Stereotactic Radiosurgery For Vestibular Schwannoma Research Articles

Stereotactic radiosurgery for vestibular schwannomas: evolution of the philosophy of treatment

Vestibular schwannomas are the most common tumors in the cerebellopontine angle. Stereotactic radiosurgery is included in the armamentarium of methods for treating these tumors along with surgical treatment. Given the annual incidence of more than 15 radiosurgical cases of vestibular schwannomas per 1 million population, the expected need for stereotactic radiosurgery of these tumors in Russia is more than 2000 cases annually.Stereotactic radiosurgery is located at the intersection of several clinical specialties: neuroradiology, neurosurgery and radiation therapy, each of which has made a significant contribution to the development of this treatment method. The most commonly used for this is the cobalt‑based Leksell Gamma Knife, specifically intended for the treatment of intracranial neoplasms. Treatment is also possible with modern linear accelerators and proton accelerators, which provide high accuracy and conformity of irradiation. The experience gained since the first application of this method in the treatment of vestibular schwannomas has made it possible not only to optimize the radiation doses to the tumor and adjacent critical structures (brain stem, inner ear), but also to study the features of post‑radiation micro‑ and macro‑ changes, their impact on the clinical course, to develop recommendations for radiosurgery with schwannomas of various sizes. All this contributes to high control of tumor growth and a low level of functional disorders, which, along with easy tolerability and minimal hospitalization time, determines lower cost of this treatment compared to the traditional surgical approach and significant social and economic effect.This lecture is intended for neurosurgeons and radiation therapists and focuses on the most significant factors that influenced the development, promotion and active use of stereotactic radiosurgery of vestibular schwannomas in cli nical practice.

496 Impact of the Mean Cochlear Biologically Effective Dose on Hearing Preservation After Stereotactic Radiosurgery for Vestibular Schwannoma

INTRODUCTION: Stereotactic radiosurgery (SRS) is a useful alternative for small to medium size vestibular schwannoma (VSs). METHODS: This is a retrospective longitudinal single center study. Were analyzed 213 patients with useful baseline hearing. Risk of hearing decline was assessed for GR classes and pure tone average (PTA) loss. Mean follow-up period was 39 months (median 36, 6-84). RESULTS: Hearing decline (GR class) 3 years after SRS was associated with higher cochlear BEDGy2.47 mean (OR 1.39, p = 0.009). BEDGy2.47 mean was more relevant compared to BEDGy2.47 max (OR 1.13, p = 0.04). Mean (p = 0.91) and maximal (p = 0.66) cochlear doses were not statistically significant. Risk of PTA loss (continuous outcome, follow-up minus baseline) was significantly corelated with BEDGy2.47 mean at 24 (beta coefficient 1.55, p = 0.002) and 36 (beta coefficient 2.01, p = 0.004) months after SRS. Mean (p = 0.27) and maximal (p= 0.87) cochlear doses were not significant. Risk of PTA loss (> 20 dB versus <=20) was associated with higher BEDGy2.47 mean at 6 (OR 1.36, p= 0.002), 12 (OR 1.36, p = 0.007) and 36 (OR 1.37, p = 0.02) months. Mean cochlear dose was statistically significant only at 24 months. Risk of hearing decline at 36 months for BEDGy2.47 mean of 7-8, 10 and 12 Gy2.47 was 28%, 57% and 85%, respectively. CONCLUSIONS: Cochlear BEDGy2.47 mean is relevant for hearing decline after SRS and more relevant as compared with BEDGy2.47 max. Three years after SRS, this was sustained for all hearing decline evaluation modalities. Our data suggests BEDGy2.47 mean cut-off of <= 8 Gy2.47 for better hearing preservation rates.

