CyberKnife Stereotactic Radiosurgery for Atypical and Malignant Meningiomas

A Case-based Guide for World Health Organization (WHO) Grade 2 Meningioma Radiosurgery and Radiation Therapy from The Radiosurgery Society

PURPOSE

Meningiomas represent the most common primary tumor of the central nervous system. Current treatment options include surgical resection with or without adjuvant radiation therapy (RT), definitive RT, and observation. However, the radiation dose, fractionation, and margins used to treat patients with WHO grade 2 meningiomas, which account for approximately 20% of all meningiomas, are not clearly defined, and deciding on the optimal treatment modality can be challenging owing to the lack of randomized data.

METHODS AND MATERIALS

In this manuscript, 3 cases of patients with WHO grade 2 meningiomas are presented with descriptions of treatment options after gross total resection, subtotal resection, and previous irradiation. Treatment recommendations were compiled from 9 central nervous system radiation oncology and neurosurgery experts from The Radiosurgery Society, and the consensus of treatment recommendations is reported.

RESULTS

Both conventional and stereotactic RT are treatment options for WHO grade 2 meningiomas. The majority of prospective data in the setting of WHO grade 2 meningiomas involve larger margins. Stereotactic radiosurgery/hypofractionated stereotactic RT are less appropriate in this setting. Conventionally fractionated RT to at least 59.4 Gy is considered standard of care with utilization of preoperative and postoperative imaging to evaluate the extent of disease and possible osseous involvement. After careful discussion, stereotactic radiosurgery/hypofractionated stereotactic RT may play a role for the subset of patients who are unable to tolerate the standard lengthy conventionally fractionated treatment course, for those with prior RT, or for small residual tumors. However, more studies are needed to determine the optimal approach.

CONCLUSIONS

This case-based evaluation of the current literature seeks to provide examples for the management of grade 2 meningiomas and give examples of both conventional and stereotactic RT.

Salvage Stereotactic Radiosurgery for Recurrent WHO Grade 2 and 3 Meningiomas: A Multicenter Study (STORM)

PURPOSE

The role of stereotactic radiosurgery (SRS) in the management of grade 2 and 3 meningiomas is not well elucidated. Unfortunately, local recurrence rates are high, and guidelines for management of recurrent disease are lacking. To address this knowledge gap, we conducted STORM (Salvage Stereotactic Radiosurgery for Recurrent WHO Grade 2 and 3 Meningiomas), a multicenter retrospective cohort study of patients treated with primary SRS for recurrent grade 2 and 3 meningiomas.

METHODS AND MATERIALS

Data on patients with recurrent grade 2 and 3 meningioma treated with SRS at first recurrence were retrospectively collected from 8 academic centers in the United States. Patients with multiple lesions at the time of initial diagnosis or more than 2 lesions at the time of first recurrence were excluded from this analysis. Patient demographics and treatment parameters were extracted at time of diagnosis, first recurrence, and second recurrence. Oncologic outcomes, including progression-free survival (PFS) and overall survival, as well as toxicity outcomes, were reported at the patient level.

RESULTS

From 2000 to 2022, 108 patients were identified (94% grade 2, 6.0% grade 3). A total of 106 patients (98%) had upfront surgical resection (60% gross-total resection) with 18% receiving adjuvant radiation therapy (RT). Median time to first progression was 2.5 years (IQR, 1.34-4.30). At first recurrence, patients were treated with single or fractionated SRS to a median marginal dose of 16 Gy to a maximum of 2 lesions (87% received single-fraction SRS). The median follow-up time after SRS was 2.6 years. The 1-, 2-, and 3-year PFS was 90%, 75%, and 57%, respectively, after treatment with SRS. The 1-, 2-, and 3-year overall survival was 97%, 94%, and 92%, respectively. In the multivariable analysis, grade 3 disease (HR, 6.80; 95% CI, 1.61-28.6), male gender (HR, 3.48; 95% CI, 1.47-8.26), and receipt of prior RT (HR, 2.69; 95% CI, 1.23-5.86) were associated with worse PFS. SRS dose and tumor volume were not correlated with progression. Treatment was well tolerated, with a 3.0% incidence of grade 2+ radiation necrosis.

