Self-Shielding Gyroscopic Radiosurgery: A Prospective Experience and Analysis of the First 100 Patients.

Background Stereotactic radiosurgery is a well-established treatment option for the management of various benign and malignant brain tumors. It can be delivered with several treatment platforms, usually requiring shielded radiation vaults to meet regulatory safety requirements. Recent technical advances have led to the first self-shielding platform enabling the delivery of gyroscopic radiosurgery (GRS). Given the limited number of GRS treatment platforms, the novelty of its characteristics, and the lack of available data, we report our prospective experience with the first 100 patients treated with GRS. Materials and methods Patients undergoing GRS for the treatment of intracranial tumors were enrolled in this prospective study. Patient and treatment characteristics, including patient satisfaction, were collected and analyzed. Results A total of 100 patients with 155 tumors were treated. The most commonly treated tumors comprised brain metastases (BM) (49%), vestibular schwannomas (31%), and meningiomas (14%). The median prescription dose for malignant and benign tumors was 20 and 13 Gy, respectively. The median prescription isodose line was 56%. Gross tumor volumes were small, with a median of 0.37 cc for BM and 0.92 cc for the other entities. The median total treatment time was 40 minutes. Dosimetric performance indices showed median values of 1.20 (conformity index), 1.24 (new conformity index), 1.74 (homogeneity index), and 3.13 (gradient index). Volumetric assessment of the treated tumors showed an overall decrease in size at the first available follow-up. Most patients were satisfied with the treatment experience. Conclusion Our first prospective experience of the use of GRS is favorable. Analyses of the dosimetric performance, treatment times, volumetric assessment, and patient satisfaction demonstrate its suitability for stereotactic treatments of intracranial tumors. Further prospective clinical and dosimetric analyses for GRS are pending.

Robotic stereotactic body radiotherapy for the management of adrenal gland metastases: a bi-institutional analysis.

PURPOSE: Adrenal gland metastases (AGMs) are a common manifestation of metastatic tumor spread, especially in non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). In patients with a limited systemic tumor burden, effective treatments for AGMs are needed. Due to varying fractionation schemes and limited reports, short-course treatment results for stereotactic body radiotherapy (SBRT) for AGMs are lacking. This work analyzes the outcomes of short-course SBRT for AGMs. METHODS: Patients who underwent robotic SBRT for AGMs with one to five fractions were eligible for analysis. RESULTS: In total, data from 55 patients with 72 AGMs from two institutions were analyzed. Most AGMs originated from renal cell carcinoma (38%) and NSCLC (35%). The median follow-up was 16.4 months. The median prescription dose and isodose line were 24 Gy and 70%, respectively. Most patients (85%) received SBRT with just one fraction. The median biologically effective dose assuming an α/ß ratio of 10 (BED10) was 80.4 Gy. The local control and progression-free survival after 1 and 2 years were 92.9%, 67.8%, and 46.2%, as well as 24.3%, respectively. Thirteen patients (24%) suffered from grade 1 or 2 toxicities. The BED10 showed a significant impact on LC (p < 0.01). Treatments with a BED10 equal to or above the median were associated with a better LC (p < 0.01). CONCLUSION: Robotic SBRT is an efficient and safe treatment modality for AGM. Treatment-associated side effects are sporadic and manageable. Results suggest short-course SBRT to be a preferable and time-saving treatment option for the management of AGMs if an adequate BED10 can be safely applied.

Single-fraction prostate-specific membrane antigen positron emission tomography- and multiparametric magnetic resonance imaging-guided stereotactic body radiotherapy for prostate cancer local recurrences.

