Radiosurgery for malignant meningioma: results in 22 patients

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.

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.

Risk Factors for Radiation Necrosis in Patients Undergoing Cranial Stereotactic Radiosurgery

Simple Summary

Radiation necrosis is a known complication after stereotactic radiosurgery of intracranial tumors. We evaluated 388 patients who underwent stereotactic radiosurgery at our institution. The most common tumors were metastases (47.2%), followed by vestibular schwannomas (32.2%) and meningiomas (13.4%). 15.7% developed radiation necrosis after a median of 8 months. According to our data, larger tumor diameter (HR 1.065) and higher radiation dose (HR 1.302) were associated with an increased risk of radiation necrosis independently of tumor type. Advanced age was shown to be a risk factor for radiation necrosis only in cases with metastasis (HR 1.066). The data from this study suggest that the development of radiation necrosis is dependent on size and dose, not on the type of the neoplasm.

Abstract

Purpose: single-staged stereotactic radiosurgery (SRS) is an established part of the multimodal treatment in neuro-oncology. Radiation necrosis after high-dose irradiation is a known complication, but there is a lack of evidence about the risk factors. The aim of this study was to evaluate possible risk factors for radiation necrosis in patients undergoing radiosurgery. Methods: patients treated with radiosurgery between January 2004 and November 2020 were retrospectively analyzed. The clinical data, imaging and medication were gathered from electronic patient records. The largest diameter of the tumors was measured using MRI scans in T1 weighted imaging with gadolinium and the edema in T2 weighted sequences. The diagnosis of a radiation necrosis was established analyzing imaging criteria combined with clinical course or pathologically confirmed by subsequent surgical intervention. Patients developing radiation necrosis detected after SRS were compared to patients without evidence of an overshooting irradiation reaction. Results: 388 patients were included retrospectively, 61 (15.7%) of whom developed a radiation necrosis. Median follow-up was 24 (6–62) months with a radiation necrosis after 8 (6–12) months. The most frequent tumors were metastases in 47.2% of the cases, followed by acoustic neuromas in 32.2% and meningiomas in 13.4%. Seventy-three (18.9%) patients already underwent one or more previous radiosurgical procedures for different lesions. The mean largest diameter of the tumors amounted to 16.3 mm (±6.1 mm). The median—80%—isodose administered was 16 (14–25) Gy. Of the radiation necroses, 25 (43.1%) required treatment, in 23 (39.7%) thereof, medical treatment was applied and in 2 (3.4%) cases, debulking surgery was performed. In this study, significantly more radiation necroses arose in patients with higher doses (HR 1.3 [CI 1.2; 1.5], p < 0.001) leading to a risk increment of over 180% between a radiation isodose of 14 and 20 Gy. The maximum diameter was a second significant risk factor (p = 0.028) with an HR of 1065 for every 1 mm increase in multivariate analysis. Conclusion: large diameter and high doses were reliable independent risk factors leading to more frequent radiation necroses, regardless of tumor type in patients undergoing radiosurgery. Alternative therapeutic procedures may be considered in lesions with large volume and an expected high radiation doses due to the increased risk of developing radiation necrosis.

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.

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.

Stereotactic radiosurgery versus stereotactic radiotherapy in the management of intracranial meningiomas: a systematic review and meta-analysis

OBJECTIVE

Stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) have been used as a primary treatment or adjuvant to resection in the management of intracranial meningiomas (ICMs). The aim of this analysis is to compare the safety and long-term efficacy of SRS and SRT in patients with primary or recurrent ICMs.

METHODS

A systematic review of the literature comparing SRT and SRS in the same study was conducted using PubMed, the Cochrane Library, Google Scholar, and EMBASE from January 1980 to December 2018. Randomized controlled trials, case-control studies, and cohort studies (prospective and retrospective) analyzing SRS versus SRT for the treatment of ICMs in adult patients (age > 16 years) were included. Pooled and subgroup analyses were based on the fixed-effect model.

RESULTS

A total of 1736 patients from 12 retrospective studies were included. The treatment modality used was: 1) SRS (n = 306), including Gamma Knife surgery (n = 36), linear accelerator (n = 261), and CyberKnife (n = 9); or 2) SRT (n = 1430), including hypofractionated SRT (hFSRT, n = 268) and full-fractionated SRT (FSRT, n = 1162). The median age of patients at the time of treatment was 59 years. The median follow-up duration after treatment was 35.5 months. The median tumor volumes at the time of treatment with SRS, hFSRT, and FSRT were 2.84 cm3, 5.45 cm3, and 12.75 cm3, respectively. The radiographic tumor control at last follow-up was significantly worse in patients who underwent SRS than SRT (odds ratio [OR] 0.47, 95% confidence interval [CI] 0.27–0.82, p = 0.007) with 7% less volume of tumor shrinkage (OR 0.93, 95% CI 0.61–1.40, p = 0.72). Compared to SRS, the radiographic tumor control was better achieved by FSRT (OR 0.46, 95% CI 0.26–0.80, p = 0.006) than by hFSRT (OR 0.81, 95% CI 0.21–3.17, p = 0.76). Moreover, SRS leads to a significantly higher risk of clinical neurological worsening during follow-up (OR 2.07, 95% CI 1.06–4.06, p = 0.03) and of immediate symptomatic edema (OR 4.58, 95% CI 1.67–12.56, p = 0.003) with respect to SRT. SRT could produce a better progression-free survival at 4–10 years compared to SRS, but this was not statistically significant (p = 0.29).

CONCLUSIONS

SRS and SRT are both safe options in the management of ICMs. However, SRT carries a better radiographic tumor control rate and a lower incidence of posttreatment symptomatic worsening and symptomatic edema, with respect to SRS. However, further prospective studies are still needed to validate these results.

Recurred Intracranial Meningioma: A Retrospective Analysis for Treatment Outcome and Prognostic Factor

Background

In this study, we aimed to compare repeated resection and radiation treatment, such as Gamma knife radiosurgery (GKRS) or conventional radiotherapy (RT), and investigate the factors influencing treatment outcome, including overall survival (OS), progression-free survival (PFS), and complication rates.

Methods

We retrospectively reviewed 67 cases of recurred intracranial meningiomas (repeated resection: 36 cases, radiation treatment: 31 cases) with 56 months of the median follow-up duration (range, 13–294 months).