Non-occlusive hydrocephalus after radiosurgery for vestibular schwannomas

Stereotactic radiosurgery has firmly entered the arsenal of methods for treating vestibular schwannomas along with traditional surgical removal, providing high control of tumor growth and a low level of functional complications. Meanwhile, there is evidence of a possible relationship between the irradiation performed and the subsequent development of non-occlusive hydrocephalus. Purpose: to retrospectively assess the current level of development of hydrocephalus after stereotactic radiosurgery for vestibular schwannomas. Materials and methods: of 541 patients who received treatment with the Gamma Knife for unilateral vestibular schwannoma, 456 (84.3%) patients initially had no signs of non-occlusive hydrocephalus (group 1), while in 85 (15.7%) patients, MRI signs of internal non-occlusive hydrocephalus were revealed at the time of radiosurgery (group 2), of whom in 1 case VP shunting had previously been performed. In all cases, non-occlusive hydrocephalus at the time of SRS had a compensated course without clinical manifestations. Results: after radiosurgery, the development of de novo non-occlusive hydrocephalus in 7 (1.5%) patients from group 1 and its progression in 11 (12.9%) patients from group 2 were noted. The overall incidence of non-occlusive hydrocephalus after radiosurgery was 3.3%. Ventriculoperitoneal shunting was required in 3 cases in group 1 and 7 cases in group 2 due to the occurrence of neurological symptoms (1.8%). Conclusion: In some cases, radiosurgery can lead to decompensation of existing non-occlusive hydrocephalus, but it rarely occurs de novo. The asymptomatic course of non-occlusive hydrocephalus allows for SRS, as the risk of decompensation with subsequent need for VP shunting is low. Patients with non-occlusive hydrocephalus before SRS require more careful monitoring with assessment of neurological status and control MRI.

Cost of Vestibular Schwannoma Treatment: A Systematic Review and Meta-Analysis

Abstract Introduction Research furthering treatment efficacy for microsurgical resection and stereotactic radiosurgery for vestibular schwannoma (VS) is ever-growing; however, there remains a paucity of research addressing treatment costs. Our aim is to define the reported costs of different treatment modalities used for VS. Methods A systematic review of the literature for VS treatment cost was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using PubMed and Web of Science databases. Literature that presented cost of VS treatment specific to the modality was included. Articles from 1990 to present day in English were considered. Cost was corrected for inflation to April 2022 dollars using the US Bureau of Labor Statistics Inflation Calculator. Results A total of 407 articles were included in the analysis. After review, eight articles provided data on cost of treatment. In total, 687 patients were included across seven studies, with study dates ranging from 1997 to 2020. The average cost of resection was $54,321.99 (range = $10,243–95,590, n = 8), radiosurgery $27,837.92 (range = $6,281–51,676, n = 6), and observation $6,304.88 (range = $2,149–11,886, n = 3). Conclusion Our findings describe the limited and significant variability of data on published costs for the treatment of VS. Given the relative clinical equipoise between treatment modalities in some scenarios, better understanding of this end-point will help physicians make more responsible recommendations in the resource-constrained environment of modern healthcare and this analysis should serve as a starting point for more robust analysis into cost-effectiveness of treatment for VS.

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.

Fractionated Stereotactic Radiotherapy Compared to Stereotactic Radiosurgery for Vestibular Schwannoma in Patients with Type 2 Neurofibromatosis

The use of radiotherapy (RT) for the treatment of vestibulocochlear schwannomas is standard in patients with type 2 neurofibromatosis (NF2). In the general population, fractionated RT (FRT) can achieve good results compared to single-dose radiosurgery (SRS). We aimed to assess whether this is true for NF2 patients as well. This retrospective cohort study included 34 patients and 54 lesions treated between 2010 and 2023 in a single university hospital. Thirty-four patient charts were assessed. The median follow-up was 62.6 months (range, 7.1-135.8 months). Lesion size (median larger diameter, 2.5 cm) was correlated with the use of FRT (P > 0.001). Younger age also was correlated with FRT (P= 0.006). Median overall survival and progression-free survival (PFS) were not reached. The overall control rate was 76.5%, and the mean PFS was 49.8 months, compared with . 90.5% and 57.2 months, respectively, for SRS and 66.7% and 44.9 months, respectively, for FRT. There were no differences between the 2 groups in hearing loss, tinnitus, and facial palsy. In the NF2 population, FRT may yield worse control rates than SRS. Whenever possible, it is preferable to not fractionate treatment for these patients. Nevertheless, the FRT results were still good. More and larger prospective trials are warranted.

Vestibular Schwannoma Stereotactic Radiosurgery in Octogenarians: Case Series.