OBJECTIVE: To analyse the efficacy and safety of focal prostate-specific membrane antigen positron emission tomography (PSMA-PET)- and multiparametric magnetic resonance imaging (mpMRI)-guided single-fraction stereotactic body radiotherapy (SBRT) for the treatment of prostate cancer (PCa) local recurrences. PATIENTS AND METHODS: Patients with PSMA-PET-positive PCa local recurrences treated with single-fraction SBRT between 2016 and 2020 were included. Identification for subsequent recurrences or metastatic spread based on increasing prostate-specific antigen (PSA) levels were evaluated using PSMA-PET imaging. RESULTS: A total of 64 patients were identified. Patients received various treatments before SBRT (31 patients with radical prostatectomy [RP], 18 external beam radiotherapy [EBRT] with RP, five EBRT, and the remaining 10 other combinations). The median follow-up was 21.6 months. The median PSA level before SBRT was 1.47 ng/mL. All patients received a single-fraction treatment with a median prescription dose and isodose line of 21 Gy and 65%, respectively. At the time of SBRT, six patients (9%) received an androgen deprivation therapy (ADT). PSA levels decreased after SBRT (P = 0.03) and three local recurrences were detected during the follow-up. The progression-free survival after 1-, 2-, and 3-years was 85.3%, 65.9%, and 51.2%, respectively. Six patients (9%) started ADT after SBRT due to disease progression. The rates of newly started ADT after 1-, 2-, and 3-years were 1.8%, 7.3%, and 22.7%, respectively. Grade 1 or 2 toxicities occurred in six patients (9%); no high-grade toxicity was observed. CONCLUSION: While the available data for SBRT in the PCa local recurrence setting describe outcomes for fractionated irradiations, the findings of this first analysis of single-fraction, PSMA-PET- and mpMRI-guided focal SBRT are encouraging. Such treatment appears to be a safe, efficient, and time-saving therapy even in intensively pretreated patients. Recurrence-directed treatments can delay the use of ADT and could avoid prostate bed irradiation in selected patients.

Image-guided robotic radiosurgery for the treatment of arteriovenous malformations.

BACKGROUND: Cerebral arteriovenous malformations (AVMs) are challenging lesions, often requiring multimodal interventions; however, data on the efficacy of stereotactic radiosurgery for cerebral AVMs are limited. This study aimed to evaluate the clinical and radiographic results following robotic radiosurgery, alone or in combination with endovascular treatment, and to investigate factors associated with obliteration and complications in patients with AVM. METHODS: We retrospectively analyzed the clinical and imaging characteristics of 123 patients with AVMs of all Spetzler-Martin grades treated at two institutions by robotic radiosurgery in single-fraction doses (CyberKnife). Embolization was performed before radiosurgery in a subset of patients to attempt to downgrade the lesions. Factors associated with AVM obliteration and complications (toxicity) were identified via univariate and multivariate analyses. RESULTS: The median follow-up time was 48.1 months (range, 3.6-123 months). Five patients were lost to follow-up. The obliteration rate in the 59 patients with a follow-up period exceeding four years was 72.8%. Complete obliteration and partial remission were achieved in 67 (56.8%) and 31 (26.3%) cases, respectively, whereas no change was observed in 20 cases (17.8%). Embolization was performed in 54/123 cases (43.9%). Complete and partial obliteration were achieved in 29 (55.7%) and 14 (26.9%) embolized patients, respectively. In the multivariate analysis, the factors associated with obliteration were age (p = .018) and the Spetzler-Martin grade (p = .041). Treatment-induced toxicity (radiation necrosis and/or edema) was observed in 15 cases (12.7%), rebleeding occurred in three cases (2.5%), and the rate of mortality associated with rebleeding was 1.7%. CONCLUSIONS: CyberKnife radiosurgery is a valid approach for treating AVMs of all Spetzler-Martin-grades, with satisfactory obliteration rates, low toxicity, and a relatively rare incidence of rebleeding.

Dynamic 18F-FET PET/CT to differentiate recurrent primary brain tumor and brain metastases from radiation necrosis after single-session robotic radiosurgery.