CONCLUSIONS

This is the largest multicenter study to evaluate salvage SRS in recurrent grade 2 and 3 meningiomas. In this select cohort of patients with primarily grade 2 meningioma with a potentially more favorable natural history of delayed, localized first recurrence amenable to salvage SRS, local control rates and toxicity profiles were favorable, warranting further prospective validation.

Adjuvant proton beam therapy in patients with grade 2 meningiomas

Background

The World Health Organization (WHO) grade 2 meningiomas behave aggressively with a high proclivity toward recurrence despite maximal surgical resection. Our institution, a pioneer of proton therapy, uses exclusively proton beam radiation, and thus, we present a retrospective cohort analysis of patients with WHO grade 2 meningiomas treated with adjuvant proton beam therapy (PBT) at our institution between 2007 and 2019. The effects of adjuvant PBT were evaluated.

Methods

Data collected include diagnosis, gender, histological subtype, WHO grade, the extent of surgical resection, adjuvant PBT radiation, details of the PBT radiation, recurrence, any additional PBT radiation, systemic medical therapy, and disease-specific survival.

Results

Among the WHO grade 2 meningiomas (n = 50) recommended PBT, 80% and 78% of patients with gross-total resection (GTR) and subtotal resection (STR), respectively, followed through with PBT. The median radiation dose of PBT was 59.5 Gy and 59.92 Gy for patients with GTR and STR, respectively, with a median of 33 fractions delivered in 1.8 Gy doses for both groups. Combined 3-year progression-free survival (PFS) was 96%, and 5-year PFS was 92%. Combined overall survival was 95% at five years. Minimal radiation side effects were reported with no grade 3 or higher toxicities.

Conclusion

Our results suggest that adjuvant PBT is well tolerated with minimal radiation toxicity. Alternative to photon radiation, PBT may be considered at least as safe and effective for adjuvant treatment of WHO grade 2 meningiomas when it is available.

Combined helical tomotherapy and Gamma Knife stereotactic radiosurgery for high-grade recurrent orbital meningioma: a case report

Orbital meningioma is a rare type of orbital tumor with high invasiveness and recurrence rates, making it extremely challenging to treat. Due to the special location of the disease, surgery often cannot completely remove the tumor, requiring postoperative radiation therapy. Here, we report a case of an elderly male patient with right-sided proptosis, visual impairment, and diplopia. Imaging diagnosis revealed a space-occupying lesion in the extraconal space of the right orbit. Pathological and immunohistochemical examination of the resected tumor confirmed it as a grade 3 anaplastic meningioma. Two months after surgery, the patient complained of right eye swelling and a magnetic resonance imaging (MRI) scan showed a recurrence of the tumor. The patient received helical tomotherapy (TOMO) in the postoperative tumor bed and high-risk areas within the orbit with a total dose of 48Gy. However, there was no significant improvement in the patient's right eye swelling, and the size of the recurrent lesion showed no significant change on imaging. Gamma knife multifractionated stereotactic radiosurgery (MF-SRS) was then given to the recurrent lesion with 50% prescription dose 13.5Gy/3f, once every other day. An imaging diagnosis performed 45 days later showed that the tumor had disappeared completely. The patient's vision remained unchanged, but diplopia was significantly relieved after MF-SRS. We propose a new hybrid treatment model for recurrent orbital meningioma, where conventional radiation therapy ensures local control of high-risk areas around the postoperative cavity, and MF-SRS maximizes the radiation dose to recurrent lesion areas while protecting surrounding tissues and organs.

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.