The management of octogenarians with vestibular schwannomas (VS) has received little attention. However, with the increase in octogenarian population, more effort is needed to clarify the value of stereotactic radiosurgery (SRS) in this population. The aim of this study was to evaluate the safety and efficacy of SRS in this patient age group. A retrospective study of 62 patients aged 80 years or older who underwent single-session SRS for symptomatic VS during a 35-year interval was performed. The median patient age was 82 years, and 61.3% were male. SRS was performed as planned adjuvant management or for delayed progression after prior partial resection in 5 patients. SRS resulted in a 5-year tumor control rate of 95.6% with a 4.8% risk of adverse radiation effects (ARE). Tumor control was unrelated to patient age, tumor volume, Koos grade, sex, SRS margin dose, or prior surgical management. Four patients underwent additional management including 1 patient with symptomatic progression requiring surgical resection, 2 patients with symptomatic hydrocephalus requiring cerebrospinal fluid diversion, and 1 patient whose tumor-related cyst required delayed cyst aspiration. Three patients developed ARE, including 1 patient with permanent facial weakness (House-Brackmann grade II), 1 who developed trigeminal neuropathy, and 1 who had worsening gait disorder. Six patients had serviceable hearing preservation before SRS, and 2 maintained serviceable hearing preservation after 4 years. A total of 44 (71%) patients died at an interval ranging from 6 to 244 months after SRS. SRS resulted in tumor and symptom control in most octogenarian patients with VS.

Impact of Cochlear Dose on Hearing Preservation Following Stereotactic Radiosurgery in Treatment of Vestibular Schwannomas: A Multi-Center Study

Stereotactic radiosurgery (SRS) is a well-established treatment for vestibular schwannomas (VS). Hearing loss remains a main morbidity of VS and its treatments, including SRS. The effects of radiation parameters of SRS on hearing remain unknown. The goal of this study is to determine the effect of tumor volume, patient demographics, pretreatment hearing status, cochlear radiation dose, total tumor radiation dose, fractionation, and other radiotherapy parameters on hearing deterioration. Multicenter retrospective analysis of 611 patients who underwent SRS for VS from 1990-2020 and had pre- and post-treatment audiograms. Pure tone averages (PTAs) increased and word recognition scores (WRSs) decreased in treated ears at 12-60 months while remaining stable in untreated ears. Higher baseline PTA, higher tumor radiation dose, higher maximum cochlear dose, and usage of single fraction resulted in higher post radiation PTA; WRS was only predicted by baseline WRS and age. Higher baseline PTA, single fraction treatment, higher tumor radiation dose, and higher maximum cochlear dose resulted in a faster deterioration in PTA. Below a maximum cochlear dose of 3 Gy, there were no statistically significant changes in PTA or WRS. Decline of hearing at one year in VS patients after SRS is directly related to maximum cochlear dose, single versus 3-fraction treatment, total tumor radiation dose, and baseline hearing level. The maximum safe cochlear dose for hearingtbrowd preservation at one year is 3 Gy, and the use of 3 fractions instead of one fraction was better at preserving hearing.

214 Impact of Cochlear Dose on Hearing Preservation Following Stereotactic Radiosurgery in Treatment of Vestibular Schwannomas: A Multi-Center Study

INTRODUCTION: Stereotactic radiosurgery (SRS) is a well-established treatment option for patients with vestibular schwannomas (VS). Hearing loss remains one of the main morbidities of VS and its treatments, including SRS. Effects of radiation parameters of SRS on hearing remains largely unknown. METHODS: Multicenter retrospective analysis of 611 patients who underwent SRS for VS from 1990 to 2020 and had pre- and post-treatment audiograms. RESULTS: Pure tone averages (PTA)s increased and word recognition scores (WRS)s decreased in the treated ears at 12 - 60 months while it remained stable in the untreated ears. Higher baseline PTA, higher tumor radiation dose, higher maximum cochlear dose, and usage of single fraction resulted in higher post radiation PTA; WRS was only predicted by baseline WRS and age. Of these parameters, higher baseline PTA, single fraction treatment, higher tumor radiation dose, and higher maximum cochlear dose resulted in a faster deterioration in PTA. Below a maximum cochlear dose of 3 Gy, there were no statistically significant changes in PTA or WRS. CONCLUSIONS: Decline of hearing at 1 year in VS patients after SRS is directly related to maximum cochlear dose, single versus 3-fraction treatment, total tumor radiation dose, and baseline hearing level. The maximum safe cochlear dose for hearing preservation at 1 year is 3 Gy, and the use of 3 fractions instead of 1 fraction was better at preserving hearing.

Reported Hearing Outcome Measures Following Stereotactic Radiosurgery for Vestibular Schwannoma: A Scoping Review.