OBJECTIVE: Cyberknife robotic radiosurgery (RRS) provides single-session high-dose radiotherapy of brain tumors with a steep dose gradient and precise real-time image-guided motion correction. Although RRS appears to cause more radiation necrosis (RN), the radiometabolic changes after RRS have not been fully clarified. 18F-FET-PET/CT is used to differentiate recurrent tumor (RT) from RN after radiosurgery when MRI findings are indecisive. We explored the usefulness of dynamic parameters derived from 18F-FET PET in differentiating RT from RN after Cyberknife treatment in a single-center study population. METHODS: We retrospectively identified brain tumor patients with static and dynamic 18F-FET-PET/CT for suspected RN after Cyberknife. Static (tumor-to-background ratio) and dynamic PET parameters (time-activity curve, time-to-peak) were quantified. Analyses were performed for all lesions taken together (TOTAL) and for brain metastases only (METS). Diagnostic accuracy of PET parameters (using mean tumor-to-background ratio >1.95 and time-to-peak of 20 min for RT as cut-offs) and their respective improvement of diagnostic probability were analyzed. RESULTS: Fourteen patients with 28 brain tumors were included in quantitative analysis. Time-activity curves alone provided the highest sensitivities (TOTAL: 95%, METS: 100%) at the cost of specificity (TOTAL: 50%, METS: 57%). Combined mean tumor-to-background ratio and time-activity curve had the highest specificities (TOTAL: 63%, METS: 71%) and led to the highest increase in diagnosis probability of up to 16% p. - versus 5% p. when only static parameters were used. CONCLUSIONS: This preliminary study shows that combined dynamic and static 18F-FET PET/CT parameters can be used in differentiating RT from RN after RRS.

Intracranial Hemorrhage in Patients with Anticoagulant Therapy Undergoing Stereotactic Radiosurgery for Brain Metastases: A Bi-Institutional Analysis.

BACKGROUND: Stereotactic radiosurgery (SRS) is a well-established treatment modality for brain metastases (BM). Given the manifold implications of metastatic cancer on the body, affected patients have an increased risk of comorbidities, such as atrial fibrillation (AF) and venous thromboembolism (VTE), which includes pulmonary embolism (PE) and deep-vein thrombosis (DVT). These may require therapeutic anticoagulant therapy (ACT). Limited data are available on the risk of intracranial hemorrhage (ICH) after SRS for patients with BM who are receiving ACT. This bi-institutional analysis aimed to describe the bleeding risk for this patient subgroup. METHODS: Patients with ACT at the time of single-fraction SRS for BM from two institutions were eligible for analysis. The cumulative incidence of ICH with death as a competing event was assessed during follow-up with magnetic resonance imaging or computed tomography. RESULTS: Forty-one patients with 97 BM were included in the analyses. The median follow-up was 8.2 months (range: 1.7-77.5 months). The median and mean BM volumes were 0.47 and 1.19 cubic centimeters, respectively. The most common reasons for ACT were PE (41%), AF (34%), and DVT (7%). The ACT was mostly performed utilizing phenprocoumon (37%), novel oral anticoagulants (32%), or low-molecular-weight heparin (20%). Nine BM from a group of five patients with ICH after SRS were identified: none of them caused neurological or any other deficits. The 6-, 12-, and 18-month cumulative bleeding incidences per metastasis were 2.1%, 12.4%, and 12.4%, respectively. The metastases with previous bleeding events and those originating from malignant melanomas were found to more frequently demonstrate ICH after SRS (p = 0.02, p = 0.01). No surgical or medical intervention was necessary for ICH management, and no observed death was associated with an ICH. CONCLUSION: Patients receiving an ACT and single-fraction SRS for small- to medium-sized BM did not seem to have a clinically relevant risk of ICH. Previous bleeding and metastases originating from a malignant melanoma may favor bleeding events after SRS. Further studies are needed to validate our reported findings.

The Role of Stereotactic Radiosurgery in the Management of Foramen Magnum Meningiomas-A Multicenter Analysis and Review of the Literature.