Results

The incidence of death rate was 29.9% over follow-up period after treatment for recurred meningiomas (20/67). As independent predictable factors for OS, benign pathology [hazard ratio (HR) 0.132, 95% confidence interval (CI) 0.048–0.362, p<0.001] and tumor size <3 cm (HR 0.167, 95% CI 0.061–0.452, p<0.001) were significantly associated with a longer OS. The incidence of progression rate was 23.9% (16/67). Only treatment modality was important for PFS as an independent predictable factor (GKRS/RT vs. open resection; HR 0.117, 95% CI 0.027–0.518, p<0.005). The complication rate was 14.9% in our study (10/67). Larger tumor size (≥3 cm, HR 0.060, 95% CI 0.007–0.509, p=0.010) was significant as an independent prognostic factor for development of complications. Although treatment modality was not included for multivariate analysis, it should be considered as a predictable factor for complications (p=0.001 in univariate analysis).

Conclusion

The role of repeated resection is questionable for recurred intracranial meningiomas, considering high progression and complication rates. Frequent and regular imaging follow-up is required to detect recurred tumor sized as small as possible, and radiation treatment can be a preferred treatment.

Predictors of response to Gamma Knife radiosurgery for intracranial meningiomas

OBJECT

In this paper, the authors’ aim was to determine short-term volumetric and diametric tumor growth and identify clinical, radiological, and dosimetric predictors of adverse radiation events (AREs) following stereotactic radiosurgery (SRS) for intracranial WHO Grade I meningiomas.

METHODS

This is a retrospective review of all WHO Grade I meningiomas that were treated with SRS (primary or adjuvant) between December 2005 and June 2012 at the University Health Network. Seventy-five patients had at least 24 months of both clinical and radiological follow-up and were, therefore, included in this study. Tumor growth was defined as any volumetric or diametric change greater than 10% per year. Any variation less than +10% was considered growth stability. Volumetric measurements were made using T1-weighted gadolinium-enhanced 3-T MRI scans and ITK-SNAP software. Tumor growth rates were calculated using the specific growth rate (SGR). Univariate statistics were used to identify predictors of post-SRS AREs. All statistical analyses were performed using IBM SPSS.

RESULTS

Women accounted for 69.3% of patients, and the mean treatment age was 58.6 years. Median follow-up was 36.2 months. Twenty-one (28%) patients had undergone prior resection. Two (3%) patients required salvage surgical intervention following SRS. The majority of the lesions (56%) were skull base tumors. Median tumor volume and diameter were 5.2 cm3 and 27.5 mm, respectively. The absence of tumor growth was observed in 39 cases (52%) based on the volumetric measurements, while the absence of tumor growth was observed in 69 cases (92%) based on the diametric measurements. Twenty-six patients (34.6%) experienced new-onset AREs, including headache (17.3%), cranial neuropathy (10.6%), speech impairment (2.7%), tremors (2.7%), and ataxia (1.3%). Fourteen patients (18.7%) experienced new-onset edema, and 4 of these patients were symptomatic. A lower conformity index (1.24 vs 1.4) was significantly associated with the development of edema (p < 0.001 power > 0.8). Patients with meningiomas that had growth rates of more than 10% per year were more likely to experience long-term headaches after SRS (p = 0.022).

CONCLUSIONS

Volume-based reporting of SRS outcomes for meningiomas may be a more accurate method given the complex morphology of some lesions. The conformity index was identified as a predictor of edema following radiosurgery.

Atypical and anaplastic meningiomas in a public hospital in São Paulo State, Brazil

Atypical/anaplastic (World Health Organization (WHO) grades II and III) are less common and have poorer outcomes than benign meningiomas. This study aimed to analyze the outcome of patients with these tumors.Method Overall/recurrence-free survivals (RFS) and the Karnofsky Performance Scale of 52 patients with grades II (42) and III (9) meningiomas surgically treated were analyzed (uni/multivariate analysis).Results Total/subtotal resections were 60.8%/35.3%. Patients <60 years-old and grade II tumors had longer survival. Grade II tumors, total resection andde novo meningioma had better RFS (univariate analysis). Patients >60 years-old, de novo meningioma and radiotherapy had longer survival and patients <60 years-old and with grade II tumors had longer RFS (multivariate analysis). Recurrence rate was 51% (39.2% Grade II and 66.7% Grade III). Operative mortality was 1.9%.Conclusion Age <60 years-old, grade II tumors and de novomeningiomas were the main predictors for better prognosis among patients with grades II and III meningiomas.

Stereotactic radiosurgery for intracranial meningiomas: current concepts and future perspectives

Meningiomas are among the most common adult brain tumors. Although the optimal management of meningiomas would provide complete elimination of the lesion, this cannot always be accomplished safely through resection. Therefore, other therapeutic modalities, such as stereotactic radiosurgery (as primary or adjunctive therapy), have emerged. In the current review, we have provided an overview of the historical outcomes of various radiosurgical modalities applied in the management of meningiomas. Furthermore, we provide a discussion on key factors (eg World Health Organization grade, lesion size, and lesion location) that affect tumor control and adverse event rates. We discuss recent changes in our understanding of meningiomas, based on molecular and genetic markers, and how these will change our perspective on the management of meningiomas. We conclude by outlining the areas in which knowledge gaps persist and provide suggestions as to how these can be addressed.

Is There a Tumor Volume Threshold for Postradiosurgical Symptoms? A Single-Institution Analysis

BACKGROUND:

Single-fraction radiosurgery may carry a higher risk of symptomatic peritumoral edema than conventionally fractionated radiotherapy, with a reported incidence of 2.5% to 37%. Previous research has shown that larger tumor volume and margin dose &gt;14 Gy are associated with increased risk of toxicity. Parasagittal location has been associated with toxicity in some studies, but not in others.

OBJECTIVE:

To determine risk factors for and patterns of postradiosurgical symptoms (PRS).

METHODS:

This single-institution retrospective chart review included 282 stereotactic radiosurgery procedures for an intracranial meningioma from January 1999 to March 2011. PRS were assessed by using the Common Terminology Criteria for Adverse Events (Version 4.0). Statistical analyses were conducted by using the 194 procedures for which treatment plans were available.

