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BACKGROUND AND OBJECTIVES: Pediatric large-volume brain arteriovenous malformations (AVMs) carry a substantial lifelong hemorrhage risk, neurological symptoms, and treatment morbidity. Single-session stereotactic radiosurgery (SRS) is often unsuitable due to constraints on dose-volume toxicity. Volume-staged SRS (VS-SRS) enables sequential dosing of large nidus volumes, potentially enhancing safety while maintaining efficacy. Evidence in children remains limited. We aimed to evaluate outcomes of VS-SRS for large AVMs in pediatric patients. METHODS: A multicenter retrospective cohort was assembled from 21 centers, including patients aged younger than 21 years treated with VS-SRS for AVMs >10 cm 3 . Clinical and radiological end points included obliteration, hemorrhage, and permanent symptomatic radiation-induced changes (RIC). RESULTS: A total of 103 patients were included (median age 14 years; IQR, 12-17). The median nidus volume at first stage was 18.2 cm 3 (IQR, 12.3-25.6). Median prescription dose per stage was 17 Gy (IQR, 16-18). The median clinical follow-up from the first stage was 57.5 months (IQR, 25-138). Obliteration occurred in 42 of 103 patients (40.8%), with actuarial rates of 6.9% (95% CI: 2.8-14) at 3 years and 29% (95% CI: 20-39) at 5 years. Hemorrhage occurred in 17 of 103 patients (16.5%) during follow-up, and permanent RIC was observed in 9 of 103 patients (8.7%). CONCLUSION: VS-SRS is a reasonably safe, selected option for pediatric large-volume AVMs when microsurgical or endovascular cure is not feasible or prudent. Delivering ≥17 Gy per stage while limiting each treatment volume to <15 cm 3 supports durable nidus control with acceptable toxicity. VS-SRS represents a key modality in multidisciplinary management of this historically difficult-to-treat population.

OBJECTIVE Ruptured, large pediatric arteriovenous malformations (AVMs) pose a significant management challenge due to high rerupture risk and the morbidity of conventional treatments. Volume-staged stereotactic radiosurgery (VS-SRS) has emerged as an alternative; however, evidence for its use in this specific population is limited. This study aimed to evaluate the long-term efficacy and safety of VS-SRS for ruptured, large AVMs in a dedicated pediatric cohort. METHODS This international, multicenter, retrospective cohort study from 21 centers analyzed outcomes for 42 pediatric patients (age < 18 years) with previously ruptured, large AVMs treated with VS-SRS. The primary outcome was complete AVM obliteration, and secondary outcomes included post-SRS hemorrhage, radiation-induced changes (RICs), and favorable outcome. Favorable outcome in this study was defined as obliteration without post-SRS hemorrhage or permanent RIC. RESULTS At the initial SRS, the median patient age was 14.5 years, and the median AVM volume was 15.0 cm 3 ; most AVMs were high grade (Spetzler-Martin grades IV and V). With a median follow-up of 41.5 months, complete AVM obliteration was achieved in 21 patients (50.0%). The cumulative obliteration rate was 37% at 5 years and 56% at 10 years. Patients with a nidus volume of ≤ 10 cm 3 had significantly higher cumulative obliteration rates than those with a nidus volume > 10 cm 3 (log-rank test, p = 0.021). Similarly, patients treated with a prescription dose > 17 Gy showed significantly higher cumulative obliteration rates compared to those treated with a dose ≤ 17 Gy (log-rank test, p = 0.012). The cumulative 5-year incidences of hemorrhage and RICs following VS-SRS were 19% and 7%, respectively. In multivariable analysis, only larger total AVM volume was an independent predictor of a lower likelihood of favorable outcome (hazard ratio 0.89, 95% CI 0.80–0.99; p = 0.036). CONCLUSIONS In this multicenter pediatric cohort, VS-SRS for ruptured, large AVMs provides a reasonable chance of long-term obliteration, but generally acceptable risks of post-SRS hemorrhage and RICs exist. VS-SRS should be considered as an option for pediatric patients with large, ruptured AVMs.