BACKGROUND: Foramen magnum meningiomas (FMMs) represent a considerable neurosurgical challenge given their location and potential morbidity. Stereotactic radiosurgery (SRS) is an established non-invasive treatment modality for various benign and malignant brain tumors. However, reports on single-session or multisession SRS for the management and treatment of FMMs are exceedingly rare. We report the largest FMM SRS series to date and describe our multicenter treatment experience utilizing robotic radiosurgery. METHODS: Patients who underwent SRS between 2005 and 2020 as a treatment for a FMM at six different centers were eligible for analysis. RESULTS: Sixty-two patients met the inclusion criteria. The median follow-up was 28.9 months. The median prescription dose and isodose line were 14 Gy and 70%, respectively. Single-session SRS accounted for 81% of treatments. The remaining patients received three to five fractions, with doses ranging from 19.5 to 25 Gy. Ten (16%) patients were treated for a tumor recurrence after surgery, and thirteen (21%) underwent adjuvant treatment. The remaining 39 FMMs (63%) received SRS as their primary treatment. For patients with an upfront surgical resection, histopathological examination revealed 22 World Health Organization grade I tumors and one grade II FMM. The median tumor volume was 2.6 cubic centimeters. No local failures were observed throughout the available follow-up, including patients with a follow-up ≥ five years (16 patients), leading to an overall local control of 100%. Tumor volume significantly decreased after treatment, with a median volume reduction of 21% at the last available follow-up (p < 0.01). The one-, three-, and five-year progression-free survival were 100%, 96.6%, and 93.0%, respectively. Most patients showed stable (47%) or improved (21%) neurological deficits at the last follow-up. No high-grade adverse events were observed. CONCLUSIONS: SRS is an effective and safe treatment modality for FMMs. Despite the paucity of available data and previous reports, SRS should be considered for selected patients, especially those with subtotal tumor resections, recurrences, and patients not suitable for surgery.

Hearing Rehabilitation with Cochlear Implants after CyberKnife Radiosurgery of Vestibular Schwannoma: A Report Based on Four Clinical Cases.

Severe sensorineural hearing loss can be a symptom of the benign tumor vestibular schwannoma (VS). The treatment of VS with non-invasive stereotactic radiosurgery (SRS) offers a high local tumor control rate and an innovative possibility of sequential hearing rehabilitation with cochlear implantation. This study evaluated the feasibility, complications, and auditory outcomes of such a therapeutic approach. Three males and one female (mean age 65.3 ± 9.4 years) scheduled for cochlear implantation and diagnosed with sporadic VS classified as T1 or T2 (according to Samii) were enrolled in this study. All patients had progressive hearing loss qualifying them for cochlear implantation. First, the tumor was treated using CyberKnife SRS. Next, sequential auditory rehabilitation with a cochlear implant (CI) was performed. Clinical outcomes and surgical feasibility were analyzed, and audiological results were evaluated using pure tone audiometry and speech recognition tests. All patients exhibited open-set speech understanding. The mean word recognition score (at 65 dB SPL, Freiburg Monosyllabic Test, FMT) improved after cochlear implantation in all four patients from 5.0 ± 10% (with hearing aid) preoperatively to 60.0 ± 22.7% six months postoperatively. Our results suggest that in patients with profound hearing loss caused by sporadic vestibular schwannoma, the tumor removal with SRS followed by cochlear implantation is an effective method of auditory rehabilitation.

Risks and Benefits of Fiducial Marker Placement in Tumor Lesions for Robotic Radiosurgery: Technical Outcomes of 357 Implantations.

Fiducial markers (FM) inserted into tumors increase the precision of irradiation during robotic radiosurgery (RRS). This retrospective study evaluated the clinical complications, marker migration, and motion amplitude of FM implantations by analyzing 288 cancer patients (58% men; 63.1 ± 13.0 years) who underwent 357 FM implantations prior to RRS with CyberKnife, between 2011 and 2019. Complications were classified according to the Society of Interventional Radiology (SIR) guidelines. The radial motion amplitude was calculated for tumors that moved with respiration. A total of 725 gold FM was inserted. SIR-rated complications occurred in 17.9% of all procedures. Most complications (32.0%, 62/194 implantations) were observed in Synchrony®-tracked lesions affected by respiratory motion, particularly in pulmonary lesions (46.9% 52/111 implantations). Concurrent biopsy sampling was associated with a higher complication rate (p = 0.001). FM migration occurred in 3.6% after CT-guided and clinical FM implantations. The largest motion amplitudes were observed in hepatic (20.5 ± 11.0 mm) and lower lung lobe (15.4 ± 10.5 mm) lesions. This study increases the awareness of the risks of FM placement, especially in thoracic lesions affected by respiratory motion. Considering the maximum motion amplitude, FM placement remains essential in hepatic and lower lung lobe lesions located >100.0 mm from the spine.

