Stereotactic Radiosurgery Group Research Articles

Risk of new tumor, carotid stenosis, and stroke after Stereotactic Radiosurgery for Pituitary Tumor: A multicenter study of 2254 patients with imaging follow-up.

Higher risk of secondary brain tumor, carotid stenosis and stroke has been reported after conventional sella irradiation for pituitary neuroendocrine tumors (PitNET). Stereotactic radiosurgery (SRS), which is a more focused approach, is now increasingly used instead. The aim was to assess the risk of secondary brain tumor, carotid stenosis/occlusion and stroke after SRS. In this multicentric retrospective study, 2,254 patients with PitNET were studied, 1,377 in the exposed group and 877 in the control group. There were 9,840.1 patient-years at risk for the SRS and 5,266.5 for the control group. The 15-year cumulative probability of secondary intracranial tumor was 2.3% (95%CI:0.5%, 4.1%) for SRS and 3.7% (95%CI:0%, 8.7%) for the control group (p=0.6), with an incidence rate of 1.32 per 1,000 and 0.95 per 1,000, respectively. SRS was not associated with increased risk of tumorigenesis when stratified by age (HR: 1.59 [95%CI: 0.57, 4.47], p=0.38). The 15-year probability of new carotid stenosis/occlusion was 0.9% (95%CI: 0.2, 1.6) in the SRS and 2% (95%CI: 0, 4.4) in the control group (p=0.8). The 15-year probability of stroke was 2.6% (95%CI: 0.6%, 4.6%) in the SRS and 11.1% (95%CI: 6%, 15.9%) in the control group (p<0.001). In cox multivariate analysis stratified by age, SRS (HR 1.85[95%CI:0.64, 5.35], p=0.26) was not associated with risk of new stroke. No increased risk of long-term secondary brain tumor, new stenosis or occlusion and stroke was demonstrated in SRS group compared to control in this study with imaging surveillance.

Health-Related Quality of Life in Patients With a Stable or Growing Vestibular Schwannoma Managed by Wait and Scan or Stereotactic Radiosurgery.

To assess the effect of wait and scan (W&S) and stereotactic radiosurgery (SRS) on health-related quality of life (HRQoL) over time in patients with a stable vestibular schwannoma (VS) and growing VS. Longitudinal, multicenter, observational study. Tertiary expert center for VS (Radboudumc Nijmegen) and Gamma-Knife center ETZ Hospital Tilburg. Changes in HRQoL, measured with the Penn Acoustic Neuroma Quality-of-Life (PANQOL), and the physical and mental component summary scores (PCS and MCS, respectively) derived from the36-Item Short Form Health Survey(SF-36), were compared among patients managed by W&S and SRS between 2017 and 2022. Second, HRQoL over time in patients with a growing VS was compared between W&S and SRS. Differences in PANQOL total and subdomain scores, PCS and MCS scores over time in the W&S (n = 73) and SRS (n = 170) groups were nonsignificant and on average did not exceed the minimal clinically important differences (mean difference of -2.56 [PANQOL total], 1.22 [PCS], and -1.76 [MCS]; all P > .05). In growing VS, comparison of W&S (n = 29) and SRS (n = 154) also revealed no significant difference (mean difference of 1.19 (PANQOL total), 1.83 (PCS) and -0.12 (MCS); all P > .05). Differences in HRQoL in patients with VS are minor and not significantly different or clinically relevant between patients managed with W&S or SRS. Similarly, patients with a growing VS managed with W&S or SRS exhibit no significant or clinical relevant difference in HRQoL during follow-up. This can aid clinicians in the counseling of patients regarding HRQoL when deciding on a management strategy after diagnosis or documented growth.

A comprehensive analysis of patients with cerebral arteriovenous malformation with headache: assessment of risk factors and treatment effectiveness

BackgroundDue to the high mortality and disability rate of intracranial hemorrhage, headache is not the main focus of research on cerebral arteriovenous malformation (AVM), so research on headaches in AVM is still scarce, and the clinical understanding is shallow. This study aims to delineate the risk factors associated with headaches in AVM and to compare the effectiveness of various intervention treatments versus conservative treatment in alleviating headache symptoms.MethodsThis study conducted a retrospective analysis of AVMs who were treated in our institution from August 2011 to December 2021. Multivariable logistic regression analysis was employed to assess the risk factors for headaches in AVMs with unruptured, non-epileptic. Additionally, the effectiveness of different intervention treatments compared to conservative management in alleviating headaches was evaluated through propensity score matching (PSM).ResultsA total of 946 patients were included in the analysis of risk factors for headaches. Multivariate logistic regression analysis identified that female (OR 1.532, 95% CI 1.173–2.001, p = 0.002), supply artery dilatation (OR 1.423, 95% CI 1.082–1.872, p = 0.012), and occipital lobe (OR 1.785, 95% CI 1.307–2.439, p < 0.001) as independent risk factors for the occurrence of headaches. There were 443 AVMs with headache symptoms. After propensity score matching, the microsurgery group (OR 7.27, 95% CI 2.82–18.7 p < 0.001), stereotactic radiosurgery group(OR 9.46, 95% CI 2.26–39.6, p = 0.002), and multimodality treatment group (OR 8.34 95% CI 2.87–24.3, p < 0.001) demonstrate significant headache relief compared to the conservative group. However, there was no significant difference between the embolization group (OR 2.24 95% CI 0.88–5.69, p = 0.091) and the conservative group.ConclusionsThis study identified potential risk factors for headaches in AVMs and found that microsurgery, stereotactic radiosurgery, and multimodal therapy had significant benefits in headache relief compared to conservative treatment. These findings provide important guidance for clinicians when developing treatment options that can help improve overall treatment outcomes and quality of life for patients.

Preoperative stereotactic radiosurgery for cerebral metastases: safe, effective, and decreases steroid dependency.

