Gamma Knife Radiosurgery for Atypical and Anaplastic Meningiomas

Radiosurgery in Grade II and III Meningiomas: A Systematic Review and Meta-Analysis

BACKGROUND

Meningiomas are the most prevalent benign intracranial tumors. When they are of the invasive subtypes, i.e., grades II and III, they can recur rapidly and present a real challenge for physicians. This study is focused on the use of stereotactic radiosurgery to manage high-grade meningiomas.

METHOD

Medline via PubMed was searched from inception to December 2022 to retrieve studies on stereotactic radiation therapy for patients with grade II-III meningiomas. This study was conducted under PRISMA guidelines.

RESULT

A total of 29 articles involving 1446 patients with grade II-III meningiomas treated with stereotactic radiation therapy were included in the present study. Of these studies, 11 were conducted exclusively on patients with atypical meningiomas (grade II), 1 targeted anaplastic meningiomas (grade III), and 17 articles were carried out on both grade II and III meningiomas. The pooled 1, 2, 3, 5, and 10-year overall survival (OS) of grade II meningiomas was 0.96 [p < 0.01], 0.89 [p = 0.01], 0.90 [p = 0.09], 0.81 [p < 0.01], and 0.66 [p = 0.55], respectively. The pooled 2, 5, and 10-year OS of grade III meningiomas was 0.64 [p = 0.01], 0.41 [p = 0.01], and 0.19 [p < 0.01], respectively.

CONCLUSIONS

Although long-term prospective studies are still required, the outcomes of stereotactic radiation therapy appear promising regarding overall outcome and progression-free survival.

Ki-67 labeling index predicts tumor progression patterns and survival in patients with atypical meningiomas following stereotactic radiosurgery

PURPOSE

This study investigated whether Ki-67 labeling index (LI) correlated with clinical outcomes after SRS for atypical meningiomas.

METHODS

This retrospective study examined 39 patients with atypical meningiomas who underwent SRS over a 10-year study period. Ki-67 LI was categorized into 3 groups: low (< 5%), intermediate (5%-10%), and high (> 10%). Local tumor control rates (LCRs), progression-free rates (PFRs), disease-specific survival (DSS) rates, and adverse radiation-induced events (AREs) were evaluated.

RESULTS

The median follow-up periods were 26 months. SRS was performed at a median prescription dose of 18 Gy for tumors with a median Ki-67 LI of 9.6%. The 3-year LCRs were 100%, 74%, and 25% in the low, intermediate, and high LI groups, respectively (p = 0.011). The 3-year PFRs were 100%, 40%, and 0% in the low, intermediate, and high LI groups (p = 0.003). The 5-year DSS rates were 100%, 89%, and 50% in the low, intermediate, and high LI groups (p = 0.019). Multivariable Cox proportional hazard analysis showed a significant correlation of high LI with lower LCR (hazard ratio [HR], 3.92; 95% confidence interval [CI] 1.18-13.04, p = 0.026), lower PFR (HR 3.80; 95% CI 1.46-9.88, p = 0.006), and shorter DSS (HR 6.55; 95% CI 1.19-35.95, p = 0.031) compared with intermediate LI. The ARE rates were minimal (8%) in the entire group.

CONCLUSION

Patients with high Ki-67 LI showed significantly more tumor progression and tumor-related death. Ki-67 LI might offer valuable predictive insights for the post-SRS management of atypical meningiomas.

Robotic Stereotactic Radiotherapy for Intracranial Meningiomas-An Opportunity for Radiation Dose De-Escalation

OBJECTIVE

To evaluate the possibility of dose de-escalation, with consideration of the efficacy and safety of robotic stereotactic CyberKnife radiotherapy in patients diagnosed with intracranial meningiomas.