RESULTS:

PRS were observed after 65 procedures (23%); 35 (12%) were grade 2 or higher. Posttreatment edema occurred in 21% of grade I PRS, 68% of grade II PRS, and 71% of grade III PRS. Tumor volume ≥7.1 cc (adjusted hazards ratio = 4.9, P = .02), prior external beam radiotherapy (adjusted hazards ratio = 2.6, P = .03), and histological grade (P = .005) predicted PRS. On multivariate analysis, parasagittal location was not predictive of PRS, although skull base location predicted a lower risk of symptomatic posttreatment edema (adjusted hazards ratio = 0.133, P = .02).

CONCLUSION:

In our series, prior external beam radiotherapy, tumor volume, and tumor grade are risk factors for PRS, while pretreatment edema approached statistical significance. Peritumoral edema is the predominant mechanism of significant PRS, and skull base tumors have a lower risk of posttreatment edema.

Peptide receptor radionuclide therapy in patients with inoperable meningiomas: our experience and review of the literature

OBJECTIVE

Few studies describe peptide receptor radionuclide therapy (PRRT) using (90)Y- or (177)Lu-labeled peptides in patients with recurrent meningiomas. No clinical data about (111)In-Pentetreotide in such patients are available. We report on (111)In-Pentetreotide therapy in patients with inoperable meningiomas and review the literature about PRRT of meningiomas.

METHODS

We reviewed clinical records of 8 patients with meningioma/meningiomatosis showing high (111)In-Pentetreotide uptake on pretherapy scintigraphy who were treated with at least one cycle of (111)In-Pentetreotide. In 2 patients, a cocktail of (111)In-Pentetreotide and beta-emitting radiolabeled peptides had been administered.

RESULTS

No patient experienced acute toxicity, neurological or renal function impairment. Mild transient bone marrow toxicity was observed in 4 patients. Objective partial response was observed in 2 patients, stable disease in 5 and disease progression in one. There were no statistically significant correlations between objective response and patient age, tumor WHO grade, baseline Karnofsky performance score, (111)In-Pentetreotide tumoral uptake grade, tumor/nontumor ratio, disease state at baseline, and cumulative dose.

CONCLUSIONS

In consideration of its efficacy and the lack of significant toxicity, PRRT of meningiomas using (111)In-Pentetreotide could be proposed even nowadays when the use of (177)Lu- or (90)Y-labeled peptides seems unsafe, namely in patients with renal impairment/toxicity.

A retrospective analysis of survival and prognostic factors after stereotactic radiosurgery for aggressive meningiomas

BACKGROUND

While most meningiomas are benign, aggressive meningiomas are associated with high levels of recurrence and mortality. A single institution's Gamma Knife radiosurgical experience with atypical and malignant meningiomas is presented, stratified by the most recent WHO classification.

METHODS

Thirty-one patients with atypical and 4 patients with malignant meningiomas treated with Gamma Knife radiosurgery between July 2000 and July 2011 were retrospectively reviewed. All patients underwent prior surgical resection. Overall survival was the primary endpoint and rate of disease recurrence in the brain was a secondary endpoint. Patients who had previous radiotherapy or prior surgical resection were included. Kaplan-Meier and Cox proportional hazards models were used to estimate survival and identify factors predictive of recurrence and survival.

RESULTS

Post-Gamma Knife recurrence was identified in 11 patients (31.4%) with a median overall survival of 36 months and progression-free survival of 25.8 months. Nine patients (25.7%) had died. Three-year overall survival (OS) and progression-free survival (PFS) rates were 78.0% and 65.0%, respectively. WHO grade II 3-year OS and PFS were 83.4% and 70.1%, while WHO grade III 3-year OS and PFS were 33.3% and 0%. Recurrence rate was significantly higher in patients with a prior history of benign meningioma, nuclear atypia, high mitotic rate, spontaneous necrosis, and WHO grade III diagnosis on univariate analysis; only WHO grade III diagnosis was significant on multivariate analysis. Overall survival was adversely affected in patients with WHO grade III diagnosis, prior history of benign meningioma, prior fractionated radiotherapy, larger tumor volume, and higher isocenter number on univariate analysis; WHO grade III diagnosis and larger treated tumor volume were significant on multivariate analysis.

CONCLUSION

Atypical and anaplastic meningiomas remain difficult tumors to treat. WHO grade III diagnosis and treated tumor volume were significantly predictive of recurrence and survival on multivariate analysis in aggressive meningioma patients treated with radiosurgery. Larger tumor size predicts poor survival, while nuclear atypia, necrosis, and increased mitotic rate are risk factors for recurrence. Clinical and pathologic predictors may help identify patients that are at higher risk for recurrence.

The role of radiosurgery in the management of WHO Grade II and III intracranial meningiomas

Object

WHO Grade II and III intracranial meningiomas are uncommon, but they portend a significantly worse prognosis than their benign Grade I counterparts. The mainstay of current management is resection to obtain cytoreduction and histological tissue diagnosis. The timing and benefit of postoperative fractionated external beam radiation therapy and stereotactic radiosurgery remain controversial. The authors review the stereotactic radiosurgery outcomes for Grade II and III meningiomas.

Methods

A comprehensive literature search was performed using PubMed to identify all radiosurgery series reporting the treatment outcomes for Grade II and III meningiomas. Case reports and case series involving fewer than 10 patients were excluded.

Results

From 1998 to 2013, 19 radiosurgery series were published in which 647 Grade II and III meningiomas were treated. Median tumor volumes were 2.2–14.6 cm3. The median margin doses were 14–21 Gy, although generally the margin doses for Grade II meningiomas were 16–20 Gy and the margin doses for Grade III meningiomas were 18–22 Gy. The median 5-year PFS was 59% for Grade II tumors and 13% for Grade III tumors, which may have been affected by patient age, prior radiation therapy, tumor volume, and radiosurgical dose and timing. The median complication rate following radiosurgery was 8%.

Conclusions

The current data for radiosurgery suggest that it has a role in the management of residual or recurrent Grade II and III meningiomas. However, better studies are needed to fully define this role. Due to the relatively low prevalence of these tumors, it is unlikely that prospective studies will be feasible. As such, well-designed retrospective analyses may improve our understanding of the effect of radiosurgery on tumor recurrence and patient survival and the incidence and impact of treatment-induced complications.