Preoperative stereotactic radiosurgery (SRS) is emerging as a viable alternative to standard postoperative SRS. Studies have suggested that preoperative SRS provides comparable tumor control and overall survival (OS) and may reduce the incidence of leptomeningeal disease (LMD) and adverse radiation effects (AREs). It is unknown, however, if preoperative SRS remains effective in cohorts including large brain metastases (> 14 cm3) or if preoperative SRS affects steroid taper/immunotherapy. Here, the authors report the results of a phase 2 single-arm trial assessing a prospectively acquired series of 26 patients who underwent preoperative SRS, without a volumetric cutoff, compared with a propensity score-matched concurrent cohort of 30 patients who underwent postoperative SRS to address these salient questions. Demographics, oncological history, surgical details, and outcomes were collected from the medical records. Coprimary endpoints were local tumor control (LTC) and a composite outcome of LTC, ARE, and LMD. Additional outcomes were OS, steroid taper details, and immunotherapy resumption. For survival analyses, cohorts were propensity score matched. Preoperative and postoperative SRS patients were comparable in terms of age, sex, Karnofsky Performance Status score, oncological history, and operative details. Gross tumor volume (GTV) was significantly higher in the preoperative group (median 12.2 vs 5.3 cm3, p < 0.001). One-year LTC (preoperative SRS: 77.2% vs postoperative SRS: 82.5%, p = 0.61) and composite outcome (68.3% vs 72.7%, p = 0.38) were not significantly different between the groups. In multivariable analysis, preoperative SRS did not have a significant effect on LTC (HR 1.57 [95% CI 0.38-6.49], p = 0.536) or the composite outcome (HR 1.18 [95% CI 0.38-3.72], p = 0.771), although the confidence intervals were large. The median OS (preoperative SRS: 17.0 vs postoperative SRS: 14.0 months, p = 0.61) was not significantly different. Rates of LMD were nonsignificantly lower in the preoperative SRS group (3.8% vs 16.7%, p = 0.200). Greater GTV volume was associated with prolonged (> 10 days) steroid taper (OR 1.24 [95% CI 1.04-1.55], p = 0.032). However, in multivariable analysis, preoperative SRS markedly reduced the steroid taper length (OR 0.13 [95% CI 0.02-0.61], p = 0.016). Time to immunotherapy was shorter in the preoperative SRS group (36 [IQR 26, 76] vs OR 228 [IQR 129, 436] days, p = 0.02). Compared with postoperative SRS, preoperative SRS is a safe and effective strategy in the management of cerebral metastases of all sizes and provides comparable tumor control without increased adverse effects. Notably, preoperative SRS enabled rapid steroid taper, even in larger tumors. Future studies should specifically examine the interaction of preoperative SRS with steroid usage and resumption of systemic therapies and the subsequent effects on systemic progression and OS.

Comparison of Repeat Versus Initial Stereotactic Radiosurgery for Intracranial Arteriovenous Malformations: A Retrospective Multicenter Matched Cohort Study

BACKGROUND AND OBJECTIVES: Studies comparing neurological and radiographic outcomes of repeat to initial stereotactic radiosurgery (SRS) intracranial arteriovenous malformations are scarce. Our aim was to perform a retrospective matched comparison of patients initially treated with SRS with those undergoing a second radiosurgical procedure. METHODS: We collected data from arteriovenous malformations managed in 21 centers that underwent initial and repeated radiosurgery from 1987 to 2022. Based on arteriovenous malformations volume, margin dose, deep venous drainage, deep, and critical location, we matched 1:1 patients who underwent an initial SRS for treatment-naive arteriovenous malformations and a group with repeated SRS treatment. RESULTS: After the selection process, our sample consisted of 328 patients in each group. Obliteration in the initial SRs group was 35.8% at 3 and 56.7% at 5 years post-SRS, while the repeat SRS group showed obliteration rates of 33.9% at 3 years and 58.6% at 5 years, without statistically significant differences (P = .75 and P = .88, respectively). There were no statistically significant differences between the 2 groups for obliteration rates (hazard ratio = 0.93; 95% CI, 0.77-1.13; P = .5), overall radiation-induced changes (RIC) (OR = 1.1; 95% CI, 0.75-1.6; P = .6), symptomatic RIC (OR = 0.78; 95% CI, 0.4-1.5; P = .4), and post-SRS hemorrhage (OR = 0.68; 95% CI; P = .3). CONCLUSION: In matched cohort analysis, a second SRS provides comparable outcomes in obliteration and RIC compared with the initial SRS. Dose reduction on repeat SRS may not be warranted.

Vestibular Schwannoma International Study of Active Surveillance Versus Stereotactic Radiosurgery: The VISAS Study

BackgroundThe present study assesses the safety and efficacy of stereotactic radiosurgery (SRS) versus observation for Koos grade I and II vestibular schwannoma (VS), benign tumors affecting hearing and neurological function. MethodsThis multicenter study analyzed data from Koos grade I and II VS patients managed with SRS (SRS group) or observation (observation group). Propensity score matching balanced patient demographics, tumor volume, and audiometry. Outcomes measured were tumor control, serviceable hearing preservation (SHP), and neurological outcomes. ResultsIn 125 matched patients in each group with a 36-month median follow-up (p=0.49), SRS yielded superior 5- and 10-year tumor control rates (99%, CI: 97.1%-100%, and 91.9%, CI: 79.4%-100%) vs. observation (45.8%, CI: 36.8%-57.2%, and 22%, CI: 13.2%-36.7%; p<0.001). SHP rates at 5 and 9 years were comparable (SRS 60.4%, CI: 49.9%-73%, vs. observation 51.4%, CI: 41.3%-63.9%, and SRS 27%, CI: 14.5%-50.5%, vs. observation 30%, CI: 17.2%-52.2%; p=0.53). SRS were associated with lower odds of tinnitus (OR=0.39, p=0.01), vestibular dysfunction (OR=0.11, p=0.004), and any cranial nerve palsy (OR=0.36, p=0.003), with no change in cranial nerves V or VII (p>0.05). Composite endpoints of tumor progression and/or any of the previous outcomes showed significant lower odds associated with SRS compared to observation alone (p < 0.001). ConclusionSRS management in matched cohorts of Koos grade I and II VS patients demonstrated superior tumor control, comparable hearing preservation rates, and significantly lower odds of experiencing neurological deficits. These findings delineate the safety and efficacy of SRS in in the management of this patient population.