Background Evidence on hearing outcome measures when assessing hearing preservation following stereotactic radiosurgery (SRS) for adults with vestibular schwannoma (VS) has not previously been collated in a structured review. Objective The objective of the present study was to perform a scoping review of the evidence regarding the choice of hearing outcomes and other methodological characteristics following SRS for adults with VS. Methods The protocol was registered in the International Platform of Registered Systematic Review and Meta-Analysis Protocols (INPLASY) and reported according to the Preferred Reporting Items for Systematic Review and Meta-Analyses extension guidelines for scoping reviews. A systematic search of five online databases revealed 1,591 studies, 247 of which met the inclusion criteria. Results The majority of studies ( n = 213, 86%) were retrospective cohort or case series with the remainder ( n = 34, 14%) prospective cohort. Pure-tone audiometry and speech intelligibility were included in 222 (90%) and 158 (64%) studies, respectively, often summarized within a classification scheme and lacking procedural details. Fifty-nine (24%) studies included self-report measures. The median duration of follow-up, when reported, was 43 months (interquartile range: 29, 4-150). Conclusion Evidence on hearing disability after SRS for VS is based on low-quality studies which are inherently susceptible to bias. This review has highlighted an urgent need for a randomized controlled trial assessing hearing outcomes in patients with VS managed with radiosurgery or radiological observation. Similarly, consensus and coproduction of a core outcome set to determine relevant hearing and communication outcome domains is required. This will ensure that patient priorities, including communication abilities in the presence of background noise and reduced participation restrictions, are addressed.

The Relevance of Biologically Effective Dose for Hearing Preservation After Stereotactic Radiosurgery for Vestibular Schwannomas: A Retrospective Longitudinal Study.

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

Cochlear Implantation after Stereotactic Radiosurgery for Vestibular Schwannoma: Initial Hearing Improvement and Longevity of Hearing Restoration.

The following research question was asked: In patients with vestibular schwannoma (VS) that underwent stereotactic radiosurgery (SRS) and cochlear implantation, were improvements in hearing function observed, and what was the cochlear implant (CI) failure rate of in these patients? PubMed/Medline, CINAHL (EBSCOhost), and Web of Science articles without restrictions on publication dates were searched. Inclusion criteria required that the article was a report, a series, or a retrospective review with individual case data available. Non-English articles were excluded. Inclusion criteria required that patients were with VS and underwent subsequent SRS and cochlear implantation. Patients receiving microsurgery or stereotactic radiotherapy on the ipsilateral ear were excluded from this study. Included studies were evaluated using full-text evaluation, and data on study characteristics (author names, gender), clinical data (syndromic information, SRS modality), hearing outcomes, and device failure were extracted. Means and averages were obtained for all continuous variables. Percentages were ascertained for all categorical variables. The majority of patients undergoing CI placement in VS treated with SRS achieved open-set speech perception (79.2%) or environmental sound awareness (6.8%). Twelve implants (20.3%) failed. Three patterns were associated with failure: 1) immediate-onset failure, 2) initial benefit with delayed failure, 3) poor local control with device explantation.

Single-Fraction vs. Fractionated Stereotactic Radiosurgery for Vestibular Schwannomas with Frameless Radiosurgery: A Single Institution Prospective Observational Study

<h3>Purpose/Objective(s)</h3> The number of patients with small- to medium-sized vestibular schwannoma (VS), defined as under 22 mm in greatest dimension, presenting with serviceable hearing has steadily increased over the last 50 years. Thus, treatment of VS often must balance a goal of tumor control with hearing preservation and other potential side effects. Improved hearing rates have been demonstrated with the use of a lower prescription dose. The effect of fractionation in preserving hearing loss is less clear. We sought to evaluate local control and hearing preservation rates in patients treated with single-fraction versus 5-fraction frameless GKRS. <h3>Materials/Methods</h3> Prospectively enrolled patients with a radiographic diagnosis of unilateral vestibular schwannoma who underwent single-fraction or 5-fraction definitive frameless GKRS between 2017 and 2020 were retrospectively reviewed in our institutional review board (IRB) approved database. We used chi-squared tests and t-tests to compare demographic and clinical characteristics by treatment modality. We then used Kaplan-Meier methods to compare the two treatment groups' local control and hearing preservation, and evaluated the statistical significance of the differences by log rank test. <h3>Results</h3> Seventy consecutive patients were treated with single-fraction or fractionated GKRS for VS from 2017 to 2020. Forty-eight patients met inclusion criteria and were included in this analysis. Twenty-three patients underwent single-fraction treatment, and 25 patients underwent fractionated treatment in 5 fractions. Median follow-up time was 2 years for both groups. Patients who were treated with multi-fraction GKRS on average, had a larger maximal tumor diameter than those treated with single-fraction GKRS. At 2 years, radiographic local control of VS treated with single-fraction was 93% compared to 92% for multi-fraction frameless GKRS (p=0.64). No patients required salvage treatment in either group. Hearing preservation was evaluated in patients with available audiograms (13/23 single-fraction and 20/25 multi-fraction). At 2 years, hearing preservation was 46% for patients treated with single-fraction GKRS compared to 78% for patients treated with multi-fraction GKRS, not including patients censored due to lack of available audiogram (p=.06). <h3>Conclusion</h3> Single-fraction and fractionated frameless GKRS provide similar clinical and radiographic local control, while maintaining similar hearing preservation rates, in the treatment of VS.