Radiotherapy and radiosurgery for meningiomas

Meningiomas comprise a histologically and clinically diverse set of tumors arising from the meningothelial lining of the central nervous system. In the past decade, remarkable progress has been made in deciphering the biology of these common neoplasms. Nevertheless, effective systemic or molecular therapies for meningiomas remain elusive and are active areas of preclinical and clinical investigation. Thus, standard treatment modalities for meningiomas are limited to maximal safe resection, radiotherapy, or radiosurgery. This review examines the history, clinical rationale, and future directions of radiotherapy and radiosurgery as integral and effective treatments for meningiomas.

Diagnostic and Therapeutic Strategy in Anaplastic (Malignant) Meningioma, CNS WHO Grade 3

Simple Summary

Only 1% of all meningioma diagnosis is classified as malignant (anaplastic) meningioma. Due to their rarity, clinical management of these tumors presents several gaps. In this review, we investigate current knowledge of anaplastic meningioma focusing on their pathological and radiological diagnosis, molecular assessment, and loco-regional and systemic management. Despite the current marginal role of systemic therapy, it is possible that the increasing knowledge of molecular altered pathways of the disease will lead to the development of novel effective systemic treatments.

Abstract

Background: Meningiomas are the most common primary central nervous system malignancies accounting for 36% of all intracranial tumors. However, only 1% of meningioma is classified as malignant (anaplastic) meningioma. Due to their rarity, clinical management of these tumors presents several gaps. Methods: We carried out a narrative review aimed to investigate current knowledge of anaplastic meningioma focusing on their pathological and radiological diagnosis, molecular assessment, and loco-regional and systemic management. Results: The most frequent genetic alteration occurring in meningioma is the inactivation in the neurofibromatosis 2 genes (merlin). The accumulation of copy number losses, including 1p, 6p/q, 10q, 14q, and 18p/q, and less frequently 2p/q, 3p, 4p/q, 7p, 8p/q, and 9p, compatible with instability, is restricted to NF2 mutated meningioma. Surgery and different RT approaches represent the milestone of grade 3 meningioma management, while there is a marginal role of systemic therapy. Conclusions: Anaplastic meningiomas are rare tumors, and diagnosis should be suspected and confirmed by trained radiologists and pathologists. Despite the current marginal role of systemic therapy, it is possible that the increasing knowledge of molecular altered pathways of the disease will lead to the development of novel effective systemic treatments.

Adjuvant radiotherapy and stereotactic radiosurgery in grade 3 meningiomas - a systematic review and meta-analysis

Malignant meningioma is a rare, aggressive form of meningioma. Radiation is commonly included in treatment guidelines either as adjuvant radiotherapy (RT) or stereotactic radiosurgery (SRS). Nevertheless, the treatment recommendations are not supported by prospective comparative trials and systematical, critical evaluation of supportive evidence is lacking. For this systematic review, studies analyzing the effectiveness of adjuvant RT and SRS in grade 3 (gr. 3) meningioma were reviewed. Thirty studies met the inclusion criteria for qualitative synthesis, and 6 studies were assessed in quantitative analysis. In quantitative analysis, the weighted average of hazard ratios for adjuvant RT in univariate analyses of overall survival (OS) was 0.55 (CI: 0.41; 0.69). The median 5-year OS after adjuvant RT in gr. 3 meningiomas was 56.3%, and the median OS ranged from 24 to 80 months for patients treated with adjuvant RT versus 13 to 41.2 months in patients not treated. For SRS, the 3-year progression free survival was 0% in one study and 57% in another. The 2-year OS ranged from 25 to 75% in 2 studies. The quality of evidence was rated as "very low" in 14 studies analyzed, and considerable allocation bias was detected. Treatment toxicity was reported in 47% of the studies. The severity, according to the CTCAE, ranged from grades I-V and 5.3 to 100% of patients experienced complications. Adjuvant RT is usually considered standard of care for WHO grade 3 meningiomas, although supporting evidence was of low quality. Better evidence from registries and prospective trials can improve the evidence base for adjuvant fractionated RT in malignant meningiomas.