Trigeminal neuralgia pain outcomes following microsurgical resection versus stereotactic radiosurgery for petroclival meningiomas: a systematic review and meta-analysis.

Petroclival meningiomas (PCMs) are challenging lesions to treat because of their deep location and proximity to critical neurovascular structures. Patients with these lesions commonly present because of local mass effect. A symptom that proves challenging to definitively manage is trigeminal neuralgia (TN), which occurs in approximately 5% of PCM cases. To date, there is no consensus on whether microsurgical resection or stereotactic radiosurgery (SRS) leads to better outcomes in the treatment of TN secondary to PCM. In this systematic review and meta-analysis, the authors aimed to evaluate the available literature on the efficacy of microsurgical resection versus SRS for controlling TN secondary to PCM. The Embase, MEDLINE, Scopus, and Cochrane databases were queried from database inception to May 17, 2022, using the search terms "(petroclival AND meningioma) AND (trigeminal AND neuralgia)." Study inclusion criteria were as follows: 1) reports on patients aged ≥ 18 years and diagnosed with TN secondary to PCM, 2) cases treated with microsurgical resection or SRS, 3) cases with at least one posttreatment follow-up report of TN pain, 4) cases with at least one outcome of tumor control, and 5) publications describing randomized controlled trials, comparative or single-arm observational studies, case reports, or case series. Exclusion criteria were 1) literature reviews, technical notes, conference abstracts, or autopsy reports; 2) publications that did not clearly differentiate data on patients with PCMs from data on patients with different tumors or with meningiomas in different locations (other intracranial or spinal meningiomas); 3) publications that contained insufficient data on treatments and outcomes; and 4) publications not written in the English language. References of eligible studies were screened to retrieve additional relevant studies. Data on pain and tumor outcomes were compared between the microsurgical resection and SRS treatment groups. The DerSimonian-Laird random-effects model with Hartung-Knapp-Sidik-Jonkman variance correction was used to pool estimates from the included studies. Two comparative observational studies and 6 single-arm observational studies describing outcomes after primary intervention were included in the analyses (138 patients). Fifty-seven patients underwent microsurgical resection and 81 underwent SRS for the management of TN secondary to PCM. By the last follow-up (mean 71 months, range 24-149 months), the resection group had significantly higher rates of pain resolution than the SRS group (82%, 95% CI 50%-100% vs 31%, 95% CI 18%-45%, respectively; p = 0.004). There was also a significantly longer median time to tumor recurrence following resection (43.75 vs 16.7 months, p < 0.01). The resection group showed lower rates of pain persistence (0%, 95% CI 0%-6% vs 25%, 95% CI 13%-39%, p = 0.001) and pain exacerbation (0% vs 12%, 95% CI 3%-23%, p = 0.001). The most common postintervention Barrow Neurological Institute pain score in the surgical group was I (66.7%) compared with III (27.2%) in the SRS group. Surgical reintervention was less frequently required following primary resection (1.8%, 95% CI 0%-37% vs 19%, 95% CI 1%-48%, p < 0.01). Microsurgical resection is associated with higher rates of TN pain resolution and lower rates of pain persistence and exacerbation than SRS in the treatment of PCM. SRS with further TN management is a viable alternative in patients who are not good candidates for microsurgical resection.

Clinical outcomes of melanoma brain metastases treated with nivolumab and ipilimumab alone versus nivolumab and ipilimumab with stereotactic radiosurgery.

Upfront dual checkpoint blockade with immune checkpoint inhibitors (ICI) has demonstrated efficacy for treating melanoma brain metastases (MBM) in asymptomatic patients. Whether the combination of stereotactic radiosurgery (SRS) with dual checkpoint blockade improves outcomes over dual-checkpoint blockade alone is unknown. We evaluated clinical outcomes of patients with MBM receiving ICI with nivolumab and ipilimumab, with and without SRS. 49 patients with 158 MBM receiving nivolumab and ipilimumab for untreated MBM between 2015 and 2022 were identified at our institution. Patient and tumor characteristics including age, Karnofsky Performance Status (KPS), presence of symptoms, cancer history, MBM burden, and therapy course were recorded. Outcomes measured from initiation of MBM-directed therapy included overall survival (OS), local control (LC), and distant intracranial control (DIC). Time-to-event analysis was conducted with the Kaplan-Meier method. 25 patients with 74 MBM received ICI alone, and 24 patients with 84 MBM received concurrent SRS. Median follow-up was 24months. No differences in age (p = 0.96), KPS (p = 0.85), presence of symptoms (p = 0.79), prior MBM (p = 0.68), prior MBM-directed surgery (p = 0.96) or SRS (p = 0.68), MBM size (p = 0.67), or MBM number (p = 0.94) were seen. There was a higher rate of nivolumab and ipilimumab course completion in the SRS group (54% vs. 24%; p = 0.029). The SRS group received prior immunotherapy more often than the ICI alone group (54% vs. 8.0%; p < 0.001). There was no significant difference in 1-year OS (72% vs. 71%, p = 0.20) and DIC (63% v 51%, p = 0.26) between groups. The SRS group had higher 1-year LC (92% vs. 64%; p = 0.002). On multivariate analysis, LC was improved with combination therapy (AHR 0.38, p = 0.01). In our analysis, patients who received SRS with nivolumab and ipilimumab had superior LC without increased risk of toxicity or compromised immunotherapy treatment completion despite the SRS cohort having higher rates of prior immunotherapy. Further prospective study of combination nivolumab and ipilimumab with SRS is warranted.

