), 0.3 mm (LR) and 0.2° (yaw) for Stereotactic radiosurgery (SRS), and 0.3 mm (SI), 0.2 mm (LR), and 0.2° (yaw) for stereotactic radiotherapy (SRT). The absolute maximum values of IM were 1 mm along the SI and LR axes and >1° along the yaw axis. In the correlation between the treatment time and the IM, the r‐values were −0.025 and 0.027 for SRS and SRT respectively, along the axes of translation. For the axes of rotation, the r‐values were 0.012 and 0.206 for SRS and SRT, respectively. Conclusion Encompass provided patient immobilization with adequate accuracy during HA treatment. The absolute maximum displacement IM was less than IMNC along the translational/rotational axes, and no statistically significant relationship between the treatment time and the IM was observed.

In Radiation Therapy Oncology Group 90-05, the maximum tolerated dose of single-fraction radiosurgery (SRS) for brain metastases of 21–30 mm was 18 Gy (biologically effective dose (BED) 45 Gy12). Since the patients in this study received prior brain irradiation, tolerable BED may be >45 Gy12 for de novo lesions. We investigated SRS and fractionated stereotactic radiotherapy (FSRT) with a higher BED for radiotherapy-naive lesions. Patients receiving SRS (19–20 Gy) and patients treated with FSRT (30–48 Gy in 3–12 fractions) with BED > 49 Gy12 for up to 4 brain metastases were compared for grade ≥ 2 radiation necrosis (RN). In the entire cohort (169 patients with 218 lesions), 1-year and 2-year RN rates were 8% after SRS vs. 2% and 13% after FSRT (p = 0.73) in per-patient analyses, and 7% after SRS vs. 7% and 10% after FSRT (p = 0.59) in per-lesion analyses. For lesions ≤ 20 mm (137 patients with 185 lesions), the RN rates were 4% (SRS) vs. 0% and 15%, respectively, (FSRT) (p = 0.60) in per-patient analyses, and 3% (SRS) vs. 0% and 11%, respectively, (FSRT) (p = 0.80) in per-lesion analyses. For lesions > 20 mm (32 patients with 33 lesions), the RN rates were 50% (SRS) vs. 9% (FSRT) (p = 0.012) in both per-patient and per-lesion analyses. In the SRS group, a lesion size > 20 mm was significantly associated with RN; in the FSRT group, lesion size had no impact on RN. Given the limitations of this study, FSRT with BED > 49 Gy12 was associated with low RN risk and may be safer than SRS for brain metastases > 20 mm.

This study aimed to evaluate prognostic factors associated with nidus obliteration following stereotactic radiosurgery (SRS) for cerebral arteriovenous malformations. From January 2001 to January 2018, 119 patients who underwent SRS with AVM were studied to analyze major prognostic factors (age, prescription dose (Gy), volume (mm3), nidus size (cm), and Spetzler–Martin (SM) grade) for nidus obliteration. A random forest and tree explainer was used to construct a predictive model of nidus obliteration. The prognostic factors affecting nidus obliteration from most to least important were age, nidus size, volume, total prescription dose, and SM grade, using a predictive model. In a specific case for nidus size (1.5 cm), total dose (23 Gy), and SM grade (2), the result showed a high obliteration score of 0.75 with the actual obliteration period of 6 months spent; the mean AUC was 0.90 in K-fold cross validation. The predictive model identified the main contributing factors associated with a prognostic of nidus obliteration from linear accelerator-based SRS for cerebral AVM. It was confirmed that the results, including the prognostic factors, are potentially useful for outcome prediction for patient and treatment.