Radiosurgery and stereotactic radiotherapy with cyberknife system for meningioma treatment

Intracranial meningiomas: an update of the 2021 World Health Organization classifications and review of management with a focus on radiation therapy

Meningiomas account for approximately one third of all primary intracranial tumors. Arising from the cells of the arachnoid mater, these neoplasms are found along meningeal surfaces within the calvarium and spinal canal. Many are discovered incidentally, and most are idiopathic, although risk factors associated with meningioma development include age, sex, prior radiation exposure, and familial genetic diseases. The World Health Organization grading system is based on histologic criteria, and are as follows: grade 1 meningiomas, a benign subtype; grade 2 meningiomas, which are of intermediately aggressive behavior and usually manifest histologic atypia; and grade 3, which demonstrate aggressive malignant behavior. Management is heavily dependent on tumor location, grade, and symptomatology. While many imaging-defined low grade appearing meningiomas are suitable for observation with serial imaging, others require aggressive management with surgery and adjuvant radiotherapy. For patients needing intervention, surgery is the optimal definitive approach with adjuvant radiation therapy guided by extent of resection, tumor grade, and location in addition to patient specific factors such as life expectancy. For grade 1 lesions, radiation can also be used as a monotherapy in the form of stereotactic radiosurgery or standard fractionated radiation therapy depending on tumor size, anatomic location, and proximity to dose-limiting organs at risk. Optimal management is paramount because of the generally long life-expectancy of patients with meningioma and the morbidity that can arise from tumor growth and recurrence as well as therapy itself.

Outcomes and predictors of response to fractionated radiotherapy as primary treatment for intracranial meningiomas

Background

Surgery is the primary treatment for most meningiomas. However, primary fractionated radiotherapy (fRT) remains an option for patients with larger meningiomas in challenging anatomic locations or patients at prohibitively high surgical risk. Outcome prediction for these patients is uncertain and cannot be guided by histopathology without available tumor tissue from surgery. Therefore, we aimed to assess the clinical factors that contribute to treatment failure in a large cohort of meningiomas consecutively treated with fRT as primary therapy, with the goal of identifying predictors of response.

Methods

Patients treated with primary fRT for intracranial meningiomas from 1998 to 2017 were reviewed. Those who received primary surgical resection, radiosurgery, previous fRT, or had <6 months of clinical follow-up were excluded. We applied logistic regression and Cox regression modeling to ascertain key predictors of treatment failure, progression-free survival (PFS), and adverse events (AE) following fRT.

Results

Our cohort included 137 meningiomas, 21 of which progressed after fRT (median PFS 3.45 years). Progressive meningiomas had a larger median gross tumor volume (GTV) compared to those that remained stable (19.1 cm³ vs 9.6 cm³, p = 2.86 × 10^-2). GTV > 11.27 cm³ was independently predictive of progression and larger GTV was associated with higher risk of significant (grades 3/4) AE following fRT. Cavernous sinus and optic nerve sheath meningiomas had overall excellent outcomes post-fRT.

Conclusions

We present a large cohort of meningiomas treated with primary fRT and find GTV and anatomic location to be key predictors of outcome, adding to the complex treatment considerations for this heterogeneous disease.

The multiomic landscape of meningiomas: a review and update

PURPOSE

Meningiomas are the most common primary brain tumor in adults. Traditionally they have been understudied compared to other central nervous system (CNS) tumors. However over the last decade, there has been renewed interest in uncovering the molecular topography of these tumors, with landmark studies identifying key driver alterations contributing to meningioma development and progression. Recent work from several independent research groups have integrated different genomic and epigenomic platforms to develop a molecular-based classification scheme for meningiomas that could supersede histopathological grading in terms of diagnostic accuracy, biological relevance, and outcome prediction, keeping pace with contemporary grading schemes for other CNS tumors including gliomas and medulloblastomas.

METHODS

Here we summarize the studies that have uncovered key alterations in meningiomas which builds towards the discovery of consensus molecular groups in meningiomas by integrating these findings. These groups supersede WHO grade and other clinical factors in being able to accurately predict tumor biology and clinical outcomes following surgery.