OBJECTIVE The aim of this study was to evaluate freedom from tumor progression and clinical outcomes in older adults with small- to medium-sized vestibular schwannoma (VS) managed by observation versus stereotactic radiosurgery (SRS) to better inform optimal management in this patient population. METHODS In this international multicenter study, patients aged ≥ 60 years with Koos grade I or II VS managed by observation or SRS were retrospectively reviewed. Propensity score matching was conducted using patient characteristics, tumor size, and hearing assessments. Outcome measures of freedom from tumor progression, serviceable hearing preservation (SHP), and neurological function (tinnitus, vestibulopathy, House-Brackmann grade, and trigeminal nerve function) were assessed for both groups. RESULTS The observation and SRS groups each comprised 51 matched patients (median age 68 years for both). Ipsilateral serviceable hearing was observed at presentation for 35 patients in each group. The median follow-up duration was 39 months in the observation group versus 27 months in the SRS group (p = 0.5). Tumor progression was significantly lower with SRS than with observation (2% vs 52.9%, p < 0.001). The rate of 5-year freedom from tumor progression was 100% in the SRS group versus 43% (95% CI 29%–64%) in the observation group. The rate of 10-year freedom from tumor progression was 90% (95% CI 73%–100%) in the SRS group versus 20% (95% CI 8.5%–49%) in the observation group. At the last follow-up, hearing loss occurred in 42.9% of the observation group and 51.4% of those who underwent SRS (p = 0.5). The 3-year SHP rate was 68% (95% CI 53%–88%) versus 65% (95% CI 49%–85%) (p = 0.8), and the 5-year SHP rate was 53% in both groups (95% CI 36%–78% in the observation group and 95% CI 35%–79% in the SRS group, p = 0.8). The composite endpoint of tumor progression and/or worsened neurological outcome, including hearing loss, tinnitus, vestibulopathy, facial nerve dysfunction (House-Brackmann grade), or trigeminal dysfunction, demonstrated a significantly lower rate in the SRS group (17.6%) compared with the observation group (66.7%) (p < 0.001). CONCLUSIONS SRS in older patients for management of Koos grade I or II VS resulted in significantly superior rates of freedom from tumor progression, comparable hearing preservation rates, and significantly higher rates of favorable overall radiographic and neurological outcomes than observation alone. Compared with observation, SRS might be the preferred management option in this patient population.

BACKGROUND AND OBJECTIVES: Stereotactic radiosurgery (SRS) for brain arteriovenous malformations (AVMs) can cause radiation-induced changes (RIC), but its interactions with AVM embolization are not well established. The aim of this study was to assess the effect of previous embolization on RIC in SRS-treated AVM patients. METHODS: Data of AVM patients treated with single-session SRS from 1987 to 2018 were retrieved from the International Radiosurgery Research Foundation. Univariable and stepwise backward logistic regression models were used to identify RIC predictors. Patients were stratified into those who received pre-SRS embolization (E + SRS) vs those who did not (SRS-only). Radiologic RIC (rRIC) was the primary end point. Secondary outcomes included symptomatic RIC (sRIC) and permanent symptomatic RIC (pRIC). RESULTS: Among 1187 AVM patients, the mean age was 36.4 years (SD 16.8), with 50.4% female patients. AVMs had a mean untreated AVM volume of 5.2 cm 3 . A total of 130 patients (11%) underwent neoadjuvant embolization (E + SRS). The overall rRIC and sRIC rates were 32.8% and 12.1%, respectively, with time to rRIC and sRIC being significantly longer in the E + SRS vs SRS-only cohorts (103.6 ± 339.4 vs 11.3 ± 12.5 and 60.4 ± 262.9 vs 9.5 ± 9.0 months, respectively). Seizures at presentation and ≥3-cm untreated AVM volume significantly correlated with a higher likelihood of rRIC (adjusted odds ratio [aOR] 2.32 [1.25-4.30] and aOR 2.77 [1.24-6.16], respectively). Age and pre-SRS embolization were associated with a significantly lower risk of rRIC (aOR 0.97 [0.96-0.99] and aOR 0.32 [0.13-0.74], respectively). The E + SRS cohort had significantly reduced odds of rRIC (aOR = 0.37 [0.15-0.89]) and pRIC (aOR = 0.04 [0.00-0.30]) after adjusting for significant covariates. CONCLUSION: Seizures at presentation and larger untreated AVM volume were independently associated with an increased risk of rRIC, whereas older age and pre-SRS embolization were protective. Notably, patients who underwent embolization before SRS had lower odds of rRIC and pRIC, with delayed onset of complications compared with SRS-only.