Image-Guided Robotic Radiosurgery for the Treatment of Same Site Spinal Metastasis Recurrences.

BACKGROUND: Due to recent medical advancements, patients suffering from metastatic spinal disease have a prolonged life expectancy than several decades ago, and some will eventually experience relapses. Data for the retreatment of spinal metastasis recurrences occurring at the very same macroscopic spot as the initially treated lesion are limited. Previous studies mainly included recurrences in the boundary areas as well as other macroscopic parts of the initially affected vertebrae. This study exclusively analyzes the efficacy and safety of spinal reirradiation for recurrences on the same site utilizing single-session robotic radiosurgery. MATERIALS AND METHODS: Patients between 2005 and 2020 who received radiotherapy for a spinal metastasis suffering from a local recurrence were eligible for analysis. Only patients undergoing a single-session reirradiation were included. All recurrences must have been occurred in the same location as the initial lesion. This was defined as a macroscopic recurrence on computed tomography occurring at the same site as the initial spinal metastasis. All other lesions, including those in the boundary areas or other parts of the initially affected vertebrae, were excluded. RESULTS: Fifty-three patients with fifty-three lesions were retreated for spinal metastases. The median dose and number of fractions for the initial radiotherapy were 36 Gy and 15, respectively. Eleven patients were initially treated with stereotactic body radiotherapy. Retreatment was performed with a median dose of 18 Gy prescribed to a median isodose of 70%. The local control was 77% after a median follow-up of 22.2 months. Patients experiencing a second recurrence received a lower dose (p = 0.04), mostly below 18 Gy, and had a worse coverage (p = 0.01) than those showing local tumor control. 51% of patients experienced an improvement in pain control after treatment delivery. Besides, four vertebral compression fractures (7% of patients) but no other adverse events higher than grade 2 were observed. CONCLUSION: Single-session robotic radiosurgery appears to be a safe, time-saving, and effective treatment modality for spinal metastasis recurrences occurring in the same initial location if a considerable dose and coverage can be applied. Treatment results are comparable to reirradiated metastases in the boundary areas.

Effectiveness and Safety of Robotic Radiosurgery for Optic Nerve Sheath Meningiomas: A Single Institution Series.

The role of robotic radiosurgery (RRS) in the treatment of optic nerve sheath meningiomas (ONSM) remains controversial and it is only performed in specialized institutions due to tight dose constraints. We evaluated the effectiveness and safety of RRS in the management of ONSM. Twenty-five patients with 27 ONSM lesions who underwent RRS using the Cyberknife (CK) system were retrospectively analyzed (median age, 47.9 years; 84.0% women). Multisession RRS was used with 4-5 fractions with a cumulative dose of 20.0-25.0 Gy in 84.0% of patients and a single fraction at a dose of 14.0-15.0 Gy in 16% of patients. Prior to RRS, seven (28%) patients experienced blindness on the lesion side. In those patients with preserved vision prior to radiosurgery, the visual acuity remained the same in 90.0% and improved in 10.0% of the patients. Overall local tumor control was 96.0% (mean follow-up period; 37.4 ± 27.2 months). Neither patient age, previous surgery, or the period from the initial diagnosis to RRS showed a dependency on visual acuity before or after radiosurgery. RRS is a safe and effective treatment for the management of ONSM. Hypofractionation of radiosurgery in patients with preserved vision before CK treatment results in stable or improved vision.

Image-Guided Robotic Radiosurgery for the Management of Spinal Ependymomas.