RESULTS

Despite differences in the nomenclature of recently uncovered molecular groups across different studies, the biological similarities between these groups enables us to likely reconciliate these groups into four consensus molecular groups: two benign groups largely dichotomized by NF2-status, and two clinically aggressive groups defined by their hypermetabolic transcriptome, and by their preponderance of proliferative, cell-cycling pathways respectively.

CONCLUSION

Future work, including by our group and others are underway to validate these molecular groups and harmonize the nomenclature for routine clinical use.

A single-center experience with linear accelerator-based stereotactic radiotherapy for meningiomas: hypofractionation and radiosurgery

PURPOSE

Meningioma is a common type of benign tumor that can be managed in several ways, ranging from close observation, surgical resection, and various types of radiation. We present here results from a 10 year experience treating meningiomas with a hypofractionated approach.

MATERIALS AND METHODS

To define the rate of tumor control and factors associated with the relief of symptoms and radiation-related complications after radiosurgery and hypofractionated radiosurgery for patients with imaging-defined intracranial meningiomas. We reviewed the charts of 48 patients treated with stereotactic radiosurgery (SRS) or hypofractionated stereotactic radiotherapy (SRT) from 2002 to 2018. A total of 37 (82%) patients had WHO Grade 1 disease, and 11 (22%) had Grade 2. Outcomes that were analyzed included local control rates and the rate and grade of any reported toxicity.

RESULTS

Only 36 patients with 38 lesions, who underwent the follow-up regime, were enrolled in the retrospective analysis. The follow-up mean was 40 months (12-120 months). 25/34 patients had surgery before the radiotherapy. Sixteen underwent SRS with a median dose of 13, 5, and 20 received hypofractionated SBRT with a median dose of 26.9 (22-45 Gy) in median six fractions (5-13 fractions). Local control at 2 and 5 years for all patients was 90 and 70%, respectively. No patient suffered from toxicity > 2 CTC. 21/36 patients showed stable disease, while 8/36 patients showed partial Remission. 7/36 developed recurrent meningioma (five in-field), only one patient with grade 1 meningioma, in a median of 22 months (13-48 months).

CONCLUSION

SFRT was superior to SRS for local control in our analysis of Grade I meningiomas. This might be due to a tendency for higher EQD2 in the PTV with SFRT compared to SRS, which was reduced to avoid brain necrosis in large PTVs. Therefore, SFRT appears preferable for typical meningioma PTVs.

Radiotherapy for Meningioma

Meningiomas are the most common primary intracranial brain tumor, and have a heterogeneous biology and an unmet need for targeted treatment options. Existing treatments for meningiomas are limited to surgery, radiotherapy, or a combination of these depending on clinical and histopathological features. Treatment recommendations for meningioma patients take into consideration radiologic features, tumor size and location, and medical comorbidities, all of which may influence the ability to undergo complete resection. Ultimately, outcomes for meningioma patients are dictated by extent of resection and histopathologic factors, such as World Health Organization (WHO) grade and proliferation index. Radiotherapy is a critical component of meningioma treatment as either a definitive intervention using stereotactic radiosurgery or external beam radiotherapy, or in the adjuvant setting for residual disease or for adverse pathologic factors, such as high WHO grade. In this chapter, we provide a comprehensive review of radiotherapy treatment modalities, therapeutic considerations, radiation planning, and clinical outcomes for meningioma patients.

Radical radiotherapy for cervical cancer and meningioma with a history of Guillain-Barré syndrome: A case report

RATIONALE

Guillain-Barré syndrome (GBS) is a rare autoimmune disease. Patients with cervical malignancies and intracranial meningiomas after the course of GBS are even rarer. There are no relevant reports at present.

PATIENT CONCERNS

We report a patient who developed cervical cancer (CC) and intracranial meningioma simultaneously after the course of GBS.

DIAGNOSES

The history, pelvic enhanced magnetic resonance imaging (MRI) and pathology confirmed cervical squamous cell carcinoma, and the head enhanced MRI confirmed meningioma.

INTERVENTION

After multi-disciplinary team, the patient received head stereotactic radiosurgery for meningioma and radical radiotherapy for CC.