Analysis of upfront resection or stereotactic radiosurgery for local control of solid and cystic cerebellar hemangioblastomas.

The purpose of this study was to identify rates of and risk factors for local tumor progression in patients who had undergone surgery or radiosurgery for the management of cerebellar hemangioblastoma and to describe treatments pursued following tumor progression. The authors conducted a retrospective single-center review of patients who had undergone treatment of a cerebellar hemangioblastoma with either surgery or stereotactic radiosurgery (SRS) between 1996 and 2019. Univariate and multivariate regression analyses were performed to examine factors associated with local tumor control. One hundred nine patients met the study inclusion criteria. Overall, these patients had a total of 577 hemangioblastomas, 229 of which were located in the cerebellum. The surgical and SRS cohorts consisted of 106 and 123 cerebellar hemangioblastomas, respectively. For patients undergoing surgery, tumors were treated with subtotal resection and gross-total resection in 5.7% and 94.3% of cases, respectively. For patients receiving SRS, the mean target volume was 0.71 cm3 and the mean margin dose was 18.0 Gy. Five-year freedom from lesion progression for the surgical and SRS groups was 99% and 82%, respectively. The surgical and SRS cohorts contained 32% versus 97% von Hippel-Lindau tumors, 78% versus 7% cystic hemangioblastomas, and 12.8- versus 0.56-cm3 mean tumor volumes, respectively. On multivariate analysis, factors associated with local tumor progression in the SRS group included older patient age (HR 1.06, 95% CI 1.03-1.09, p < 0.001) and a cystic component (HR 9.0, 95% CI 2.03-32.0, p = 0.001). Repeat SRS as salvage therapy was used more often for smaller tumor recurrences, and no tumor recurrences of < 1.0 cm3 required additional salvage surgery following repeat SRS. Both surgery and SRS achieve high rates of local control of hemangioblastomas. Age and cystic features are associated with local progression after SRS treatment for cerebellar hemangioblastomas. In cases of local tumor recurrence, salvage surgery and repeat SRS are valid forms of treatment to achieve local tumor control, although resection may be preferable for larger recurrences.

Comparison of microvascular decompression, percutaneous radiofrequency rhizotomy, and stereotactic radiosurgery in the treatment of trigeminal neuralgia: A long term quasi-experimental study.

Microvascular decompression (MVD), radiofrequency rhizotomy (RFR), and stereotactic radiosurgery (SRS) are surgical techniques frequently used in the treatment of idiopathic trigeminal neuralgia (TN), although the results reported for each of these are diverse. This study aimed to compare long-term pain control obtained by MVD, SRS, and RFR in patients with idiopathic TN. To compare the results obtained by MVD, SRS, and RFR we chose a quasi-experimental, ambispective design with control groups but no pretest. A total of 52 participants (MVD n = 33, RFR n = 10, SRS n = 9) were included. Using standardized outcome measures, pain intensity, pain relief, quality of life, and satisfaction with treatment were assessed by an independent investigator. The TREND statement for reporting non-randomized evaluations was applied. Clinical outcomes were evaluated at the initial postoperative period and at 6 months, 1, 2, 3, 4, and 5 years postoperatively. MVD has shown better results in pain scales compared to ablative procedures. Significant differences between groups were found regarding pain intensity and pain relief at the initial postoperative period (p < 0.001) and 6 months (p = 0.022), 1 year (p < 0.001), 2 years (p = 0.002), and 3 years (p = 0.004) after the intervention. Those differences exceeded the thresholds of the minimal clinically important difference. A higher percentage of patients free of pain was observed in the group of patients treated by MVD, with significant differences at the initial postoperative period (p < 0.001) and 6 months (p = 0.02), 1 year (p = 0.001), and 2 years (p = 0.04) after the procedure. Also, a higher risk of pain recurrence was observed in the RFR and SRS groups (HR 3.15, 95% CI 1.33-7.46; p = 0.009; and HR 4.26, 95% CI 1.77-10.2; p = 0.001, respectively) compared to the MVD group. No significant differences were found in terms of quality of life and satisfaction with treatment. A higher incidence of complications was observed in the MVD group. Concerning pain control and risk of pain recurrence, MVD is superior to RFR and SRS, but not in terms of quality of life, satisfaction with treatment, and safety profile.

Fractionated Stereotactic Radiotherapy vs. Stereotactic Radiosurgery for Vestibular Schwannoma: Local Control, Hearing Preservation, and Toxicities

The use of radiation therapy (RT) in vestibular schwannoma (VS) is well-established, but limited studies detail outcomes in patients treated with fractionated stereotactic radiotherapy (FSRT) versus stereotactic radiosurgery (SRS). In this study, we provide an outcome-based comparison of FSRT versus SRS in patients with VS with emphases on local control, hearing preservation, and toxicities. We hypothesize that FSRT and SRS will have similar rates of local control with FSRT having improved rates of hearing preservation. Patients treated at a single tertiary referral center between 2013 and 2018 for VS using FSRT (46.8 Gy in 26 fractions) or SRS (12 Gy in 1 fraction) were identified. Records from radiation oncology, neurosurgery, and otolaryngology were included. Endpoints included local control, defined as absence of tumor progression or need for salvage treatment, hearing preservation, quantified by Gardner-Robinson (GR) scoring and defined as maintaining GR1-2 hearing, and toxicities as per Common Terminology Criteria for Adverse Events (CTCAE), version 5. A total of 77 patients with VS were identified, of which 50 had FSRT and 27 had SRS. In the FSRT group, the median patient age was 58 years (range 23-81) and 50% were female, whereas the median patient age was 68 years (range 24-90) and 41% females were in the SRS group. 81% (n = 35) patients in the FSRT group and 24% (n = 6) in the SRS group had serviceable hearing prior to RT. Median follow-up was 51.2 months (range 4.3-103.2) in the FSRT group and 21.0 months (range 2.7-98.6) in the SRS group. The 2-year, 3-year, and 5-year local control rates in the FSRT and SRS groups were 100% and 100%, 97% and 76%, 94% and 76%, respectively. Of those with local progression, 33% (n = 1) in the FSRT group was salvaged with stereotactic body radiation therapy (SBRT) and 100% (n = 2) in the SRS group was salvaged with FSRT. For patients with serviceable hearing prior to RT, hearing preservations rates were 46% and 17% with a median time to hearing loss of 8.2 months (range 4.0-59.5) and 7.7 months (range 2.0-11.9) in the FSRT and SRS groups, respectively. Progression-free survival analyses showed superior hearing preservation in those treated with FSRT compared to SRS (p-value = 0.0064), especially those receiving FSRT who initially presented with GR1 vs GR2 hearing (p-value = 0.0095). There were 60 reported toxicities with 12% (n = 7) Grade 2+ in the FSRT group, whereas the SRS group had 5 toxicities with 40% (n = 2) Grade 2+. Both FSRT and SRS provide favorable local control for VS, with most progressions salvageable. Hearing preservation rate is higher in the FSRT group. This favors the use of FSRT in those with serviceable hearing, with patients with baseline GR1 hearing demonstrating additional benefit. Further prospective randomized studies are needed to better identify treatment outcomes and prognostic factors.