METHODS

The study group consisted of 172 patients (42 men and 130 women) treated in III Radiotherapy and Chemotherapy Clinic of Maria Sklodowska-Curie National Research Institute of Oncology in Gliwice between January 2011 and July 2018. The qualification for dose de-escalation was based on MRI (magnetic resonance imaging) features: largest tumor diameter less than 5 cm, well-defined tumor margins, no edema, and no brain infiltration. The age of patients was 21-79 years (median 59 years) at diagnosis and 24-80 years (median 62 years) at radiotherapy. Sixty-seven patients (Group A) were irradiated after initial surgery. Histopathological findings were meningioma grade WHO 1 in 51 and WHO 2 in 16 cases. Group B (105 patients) had no prior surgery and the diagnosis was based on the typical features of meningioma on MRI. All patients qualified for the robotic stereotactic CyberKnife radiotherapy, and the total dose received was 18 Gy in three fractions to reference isodose 78-92%.

RESULTS

Follow-up period was 18 to 124 months (median 67.5 months). Five- and eight-year progression free survival was 90.3% and 89.4%, respectively. Two patients died during the follow-up period. Progression of tumor after radiotherapy was registered in 16 cases. Four patients required surgery due to progressive disease, and three of them were progression free during further follow-up. Twelve patients received a second course of robotic radiotherapy, 11 of them had stable disease, and one patient showed further tumor growth but died of heart failure. Crude progression free survival after both primary and secondary treatment was 98.8%. Radiotherapy was well-tolerated: acute toxicity grade 1/2 (EORTC-RTOG scale) was seen in 10.5% of patients. We did not observe any late effects of radiotherapy.

CONCLUSION

Stereotactic CyberKnife radiotherapy with total dose of 18 Gy delivered in three fractions showed comparable efficacy to treatment schedules with higher doses. This could support the idea of dose de-escalation in the treatment of intracranial meningiomas.

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.

Efficacy of radiotherapy and stereotactic radiosurgery as adjuvant or salvage treatment in atypical and anaplastic (WHO grade II and III) meningiomas: a systematic review and meta-analysis

The role of radiotherapy (RT) and stereotactic radiosurgery (SRS) as adjuvant or salvage treatment in high-grade meningiomas (HGM) is still debated. Despite advances in modern neuro-oncology, HGM (WHO grade II and III) remains refractory to multimodal therapies. Published reports present aggregated data and are extremely varied in population size, exclusion criteria, selection bias, and inclusion of mixed histologic grades, making it extremely difficult to draw conclusions when taken individually. This current work aims to gather the existing evidence on RT and SRS as adjuvants following surgery or salvage treatment at recurrence after multimodality therapy failure and to conduct a systematic comparison between these two modalities. An extensive systematic literature review and meta-analysis were performed. A total of 42 papers were eligible for final analysis (RT n = 27; SRS n = 15) after searching MEDLINE via PubMed, Web-of-science, Cochrane Wiley, and Embase databases. Adjuvant regimens were addressed in 37 papers (RT n = 26; SRS n = 11); salvage regimens were described in 5 articles (RT n = 1; SRS n = 4). The primary outcomes of the study were the overall recurrence rate and mortality. Other actuarial rates (local and distant control, OS, PFS, and complications) were retrieved and analyzed as secondary outcomes. A total of 2853 patients harboring 3077 HGM were included. The majority were grade II (87%) with a mean pre-radiation volume of 8.7 cc. Adjuvant regimen: 2742 patients (76.4% RT; 23.6% SRS) with an overall grade II/III rate of 6.6/1. Lesions treated adjSRS were more frequently grade III (17 vs 12%, p < 0.001), and received subtotal resection (57 vs 27%, p = 0.001) compared to the RT cohort. AdjSRS cohort had a significantly shorter mean follow-up than adjRT (36.7 vs 50.3 months, p = 0.01). The overall recurrence rate was 38% in adjRT vs 25% in adjSRS (p = 0.01), while mortality did not differ between the groups (20% vs 23%, respectively; p = 0.80). The median time to recurrence was 1.5 times longer in the RT group (p = 0.30). Five-year local control was 55% in adjRT and 26% in adjSRS (p = 0.01), while 5-year OS was 73% and 78% (p = 0.62), and 5-year PFS was 62% and 40% in adjRT and adjSRS (p = 0.008). No difference in the incidence of complications (24% vs 14%, p = 0.53). Salvage regimen: 110 patients (37.3% RT; 62.7% SRS) with a grade II/III rate of 8.6/1. The recurrence rate was 46% in salRT vs 24% in salSRS (p = 0.39), time to recurrence was 1.8 times longer in the salRT group (35 vs 18.5 months, p = 0.74). Mortality was slightly yet not significantly higher in salRT (34% vs 12%, p = 0.54). Data on local and distant control were only available for salSRS. The 5-year OS was 49% and 83% (p = 0.90), and the 5-year PFS was 39% and 50% in salRT and salSRS (p = 0.66), respectively. High-grade meningiomas (WHO grade II and III) receiving adjuvant RT showed a higher overall recurrence rate than meningiomas receiving adjuvant SRS. The adjRT cohort, however, achieved higher 5-year LC and PFS rates, thus suggesting a potentially longer time to recurrence compared to adjSRS patients, who, meanwhile, experienced a significantly shorter follow-up. This result must also consider the higher number of grade III lesions and the smaller extent of resection achieved in the adjSRS group. Overall mortality did not differ between the two groups. No differences in outcome measures were observed in salvage regimens.