BACKGROUND: Ependymomas are rare neoplasms of the central nervous system (CNS), usually localized intracranially and most commonly diagnosed in children. Spinal ependymomas are more frequent in young adults. They are either primary lesions or manifest as disseminated seeding of cranial tumors. Data on the management of spinal ependymoma lesions remain scarce, especially concerning stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT). The purpose of this study is to report the treatment outcomes of two institutions using robotic radiosurgery (RRS) for the treatment of spinal ependymomas. MATERIALS AND METHODS: All patients with a histopathologically confirmed diagnosis of an ependymoma WHO grade II or III who were treated with RRS for one or more spinal lesions were included in this analysis. RESULTS: Twelve patients underwent RRS for the treatment of 32 spinal ependymoma lesions between 2005 and 2020. Two patients were below the age of 18 when treated, whereas nine patients (75%) suffered from a primary spinal ependymoma. The median dose was 15 Gy prescribed to a median isodose of 70%, with 27 lesions (84%) receiving a single-session treatment. The local control (LC) after a median follow-up of 56.7 months was 84%. LC rates at 1, 3, and 5 years were 92, 85, and 77%, respectively. The Kaplan-Meier estimated overall survival after 1, 3, and 5 years were 75, 75, and 64%, respectively. Five patients died, all of them suffering from an anaplastic ependymoma, with widespread CNS tumor progression being the reason for death in four patients. The majority of patients (58%) showed a stable neurological status at the last available follow-up. Overall, the treatment was well tolerated. CONCLUSION: RRS appears to be a safe and efficient treatment modality for managing primary and secondary spinal ependymal tumors in patients with multiple lesions and local recurrences.

Longitudinal Changes of Quality of Life and Hearing Following Radiosurgery for Vestibular Schwannoma.

BACKGROUND: Most existing publications on quality of life (QoL) following stereotactic radiosurgery (SRS) for vestibular schwannomas (VS) gather information retrospectively by conducting surveys several years after treatment. The purpose of this study is therefore to provide longitudinal QoL data and assess how changes in hearing impact QoL. METHODS: Patients completed the 12-item short-form (SF-12) health survey prior to treatment and at every follow-up visit. One hundred and seventy-five patients who had complete forms prior to treatment as well as at an early and at a late follow-up were included in the analysis. For 51 of these patients, longitudinal audiometry data were available. RESULTS: Median follow-up was 7.2 years. Patients experienced a significant reduction in the physical composite score (PCS, p = 0.011) compared to before treatment. The mental composite score (MCS) increased significantly (p = 0.032). A decrease in PCS was not significantly correlated with an increased hearing threshold on the affected but rather on the unaffected ear (r(49) = -0.32, p = 0.023). CONCLUSIONS: It is unclear whether the decline in the PCS is due to treatment-related toxicity or the normal decline of PCS with age. Ensuring proper hearing on the untreated ear might be crucial to ensure good QoL for patients treated with SRS for VS, though this association should be confirmed in additional studies.

Robotic Radiosurgery for Persistent Postoperative Acromegaly in Patients with Cavernous Sinus-Invading Pituitary Adenomas-A Multicenter Experience.

BACKGROUND: The rates of incomplete surgical resection for pituitary macroadenomas with cavernous sinus invasion are high. In growth hormone-producing adenomas, there is a considerable risk for persistent acromegaly. Thus, effective treatment options are needed to limit patient morbidity and mortality. This multicenter study assesses the efficacy and safety of robotic radiosurgery (RRS) for patients with cavernous sinus-invading adenomas with persistent acromegaly. METHODS: Patients who underwent RRS with CyberKnife for postoperative acromegaly were eligible. RESULTS: Fifty patients were included. At a median follow-up of 57 months, the local control was 100%. The pretreatment insulin-like growth factor 1 (IGF-1) levels and indexes were 381 ng/mL and 1.49, respectively. The median dose and prescription isodose were 18 Gy and 70%, respectively. Six months after RRS, and at the last follow-up, the IGF-1 levels and indexes were 277 ng/mL and 1.14, as well as 196 ng/mL and 0.83, respectively (p = 0.0001 and p = 0.0002). The IGF-1 index was a predictor for biochemical remission (p = 0.04). Nine patients achieved biochemical remission and 24 patients showed biochemical disease control. Three patients developed a new hypopituitarism. CONCLUSIONS: RRS is an effective treatment for this challenging patient population. IGF-1 levels are decreasing after treatment and most patients experience biochemical disease control or remission.