OUTCOMES

The follow up for 1 year after treatment revealed a complete remission of the cervical tumor, stable disease of the meningioma, and no signs of GBS recurrence. Up to now, the general condition of the patient is acceptable and the curative effect is satisfactory.

LESSONS

This case report aims to improve the oncologists' understanding of malignant tumors with rare autoimmune diseases and provide treatment reference for similar diseases in the future.

Consensus core clinical data elements for meningiomas

BACKGROUND

With increasing molecular analyses of meningiomas, there is a need to harmonize language used to capture clinical data across centers to ensure that molecular alterations are appropriately linked to clinical variables of interest. Here the International Consortium on Meningiomas presents a set of core and supplemental meningioma-specific Common Data Elements (CDEs) to facilitate comparative and pooled analyses.

METHODS

The generation of CDEs followed the four-phase process similar to other National Institute of Neurological Disorders and Stroke (NINDS) CDE projects: discovery, internal validation, external validation, and distribution.

RESULTS

The CDEs were organized into patient- and tumor-level modules. In total, 17 core CDEs (10 patient-level and 7-tumour-level) as well as 14 supplemental CDEs (7 patient-level and 7 tumour-level) were defined and described. These CDEs are now made publicly available for dissemination and adoption.

CONCLUSIONS

CDEs provide a framework for discussion in the neuro-oncology community that will facilitate data sharing for collaborative research projects and aid in developing a common language for comparative and pooled analyses. The meningioma-specific CDEs presented here are intended to be dynamic parameters that evolve with time and The Consortium welcomes international feedback for further refinement and implementation of these CDEs.

Importance of Pre-treatment Fractional Anisotropy Value in Predicting Volumetric Response in Patients with Meningioma Treated with Gamma Knife Radiosurgery

Background

The importance of pre-treatment Diffusion Tensor Imaging (DTI) parameters in determining the response to treatment after radiosurgery in patients with meningioma has not yet been clearly revealed.

Objective

This study was conducted to determine tumor volume changes in terms of radiological response in patients with meningioma treated with Gamma Knife Radiosurgery (GKR) and to analyze the relationship between Total Tumor Volume (TTV) and Diffusion Tensor Imaging (DTI) parameters. In addition, we investigated whether the response to treatment can be predicted by pre-radiosurgery DTI findings.

Methods

Fifty-four patients were assessed using MRI and DTI before and after GKR. Mean Diffusivity (MD), Fractional Anisotropy (FA), Radial Diffusivity (RD), and TTV of tumour were determined. Patients with 10% or more decrease in TTV after GKR were classified as group 1 and those with less than 10% decrease in volume or increase in volume were considered group 2. The relationships between MD, RD, and FA values and TTV were investigated.

Results

A decrease of 46.34% in TTV was detected in group 1 after GKR, while TTV increased by 42.91% in group 2. The lowest pre-treatment FA value was detected in group 1. In addition, after GKR, FA values showed a significant increase in group 1. MD and RD values increased in both groups after radiosurgery. There was a negative correlation between pre-treatment FA, RD, and MD values after radiosurgery.

Conclusion

Detection of low FA values due to the poor fiber content in meningioma before radiosurgery may be a guide in predicting the response to treatment. Further studies are required to have a better understanding of the relationship between pre- and post-treatment follow-up FA values and tumor volume in determining the efficacy of GKR in patients with meningioma.

A Giant Nondural-Based Lumbosacral Clear Cell Meningioma Mimicking Schwannoma: A Case Report and Review of the Literature