Multisession radiosurgery for grade 2 (WHO), high risk meningiomas. A phase II clinical trial

Purpose

Patients suffering from recurrent and residual grade 2 (WHO) meningiomas after subtotal excision should be considered as high-risk groups with an uncertain prognosis. Adjuvant radiotherapy seems to be the best approach to reduce disease progression. The primary aim of this phase II explorative, monocentric, single arm study was to evaluate the safety of adjuvant multisession radiosurgery (mRS) in this group of patients; the efficacy in terms of tumour local control was the secondary endpoint.

Methods

Patients recruited from April 2017 to May 2019 were over 18 years old, had a histologically-documented intracranial recurrent or residual Grade 2 meningioma (WHO 2016) and a KPS > 70. Patients with NF2, concomitant neoplasm or pregnancy were excluded. Descriptive statistics were provided for categorical variables. Progression free survival (PFS) was modelled using the Kaplan–Meier method.

Results

Twenty-four patients were enrolled. All 24 patients underwent mRS: twenty-two patients received 28 Gy in 4 fractions, 2 patients received 24 Gy in 4 Treatment related adverse events (CTCAE 4.3) were limited to grade 2 in 1 patient (4.1%). At a median follow-up of 28 months, 8 patients (33.3%) had disease progression, either out-of-field or infield, compared with the planning target volume. Considering both infield and out-of-field progressions, 3-year PFS was 47% (95% confidence interval, CI, 22–69%); considering only the infield ones, 3-year PFS was 86% (95% CI 55–96%), and local control at last follow-up was 92%.

Conclusion

mRS provides good local control of the tumour volume (TV) and is associated with a low rate of toxicity. These results call for further investigation to confirm favourable outcomes in patients with high-risk meningioma.

Trial information

NCT05081908, October 18, 2021, retrospectively registered.

Radiation therapy for atypical and anaplastic meningiomas: an overview of current results and controversial issues

Meningiomas are the most common intracranial tumors. Most meningiomas are WHO grade 1 tumors whereas less than one-quarter of all meningiomas are classified as atypical (WHO grade 2) and anaplastic (WHO grade 3) tumors, based on local invasiveness and cellular features of atypia. Surgical resection remains the cornerstone of meningioma therapy and represents the definitive treatment for the majority of patients; however, grade 2 and grade 3 meningiomas display more aggressive behavior and are difficult to treat. Several retrospective series have shown the efficacy and safety of postoperative adjuvant external beam radiation therapy (RT) for patients with atypical and anaplastic meningiomas. More recently, two phase II prospective trials by the Radiation Therapy Oncology Group (RTOG 0539) and the European Organisation for Research and Treatment of Cancer (EORTC 2042) have confirmed the potential benefits of fractionated RT for patients with intermediate and high-risk meningiomas; however, several issues remain a matter of debate. Controversial topics include the timing of radiation treatment in patients with totally resected atypical meningiomas, the optimal radiation technique, dose and fractionation, and treatment planning/target delineation. Ongoing randomized trials are evaluating the efficacy of early adjuvant RT over observation in patients undergoing gross total resection.

The role of single-fraction stereotactic radiosurgery for atypical meningiomas (WHO grade II): treatment results based on a 25-year experience

PURPOSE

To clarify the role of stereotactic radiosurgery (SRS) for atypical meningiomas (AM).

METHODS

A retrospective analysis of 68 patients with AM having SRS from 1995 until 2019.