Clinical Outcomes Following Postoperative Cavity Stereotactic Radiosurgery for Brain Metastases

We evaluated outcomes of patients with brain metastases (BM) treated with surgical resection and postoperative cavity stereotactic radiosurgery (SRS) to identify which baseline characteristics and treatment factors may increase risk for local recurrence (LR). From June 2017 to December 2021, 68 patients underwent surgical resection for BM followed by single-fraction SRS (n = 15) or fractionated SRS (FSRS) in 3 (n = 24) or 5 (n = 29) fractions to the postoperative cavity using frameless LINAC-based technique. Patients treated with surgery alone or surgery with postoperative whole brain radiotherapy (WBRT) were excluded. Median prescription doses were 1600 cGy (range: 1440-1875) in 1 fraction, 2400 cGy (range: 2100-2700) in 3 fractions, and 3000 cGy (range: 2500-3000) in 5 fractions. Local control (LC) and overall survival (OS) were estimated by the Kaplan-Meier method. Cox proportional hazards models were used to compare groups. Median follow-up was 19.5 months (IQR: 9.0-34.7). Median patient age was 62.5 years (range: 24-80), and 38 (55.9%) patients were male. Primary tumors were lung (n = 29), including NSCLC (n = 28) and SCLC (n = 1), melanoma (n = 12), breast (n = 11), and other (n = 16). Median preoperative tumor maximal dimension was 3.5cm (range: 1.1-6.3). Median planning treatment volume (PTV) was larger in the FSRS group (26.2cc (range: 6.5-151.8)) than in the SRS group (7.7cc (range: 1.1-11.5)) (p<0.001). Median number of concurrently treated intact lesions was 0 (range: 0-13). Median time from surgery to SRS was 32 days (range: 14-77). Forty-eight (70.6%) patients were treated with immunotherapy or targeted therapy. Median OS was 22.3 months (95% CI: 14.4-30.9). The 1-year and 2-year OS rates were 70% and 48%, respectively. The 1-year and 2-year LC rates were 86% and 73%, respectively. Median time to LR was 8.4 months (95% CI: 4.4-11.0). Among the 14 patients with LR, 11 had undergone salvage therapy at last follow-up which included repeat SRS (n = 4), WBRT (n = 3), palliative local radiotherapy (n = 2), surgery followed by repeat SRS (n = 1), and systemic therapy (n = 1). Eleven (16.2%) patients ultimately underwent WBRT post-SRS for local and/or distant failure. No difference in LC was observed based on primary tumor, time interval between resection and SRS, PTV volume, prescription dose, or fractionation regimen (SRS v. FSRS). However, all LR in the 3-fraction group occurred in patients who received less than 2700 cGy. Favorable LC and OS outcomes were observed following postoperative cavity SRS for resected BM in a modern cohort with a large percentage of patients receiving immunotherapy or targeted therapy. No prognostic factors were identified for LC which may be attributable to the cohort size and small number of events observed. However, our findings suggest that patients who undergo 3-fraction FSRS should be treated to a total dose of 2700 cGy to maximize LC.

Comparison of Tumor Control After Stereotactic Radiosurgery or Pencil Beam Proton Therapy for Newly Diagnosed Clival Chordomas: A Single-Center Retrospective Study

To compare outcomes of proton radiation therapy (PRT), stereotactic radiosurgery (SRS), and x-ray-based radiation with an SRS boost (XRT+ SRS) for newly diagnosed clival chordoma. Consecutive patients who underwent PRT or SRS in our facility were retrospectively reviewed. A total of 59 patients were identified (PRT, 36; SRS, 11; XRT+ SRS, 12). The mean age (± standard deviation) was 46 ± 20 years, with 54% being male. The mean tumor diameter (± standard deviation) was 3.7 ± 1.5 cm, and 21 (36%) involved the lower clivus. Gross total or near-total resection was attained in 27 patients (46%), all of whom received PRT. PRT was administered with a median prescribed dose of 70.8 Gy (range, 66.0-76.0). SRS involved a median marginal dose of 16 Gy (range, 14-20) and a median maximal dose of 36 Gy (range, 30-45). The XRT+ SRS group was treated with an SRS marginal dose of 12.5 Gy (range, 10-20), a maximal dose of 27 Gy (range, 20-40), and an XRT prescription dose of 50.4 Gy (range, 45.0-59.4). Fifteen recurrences were observed (PRT, 6; SRS, 5; XRT+ SRS, 4). For the entire cohort (n= 59), recurrence was associated with the degree of resection (P= 0.042), but not with radiation groups (P= 0.98). For patients after subtotal resection or biopsy (n= 32), the SRS ± XRT group was associated with few recurrences (hazard ratio, 0.260; 95% confidence interval, 0.069-0.98; P= 0.046). Patients after subtotal resection or biopsy may benefit from the incorporation of SRS.