Image-Guided Robotic Radiosurgery for the Management of Intramedullary Spinal Cord Metastases-A Multicenter Experience.

BACKGROUND: Intramedullary metastases are rare and bear a dismal prognosis. Limited data are available on the treatment of such lesions. As surgery may be the mainstay of treatment for patients with resectable and localized metastatic spread, previous case reports and case series suggest radiosurgery to be another viable treatment modality. This multicenter study analyzes the efficacy and safety of robotic radiosurgery (RRS) for intramedullary metastases. METHODS: Patients who received RRS for the treatment of at least one intramedullary metastasis were included. RESULTS: Thirty-three patients with 46 intramedullary metastases were treated with a median dose of 16 Gy prescribed to a median isodose of 70%. The local control was 79% after a median follow-up of 8.5 months. The median overall survival (OS) was 11.7 months, with a 12- and 24-month OS of 47 and 31%. The 12-month progression-free survival was 42% and at 24 months 25%. In addition, 57% of patients showed either an improved or stable neurological function after treatment delivery. Systemic disease progression was the main cause of death. No significant treatment-related toxicities were observed. CONCLUSIONS: RRS appears to be a safe, time-saving and effective treatment modality for intramedullary metastases, especially for patients with unresectable lesions and high burden of disease.

Image-guided robotic radiosurgery for glomus jugulare tumors-Multicenter experience and review of the literature.

BACKGROUND: Glomus jugulare tumors (GJTs) are challenging to treat due to their vascularization and location. This analysis evaluates the effectiveness and safety of image-guided robotic radiosurgery (RRS) for GJTs in a multicenter study and reviews the existing radiosurgical literature. METHODS: We analyzed outcome data from 101 patients to evaluate local control (LC), changes in pretreatment deficits, and toxicity. Moreover, radiosurgical studies for GJTs have been reviewed. RESULTS: After a median follow-up of 35 months, the overall LC was 99%. Eighty-eight patients were treated with a single dose, 13 received up to 5 fractions. The median tumor volume was 5.6 cc; the median treatment dose for single-session treatments is 16 Gy, and for multisession treatments is 21 Gy. Fifty-six percentage of patients experienced symptom improvement or recovered entirely. CONCLUSIONS: RRS is an effective primary and secondary treatment option for GJTs. The available literature suggests that radiosurgery is a treatment option for most GJTs.

The rationale and development of a CyberKnife© registry for pediatric patients with CNS lesions.

BACKGROUND: CyberKnife© Radiosurgery (CKRS) is a recognized treatment concept for CNS lesions in adults due to its high precision and efficacy beside a high patient comfort. However, scientific evidence for this treatment modality in pediatric patients is scarce. A dedicated registry was designed to document CyberKnife© procedures in children, aiming to test the hypothesis that it is safe and efficient for the treatment of CNS lesions. METHODS: The CyberKnife© registry is designed as a retrospective and prospective multicenter observational study (German Clinical Trials Register ( https://www.drks.de ), DRKS-ID 00016973). Patient recruitment will be ongoing throughout a 5-year period and includes collection of demographic, treatment, clinical, and imaging data. Follow-up results will be monitored for 10 years. All data will be registered in a centralized electronic database at the Charité-Universitätsmedizin. The primary endpoint is stable disease for benign and vascular lesions at 5 years of follow-up and local tumor control for malign lesions at 1- and 2-year follow-up. Secondary endpoints are radiation toxicity, side effects, and neurocognitive development. CONCLUSION: The CyberKnife© registry intends to generate scientific evidence for all treatment- and outcome-related aspects in pediatric patients with treated CNS lesions. The registry may define safety and efficacy of CKRS in children and serve as a basis for future clinical trials, inter-methodological comparisons and changes of treatment algorithms.

68Ga-PSMA-PET/CT-based radiosurgery and stereotactic body radiotherapy for oligometastatic prostate cancer.