Abstract BACKGROUND Ovarian cancer rarely metastasises to the brain, thus studies reporting the outcomes of affected patients are lacking. Stereotactic radiosurgery (SRS) is now the mainstay of management for patients with brain metastases (BM) from most primary sites, but little evidence of its efficacy in ovarian cancer is available. The current study was undertaken to provide guidance for SRS management using pooled data from multiple institutions. MATERIAL AND METHODS Centers participating in the IRRF (International Radiosurgery Research Foundation) were asked to provide outcome data for patients who had SRS for ovarian cancer brain metastases between 2020 and 2024 and at least one clinical and imaging follow-up after the procedure. Primary endpoints included survival from SRS, local tumor response according to RANO-BM criteria and occurrence of adverse radiation effects (ARE). Cox regression analyses were performed to identify variables impact each endpoint. RESULTS 128 patients had SRS for a total of 532 BM treated. Epithelial histology was the most common (91%). Median age at SRS was 62 years (IQR 56-70). Median KPS was 80% (IQR 80-90%) and 71.9% of patients had neurological symptoms at presentation. Other active systemic metastases were present in 41.4%. The median number of treated BM was 2 (IQR1-3) and the median cumulative treatment volume was 6 cc (IQR 2-12.9). The median margin dose was 18 Gy (IQR 16-20). At last follow-up, 19.5% of patients were still alive. The median overall survival (OS) after SRS was 27 months, and 6-, 12- and 24-month OS was 83.8%, 74.2% and 52.2%, respectively. Multivariate analyses revealed that increasing age at SRS (HR 1.02, p=0.05), active systemic metastases (HR 2, p=0.005) and increasing number of brain metastases (HR 1.05, p=0.04) were associated with worse survival, while repeating SRS (HR 0.4, p=0.002) led to improved survival. Local failure occurred in 12.8% of treated BM. Actuarial progression-free survival (PFS) at 6, 12 and 24 months was 92.3%, 86.6% and 70.3%, respectively. Only prior WBRT (HR 4.36, p=0.03) led to worse local control on multivariate analyses. New remote BM appeared in 49.5% of patients and 14.5% suffered from leptomeningeal dissemination. ARE were seen in 12.1% of BM but were symptomatic in only 3.2%. On multivariate analyses, prior SRS (HR 3.13, p=0.002) was associated with increased risk of ARE. CONCLUSION Ovarian cancer brain metastases can be safely and effectively managed with SRS as the primary treatment modality in most patients.

BACKGROUND AND OBJECTIVES: The therapeutic approach for small- and medium-sized vestibular schwannoma (VS) with normal hearing function remains controversial, with limited comparative data regarding hearing outcomes after stereotactic radiosurgery (SRS) or observation (OBS). We evaluated the serviceable hearing preservation, loss of American Academy of Otolaryngology-Head and Neck Surgery class A hearing, and tumor control (TC) across individuals with Koos grade I and II VSs and normal hearing at presentation who underwent SRS or OBS. METHODS: In this multicenter international study, we retrospectively analyzed the hearing, radiological, and neurological outcomes of patients who underwent SRS (SRS group) or OBS (OBS group). The cohorts were matched using propensity scores based on age, sex, tumor volume, pure-tone average, and speech discrimination score at a 1:1 ratio without replacement. RESULTS: After matching, each group comprised 57 patients. The median follow-up was 49 and 37 months for the SRS and the OBS groups, respectively ( P = .3). The 5- and 9-year serviceable hearing preservation rates in the SRS group were 76.2% and 42.4% vs 56.1% and 16.8% in the OBS group ( P = .17). Class A preservation occurred in 57.9% (33/57) of the SRS and 52.6% (30/57) of the OBS cohorts ( P = .70). Regarding the TC rates, SRS was associated with significantly higher TC rates ( P < .0001). CONCLUSION: We found that SRS is significantly superior regarding TC and provided noninferior hearing outcomes compared with OBS in VS patients with American Academy of Otolaryngology-Head and Neck Surgery class A hearing at presentation. Therefore, we suggest performing SRS in individuals with VS and normal hearing function.