Long term clinical outcomes of malignant meningiomas

Objective

Malignant meningiomas are rare and have worse prognosis than benign meningiomas. We report our experience of a malignant meningioma and review relevant literature in an attempt to investigate the clinical features, treatment, and prognosis of these tumors.

Methods

Fifteen patients underwent surgical treatment for intracranial malignant meningiomas between year 1990 and 2012 in our institution. Anaplastic meningiomas were diagnosed in thirteen cases and papillary meningiomas in two. Fourteen patients (93.3%) received radiotherapy after surgical resection. All patients were followed regularly including clinical-neurological follow-up as well as magnetic resonance imaging. Progression was determined radiographically when there was more than 10% of mass volume increase or when there were onset or worsening of neurological symptoms not attributable to other causes.

Results

Six patients were male and nine were women, and their mean age was 56.9 years (range 36-78). The median follow-up was 54 months (range 3-246). According to our study result, the 5-year progression free survival rate of malignant meningiomas was 53.6%. There were 2 cases (13.3%) of postoperative complications. Recurrences were confirmed in 4 patients (26.7%) during follow-up, the median recurrence time was 35 months (range 12-61), and further procedures were performed. Two of the recurred patients were treated with radiosurgery after secondary tumor resection, and other two patients were treated with radiosurgery alone. There was no more recurred disease patients in the follow-up period after then.

Conclusion

We report the outcomes of the aggressive surgery with radiation of malignant meningiomas. Although the data is limited, we found that radiosurgery treatment had favorable tumor control on recurred patients from our experience.

Boron neutron capture therapy for recurrent high-grade meningiomas

OBJECT

Similar to glioblastomas, high-grade meningiomas are difficult pathologies to control. In this study, the authors used boron neutron capture therapy (BNCT), a tumor-selective intensive particle radiation modality, to treat high-grade meningioma.

METHODS

From June 2005 to September 2011, BNCT was applied 28 times in 20 cases of recurrent high-grade meningioma. All patients had previously undergone intensive treatments such as repetitive surgeries and multiple sessions of radiation therapy. Fluorine-18-labeled boronophenylalanine ((18)F-BPA) PET was performed before BNCT in 19 of the 20 cases; BPA is itself a therapeutic compound. Compound uptake, tumor shrinkage, long-term control rate including survival time, and failure pattern of the treated patients were all evaluated.

RESULTS

Eighteen of 19 cases studied using (18)F-BPA PET showed good BPA uptake, with ratios of tumor to normal brain greater than 2.7. These ratios indicated the likely effects of BNCT prior to neutron irradiation. The original tumor sizes were between 4.3 cm(3) and 109 cm(3). A mean tumor volume reduction of 64.5% was obtained after BNCT within just 2 months. The median follow-up duration was 13 months. Six patients are still alive; at present, the median survival times after BNCT and diagnosis are 14.1 months (95% CI 8.6-40.4 months) and 45.7 months (95% CI 32.4-70.7 months), respectively. Clinical symptoms before BNCT, such as hemiparesis and facial pain, were improved after BNCT in symptomatic cases. Systemic metastasis, intracranial distant recurrence outside the radiation field, CSF dissemination, and local tumor progression were observed in 6, 7, 3, and 3 cases, respectively, during the clinical course. Apparent pseudoprogression was observed in at least 3 cases. Symptomatic radiation injuries occurred in 6 cases, and were controllable in all but 1 case.

CONCLUSIONS

Boron neutron capture therapy may be especially effective in cases of high-grade meningioma.

Stereotactic radiosurgery for malignant extracerebral intracranial tumors: patient selection, efficacy, and technical nuances

Intracranial tumors extrinsic to the brain include a variety of histological types, including meningiomas and pituitary tumors, both of which are most commonly benign but can present with malignant biology and clinical behavior. In the same compartment arise a number of frankly malignant tumors, which include chordomas, metastases (to bone or dura), and sarcomas (e.g., chondrosarcoma). These malignant tumors derive from bone, dura, or vascular elements and pose significant therapeutic challenges. Because of the anatomical constraints imposed by the cranial base and by venous sinuses, and because of the relentless tendency to recur shown by malignant tumors of meningeal origin, surgery often achieves incomplete removal. Some tumors are not resectable without the use of complex approaches that endanger adjacent neurovascular structures. For these reasons, stereotactic radiosurgery (SRS) has an important role in primary treatment of malignant intracranial extracerebral tumors and, most commonly, in treating residual or recurrent disease after resection has established the diagnosis and decompressed the tumor's environs. Here we review the role and technique of SRS in a variety of these unusual lesions, including malignant meningioma, glomus tumor, pituitary carcinoma, skull base metastasis, chordoma, and chondrosarcoma. Understanding the specific nuances of each is helpful in allowing optimal planning of patient selection, dose level, and dose contours for best treatment results. Currently, SRS can be useful in achieving effective palliation of these malignant tumors but does not usually provide a cure. In the future, better results are anticipated because of new methods of metabolic imaging for delineating tumor extent and new radiosensitizers that enhance tumor kill within a safe range of doses at the tumor margin.

Management of non-benign meningiomas with Gamma Knife radiosurgery

OBJECTIVE

Results of Gamma Knife radiosurgery (GKS) were retrospectively evaluated in 16 patients with histologically confirmed atypical and anaplastic intracranial meningiomas.

MATERIALS AND METHODS

There were nine men and seven women (mean age 61.0 years). Atypical meningiomas were diagnosed in nine cases and anaplastic meningiomas in seven. In nine patients there was malignant transformation of a tumor that had initially proved to be benign. In total, 21 radiosurgical procedures were performed. The mean tumor volume at the time of GKS was 7.1 cm3. The mean marginal and maximum irradiation doses were 18.8 and 37.0 Gy, respectively. The mean length of follow-up after treatment was 37.1 months.

FINDINGS

Of 21 radiosurgical procedures, 6 (29 %) led to stabilization of tumor growth during the mean follow-up of 40.5 months. It was significantly associated with small lesion volume (P = 0.02), and greater marginal (P = 0.04) and maximum (P = 0.02) irradiation doses. Seven patients underwent eight surgical resections of a progressing tumor during the mean period of 26.1 months after irradiation. Five patients (31 %) died because of tumor progression within the average time period of 16.8 months after GKS. Overall, at the time of the last follow-up just two patients (13 %) had no evidence of tumor regrowth, and only three patients (19 %) maintained good activities of daily living during 12, 59, and 69 months, respectively, after radiosurgery.