BACKGROUND: Androgen deprivation therapy (ADT) remains the standard therapy for patients with oligometastatic prostate cancer (OMPC). Prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA-PET/CT)-based stereotactic body radiotherapy (SBRT) is emerging as an alternative option to postpone starting ADT and its associated side effects including the development of drug resistance. The aim of this study was to determine progression free-survival (PFS) and treatment failure free-survival (TFFS) after PSMA-PET/CT-based SBRT in OMPC patients. The efficacy and safety of single fraction radiosurgery (SFRS) and ADT delay were investigated. METHODS: Patients with ≤5 metastases from OMPC, with/without ADT treated with PSMA-PET/CT-based SBRT were retrospectively analyzed. PFS and TFFS were primary endpoints. Secondary endpoints were local control (LC), overall survival (OS) and ADT-free survival (ADTFS). RESULTS: Fifty patients with a total of 75 metastases detected by PSMA-PET/CT were analyzed. At the time of SBRT, 70% of patients were castration-sensitive. Overall, 80% of metastases were treated with SFRS (median dose 20 Gy, range: 16-25). After median follow-up of 34 months (range: 5-70) median PFS and TFFS were 12 months (range: 2-63) and 14 months (range: 2-70), respectively. Thirty-two (64%) patients had repeat oligometastatic disease. Twenty-four (48%) patients with progression underwent second SBRT course. Two-year LC after SFRS was 96%. Grade 1 and 2 toxicity occurred in 3 (6%) and 1 (2%) patients, respectively. ADTFS and OS rates at 2-years were 60.5% and 100%, respectively. In multivariate analysis, TFFS significantly improved in patients with time to first metastasis (TTM) >36 months (p = 0.01) and PSA before SBRT ≤1 ng/ml (p = 0.03). CONCLUSION: For patients with OMPC, SBRT might be used as an alternative to ADT. This way, the start/escalation of palliative ADT and its side effects can be deferred. Metastases treated with PSMA-PET/CT-based SFRS reached excellent LC with minimal toxicity. Low PSA levels and longer TTM predict elongated TFFS.

Efficacy and safety of CyberKnife radiosurgery in elderly patients with brain metastases: a retrospective clinical evaluation.

BACKGROUND: Stereotactic radiosurgery (SRS) has been increasingly applied for up to 10 brain metastases instead of whole brain radiation therapy (WBRT) to achieve local tumor control while reducing neurotoxicity. Furthermore, brain-metastasis incidence is rising due to the increasing survival of patients with cancer. Our aim was to analyze the efficacy and safety of CyberKnife (CK) radiosurgery for elderly patients. METHODS: We retrospectively identified all patients with brain metastases ≥ 65 years old treated with CK-SRS at our institution since 2011 and analyzed data of primary diseases, multimodality treatments, and local therapy effect based on imaging follow-up and treatment safety. Kaplan-Meier analysis for local progression-free interval and overall survival were performed. RESULTS: We identified 97 patients (233 lesions) fulfilling the criteria at the first CK-SRS. The mean age was 73.2 ± 5.8 (range: 65.0-87.0) years. Overall, 13.4% of the patients were > 80 years old. The three most frequent primary cancers were lung (40.2%), kidney (22.7%), and malignant melanoma (15.5%). In 38.5% (47/122 treatments) multiple brain metastases were treated with the CK-SRS, with up to eight lesions in one session. The median planning target volume (PTV) was 1.05 (range: 0.01-19.80) cm3. A single fraction was applied in 92.3% of the lesions with a median prescription dose of 19 (range: 12-21) Gy. The estimated overall survivals at 3-, 6-, and 12 months after SRS were 79, 55, and 23%, respectively. The estimated local tumor progression-free intervals at 6-, 12-, 24-, 36-, and 72 months after SRS were 99.2, 89.0, 67.2, 64.6, and 64.6%, respectively. Older age and female sex were predictive factors of local progression. The Karnofsky performance score remained stable in 97.9% of the patients; only one patient developed a neurological deficit after SRS of a cerebellar lesion (ataxia, CTCAE Grade 2). CONCLUSIONS: SRS is a safe and efficient option for the treatment of elderly patients with brain metastases with good local control rates without the side effects of WBRT. Older age and female sex seem to be predictive factors of local progression. Prospective studies are warranted to clarify the role of SRS treatment for elderly patients.