Comparison of preoperative versus postoperative treatment dosimetry plans of single-fraction stereotactic radiosurgery for surgically resected brain metastases.

Stereotactic radiosurgery (SRS) for operative brain metastasis (BrM) is usually administered 1 to 6 weeks after resection. Preoperative versus postoperative timing of SRS delivery related to surgery remains a critical question, as a pattern of failure is the development of leptomeningeal disease (LMD) in as many as 35% of patients who undergo postoperative SRS or the occurrence of radiation necrosis. As they await level I clinical data from ongoing trials, the authors aimed to bridge the gap by comparing postoperative with simulated preoperative single-fraction SRS dosimetry plans for patients with surgically resected BrM. The authors queried their institutional database to retrospectively identify patients who underwent postoperative Gamma Knife SRS (GKSRS) after resection of BrM between January 2014 and January 2021. Exclusion criteria were prior radiation delivered to the lesion, age < 18 years, and prior diagnosis of LMD. Once identified, a simulated preoperative SRS plan was designed to treat the unresected BrM and compared with the standard postoperative treatment delivered to the resection cavity per Radiation Therapy Oncology Group (RTOG) 90-05 guidelines. Numerous comparisons between preoperative and postoperative GKSRS treatment parameters were then made using paired statistical analyses. The authors' cohort included 45 patients with a median age of 59 years who were treated with GKSRS after resection of a BrM. Primary cancer origins included colorectal cancer (27%), non-small cell lung cancer (22%), breast cancer (11%), melanoma (11%), and others (29%). The mean tumor and cavity volumes were 15.06 cm3 and 12.61 cm3, respectively. In a paired comparison, there was no significant difference in the planned treatment volumes between the two groups. When the authors compared the volume of surrounding brain that received 12 Gy or more (V12Gy), an important predictor of radiation necrosis, 64% of patient plans in the postoperative SRS group (29/45, p = 0.008) recorded greater V12 volumes. Preoperative plans were more conformal (p < 0.001) and exhibited sharper dose drop-off at the lesion margins (p = 0.0018) when compared with postoperative plans. Comparison of simulated preoperative and delivered postoperative SRS plans administered to the BrM or resection cavity suggested that preoperative SRS allows for more highly conformal lesional coverage and sharper dose drop-off compared with postoperative plans. Furthermore, V12Gy was lower in the presurgical GKSRS plans, which may account for the decreased incidence of radiation necrosis seen in prior retrospective studies.

Efficacy and safety of stereotactic radiosurgery versus endovascular treatment for symptomatic cavernous sinus dural arteriovenous fistula without ophthalmological emergency: a single-center 10-year experience.

Stereotactic radiosurgery (SRS) is emerging as a treatment option for cavernous sinus dural arteriovenous fistula (CS dAVF); it is less invasive and has a lower complication rate than conventional surgeries. However, little is known regarding the advantages and limitations of SRS compared to those of endovascular treatment (EVT). The aim of this study was to compare the efficacy and safety between EVT and SRS for treatment of CS dAVF. Between January 2011 and April 2021, a total of 86 consecutive patients diagnosed with CS dAVF were treated with EVT or SRS. Among them, 8 patients with ophthalmological emergency and 8 without follow-up data at ≥ 12 months were excluded. During the same period, no neurological deficit due to intracranial hemorrhage or seizure was noted in any of the patients. Ultimately, 70 patients (EVT 33, SRS 37) were included in this study. Demographic characteristics, initial clinical presentations, clinical outcomes, and radiological findings were retrospectively reviewed and compared. Procedure-related complications were also assessed after the treatments. The patients' baseline characteristics (except conjunctival symptoms) and angiographic features of CS dAVF were not significantly different between the EVT and SRS groups. Conjunctival symptoms were more frequently noted in the EVT than in the SRS group (69.7% vs 40.5%, p = 0.015). After EVT, initial complete obliteration was achieved in 20 cases (60.6%). Complete obliteration was achieved at 6 months in 86.4% of cases with EVT and in 77.8% of those treated with SRS (p = 0.507), and at 12 months in 86.4% cases with EVT and in 94.4% of those treated with SRS (p = 0.357). Worsening of symptoms developed at 1 month in 24.2% of cases with EVT and in 5.4% of those treated with SRS (p = 0.038); at 6 months in 22.6% of cases with EVT and in 10.8% of those treated with SRS; and at 12 months in 30.0% of cases with EVT and in 13.5% of those treated with SRS (p = 0.099). The angioarchitecture of CS dAVF did not affect angiographic obliteration after SRS. Procedure-related morbidity and mortality occurred more frequently in the EVT than in the SRS group (27.3% vs 8.1%, p = 0.034). Both EVT and SRS were effective for the treatment of CS dAVF without ophthalmological emergency. However, procedure-related morbidity and mortality was less frequent in SRS than in EVT, and consequently SRS may be more advantageous in terms of safety.