Vestibular schwannoma associated with neurofibromatosis type 2: Clinical course following stereotactic radiosurgery.

ObjectiveA lack of understanding of the clinical course of neurofibromatosis type 2 (NF2)-associated vestibular schwannoma (VS) often complicates the decision-making in terms of optimal timing and mode of treatment. We investigated the outcomes of stereotactic radiosurgery (SRS) in this population.MethodsWe retrospectively analyzed NF2 patients treated with Gamma-Knife SRS for VS in our tertiary referral center. A total of 41 treated lesions from 33 patients were collected with a follow-up period of 69.1 (45.0-104.8) months. We reviewed the treatment history, hearing function, and other treatment-related morbidities in individual cases. We also analyzed pre- and post-treatment tumor volumes via imaging studies. Longitudinal volumetric analyses were conducted for the tumor volume response of the 41 treated lesions following SRS. The growth pattern of 22 unirradiated lesions during an observation period of 83.4 (61.1-120.4) months was separately evaluated.ResultsMost treated lesions showed effective tumor control up to 85% at 60 months after SRS, whereas unirradiated lesions progressed with a relative volume increase of 14.0% (7.8-27.0) per year during the observation period. Twelve (29%) cases showed pseudoprogression with significant volume expansion in the early follow-up period, which practically reduced the rate of tumor control to 57% at 24 months. Among the patients with serviceable hearing, two (20%) cases lost the hearing function on the treated side during the early follow-up period within 24 months.ConclusionsProgressive NF2-associated VS can be adequately controlled by SRS but the short-term effects of this treatment are not highly advantageous in terms of preserving hearing function. SRS treatment candidates should therefore be carefully selected.

CO63 Vestibular Symptoms, Hearing Preservation, and Facial Symmetry in Surgery Vs SRS for Vestibular Schwannomas: A Systematic Review and Meta-Analysis

Surgery and radiosurgery represent the most common treatment options for vestibular schwannoma. A systematic review and meta-analysis were conducted to compare the outcomes of surgery versus stereotactic radiosurgery (SRS).

Biologically effective dose correlates with linear tumor volume changes after upfront single-fraction stereotactic radiosurgery for vestibular schwannomas

Biologically effective dose correlates with linear tumor volume changes after upfront single-fraction stereotactic radiosurgery for vestibular schwannomas

Stereotactic radiosurgery for vestibular schwannoma: early and long-term radiation-induced changes and tumor growth control

To investigate the changes of vestibular schwannoma in different periods after radiosurgery. We analyzed early and long-term radiation-induced changes in 333 patients who received Gamma Knife treatment at the Burdenko Neurosurgery Center between April 2005 and December 2015. Mean follow-up period was 60 months (range 15-167). There were 89 men (26.7%) and 244 (73.4%) women. Mean age of patients was 48.2 years. Mean baseline tumor volume was 4.1 cm3 (range 0.1-14.5). Dynamics of changes was assessed using volumetric comparison. Tumor shrinkage without pseudo-progression was observed in 149 (44.7%) patients. Typical pseudo-progression in different variants was found in 131 (39.3%) patients, i.e. short-term (1 year) and long-term (≥2 years) course, complete and incomplete process. Eleven patients had atypical pseudo-progression after initial tumor shrinkage. Progression-free 5- and 10-year survival in the entire group was 87 and 81%, respectively. Progression-free 5-year survival rate was 95 and 92% in patients with and without pseudo-progression, respectively. Ten-year survival rate was 89 and 89%, respectively. Knowledge of pseudo-progression features is essential for the most reasonable and reliable assessment of treatment results and justification of timing and frequency of subsequent MR control. Atypical course of pseudo-progression can simulate tumor recurrence. In case of tumor enlargement at any follow-up stage after radiosurgery, advisability of surgery should be determined considering clinical data and likelihood of tumor shrinkage following natural regression of post-radiation tumor enlargement.