RESULTS

Nineteen patients (28%) had undergone prior external beam radiation therapy (EBRT) (median dose, 54 Gy). The median follow-up period was 52 months. Eighteen (26%), 17 (25%), and 33 (49%) patients received SRS as an upfront adjuvant (≤ 6 months), early salvage (7-18 months), or late salvage treatment (> 18 months), respectively. The 3-, 5-, and 10-year progression-free survivals (PFSs) were 52%, 35%, and 25%, respectively. The 3-, 5-, and 10-year disease-specific survivals were 85%, 78%, and 61%, respectively. Adverse radiation events (AREs) were observed in 12 patients (18%), with increased or new seizures being the most frequent complication (n = 7). Prior EBRT was associated with reduced PFS (HR 5.92, P < 0.01), reduced DSS (HR 5.84, P < 0.01), and an increased risk of ARE (HR 3.31, P = 0.04). Timing of SRS was correlated with reduced PFS for patients having early salvage treatment compared to upfront adjuvant (HR 3.17, P = 0.01) or late salvage treatment (HR 4.39, P < 0.01).

CONCLUSION

PFS for patients with residual/recurrent AM remains poor despite SRS. Prior EBRT was associated with worse tumor control, higher tumor-related mortality, and an increased risk of ARE. Further study on the timing of SRS is needed to determine if upfront adjunctive SRS improves tumor control compared to salvage SRS.

Clinical Factors and Outcomes of Atypical Meningioma: A Population-Based Study

Objective

Atypical meningioma is a non-benign tumor, and its prognostic factors and treatment strategies are unclear.

Methods

Patients with atypical meningioma, between 2004 and 2016, were collected from the Surveillance, Epidemiology, and End Results database. Then, we randomly divided patients into a training set and a validation set at a ratio of 8:2. The nomogram was constructed based on the multivariate Cox regression analyses. And the concordance index, calibration curves, and receiver operating character were used to assess the predictive ability of the nomogram. We divided the patient scores into three groups and constructed a survival curve using Kaplan–Meier analysis.

Results

After our inclusion and exclusion criteria, 2358 patients were histologically diagnosed of atypical meningioma. The prognostic nomogram comprised factors of overall survival, including age, tumor size and surgery. The concordance index was 0.715 (95%CI=0.688-0.742) for overall survival in the training set and 0.688 (95%CI=0.629-0.747) for overall survival in the validation set. The calibration curves and receiver operating character also indicated the good predictability of the nomogram. Risk stratification revealed a statistically significant difference among the three groups of patients according to quartiles of risk score.

Conclusion

Gross total resection is an independent factor for survival, and radiation after non-gross total resection potentially confers a survival advantage for patients with atypical meningioma.

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

BACKGROUND

CyberKnife© Radiosurgery (CKRS) is a recognized treatment concept for CNS lesions in adults due to its high precision and efficacy beside a high patient comfort. However, scientific evidence for this treatment modality in pediatric patients is scarce. A dedicated registry was designed to document CyberKnife© procedures in children, aiming to test the hypothesis that it is safe and efficient for the treatment of CNS lesions.

METHODS

The CyberKnife© registry is designed as a retrospective and prospective multicenter observational study (German Clinical Trials Register ( https://www.drks.de ), DRKS-ID 00016973). Patient recruitment will be ongoing throughout a 5-year period and includes collection of demographic, treatment, clinical, and imaging data. Follow-up results will be monitored for 10 years. All data will be registered in a centralized electronic database at the Charité-Universitätsmedizin. The primary endpoint is stable disease for benign and vascular lesions at 5 years of follow-up and local tumor control for malign lesions at 1- and 2-year follow-up. Secondary endpoints are radiation toxicity, side effects, and neurocognitive development.

CONCLUSION

The CyberKnife© registry intends to generate scientific evidence for all treatment- and outcome-related aspects in pediatric patients with treated CNS lesions. The registry may define safety and efficacy of CKRS in children and serve as a basis for future clinical trials, inter-methodological comparisons and changes of treatment algorithms.

Stereotactic radiosurgery for treating meningiomas eligible for complete resection

BACKGROUND

For meningiomas, complete resection is recommended as first-line treatment while stereotactic radiosurgery (SRS) is established for meningiomas of smaller size considered inoperable. If the patient´s medical condition or preference excludes surgery, SRS remains a treatment option. We evaluated the efficacy and safety of SRS in a cohort comprising these cases.