CONCLUSION

GKS has limited efficacy in cases of non-benign meningioma. Better tumor control rates can be attained for small neoplasms treated with greater marginal and maximum irradiation doses.

Gamma knife stereotactic radiosurgery for atypical and malignant meningiomas

BACKGROUND

Non-benign meningioma has a known trend to recur repeatedly. The results of Gamma Knife stereotactic radiosurgery (GKS) for recurrent or residual atypical and malignant meningiomas are reported.

METHODS

Thirty patients (13 men, 17 women) with World Health Organization (WHO) grade II (24 cases) or grade III (6 cases) intracranial meningiomas underwent GKS. Their age varied from 30 to 86 years (mean 64 years). Before GKS, the tumor was surgically resected in all patients, and 11 of them also underwent conventional external beam radiation therapy, LINAC-based stereotactic radiotherapy (SRT), or intensity-modulated radiation therapy.

FINDINGS

Of the 30 patients, 23 were followed after the initial GKS for a median period of 28 months (range 2-135 months). Local tumor control after treatment was 74 % at 1 year, 52 % at 2 years, and 34 % at 3 years. A total of 15 patients underwent repeat GKS (one to nine times) because of local or distant intracranial tumor progression, seven were subjected to surgical re-resection of the neoplasm, and four had additional SRT. At the time of the last follow-up, 21 patients were alive, and 2 had died. One of the latter expired because of brain tumor progression at 91 months after the initial GKS, and the other patient died from lung cancer.

CONCLUSIONS

Although atypical and malignant meningiomas have a trend to recur repeatedly, aggressive tumor management with repeat GKS at the time of progression can provide long survival in these patients.

Single-Fraction Radiosurgery of Benign Intracranial Meningiomas

BACKGROUND:

Stereotactic radiosurgery (SRS) of benign intracranial meningiomas is an accepted management option for well-selected patients.

OBJECTIVE:

To analyze patients who had single-fraction SRS for benign intracranial meningiomas to determine factors associated with tumor control and neurologic complications.

METHODS:

Retrospective review was performed of 416 patients (304 women/112 men) who had single-fraction SRS for imaging defined (n = 252) or confirmed World Health Organization grade I (n = 164) meningiomas from 1990 to 2008. Excluded were patients with radiation-induced tumors, multiple meningiomas, neurofibromatosis type 2, and previous or concurrent radiotherapy. The majority of tumors (n = 337; 81%) involved the cranial base or tentorium. The median tumor volume was 7.3 cm3; the median tumor margin dose was 16 Gy. The median follow-up was 60 months.

RESULTS:

The disease-specific survival rate was 97% at 5 years and 94% at 10 years. The 5- and 10-year local tumor control rate was 96% and 89%, respectively. Male sex (hazard ratio [HR]: 2.5, P = .03), previous surgery (HR: 6.9, P = .002) and patients with tumors located in the parasagittal/falx/convexity regions (HR: 2.8, P = .02) were negative risk factors for local tumor control. In 45 patients (11%) permanent radiation-related complications developed at a median of 9 months after SRS. The 1- and 5-year radiation-related complication rate was 6% and 11%, respectively. Risk factors for permanent radiation-related complication rate were increasing tumor volume (HR: 1.05, P = .008) and patients with tumors of the parasagittal/falx/convexity regions (HR: 3.0, P = .005).

CONCLUSION:

Single-fraction SRS at the studied dose range provided a high rate of tumor control for patients with benign intracranial meningiomas. Patients with small volume, nonoperated cranial base or tentorial meningiomas had the best outcomes after single-fraction SRS.

μMLC-LINAC radiosurgery for intracranial meningiomas of complex shape

BACKGROUND

We present the long-term results of a consecutive series of patients with meningiomas treated by LINAC-radiosurgery using the micro-multi-leaf collimator technique (μMLC).

METHODS

Between May 2001 and July 2009, 78 patients (m: f = 024:54; median age, 56.8 years; range, 20.1-81 years) with 87 intracranial meningiomas (78 WHO I, seven WHO II, two WHO III) were treated with μMLC-LINAC radiosurgery at our institution, either as a primary or salvage treatment following one or more microsurgical procedures. Fifty-eight of 87 tumors (66.7%) were located in the skull base. The remaining 29 meningiomas (33.3%) were located in the convexity of the brain. The median tumor volume was 4.8 ml (range, 0.2-18.3 ml). The median tumor surface dose, maximal dose, and therapeutic isodose were 12 Gy, 16 Gy, and 75%, respectively.

RESULTS

For retrospective evaluation, we included 70 patients (78 tumors) with a minimum radiological follow-up of 24 months. After a median follow-up of 79.7 months (range, 24.2-109.1 months), 24 patients (34.3%) improved in their clinical status (paresis of N. abducens 18/48, facial paresis 4/8, and hemiparesis 2/9), 41 patients remained stable (58.6%), three patients had treatment-related temporary complaints (4.3%); two patients developed vertigo, and one had a left-sided hemihypesthesia. All complaints recovered completely after steroid medication within 2 weeks. Two patients (2.8%) developed permanent trigeminal neuralgia. Follow-up MR images showed a partial remission in 21 tumors (26.9%) and a stable tumor size in 55 cases (70.5%). Two patients with high-grade meningiomas showed a tumor progression (one WHO II and one WHO III meningioma). At the end of follow-up (July 2010), the actuarial 5- and 9-year progression-free survival after radiosurgery were 98 and 96%, respectively. There was no treatment-related mortality.

CONCLUSIONS

LINAC radiosurgery using a micro multi-leaf collimator for complex shaped intracranial meningiomas is effective yielding a high local tumor control, whereas the treatment-related morbidity remains low.