Stereotactic Therapies for Meningiomas

Although surgery remains the mainstay of treatment for most meningiomas, radiotherapy, specifically stereotactic radiosurgery, has become more commonplace as first-line therapy for select meningioma cases, particularly small meningiomas in challenging or high-risk anatomic locations. Radiosurgery for specific groups of meningiomas have been found to provide local control rates comparable to surgery alone. In this chapter stereotactic techniques for the treatment of meningiomas such as stereotactic radiosurgery by using Gamma knife or Linear Accelerator-based techniques (modified LINAC, Cyberknife, etc.) as well as stereotactically guided implantation or radioactive seeds for brachytherapy are introduced.

Post Surgical Management of WHO Grade II Meningiomas: Our Experience, the Role of Gamma Knife and a Literature Review

Purpose: Grade II meningiomas are rarer than Grade I, and when operated on, bear a higher risk of local recurrence, with a 5-year progression free survival (PFS) ranging from 59 to 90%. Radiotherapy (RT) or radiosurgery, such as Gamma Knife radiosurgery (GKRS) can reduce the risk of relapse in patients with residual disease, even if their role, particularly after gross total resection (GTR), is still under debate. Main goal of this study was to compare the outcomes of different post-surgical management of grade II meningiomas, grouped by degree of surgical removal (Simpson Grade); next in order we wanted to define the role of GKRS for the treatment of residual disease or relapse. Methods: from November 2016 to November 2020 all patients harboring grade II meningiomas, were divided into three groups, based on post-surgical management: (1) wait and see, (2) conventional adjuvant radiotherapy and (3) stereotactic GKRS radiosurgery. Relapse rate and PFS were registered at the time of last follow up and results were classified as stable, recurrence next to or distant from the surgical cavity. In the second part of the study we collected data of all patients who underwent GKRS in our Centers from November 2017 to November 2020. Results: A total of 37 patients were recruited, including seven patients with multiple meningiomas. Out of 47 meningiomas, 33 (70.2%) were followed with a wait and see strategy, six (12.7%) were treated with adjuvant radiotherapy, and 8 patients (17.0%) with adjuvant GKRS. Follow up data were available for 43 (91.4%) meningiomas. Within the wait and see group, recurrence rates differed based on Simpson grades, lower recurrence rates being observed in three Simpson I cases (30%) compared to twelve relapses (60%) in patients with Simpson grade II/III. Finally, out of the 24 meningiomas undergoing GKRS (8 residual and 16 recurrence), 21 remained stable at follow up. Conclusions: Gross total resection (GTR) Simpson II and III have a significantly worse outcome as compared to Simpson I. The absence of adjuvant treatment leads to significant worsening of the disease progression curve. Adjuvant radiotherapy, especially GKRS, provides good local control of the disease and should be considered as an adjuvant treatment in all cases where Simpson I resection is not possible.