METHODS

In this retrospective single-centre analysis we included patients receiving single fraction SRS either by modified LINAC or robotic guidance by Cyberknife for potentially resectable intracranial meningiomas. Treatment-related adverse events as well as local and regional control rates were determined from follow-up imaging and estimated by the Kaplan-Meier method.

RESULTS

We analyzed 188 patients with 218 meningiomas. The median radiological, and clinical follow-up periods were 51.4 (6.2-289.6) and 55.8 (6.2-300.9) months. The median tumor volume was 4.2 ml (0.1-22), and the mean marginal radiation dose was 13.0 ± 3.1 Gy, with reference to the 80.0 ± 11.2% isodose level. Local recurrence was observed in one case (0.5%) after 239 months. The estimated 2-, 5-, 10- and 15-year regional recurrence rates were 1.5%, 3.0%, 6.6% and 6.6%, respectively. Early adverse events (≤ 6 months after SRS) occurred in 11.2% (CTCEA grade 1-2) and resolved during follow-up in 7.4% of patients, while late adverse events were documented in 14.4% (grade 1-2; one case grade 3). Adverse effects (early and late) were associated with the presence of symptoms or neurological deficits prior to SRS (p < 0.03) and correlated with the treatment volume (p < 0.02).

CONCLUSION

In this analysis SRS appears to be an effective treatment for patients with meningiomas eligible for complete resection and provides reliable long-term local tumor control with low rates of mild morbidity.

Efficacy and toxicity of particle radiotherapy in WHO grade II and grade III meningiomas: a systematic review

OBJECTIVEAdjuvant radiotherapy has become a common addition to the management of high-grade meningiomas, as immediate treatment with radiation following resection has been associated with significantly improved outcomes. Recent investigations into particle therapy have expanded into the management of high-risk meningiomas. Here, the authors systematically review studies on the efficacy and utility of particle-based radiotherapy in the management of high-grade meningioma.METHODSA literature search was developed by first defining the population, intervention, comparison, outcomes, and study design (PICOS). A search strategy was designed for each of three electronic databases: PubMed, Embase, and Scopus. Data extraction was conducted in accordance with the PRISMA guidelines. Outcomes of interest included local disease control, overall survival, and toxicity, which were compared with historical data on photon-based therapies.RESULTSEleven retrospective studies including 240 patients with atypical (WHO grade II) and anaplastic (WHO grade III) meningioma undergoing particle radiation therapy were identified. Five of the 11 studies included in this systematic review focused specifically on WHO grade II and III meningiomas; the others also included WHO grade I meningioma. Across all of the studies, the median follow-up ranged from 6 to 145 months. Local control rates for high-grade meningiomas ranged from 46.7% to 86% by the last follow-up or at 5 years. Overall survival rates ranged from 0% to 100% with better prognoses for atypical than for malignant meningiomas. Radiation necrosis was the most common adverse effect of treatment, occurring in 3.9% of specified cases.CONCLUSIONSDespite the lack of randomized prospective trials, this review of existing retrospective studies suggests that particle therapy, whether an adjuvant or a stand-alone treatment, confers survival benefit with a relatively low risk for severe treatment-derived toxicity compared to standard photon-based therapy. However, additional controlled studies are needed.

Stereotactic Radiosurgery for Atypical and Anaplastic Meningiomas

BACKGROUND

Although most meningiomas will be benign, a small proportion will have atypical or anaplastic histologic features and will exhibit more aggressive behavior. The treatment of these tumors has been controversial, especially for patients with recurrence after resection and radiotherapy. We have presented a large series of atypical and anaplastic meningiomas treated with stereotactic radiosurgery (SRS).

METHODS

We performed a retrospective review of a single-institution radiosurgery database and identified 48 patients with 183 lesions who had undergone 99 SRS sessions from 1999 to 2019. The median dose was 15 Gy prescribed to the 50% isodose line. The center of the failures was plotted, and the distance from the treated tumor to the center of the failure was measured. Simulated treatment volumes for external beam radiotherapy were generated according to the target, and failures were characterized as local, marginal, or distant according to the simulated volume.