Stereotactic Radiosurgery vs Conventional Radiotherapy for Localized Vertebral Metastases of the Spine

Spine metastasis can be treated with high-dose radiation therapy with advanced delivery technology for long-term tumor and pain control. To assess whether patient-reported pain relief was improved with stereotactic radiosurgery (SRS) as compared with conventional external beam radiotherapy (cEBRT) for patients with 1 to 3 sites of vertebral metastases. In this randomized clinical trial, patients with 1 to 3 vertebral metastases were randomized 2:1 to the SRS or cEBRT groups. This NRG 0631 phase 3 study was performed as multi-institutional enrollment within NRG Oncology. Eligibility criteria included the following: (1) solitary vertebral metastasis, (2) 2 contiguous vertebral levels involved, or (3) maximum of 3 separate sites. Each site may involve up to 2 contiguous vertebral bodies. A total of 353 patients enrolled in the trial, and 339 patients were analyzed. This analysis includes data extracted on March 9, 2020. Patients randomized to the SRS group were treated with a single dose of 16 or 18 Gy (to convert to rad, multiply by 100) given to the involved vertebral level(s) only, not including any additional spine levels. Patients assigned to cEBRT were treated with 8 Gy given to the involved vertebra plus 1 additional vertebra above and below. The primary end point was patient-reported pain response defined as at least a 3-point improvement on the Numerical Rating Pain Scale (NRPS) without worsening in pain at the secondary site(s) or the use of pain medication. Secondary end points included treatment-related toxic effects, quality of life, and long-term effects on vertebral bone and spinal cord. A total of 339 patients (mean [SD] age of SRS group vs cEBRT group, respectively, 61.9 [13.1] years vs 63.7 [11.9] years; 114 [54.5%] male in SRS group vs 70 [53.8%] male in cEBRT group) were analyzed. The baseline mean (SD) pain score at the index vertebra was 6.06 (2.61) in the SRS group and 5.88 (2.41) in the cEBRT group. The primary end point of pain response at 3 months favored cEBRT (41.3% for SRS vs 60.5% for cEBRT; difference, -19 percentage points; 95% CI, -32.9 to -5.5; 1-sided P = .99; 2-sided P = .01). Zubrod score (a measure of performance status ranging from 0 to 4, with 0 being fully functional and asymptomatic, and 4 being bedridden) was the significant factor influencing pain response. There were no differences in the proportion of acute or late adverse effects. Vertebral compression fracture at 24 months was 19.5% with SRS and 21.6% with cEBRT (P = .59). There were no spinal cord complications reported at 24 months. In this randomized clinical trial, superiority of SRS for the primary end point of patient-reported pain response at 3 months was not found, and there were no spinal cord complications at 2 years after SRS. This finding may inform further investigation of using spine radiosurgery in the setting of oligometastases, where durability of cancer control is essential. ClinicalTrials.gov Identifier: NCT00922974.

Abstract P1-10-05: Safety of stereotactic body radiation therapy, stereotactic radiosurgery, and other radiation therapy with use of CDK 4/6 inhibitors for hormone receptor positive (HR+), HER2- metastatic breast cancer: a retrospective cohort study

Abstract Objective Patients with hormone receptor positive (HR+), HER2- metastatic breast cancer frequently require radiation therapy (RT) in addition to systemic therapy for disease control and symptom management. CDK 4/6 inhibitors are increasingly used in the care of hormone positive breast cancers. Stereotactic body radiotherapy (SBRT), a form of very focused high dose radiation, is also increasingly used in the care of metastatic breast cancer. Limited data have reported on the safety of palliative RT with CDK4/6 inhibitors, with some reports demonstrating synergistic effects with potential for increased toxicity. The objective of our study is to assess toxicity among patients who received SBRT, stereotactic radiosurgery (SRS), or other high dose RT along with CDK 4/6 inhibitors for treatment of metastatic breast cancer. Methods Women with metastatic breast cancer who received SBRT, SRS, or other higher dose RT with CDK 4/6 inhibitors at any point in their treatment between 2013 and 2021 were retrospectively identified. Timing of radiation therapy, either before, during, or after CDK 4/6 inhibitor use was assessed, as well as the interval between the two treatments. Treatment sites for radiotherapy included lung/chest, spine, and brain metastases. Physician assessed adverse events were obtained through clinical follow up and graded using CTCAE v5. Local control and OS were reported. Results Twenty patients met study inclusion criteria. Patients received radiation therapy and CDK 4/6 inhibitors concurrently (within 7 days) [n=7, 35%], within 30 days (RT pre-CDK 4/6 inhibitor use) [n=3, 15%], and greater than 30 days (RT pre-CDK 4/6 inhibitor use [n=6, 30%] and RT post-CDK 4/6 inhibitor use [n=4, 20%]). Radiation treatment sites were spine [n=10, 55%], brain [n=6, 30%], and lung/chest wall [n=3, 15%]. Radiation doses were as follows: 60 Gy in 5 fractions [n=1, 5%], 50 Gy in 5 fractions [n=2, 10%], 55 Gy in 20 fractions (chest wall recurrence) [n=1, 5%], 35 Gy in 15 fractions [n=1, 5%], 30 Gy in 10 fractions [n=6, 30%], 30 Gy in 3 fractions [n= 4, 20%], 24 Gy in 1 fraction [n=3, 15%], 20 Gy in 5 fractions [n=2, 10%]. Palbociclib was used in 85% of patients [n=17] and abemaciclib in 15% [n=3]. Median follow up for surviving patients was 4.7 years [IQR: 2.5-6.8 years]. Local control was achieved in 85% of patients [n=17]. Median OS was 2.7 years [IQR: 0.1-6.8 years]. Grade 2 toxicity [n=9, 45%] and grade 3 toxicity [n=3, 15%] was reported across all three treatment areas, with grade 2 or 3 fatigue [n=7, 35%] being the most frequently reported toxicity. In the spine treatment group, 1 patient who had CDK 4/6 inhibitor use within 30 days of radiotherapy experienced a grade 3 vertebral compression fracture as well as grade 3 fatigue. In the lung/chest wall treatment group, the patient treated to 55 Gy in 20 fractions to the chest wall with concurrent use had grade 3 skin/wound toxicity requiring prolonged wound care before healing. In the intra-cranial SRS group, grade 3 fatigue was reported in 1 patient with concurrent use. Conclusion The use of CDK 4/6 inhibitors concurrently with or within 30 days of radiation therapy was generally well tolerated with limited grade 3 toxicity. Two of three reports of grade 3 toxicity occurred with concurrent treatment. Due to the potential radiosensitizing properties of CDK 4/6 inhibitors, it may be prudent to hold combined treatment when clinically feasible. Further study is needed to validate these results. Citation Format: Kiran Chauhan, Roman O. Kowalchuk, Allison E. Garda, Dean A. Shumway, Mark R. Waddle, Robert Mutter, Kimberly Corbin. Safety of stereotactic body radiation therapy, stereotactic radiosurgery, and other radiation therapy with use of CDK 4/6 inhibitors for hormone receptor positive (HR+), HER2- metastatic breast cancer: a retrospective cohort study [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-10-05.