BACKGROUND AND OBJECTIVES: Single-session stereotactic radiosurgery (SRS) has limited role for large arteriovenous malformations (AVM). Volume-staged SRS (VS-SRS) is used to optimize outcomes, but studies reporting results are limited. METHODS: This multicenter retrospective cohort of 378 patients from 21 centers reports results of VS-SRS for the entire AVM nidus. We report favorable outcome, obliteration, hemorrhage, and permanent symptomatic adverse radiation effect rates. RESULTS: The median age was 31 years (IQR: 19-44) at the first volume stage, with patients treated in 2–4 stages. The median total nidus volume was 21 cm 3 (IQR: 13.9-30.1 cm 3 ), and a median prescription dose of 17 Gy (IQR: 16-18 Gy) was used. The median radiographic and clinical follow-up were 48 and 55 months, respectively. Seventy-seven patients (20.4%) had a favorable outcome, with the 3-year and 5-year rates being 3.9% and 18%, respectively. 127 patients (33.6%) achieved obliteration, with the 3-year and 5-year rates being 6.8% and 26%, respectively. Obliteration rates of AVMs <15 cm 3 were 81% and 31%, respectively. The latency period hemorrhage incidence rate was 3.02 cases per 100 patient-years; 52 patients (13.8%) had a bleed. Seventy-two patients (19%) had symptomatic adverse radiation effect; in 38 patients (10.1%), these were permanent. Total nidus volume, prescription dose at first stage, diffuse nidus, and prior hemorrhage were all independent affecting outcome rates. CONCLUSION: VS-SRS can be used to treat large AVMs as a standalone treatment. Obliteration rates and favorable outcomes are lower than that with smaller AVMs, and repeat treatment is often required. Optimizing treatment plans, by increasing prescription doses, reducing treatment volume at each stage, and increasing the number of stages, may lead to better outcomes.

BACKGROUND AND OBJECTIVES: Gynecological cancers represent 10% to 15% of cancers in women, but brain metastases (BM) are uncommon, with limited evidence regarding their management. This study investigates the role of stereotactic radiosurgery (SRS) for BM from primary gynecological cancers. METHODS: Institutions of the International Radiosurgery Research Foundation participated in this study. Inclusion criteria required histological diagnosis of epithelial ovarian, cervical, or endometrial cancer, SRS between 2000 and 2020, and at least 1 imaging or clinical follow-up. RESULTS: A total of 276 patients having SRS for 977 BM were included. Median age at SRS was 62 years (IQR, 55-70). Primary cancer origin was ovarian in 128 (46%), cervical in 43 (16%), and endometrial in 105 patients (38%). Median Karnofsky Performance Scale was 80%, and systemic disease was active in 124 (45%) of patients. A median of 1 metastasis was treated (IQR, 1-3) per patient. Median individual metastasis volume was 0.27 cc (IQR, 0.05-1.59 cc). The majority (91%) received single-fraction SRS, using a median margin dose of 18 Gy (IQR, 16-20 Gy). Actuarial overall survival was 77%, 65%, and 44% at 6, 12, and 24 months, respectively. Predictors of worsened survival included older age, cervical and endometrial primary, previous whole-brain radiation therapy (WBRT), active systemic disease, worsened Karnofsky Performance Scale, absence of subsequent surgery, and increasing number of BM. Actuarial local control was 94% at 6 months, 89% at 12 months, and 78% at 24 months. Previous SRS or WBRT, tumor bed treatment, and cervical histology increased the risk of local failure. New remote BM and leptomeningeal dissemination occurred in 44% and 11% of patients, respectively. Adverse radiation effects (ARE) occurred in 13% of cases but were symptomatic in only 3%. Previous WBRT or SRS and increased tumor diameter increased the risk of ARE. CONCLUSION: SRS is an effective management for BM from gynecological cancers with low risks of symptomatic ARE.

OBJECTIVE This study aimed to evaluate local control (LC) of tumors, patient overall survival (OS), and the safety of stereotactic radiosurgery (SRS) for esophageal cancer brain metastases (EBMs). METHODS This retrospective cohort study used data from 15 International Radiosurgery Research Foundation facilities encompassing 67 patients with 185 EBMs managed using SRS between January 2000 and May 2022. The median patient age was 63 years, with a male predominance (92.5%). Most patients (64.2%) had a single brain metastasis, while 7.5% had more than 5 metastases. The median tumor volume was 0.9 cm 3 , and the median margin dose delivered to the tumor was 20 Gy. RESULTS The median OS post-SRS was 15.2 months, with 1- and 2-year OS rates of 65.7% and 32.3%, respectively. A significant inverse correlation was found between the number of EBMs and OS in the univariable analysis. LC rates at 1 and 2 years were 89% and 76%, respectively. Adverse radiation effects (AREs) were observed in 17.9% of patients, with 13.4% being mild and transient and 4.5% severely symptomatic (Common Terminology Criteria for Adverse Events grade 3). New intracranial disease developed in 58.2% of patients, with 1- and 2-year rates of 58% and 73%, respectively. CONCLUSIONS SRS for EBMs demonstrated high survival rates and effective tumor control, with a low incidence of severe AREs. These findings highlight the potential role of SRS in the multidisciplinary multimodality management paradigm of EBM.