RESULTS

The 5-year disease-free and overall survival rate measured from the initial SRS session was 45.8% and 74.7%, respectively. The 5-year lesional control rate was 68.9%. The most common pattern of first failure was isolated distant failure, followed by isolated local or marginal failure. The incidence of distant failure was significantly greater after treatment of >2 lesions in a single SRS session. Isolated local/marginal failure was associated with grade III tumors and an increasing tumor size.

CONCLUSIONS

High-risk meningiomas are a heterogeneous group of tumors with a propensity for multiple failures. The most common pattern of relapse after SRS was distant. However, local control remains an issue. Further studies evaluating dose-escalation strategies are warranted.

Malignant Meningioma: An International Multicentre Retrospective Study

BACKGROUND

In contrast to benign meningiomas, malignant meningiomas (MM) are rare and associated with an unfavourable prognosis. Reports on MM concern fairly small cohorts, often comprising less than 30 cases.

OBJECTIVE

To describe the outcome MM and identify factors that may influence survival.

METHODS

Pathology reports and clinical data of 178 patients treated between 1989 and 2017 for a MM at 6 different international institutions were retrospectively reviewed. Seventy-six patients (42.7%) had a previous history of grade I or grade II meningioma. The patients underwent a total of 380 surgical resections and 72.5% received radiotherapy. Median follow-up was 4.5 yr.

RESULTS

At data collection, 111 patients were deceased (63.4%) and only 23 patients (13.7%) were alive without any residual tumor on the most recent scan. Median overall survival was 2.9 yr, 95% confidence interval [CI; 2.4, 4.5]. Overall survival rates at 1, 5, and 10 yr, respectively, were: 77.7%, 95% CI [71.6, 84.3], 40%, 95% CI [32.7, 49], and 27.9%, 95% CI [20.9, 37.3]. In the multivariable analysis, age at MM surgery <65 yr (hazard ratio [HR] = 0.44, 95% CI [0.29, 0.67], P < .001), previous benign or atypical meningioma surgery (HR = 1.9, 95% CI [1.23, 2.92], P = .004), completeness of resection (HR = 0.51, 95% CI [0.34, 0.78], P = .002), and adjuvant radiotherapy (HR = 0.64, 95% CI [0.42, 0.98], P = .039) were established as independent prognostic factors for survival.

CONCLUSION

This large series confirms the poor prognosis associated with MM, the treatment of which remains challenging. Patients under 65-yr-old with primary MM may live longer after complete resection and postoperative radiotherapy. Even with aggressive treatments, local control remains difficult to achieve.

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.

Role of gamma knife radiosurgery for recurrent or residual World Health Organization grade II and III intracranial meningiomas

Background: To analysis the role of gamma knife radiosurgery (GKRS) in treatment of the recurrent or residual World Health Organization (WHO) grade II and III meningiomas.Methods: Between 1995 and 2015, a total of 1163 meningioma patients were treated with GKRS at our single institute; 26 atypical and 6 anaplastic meningiomas were enrolled. The group consisted of 16 men and 16 women with a median age of 59.5 years (range 30-78 years). The median follow-up was 106.5 months (range 40-216 months). All were cases of tumour recurrence except 7 cases of residual lesions. Six patients were given fractionated radiotherapy before the initial course of GKRS (median dose, 56 Gy).Results: The median tumour volume was 3035 mm³ (range 247-11400 mm³). The median prescribed dose to high grade meningioma margin was 14 Gy (range 12-20 Gy,). The median prescribed dose to WHO II and III meningioma were 14 Gy (range 12-18 Gy) and 15 Gy (range 14-20 Gy), respectively. After radiosurgery, local tumour control rate was 50%. Tumour progression was observed in 28 patients; 16 recurrences were local (12 atypical and 4 anaplastic), 8 were marginal (7 atypical and 1 anaplastic), and 4 were distal (3 atypical and 1 anaplastic). Seven patients (21.88%) developed adverse radiation effects after GKRS. WHO grade was strongly associated with survival, with grade II showing a much longer survival (p = 0.01), and a prior history of radiation was associated with decreased survival (p = 0.003). Multivariate analysis showed that WHO grade (hazard ratio, HR: 5.051, p = 0.01) and prior radiation (HR: 5.763, p = 0.004) were independently associated with survival.Conclusions: WHO grade and a prior history of radiation therapy are reliable long-term predictors of overall outcome when treated with GKRS.