Meningiomas

Meningiomas arise in various locations. Convexity tumors are relatively simple to remove. Skull base tumors and tumors adjacent to the major cerebral veins and venous sinuses can be very difficult to extirpate. Attempts at radical resection can lead to serious morbidity. The combination of bulk reduction using microsurgery followed by GKNS gives greatly improved survival and very low morbidity. With smaller tumors, GKNS may be used as the primary treatment. Increasing numbers of asymptomatic meningiomas are demonstrated either as an unexpected finding or as a residual or recurrent tumor after surgery. In all of these situations, GKNS gives a better result than observation or reoperation.

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.

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.

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.

Brachytherapy as an Adjuvant for Recurrent Atypical and Malignant Meningiomas

BACKGROUND

Recurrent atypical and malignant meningiomas have poor outcomes with surgical therapy alone. Neither adjuvant chemotherapy nor postoperative radiation therapy remedies this problem.

OBJECTIVE

To evaluate our experience with the treatment of 15 patients treated with I-125 or Cs-131 brachytherapy radiation seeds as an adjuvant in these difficult cases.

METHODS

Patients with high-grade recurrent meningioma who underwent resection and intraoperative placement of brachytherapy seeds at our institution from 2002 to 2014 were identified and studied by retrospective chart review.

RESULTS

Fifteen patients with median age of 68.8 yr were treated with I-125 (n = 13) or Cs-131 (n = 2) brachytherapy seeds for cases of recurrent, grade II (n = 8), or grade III (n = 7) meningioma at our institution from 2002 to 2014. These lesions originated from a variety of locations including, convexity (3), falcine (3), frontal (2), occipital (1), parietal (2), 2 sphenoid wing (2), and temporal (2), based recurrent meningiomas. Patients had a median of 2 prior open surgical interventions and received local radiation therapy with a median dose of 55 Gy prior to brachytherapy. Survival at 2.5 yr was 56% for grade II and 17% for grade III lesions. Survival was significantly associated with patient age but not tumoral pathology. Forty percent of patients required reoperations for wound complications following brachytherapy.

CONCLUSION

Brachytherapy with implantation of permanent radiation seeds provides a viable alternative treatment for recurrent meningioma while carrying a significant clinical risk of wound infection and need for reoperation.

Multimodal Management of Metastatic Malignant Meningiomas: The Role of Radiosurgery in Long-Term Local Control

BACKGROUND

Metastatic meningiomas (MMs) are rare (0.1 of 100 cases). Their treatment requires a multimodal approach, with surgery, radiotherapy, chemotherapy, and radiosurgery, which allows a long-term local control (LC) and an extension of free survival. In this study, the authors performed a review of the literature and reported 2 cases of patients affected by extracranial MMs, with long-term follow-up.

CASE DESCRIPTION

Case 1: A 48-year-old woman was admitted for resection of an extra-axial falx lesion (meningioma G1). After 2 years, the lesion got a local recurrence, resected with a histologic diagnosis of meningioma G3. During the next 9 years, the patient underwent 5 Gamma Knife radiosurgery (GKRS) procedures for local recurrence. At 56 years, she was readmitted for a surgical local recurrence (histologic definition: anaplastic meningioma G3). At the age of 62, the patient underwent a right lobectomy for a lung mass (histologic diagnosis: anaplastic meningioma G3). After that, multiple lesions at soma L5 and adrenal gland were discovered and then monitored. Case 2: A 48-year-old woman was operated for a lesion involving torcular herophili (meningioma G2). After 3 years, a local recurrence requires GKRS combined with tamoxifen. In the next 7 years, she underwent 5 GKRS procedures for local recurrence. The patient also underwent chemotherapy with octreotide. At the age of 61, she discovered multiple lesions in both lungs, liver, and kidney. A hepatic biopsy showed anaplastic meningioma G3. Also this patient does not suffer from any neurologic or clinical deficits.