Spinal clear cell meningiomas (CCMs) are rare and dural-based lesion usually affecting the younger population. We report the rare case of giant nondural-based spinal CCM mimicking schwannoma and review the literature. A literature search was performed at PubMed and Embase until January 1, 2020. A total of 19 cases of nondural-based spinal CCM was reported. The following relevant data were extracted: authors, publication year, patient and tumor characteristics, treatment, and outcome. The mean age of the presentation was 20.58 years. Twelve (63.16%) were female and seven patients (36.84%) were male. The most common location was lumbosacral region 15 (79%). Fifteen (79%) tumors had cranio-caudal dimension ≤2 vertebral level, and only four (21%) tumors had dimension ≥2 vertebral level. Gross total resection (GTR) was performed in 18 (95%) patients and subtotal resection (STR) in 1 patient. Recurrences were reported in five (26.14%) patients. Four of them showed recurrences within 6 months; earliest at 2.3 months in the patient had undergone STR. Our patient is 19-year-old male diagnosed with a lumbosacral intradural lesion. Craniocaudal dimension is ≥2 vertebral level shows the foraminal extension and vertebral scalloping. GTR is performed. Intraoperatively, the tumor has foraminal extension and shows attachment with right S1S2 nerve root. No dural attachment is found. Six-month follow-up magnetic resonance image shows no evidence of disease. Nondural-based spinal CCMs are extremely rare and should be kept as a differential diagnosis in young patients with giant intradural tumor, and whose radiological features suggesting of schwannoma. It affects young patients and usually involves more than one vertebral level. The chances of recurrences and metastasis are always high even after GTR; hence, close follow-up of the entire neuraxis is warranted.

Shortened Tracer Uptake Time in GA-68-DOTATOC-PET of Meningiomas Does Not Impair Diagnostic Accuracy and PET Volume Definition

Ga-68-DOTATOC-PET/MRI can affect the planning target volume (PTV) definition of meningiomas before radiosurgery. A shorter tracer uptake time before image acquisition could allow the examination of more patients. The aim of this study was to investigate if shortening uptake time is possible without compromising diagnostic accuracy and PET volume. Fifteen patients (f = 12; mean age 52 years (34-80 years)) with meningiomas were prospectively examined with dynamic [68Ga]Ga-68-labeled [DOTA0-Phe1-Tyr3] octreotide (Ga-68-DOTATOC)-PET/MRI over 70 min before radiosurgery planning. Meningiomas were delineated manually in the PET dataset. PET volumes at each time point were compared to the reference standard 60 min post tracer injection (p.i.) using the Friedman test followed by a Wilcoxon signed-rank test and Bonferroni correction. In all patients, the earliest time point with 100% lesion detection compared to 60 min p.i. was identified. PET volumes did not change significantly from 15 min p.i. (p = 1.0) compared to 60 min p.i. The earliest time point with 100% lesion detection in all patients was 10 min p.i. In patients with meningiomas undergoing Ga-68-DOTATOC-PET, the tracer uptake time can safely be reduced to 15 min p.i. with comparable PET volume and 100% lesion detection compared to 60 min p.i.

Treatment of intracranial meningioma with single-session and fractionated radiosurgery: a propensity score matching study

Single-session stereotactic radiosurgery (SSRS) is recognized as a safe and efficient treatment for meningioma. We aim to compare the long-term efficacy and safety of fractionated stereotactic radiotherapy (FSRT) with SSRS in the treatment of grade I meningioma. A total of 228 patients with 245 tumors treated with radiosurgery between March 2006 and June 2017were retrospectively evaluated. Of these, 147 (64.5%) patients were treated with SSRS. The remaining 81 patients (35.5%) were treated with a fractionated technique. Protocols to treat meningioma were classified as 12-16 Gy per fraction for SSRS and 7 Gy/fraction/day for three consecutive days to reach a total dose of 21 Gy for FSRT. In univariate and multivariate analyses, tumor volume was found to be associated with local control rate (hazard ratio = 4.98, p = 0.025). The difference in actuarial local control rate (LCR) between the SSRS and FSRT groups after propensity score matching (PSM) was not statistically significant during the 2-year (96.86% versus 100.00%, respectively; p = 0.175), 5-year (94.76% versus 97.56%, respectively; p = 0.373), and 10-year (74.40% versus 91.46%, respectively; p = 0.204) follow-up period. FSRT and SSRS were equally well-tolerated and effective for the treatment of intracranial benign meningioma during the10-year follow-up period.