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.

Prognostic factors for patients with World Health Organization grade III meningiomas treated at a single center

We analyzed the characteristics of patients with World Health Organization (WHO) grade III meningioma to identify factors that may predict tumor recurrence and overall survival (OS).We retrospectively reviewed the patients diagnosed with WHO grade III meningioma who were surgically treated at our institute between 2008 and 2016. Survival outcome was assessed by Kaplan-Meier analysis. Cox regression analyses were performed to identify the prognostic factors associated with tumor recurrence and OS.Forty-two patients were included. The mean follow-up time was 23.2 months (range 2-75 months). At the end of analysis, 30 patients were found with tumor recurrence. The 1-year, 3-year, and 5-year recurrence-free survival (RFS) were 51.6%, 33.9%, and 12.0%, respectively. At final follow-up, 23 patients were deceased, the 1-year, 3-year, and 5-year OS were 66.2%, 39.7%, and 35.8%, respectively. Twenty-eight newly diagnosed patients were included, and the 1-year, 3-year, and 5-year RFS were 63.5%, 44.3%, and 19.4%, respectively, and the 1-year, 3-year, and 5-year OS were 74.6%, 52.5%, and 46.7%, respectively. Extent of resection was the only factor associated with tumor recurrence and OS.WHO grade III meningioma is rare, and difficult to manage with a high rate of recurrence and poor OS. Extent of resection is an independent prognostic factor related to tumor recurrence and OS. We could not confirm the usefulness of Ki-67. We suggest that more aggressive treatment, such as safety maximizing cytoreduction by surgery, would improve treatment outcomes.

Adjuvant Radiosurgery Versus Serial Surveillance Following Subtotal Resection of Atypical Meningioma: A Systematic Analysis

BACKGROUND

Atypical meningioma (AM) is an aggressive subtype of meningioma associated with a high recurrence rates (RR) following surgical resection. Recent studies have compared outcomes of various treatment strategies, but advantages of adjuvant radiosurgery (ARS) over serial surveillance (SS) following subtotal resection (STR) remain unclear. To further elucidate this issue, we systematically analyzed the current literature on AM and compared outcomes of ARS versus SS after STR.

METHODS

Embase, PubMed, and Cochrane databases were queried using relevant search terms. Retrospective case series that described patients with AM treated with ARS and SS after STR were included. Tests of proportions were performed to detect significant variations in RR, 5-year progression-free survival (PFS), and 5-year overall survival (OS) between the treatment strategies (ARS vs. SS) and among individual studies.

RESULTS

A total of 619 patients (263 in the ARS group and 356 in the SS group) were identified. Mean RR, 5-year PFS, and 5-year OS were 53.5%, 50.3%, and 74.9%, respectively, for ARS versus 89.8%, 19.1%, and 89.8% for SS. RR differed between treatment strategies and ARS studies (P < 0.001), and 5-year PFS differed among treatment strategies, ARS, and SS studies (P < 0.001, P = 0.007, and P < 0.001, respectively).

CONCLUSIONS

The data presented here show significant differences in RR and 5-year PFS between ARS and SS, suggesting a potential benefit of ARS. As our understanding of the clinical outcomes of various treatment strategies for AM increases, we also move closer to integrating modalities, such as radiosurgery, into management guidelines.