CONCLUSIONS

LC in malignant meningioma is achievable through a multimodal approach; GKRS makes possible LC, but a novel aspect of these lesions is opened to discussion: the metastases. These reports show that multimodal treatment for MMs is an effective approach with good LC and improvement of overall survival. However, a long survival may allow systemic diffusion of the disease, in particular, when sagittal sinus is involved.

Impact of radiotherapy in atypical meningioma recurrence: literature review

Evaluate whether radiotherapy (RT) after the neurosurgical treatment of atypical meningiomas (AM) has an impact on the reduction rate of recurrence. A Medline search through October 2017 using "atypical meningioma" returned 1277 papers for initial review. Inclusion criteria were as follows. We analyzed the database and included articles in which the anatomic pathological classification of atypical meningiomas was in accordance with WHO 2007 or WHO 2016 criteria, patients > 18 years of age, and there was postoperative external beam radiation to the tumor bed. Exclusion criteria were WHO grade I or III meningioma, patients who underwent whole-brain radiation, RT used as salvage therapy for recurrence, palliative dose of RT (< 45 Gy), recurrent AMs, and multiple AMs. Papers reporting outcomes in which atypical and anaplastic meningiomas were analyzed together were rejected, as were papers with small samples that may compromise evaluation. After filtering our initial selection, only 17 papers were selected. After reviewing the seventeen articles including a total of 1761 patients (972 female and 799 male; 1.21 female/1.0 male), the difference in proportion of tumor recurrence between patients with and without radiotherapy after neurosurgical procedure was 1.0448, 95% CI [0.8318 to 1.3125], p value = 0.7062. On the basis of this review, there is no evidence to suggest that RT decreases the rate of recurrence in patients with atypical meningiomas.

Multimodal treatment of parasagittal meningiomas: a single-center experience

OBJECTIVE

Treatment of parasagittal meningiomas is still considered a challenge in modern microsurgery. The use of microsurgical resection, radiosurgery, or a microsurgery-radiosurgery combination treatment strategy is often debated. The aim of this study was to evaluate the treatment of parasagittal meningioma and provide evidence that a multimodal approach reduces complication rates and achieves good tumor control rates.

METHODS

The authors retrospectively reviewed long-term follow-up data on 117 patients who had been treated for parasagittal meningiomas at their institution between 1993 and 2013. Treatment included microsurgery, Gamma Knife radiosurgery (GKRS), and radiotherapy.

RESULTS

The median tumor volume prior to the first microsurgical resection was largest in the microsurgery-radiosurgery combination treatment group. Invasion of the superior sagittal sinus was significantly associated with a Simpson Grade IV resection and subsequent radiosurgery treatment. The Simpson resection grade did not influence time to progression or recurrence in benign meningioma cases. Complete sinus occlusion was followed by microsurgical resection of the occluded sinus, by tumor resection without resection of the sinus, or by GKRS. Histopathology revealed WHO Grade I tumors in most patients. However, a high percentage (33%) of atypical or malignant meningiomas were diagnosed after the last microsurgical resection. The time to recurrence or progression after microsurgery was significantly longer in patients with WHO Grade I meningiomas than in those with Grade II or III meningiomas. At follow-up, tumor control rates after GKRS were 91% for presumed meningioma, 85% for benign meningioma, 71% for atypical meningioma, and 38% for malignant meningioma.

CONCLUSIONS

A multimodal treatment approach to parasagittal meningiomas reduces the rate of complications. Thus, microsurgery, radiotherapy, and radiosurgery are complementary treatment options. Gamma Knife radiosurgery is safe and effective in patients with meningiomas invading the superior sagittal sinus. The procedure can be part of a multimodal treatment plan or administered as a single treatment in well-selected patients.

World Health Organization Grade II Meningiomas: The Role of Adjuvant/Salvage Gamma Knife Surgery After Initial Surgery and Prognostic Factor Assessment

OBJECTIVE

This study was performed to evaluate the efficiency of Gamma Knife surgery (GKS) on reducing recurrence of World Health Organization (WHO) grade II meningiomas after surgery and to define the risk factors associated with tumor recurrence/progression and patient's death.