Trends in the utilization of radiotherapy for spinal meningiomas: insights from the 2004-2015 National Cancer Database

OBJECTIVERecent studies have reported on the utility of radiosurgery for local control and symptom relief in spinal meningioma. The authors sought to evaluate national utilization trends in radiotherapy (including radiosurgery), investigate possible factors associated with its use in patients with spinal meningioma, and its impact on survival for atypical tumors.METHODSUsing the ICD-O-3 topographical codes C70.1, C72.0, and C72.1 and histological codes 9530-9535 and 9537-9539, the authors queried the National Cancer Database for patients in whom spinal meningioma had been diagnosed between 2004 and 2015. Patients who had undergone radiation in addition to surgery and those who had received radiation as the only treatment were analyzed for factors associated with each treatment.RESULTSFrom among 10,458 patients with spinal meningioma in the database, the authors found a total of 268 patients who had received any type of radiation. The patients were divided into two main groups for the analysis of radiation alone (137 [51.1%]) and radiation plus surgery (131 [48.9%]). An age > 69 years (p < 0.001), male sex (p = 0.03), and tumor size 5 to < 6 cm (p < 0.001) were found to be associated with significantly higher odds of receiving radiation alone, whereas a Charlson-Deyo Comorbidity Index ≥ 2 (p = 0.01) was associated with significantly lower odds of receiving radiation alone. Moreover, a larger tumor size (2 to < 3 cm, p = 0.01; 3 to < 4 cm, p < 0.001; 4 to < 5 cm, p < 0.001; 5 to < 6 cm, p < 0.001; and ≥ 6 cm, p < 0.001; reference = 1 to < 2 cm), as well as borderline (p < 0.001) and malignant (p < 0.001) tumors were found to be associated with increased odds of undergoing radiation in addition to surgery. Receiving adjuvant radiation conferred a significant reduction in overall mortality among patients with borderline or malignant spinal meningiomas (HR 2.12, 95% CI 1.02-4.1, p = 0.02).CONCLUSIONSThe current analysis of cases from a national cancer database revealed a small increase in the use of radiation for the management of spinal meningioma without a significant increase in overall survival. Larger tumor size and borderline or malignant behavior were found to be associated with increased radiation use. Data in the present analysis failed to show an overall survival benefit in utilizing adjuvant radiation for atypical tumors.

Advances in multidisciplinary therapy for meningiomas

Surgery has long been established as the first-line treatment for the majority of symptomatic and enlarging meningiomas, and evidence for its success is derived from retrospective case series. Despite surgical resection, a subset of meningiomas display aggressive behavior with early recurrences that are difficult to treat. The decision to radically resect meningiomas and involved structures is balanced against the risk for neurological injury in patients. Radiation therapy has largely been used as a complementary and safe therapeutic strategy in meningiomas with evidence primarily stemming from retrospective, single-institution reports. Two of the first cooperative group studies (RTOG 0539 and EORTC 22042) evaluating the outcomes of adjuvant radiation therapy in higher-risk meningiomas have shown promising preliminary results. Historically, systemic therapy has resulted in disappointing results in meningiomas. However, several clinical trials are under way evaluating the efficacy of chemotherapies, such as trabectedin, and novel molecular agents targeting Smoothened, AKT1, and focal adhesion kinase in patients with recurrent meningiomas.

DNA repair and cell synthesis proteins: immunohistochemical expression and correlation with recurrence-regrowth in meningiomas

Meningiomas are considered the second most common neoplasm of the central nervous system in adults. Most of them are benign with slow growth, frequent in women and with a high recurrence rate. In tumors, DNA error repair processes lose efficacy, providing mutagenesis and genomic instability. This work evaluated the expression of proteins involved in cell synthesis (cyclin D1) and DNA errors repair (MUTYH, XPF, XPG) in meningiomas, relating them to clinical, tumor and survival variables. The study included 85 patients, with a mean age of 52 ± 13.3 years and most of them women (2:1 ratio). Sixty-seven cases were grade I (79%). Grade II tumors were independent predictors of recurrence-regrowth (HR: 2.8; p = 0.038). The high expression of cyclin D1 was associated with grade II (p = 0.001) and low MUTYH expression with grade I (p = 0.04). Strong expression of XPF and XPG was associated with grade II (p = 0.002; p < 0.001) and with recurrence-regrowth (p = 0.04; p = 0.003). Strong XPF expression was significantly related to large tumors (p = 0.03). An association of cyclin D1, MUTYH and XPF were found. Survival was not associated with the expression of any of the proteins studied. To know the role of DNA repair proteins and cell synthesis is important for understanding the processes of origin and tumor development. Grade II meningiomas and strong expression of XPF and XPG were predictors of recurrence or regrowth and may assist in clinical management, considering the high recurrence of meningiomas and the absence of consensus regarding treatment.