Biologically effective dose correlates with linear tumor volume changes after upfront single-fraction stereotactic radiosurgery for vestibular schwannomas

Vestibular schwannomas (VSs) are benign, slow-growing tumors. Management options include observation, surgery, and radiation. In this retrospective trial, we aimed at evaluating whether biologically effective dose (BED) plays a role in tumor volume changes after single-fraction first intention stereotactic radiosurgery (SRS) for VS. We compiled a single-institution experience (n = 159, Lausanne University Hospital, Switzerland). The indication for SRS was decided after multidisciplinary discussion. Only cases with minimum 3 years follow-up were included. The Koos grading, a reliable method for tumor classification was used. Radiosurgery was performed using Gamma Knife (GK) and a uniform marginal prescription dose of 12 Gy. Mean BED was 66.3 Gy (standard deviation 3.8, range 54.1–73.9). The mean follow-up period was 5.1 years (standard deviation 1.7, range 3–9.2). The primary outcome was changes in 3D volumes after SRS as function of BED and of integral dose received by the VS. Random-effect linear regression model showed that tumor volume significantly and linearly decreased over time with higher BED (p < 0.0001). Changes in tumor volume were also significantly associated with age, sex, number of isocenters, gradient index, and Koos grade. However, the effect of BED on tumor volume change was moderated by time after SRS and Koos grade. Lower integral doses received by the VSs were inversely correlated with BED in relationship with tumor volume changes (p < 0.0001). Six (3.4%) patients needed further intervention. For patients having uniformly received the same marginal dose prescription, higher BED linearly and significantly correlated with tumor volume changes after SRS for VSs. BED could represent a potential new treatment paradigm for patients with benign tumors, such as VSs, for attaining a desired radiobiological effect. This could further increase the efficacy and decrease the toxicity of SRS not only in benign tumors but also in other SRS indications.

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

Simple SummarySince vestibular schwannomas are slow-growing tumors that can be controlled with different treatment modalities such as neurosurgery or radiotherapy, preserving quality of life is an important consideration. In this study, we analyzed how quality of life (QoL) changes for patients who receive stereotactic radiation in the months and years after treatment and if there is a correlation between changes in QoL and changes in hearing function. The results suggest that proper hearing of the unaffected ear might compensate for a hearing loss of the other ear due to the tumor or the treatment and in turn preserve QoL. However, this association should be confirmed in additional studies.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.

Stereotactic Radiosurgery for Vestibular Schwannoma Outcomes in Patients With Perfect Word Recognition-A Retrospective Cohort Study.

To investigate tumor control rate and hearing outcomes following stereotactic radiosurgery (SRS) for vestibular schwannoma (VS) cases with perfect (100%) word recognition score (WRS). A retrospective cohort study. Tertiary referral center. Inclusion criteria were receiving primary SRS, a pretreatment WRS of 100%, and availability of both pre- and posttreatment audiometric data for evaluation. SRS delivered by Cyberknife. Tumor growth rates and audiological outcomes after SRS. The cohort consisted of 139 patients, with more than 1-year follow-up (mean 6.1 yrs). SRS tumor control rate was 87% for the whole cohort. Growth before SRS was documented in 24% (n = 34 of 139). The proportion of sporadic VS cases who maintained hearing (decline <10 dB of pure-tone audiometry or <20% of WRS) at 3 years was 50%, at 5 years was 45%, and at 10 years was 42%. In multivariate analysis, increased age was found to be predictive of increased hearing loss (p = 0.03), while the following factors were shown not to be significant: sex (p = 0.5), tumor size (p = 0.2), pre-SRS tumor growth (p = 0.5), and target volume (p = 0.42). Among patients with VS who had perfect WRS and underwent SRS, the overall tumor control rate was 87% comparable to observation. Hearing maintenance and preservation of "serviceable" hearing rates after 5 years in VS patients with perfect WRS treated by SRS is less than that when comparing to similar observation cohorts. Given this finding we do not advocate using SRS to preserve hearing, over observation, in tumors with perfect WRS.