Patterns of failure after treatment of atypical meningioma with gamma knife radiosurgery

Atypical meningiomas have poor local control with emerging literature indicating the use of radiosurgery in treatment. The purpose of this study was to evaluate clinical outcomes including local control and failure pattern after Gamma Knife radiosurgery (GKRS) and factors that may affect these outcomes. Between 1999 and 2008, 24 patients were treated with GKRS as either primary or salvage treatment for pathologically proven atypical meningiomas. Treatment failures were determined by serial magnetic resonance imaging. A median marginal dose of 14 Gy was used (range 10.5-18 Gy). Overall local control rates at 1, 2, and 5 years were 75, 51, and 44%, respectively. With median follow-up time of 42.5 months, 14 of 24 patients experienced a treatment failure at time of last follow-up. Eight recurrences were in-field, four were marginal failures, and two were distant failures. Wilcoxon analysis revealed that the conformality index (CI) was a significant predictor of local recurrence (P = 0.04). CI did not predict for distant recurrences (P = 0.16). On multivariate analysis evaluating factors predicting progression free survival, dose >14 Gy was found to be statistically significant (P = 0.01). There appears to be a dose response using GKRS beyond 14 Gy but given the suboptimal local control rates in this study, higher doses may still be needed to obtain better local control.

Update on meningiomas

Although meningiomas are the most common tumor in the central nervous system, their incidence, epidemiology, and clinical outcomes have historically been poorly defined. This has been attributed to their benign course, difficulty obtaining histologic diagnosis, and lack of uniform database registration. Their clinical behavior can range from a silent incidentaloma to a lethal tumor. Projections of an aging population should raise medical awareness of an expectant rise in the incidence of meningiomas. This disease increases with advancing age, has a female predilection, and exposure to ionizing radiation is associated with a higher risk for disease development. There have been minimal advances in treatment, except in radiation therapy. Although no U.S. Food and Drug Administration-approved systemic therapy exists, there are treatment options that include hydroxyurea and sandostatin. Currently, no molecularly targeted therapy has provided clinical benefit, although recurring molecular alterations are present and novel therapies are being investigated.

Stereotactic LINAC radiosurgery for incompletely resected or recurrent atypical and anaplastic meningiomas

BACKGROUND

The optimal management of subtotally resected or recurrent malignant meningiomas remains controversial. We evaluated the efficacy of linear accelerator (LINAC) radiosurgery for atypical and anaplastic meningiomas after incomplete resection or treatment of recurrences.

METHODS

Between August 1990 and December 2003, 16 patients with 28 meningiomas WHO II and III were treated by stereotactic LINAC radiosurgery at our institution. The median radiological follow-up was 60.3 months, respectively (range: 7.2-173.9 months). Fourteen tumors in nine patients were classified as WHO II and 14 tumors in seven patients as WHO III. The median surface dose was 14 Gy (range: 10-15 Gy) with a median tumor volume of 4.8 ml (range: 0.51-51.4 ml).

RESULTS

Clinical condition improved in four patients, remained unchanged in nine and deteriorated in one. Tumor shrinkage was seen in eight of 28 meningiomas and a stable disease in 12. Eight of 28 meningiomas showed local tumor progression. The overall tumor control rate (TCR) was 84%, 70%, 70% after 3, 5, 10 years. According to grading the corresponding TCR after 3, 5, 10 years was 91%, 81%, 81% for grade II and 77%, 60%, 60% for grade III meningiomas. Overall progression-free survival (PFS) was 74%, 67%, 58% after 3, 5, 10 years. According to grading the PFS after 3, 5, 10 years was 88%, 75%, 75% for grade II meningiomas and 57%, 57%, 43% for grade III meningiomas.

CONCLUSION

Our results show the efficacy and safety of LINAC radiosurgery for incompletely resected or recurrent malignant meningiomas with a relatively high local tumor control and low morbidity.

Outcome and survival following primary and repeat surgery for World Health Organization Grade III meningiomas

OBJECT

Despite an increased understanding of the biology of malignant meningioma tumor progression, there is a paucity of published clinical data on factors affecting outcomes following treatment for these lesions. The authors present the largest case series to date dealing with these tumors, providing analysis of 63 patients.

METHODS

The authors identified all patients undergoing resection of WHO Grade III tumors at their institution over a 16-year period. They analyzed clinical data from these patients, and performed Kaplan-Meier and Cox regression analyses to determine the impact of different clinical characteristics and different treatment modalities on survival following initial and repeat surgery for these lesions.

RESULTS

Sixty-three patients met inclusion criteria and were analyzed further. The median clinical follow-up time was 5 years (range 1-22 years). The 2-, 5-, and 10-year overall survival rates following initial operation were 82, 61, and 40%, respectively. Kaplan-Meier analysis demonstrated a marked survival benefit with repeat operation (53 vs 25 months, p = 0.02). Interestingly, patients treated with near-total resection experienced improved overall survival when compared with patients treated with gross-total resection at initial (p = 0.035) and repeat operations (p = 0.005). Twelve (19%) of 63 patients experienced significant neurological morbidity referable to the resection of their tumors.

CONCLUSIONS

Surgery is an effective treatment for WHO Grade III meningiomas at presentation and recurrence; however, aggressive attempts to achieve gross-total resection can be associated with significant neurological risk.

Long-term experience with World Health Organization grade III (malignant) meningiomas at a single institution

PURPOSE

To evaluate the outcomes for patients with Grade III meningiomas as defined by the 2007 World Health Organization standards.

METHODS AND MATERIALS

The slides from patients who had been treated at the Cleveland Clinic for malignant meningiomas were reviewed by a single neuropathologist. The data from 13 patients treated between 1984 and 2006 satisfied the World Health Organization 2007 definition of Grade III meningioma. A total of 24 surgeries were performed, including 13 primary, 7 salvage, and 4 second salvage. Also, 14 courses of radiotherapy (RT) were administered, including fractionated RT in 3 patients after primary surgery, fractionated RT in 4 patients after salvage surgery, salvage stereotactic radiosurgery to six separate areas in 3 patients, and salvage intensity-modulated RT in 1 patient.

RESULTS

From the primary surgery, the median survival was 3.4 years, the 5-year survival rate was 47.2%, and the 8-year survival rate was 12.2%. The median time to recurrence was 9.6 months. A trend was seen toward longer survival for patients who had received adjuvant RT after initial surgery compared with those treated with surgery alone. Two patients developed radiation necrosis, and three had surgical complications.

CONCLUSION

This is one of the few studies reporting the outcomes for malignant meningioma patients according to recent definitions. Our results are consistent with existing reports of the overall poor outcomes for atypical and malignant meningioma patients. From the available data, surgical resection followed by RT and salvage therapy can lead to extended survival.