Indications, feasibility, safety, and efficacy of CyberKnife radiotherapy for the treatment of olfactory groove meningiomas: a single institutional retrospective series

Purpose

To assess the safety and efficacy of CyberKnife® radiotherapy (CKRT) for the treatment of olfactory groove meningiomas (OGMs).

Methods

A retrospective review was performed of 13 patients with OGM treated with CKRT from September 2005 to May 2018 at our institution. Nine patients were treated primarily with CKRT, 3 for residual disease following resection, and 1 for disease recurrence.

Results

Five patients were treated with stereotactic radiosurgery (SRS), 6 with hypofractionated stereotactic radiotherapy (HSRT), and 2 with fractionated stereotactic radiotherapy (FSRT). The median tumor volume was 8.12 cm³. The median prescribed dose was 14.8 Gy for SRS, 27.3 Gy for HSRT, and 50.2 Gy for FSRT. The median maximal dose delivered was 32.27 Gy. Median post treatment follow-up was 48 months. Twelve of 13 patients yielded a 100% regional control rate with a median tumor volume reduction of 31.7%. Six of the 12 patients had reduced tumor volumes while the other 6 had no changes. The thirteenth patient had significant radiation-induced edema requiring surgical decompression. Twelve patients were alive and neurologically stable at the time of the review. One patient died from pneumonia unrelated to his CKRT treatment.

Conclusions

CKRT appears to be safe and effective for the treatment of OGMs.

Image-Guided Robotic Radiosurgery for Treatment of Recurrent Grade II and III Meningiomas. A Single-Center Study

OBJECTIVE

Stereotactic radiosurgery (SRS) has been increasingly applied for malignant meningiomas as an alternative to conventionally fractioned radiation therapy. We performed a retrospective analysis of an institutional patient cohort with malignant meningiomas treated by image-guided SRS.

METHODS

All patients with atypical or anaplastic meningiomas who were treated by SRS using CyberKnife (CK) were identified. Local failure and regional and/or distant recurrences were evaluated together with toxicity and overall survival.

RESULTS

We identified 127 treated lesions (105 atypical and 22 anaplastic) in 35 patients. The mean time interval between the last surgery and subsequent CK-SRS was 30.8 ± 24.5 months. Most lesions (83.5%) were treated using single-fraction CK-SRS. The median planning target volume of all 127 lesions was 1.71 cm³ (range, 0.06-22.5 cm³). The median follow-up period was 23 months (range, 2.1-60.3 months). The estimated local control rates were 97%, 77%, and 67% at 12, 36, and 60 months, respectively, in atypical meningiomas and 66% each at 12 and 24 months in anaplastic meningiomas. The regional progression-free survival was 93%, 73%, and 59% at 12, 36, and 60 months, respectively, in atypical lesions and 93% and 46% at 12 and 24 months in anaplastic lesions. The estimated distant tumor progression-free interval in atypical lesions was 80%, 44%, and 44% at 12, 36, and 60 months, respectively, and 49% and 24% at 12 and 24 months, respectively, in anaplastic lesions. Age was identified as a risk factor for local failure.

CONCLUSIONS

Although the real boundaries of efficacy of SRS have to be further evaluated in a prospective trial, it seems that aggressive treatment by high-dose single or multisession SRS of recurring malignant meningiomas provides satisfactory local control rates.

Linear Accelerator-Based Stereotactic Radiotherapy for Low-Grade Meningiomas: Improved Local Control With Hypofractionation

Background and purpose:

Meningioma is a common type of benign tumor that can be managed in several ways, ranging from close observation, surgical resection, and various types of radiation. We present here results from a 10-year experience treating meningiomas with a hypofractionated approach.

Materials and methods:

We reviewed the charts of 56 patients treated with stereotactic radiosurgery (SRS) or hypofractionated stereotactic radiotherapy (SRT) from 2008 to 2017. A total of 46 (82%) patients had WHO Grade 1 disease and 10 (18%) had Grade 2. Outcomes that were analyzed included local control rates and the rate and grade of any reported toxicity.