Stereotactic radiosurgery versus whole-brain radiotherapy after resection of solitary brain metastasis: A systematic review and meta-analysis

ObjectiveThe standard of care in patients with solitary brain metastasis involves surgical resection and postoperative whole-brain radiotherapy (WBRT). However, WBRT is associated with adverse effects, mainly neurocognitive deterioration. Stereotactic radiosurgery (SRS) is a more targeted form of radiation therapy that could be as effective as WBRT without the detrimental neurocognitive decline. MethodsWe performed the first systematic review and meta-analysis comparing postoperative SRS versus postoperative WBRT in patients with one resected brain metastasis. PubMed, Scopus, and Cochrane library were systematically searched for studies comparing the efficacy of the two radiation modalities in terms of local and distant brain control, leptomeningeal disease control, and overall survival. Additionally, we extracted patients’ neurocognitive function and quality of life after each postoperative radiation form. ResultsFour studies with 248 patients (128: WBRT, 120: SRS) were included in our analysis. There was no difference between SRS and WBRT in the risk of local recurrence (RR = 0.92, CI = 0.51–1.66, p = 0.78, I2 = 0%) and leptomeningeal disease (RR = 1.21, CI = 0.49–2.98, p = 0.67, I2 = 18%), neither in the patients’ overall survival (HR = 1.06, CI = 0.61–1.85, p = 0.83, I2 = 63%). Nevertheless, SRS appeared to increase the risk of distant brain failure (RR = 2.03, CI = 0.94–4.40, p = 0.07, I2 = 61%). Neurocognitive function and quality of life in the SRS group were equal or superior to the WBRT group. ConclusionsAlthough SRS may increase the risk of distant brain failure, it appears to be as effective as WBRT in terms of local control, risk of leptomeningeal disease, and overall survival while sparing the patients of the detrimental, WBRT-associated cognitive deterioration.

Facial Nerve Schwannoma Treatment with Stereotactic Radiosurgery (SRS) versus Resection followed by SRS: Outcomes and a Management Protocol

Abstract Background Stereotactic radiosurgery (SRS) and resection are treatment options for patients with facial nerve schwannomas without mass effect. Objective This article evaluates outcomes of patients treated with SRS versus resection + SRS. Method We retrospectively compared 43 patients treated with SRS to 12 patients treated with resection + SRS. The primary study outcome was unfavorable combined endpoint, defined as worsening or new clinical symptoms, and/or tumor radiological progression. SRS (38.81 ± 5.3) and resection + SRS (67.14 ± 11.8) groups had similar clinical follow-ups. Results At the time of SRS, the tumor volumes of SRS (mean ± standard error; 1.83 ± 0.35 mL) and resection + SRS (2.51 ± 0.75 mL) groups were similar. SRS (12.15 ± 0.08 Gy) and resection + SRS (12.16 ± 0.14 Gy) groups received similar radiation doses. SRS group (42/43, 98%) had better local tumor control than the resection + SRS group (10/12, 83%, p = 0.04). Most of SRS (32/43, 74%) and resection + SRS (10/12, 83%) group patients reached a favorable combined endpoint following SRS (p = 0.52). Considering surgical associated side effects, only 2/10 patients of the resection + SRS group reached a favorable endpoint (p &lt; 0.001).Patients of SRS group, who are &gt; 34 years old (p = 0.02), have larger tumors (&gt; 4 mL, 0.04), internal auditory canal (IAC) segment tumor involvement (p = 0.01) were more likely to reach an unfavorable endpoint. Resection + SRS group patients did not show such a difference. Conclusion While resection is still needed for larger tumors, SRS offers better clinical and radiological outcomes compared to resection followed by SRS for facial schwannomas. Younger age, smaller tumors, and non-IAC situated tumors are factors that portend a favorable outcome.

Leukoencephalopathy in patients with brain metastases who received radiosurgery with or without whole brain radiotherapy.

Whole brain radiation therapy (WBRT) for brain metastases (BMs) is a common cause of radiation-induced leukoencephalopathy; however the safety of alternative stereotactic radiosurgery (SRS) remains unclear. This study examined the incidence of leukoencephalopathy in patients treated with SRS alone versus WBRT plus SRS for BMs with a focus on the relationship between prognostic factors and leukoencephalopathy. Analysis was performed between 2002 and 2021. The total enrollment was 993 patients with the distribution: WBRT plus SRS (n = 291) and SRS only (n = 702). Leukoencephalopathy was graded from 0 to 3 for changes in white matter indicated by the MRI after WBRT or SRS. Patient characteristics and SRS dosimetric parameters were reviewed to identify factors that contributed to the incidence of leukoencephalopathy or overall survival. The incidence of leukoencephalopathy was consistently higher in WBRT plus SRS group than in SRS alone group (p < 0.001). Leukoencephalopathy was also associated with a larger total tumor volume (≧28cm3; p = 0.028) and age (> 77years; p = 0.025). Nonetheless, the SRS integral dose to skull in the subgroup of WBRT plus SRS treatment was not demonstrated significance in development of leukoencephalopathy (p = 0.986 for integral dose 1-2J, p = 0.776 for integral dose > 2J). This study revealed that SRS is safe for oligo-BMs in terms of leukoencephalopathy development. Patient age and total tumor volume were identified as important factors in assessing the development of leukoencephalopathy. The additional of SRS (even at an integral dose > 2J) did not increase the incidence of leukoencephalopathy.