Combined proton and photon conformal radiotherapy for intracranial atypical and malignant meningioma

PURPOSE

To evaluate retrospectively the efficacy of conformal fractionated radiotherapy combining proton and photon beams after primary surgery for treatment of atypical and malignant meningiomas.

PATIENTS AND METHODS

Between September 1999 and October 2006, 24 patients (12 male, 12 female) with histopathologically proven meningioma (atypical 19, malignant 5) received postoperative combined radiotherapy with a 201-MeV proton beam at the Centre Protontherapie d'Orsay and a high-energy photon beam. Six patients underwent gross total resection and 18 a subtotal resection. Median gross tumor volume and clinical target volume were 44.7 cm(3) and 153.3 cm(3), respectively. Mean total irradiation dose was 65.01 CGE (cobalt gray equivalent), with a mean proton total dose of 34.05 CGE and a mean photon total dose 30.96 CGE.

RESULTS

The median (range) follow-up interval was 32.2 (1-72) months. The overall mean local relapse-free interval was 27.2 (10-50) months, 28.3 (10-50) months for atypical meningioma and 23 (13-33) months for malignant meningioma. Ten tumors recurred locally. One-, 2-, 3-, 4-, 5-, and 8- year local control rates for the entire group of patients were 82.9% +/- 7.8%, 82.9% +/- 7.8%, 61.3% +/- 11%, 61.3% +/- 11%, 46.7% +/- 12.3%, and 46.7% +/- 12.3%, respectively. One-, 2-, 3-, 4-, 5-, and 8- year overall survival rates were 100%, 95.5% +/- 4.4%, 80.4% +/- 8.8%, 65.3% +/- 10.6%, 53.2% +/- 11.6%, and 42.6% +/- 13%, respectively. Survival was significantly associated with total dose. There was no acute morbidity of radiotherapy. One patient developed radiation necrosis 16 months after treatment.

CONCLUSIONS

Postoperative combination of conformal radiotherapy with protons and photons for atypical and malignant meningiomas is a well-tolerated treatment producing long-term tumor stabilization.

Radiotherapy as an adjuvant in the management of intracranial meningiomas: are we practising evidence-based medicine?

Although increasingly used, the precise role of radiotherapy in the management of meningiomas is still disputed. The objective of this study, therefore, was to appraise the evidence for adjuvant radiotherapy in benign and atypical intracranial meningiomas, and to compare and contrast it with the current opinion and practice of neurosurgeons in the United Kingdom and the Republic of Ireland. The use of radiotherapy as a primary treatment strategy or its use in the treatment of recurrence was not considered. We performed a systematic review of the evidence for adjuvant radiotherapy in benign and atypical intracranial meningiomas, surveyed current opinion amongst neurosurgeons involved in such cases and ascertained local practice using data from the regional cancer registry. Overall, 10 cohorts were identified that fulfilled our eligibility criteria. Four studies showed significantly improved local control in patients receiving adjuvant radiotherapy for incompletely resected grade I meningiomas. Our survey demonstrated that the vast majority (98%) of neurosurgeons would not recommend adjuvant radiotherapy in grade I meningioma. In grade II meningioma, most (80%) would not advocate adjuvant radiotherapy if completely excised, but the majority (59%) would recommend radiotherapy in cases of subtotal resection. Significant variation in opinion between centres exists, however, particularly in cases of completely resected atypical meningiomas (p = 0.02). Data from the Eastern Cancer Registration and Information Centre appears to be in line with these findings: less than 10% of patients with grade I meningiomas, but almost 30% of patients with grade II meningiomas received adjuvant radiotherapy in the Eastern region. In conclusion, our study has highlighted significant variation in opinion and practice, reflecting a lack of class 1 evidence to support the use of adjuvant radiotherapy in the treatment of meningiomas. Efforts are underway to address this with a randomized multicentre trial comparing a policy of watchful waiting versus adjuvant irradiation.

Stent placement for management of a small parasagittal meningioma. Technical note

The patient in this report had a parasagittal meningioma with an intrasinus extension that presented with features of benign intracranial hypertension and no focal neurological deficit or seizure. The meningioma was managed with a combination of endovascular stent placement and radiotherapy. The authors describe the investigation and technical aspects of stent placement for the stenosed sinus. Good symptomatic relief in the patient was achieved.

Current concepts in management of meningiomas and schwannomas

Meningiomas and schwannomas are the two most common extra-axial intracranial tumors in adults. Since their initial discovery, these often-benign lesions have shared a parallel metamorphosis in their management. The goal of this article is to provide a review of the current literature surrounding the mainstays of therapy for these lesions.

Intracranial meningiomas: an overview of diagnosis and treatment

Meningiomas are extraaxial central nervous system tumors most often discovered in middle to late adult life, and are more often seen in women. Ninety percent of meningiomas are benign, 6% are atypical, and 2% are malignant. Most patients in whom a meningioma is diagnosed undergo resection to relieve neurological symptoms. Complete resection is often curative. For the majority of incompletely resected or recurrent tumors not previously irradiated, radiotherapy is administered. Radiotherapy may be administered as either conventional external-beam radiation therapy or stereotactically by linear accelerator, Leksell Gamma Knife, or Cyberknife radiosurgery. Advocates of stereo-tactic radiotherapy have suggested this therapy in lieu of surgery particularly in high-risk patients, those with meningiomas in eloquent or surgically inaccessible locations, and elderly patients. When the meningioma is unresectable or all other treatments (surgery and radiotherapy) have failed, hormonal therapy or chemotherapy may be considered. Notwithstanding limited data, hydroxyurea has been modestly successful in patients with recurrent meningiomas.

De novo versus transformed atypical and anaplastic meningiomas: comparisons of clinical course, cytogenetics, cytokinetics, and outcome

OBJECTIVE

The clinical course of atypical and anaplastic meningiomas is heterogeneous. As malignant gliomas, aggressive meningiomas may arise de novo or transform from a benign tumor. This study aims to compare differences in clinical behavior, cytogenetics, cytokinetics, receptor status, and outcome between de novo malignant meningiomas and meningiomas that progressed to malignancy.