Results:

A total of 38 women and 18 men underwent SRS to a median dose of 15 Gy (n = 24) or hypofractionated SRT with a median dose of 25 Gy in five fractions (n = 34). Of the 56 patients, 22 had surgery before receiving treatment. The median follow-up was 36 (6-110) months. Local control at 2 and 5 years for all patients was 90% and 88%, respectively. Comparing fractionated to single-fraction treatment, there was improved local control with fractionation (91% vs 80% local control at 2 years, P = .009). There was one episode of late radionecrosis on imaging with associated symptoms after single-fraction treatment and one patient requiring resection of meningioma related to worsening symptoms (and local recurrence) after five-fraction SRT.

Conclusions:

This study provides further evidence for high rates of local control and minimal toxicity using a hypofractionated SRT approach, with improvement in local control through use of hypofractionation.

Hearing preservation after Gamma Knife radiosurgery for cerebellopontine angle meningiomas

OBJECTIVE

The objective of this study was to assess hearing function after Gamma Knife treatment of cerebellopontine angle (CPA) meningiomas and assess factors affecting hearing outcome. Additionally, the authors opted to compare these results with those after Gamma Knife treatment of vestibular schwannomas (VSs), because most of the information on hearing outcome after stereotactic radiosurgery (SRS) comes from reports on VS treatment. Hearing preservation, to the best of the authors’ knowledge, has never been separately addressed in studies involving Gamma Knife radiosurgery (GKRS) for CPA meningiomas.

METHODS

This study included all patients who underwent a single session of GKRS between 2002 and 2014. The patients were divided into two groups. Group A included 66 patients with CPA meningiomas with serviceable hearing and tumor extension into the region centered on the internal auditory meatus. Group B included 144 patients with VSs with serviceable hearing. All patients had serviceable hearing before treatment (Gardner-Robertson [GR] Grades I and II). The median prescription dose was 12 Gy (range 10–12 Gy) in both groups. The median follow-up of groups A and B was 42 months (range 6–149 months) and 49 months (range 6–149 months), respectively.

RESULTS

At the last follow-up, the tumor control rate was 97% and 94% in groups A and B, respectively. Hearing preservation was defined as maintained serviceable hearing according to GR hearing score. The hearing preservation rate was 98% and 66% and the 7-year actuarial serviceable hearing preservation rate was 75% and 56%, respectively, between both groups. In group A, the median maximum cochlear dose in the patients with stable and worsened hearing grade was 6.3 Gy and 5.5 Gy, respectively. In group B, factors affecting hearing preservation were cochlear dose ≤ 7 Gy, follow-up duration, and tumor control. The only determinant of hearing preservation between both groups was tumor type.

CONCLUSIONS

GKRS for CPA meningiomas provides excellent hearing preservation in addition to high tumor control rate. Hearing outcome is better with CPA meningiomas than with VSs. Further long-term prospective studies on determinants of hearing outcome after GKRS for CPA meningiomas should be conducted.

Linac-based fractionated stereotactic radiosurgery for high-risk meningioma

PURPOSE

Single-fraction stereotactic radiosurgery(SRS) for meningioma has high rates of symptomatic perilesional edema in some settings. Fractionated stereotactic radiosurgery(fSRS) could decrease edema rates while maintaining tumor control.

METHODS AND MATERIALS

Patients at an institution were retrospectively reviewed(2013-2017). Adults receiving definitive, linear accelerator(linac)-based fSRS (25-30Gy/5 fractions) were included. fSRS was recommended for tumors at high risk for perilesional edema with SRS due to large size, prior irradiation, or proximity to organs at risk. Endpoints included rates of symptomatic, radiographically-defined perilesional edema and local control(LC).

RESULTS

12 Patients with 13 meningiomas met criteria. 24-month actuarial LC and overall survival were 87% and 100%. Symptomatic, post-treatment edema was identified on follow-up MRI in 31% of cases. No variables predicted edema, but affected lesions were larger(6.82 v. 2.46cc).

CONCLUSION

Linac-based fSRS for meningioma has high local control and modest toxicity rates similar to SRS in the literature. Prospective studies comparing fSRS/SRS are warranted.