METHODS

This retrospective study included 75 patients who were diagnosed with WHO grade II meningiomas after initial surgery. The Kaplan-Meier method with a log-rank test was used to calculate the survival curves. Univariate and multivariate Cox proportional hazards model were used to identify the risk factors associated with tumor recurrence/progression and patient's death.

RESULTS

The median follow-up period was 70 months. The overall survival (OS) was 97.2% at 2 years and 89.8% at 5 years. The progression-free survival (PFS) at 1, 3, and 5 years was 89.3%, 72.6%, and 59.3%, respectively. Comparing the effects on PFS and OS between different groups, there were no statistically significant differences between the surgery-alone group and the surgery with adjuvant/salvage GKS group (P = 0.512; P = 0.949). In multivariate Cox proportional hazards model analysis, extent of resection (P = 0.001) and tumor location (P = 0.015) were associated with tumor recurrence; only histologic subtypes (P = 0.005) were associated with patient's death.

CONCLUSIONS

There was no significant PFS or OS benefit for patients with WHO grade II meningiomas treated with adjuvant/salvage GKS postoperatively. Convexity meningiomas with gross total resection tended to benefit PFS. We suggest trying to achieve maximum safe gross total resection for patients with WHO grade II meningiomas, then following up closely.

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.

Grade II meningiomas and Gamma Knife radiosurgery: analysis of success and failure to improve treatment paradigm

OBJECTIVE

Grade II meningiomas, which currently account for 25% of all meningiomas, are subject to multiple recurrences throughout the course of the disease and represent a challenge for the neurosurgeon. Radiosurgery is increasingly performed for the treatment of Grade II meningiomas and is quite efficient in controlling relapses locally at the site of the lesion, but it cannot prevent margin relapses. The aim of this retrospective study was to analyze the technical parameters involved in producing marginal relapses and to optimize loco-marginal control to improve therapeutic strategy.

METHODS

Eighteen patients presenting 58 lesions were treated by Gamma Knife radiosurgery (GKRS) between 2010 and 2015 in Hopital de la Pitié-Salpêtrière. The median patient age was 68 years (25%−75% interval: 61–72 years), and the sex ratio (M/F) was 13:5. The median delay between surgery and first GKRS was 3 years. Patients were classified as having Grade II meningioma using World Health Organization (WHO) 2007 criteria. The tumor growth rate was computed by comparing 2 volumetric measurements before treatment. After GKRS, iterative MRI, performed every 6 months, detected a relapse if tumor volume increased by more than 20%. Patterns of relapse were defined as being local, marginal, or distal. Survival curves were estimated using the Kaplan-Meier method, and the relationship between criterion and potential risk factors was tested by the log-rank test and univariable Cox model.

RESULTS

The median follow-up was 36 months (range 8–57 months). During this period, 3 patients presented with a local relapse, 5 patients with a marginal relapse, and 7 patients with a distal relapse. Crude local control was 84.5%. The local control actuarial rate was 89% at 1 year and 71% at 3 years. The marginal control actuarial rate was 81% at 1 year and 74% at 2 years. The distal control actuarial rate was 100% at 1 year, 81% at 2 years, and 53% at 3 years. Median distal control was 38 months. Progression-free survival (PFS) was 71% at 1 year, 36% at 2 years, and 23% at 3 years. Median PFS was 18 months. Lesions treated with a minimum radiation dose of ≤ 12 Gy had significantly more local relapses than those treated with a dose > 12 Gy (p = 0.04) in univariate analysis.

Marginal control was significantly influenced by tumor growth rate, with a lower growth rate being highly associated with improved marginal control (p = 0.002). There was a trend toward a relationship between dose and marginal control, but it was not significant (p = 0.09). PFS was significantly associated with delay between first surgery and GKRS (p = 0.03). The authors noticed few complications with no sequelae.

CONCLUSIONS

In order to optimize loco-marginal control, radiosurgical treatment should require a minimum dose of > 12 Gy and an extended target volume along the dural insertion. Ideally, these parameters should correspond to the aggressiveness of the lesion, based on genetic features of the tumor.

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.