METHODS

Data from 36 patients with atypical or anaplastic meningiomas were selected for retrospective analysis and divided into two subgroups: 1) de novo atypical or anaplastic tumors and 2) tumors that progressed from a lower grade. We analyzed data concerning patients' sex, age, tumor location, number of operations, status of hormone receptors, proliferative indices, cytogenetic findings, additional therapy, and survival. For meningiomas with progression, we calculated the interval between initial diagnosis and tumor progression.

RESULTS

For atypical meningiomas, the subgroups had significant differences in status of progesterone receptors, proliferative indices, cytogenetics, and patients' outcome. The anaplastic group had similar differences, but they did not reach statistical significance because of the small numbers. There was a loss of part or monosomy of chromosome 10 and an increased monosomy or derivative chromosome 1 combined with monosomy of chromosome 14. These phenomena occurred mainly in patients with malignant transformation who had a worse outcome.

CONCLUSION

De novo malignant meningiomas and meningiomas with malignant transformation may represent distinct subgroups of atypical and anaplastic meningiomas.

Long-term follow-up of meningiomas of the cavernous sinus after surgical treatment alone

Object

The authors report on the long-term outcome in 100 consecutive patients with meningiomas arising from the cavernous sinus (CS) with compressive extension outside the CS. The treatment in all cases was surgery alone without adjuvant radiosurgery or radiotherapy. The aim of this study was to evaluate the percentage of patients in whom surgery alone was able to produce long-term tumor control.

Methods

All 100 patients harbored meningiomas with supra- and/or laterocavernous extension, and 27 had petro-clival extension. Surgery was performed via frontopterionotemporal craniotomy associated with orbital and/or zygomatic osteotomy in 97 patients. Proximal control of the internal carotid artery at the foramen lacerum was undertaken in 65 patients; the paraclinoid carotid segment was exposed extradurally at the space made by the anterior clinoidectomy in 81 patients. For the petroclival tumor extension, a second-stage surgery was performed via a presigmoid–retro-labyrinthine or retrosigmoid approach in 13 and 14 patients, respectively.

Results

The mortality rate was 5% and two patients had severe hemiplegic or aphasic sequelae. The creation or aggravation of disorders in vision, ocular motility, or trigeminal function occurred in 19, 29, and 24% of patients respectively, with a significantly higher rate of complications when resection was performed inside the CS (p < 0.05).

Gross-total removal of both the extra- and intracavernous portions was achieved in 12 patients (Group 1), removal of the extracavernous portions with only a partial resection of the intracavernous portion in 28 patients (Group 2), and removal only of the extracavernous portions was performed in 60 patients (Group 3). The follow-up period ranged from 3 to 20 years (mean 8.3 years). There was no tumor recurrence in Group 1. In the 83 surviving patients in Groups 2 and 3 combined, the tumor remnant did not regrow in 72 patients (86.7%); regrowth was noted in 11 (13.3%).

Conclusions

The results suggest that there is no significant oncological benefit in performing surgery within the CS. Because entering the CS entails a significantly higher risk of complications, radiosurgical treatment should be reserved for remnants with secondary growth and clinical manifestations.

Boron neutron capture therapy for malignant tumors related to meningiomas

OBJECTIVE

Malignant meningiomas, similar to glioblastomas, are difficult tumors to control. We tried to control malignant tumors related to meningiomas by boron neutron capture therapy (BNCT).

METHODS

Since June 2005, we applied BNCT with 13 rounds of neutron irradiation to seven cases of malignant tumors related to meningiomas. Three were anaplastic meningiomas, two were papillary meningiomas, one was an atypical meningioma, and one was a sarcoma transformed from a meningioma with cervical lymph node metastasis. All patients had previously undergone repetitive surgeries and radiotherapy. Follow-up images were available for six patients with an observation period between 7 and 13 months. We applied 18F-boronophenylalanine (BPA)-positron emission tomography (PET) before BNCT in six of the seven patients. One patient underwent methionine-PET instead of 18F-BPA-PET.

RESULTS

Five of the six patients who underwent BPA-PET analysis showed good BPA uptake, with a greater than 2.7 tumor-to-healthy brain ratio. The atypical meningioma case showed a tumor-to-healthy brain ratio of 2.0. The original tumor sizes were between 13.6 and 109 ml. Two of the three anaplastic meningiomas showed a complete response, and all six patients available for follow-up imaging showed radiographic improvements. Clinical symptoms before BNCT, such as hemiparesis and facial pain, were improved after BNCT in all but one patient. In this patient, a huge atypical meningioma arose from the falcotentorial junction and extended to the bilateral occipital lobes and brainstem; visual problems worsened after repetitive BNCT, with an increase in peritumoral edema.

CONCLUSION

Malignant meningiomas seem to be good candidates for BNCT.

Relationship between malignant subtypes of meningioma and clinical outcome

We evaluated the relationship between histological malignant subtypes (WHO grade II or III) of meningioma and clinical outcome. Of 485 patients treated surgically for intracranial meningioma at our hospital between 1994 and 2004, 49 (10%; 18 male, 31 female) had potentially malignant features. The histological tumor subtypes within this group of patients included: atypical (n=23); clear cell (n=3); chordoid (n=5); rhabdoid (n=16); and anaplastic (n=4). Correlations among prognosis, recurrence, and the following factors were analyzed for each histological subtype: the Simpson grade of surgical resection (grades I-III vs. grade IV), tumor location (convexity vs. other), the Ki-67 index, and use of postoperative radiotherapy. The median value of the Ki-67 index was 16.2% (range: 1.0-57.2%). The surgical resections were of Simpson grades I-III and IV in 43 and six of the 49 patients, respectively. Tumors recurred after the initial surgical resection in 14 of the 49 patients. In view of the relatively high proportion of malignant subtypes (10%), we suggest that all meningiomas should be evaluated for malignancy. The extent of surgical resection, the histological subtype, and the Ki-67 index can help to predict the clinical outcome for meningioma patients.

Boron neutron capture therapy for recurrent malignant meningioma. Case report

Malignant meningioma is a rare brain tumor with a high risk of recurrence. If this tumor recurs after complete resection and adjuvant radiotherapy, there is no optimal treatment to control it. The authors report the first case of recurrent malignant meningioma treated using boron neutron capture therapy (BNCT). This 25-year-old pregnant woman presented with a large frontal tumor. After her baby was born, she underwent gross-total resection of the tumor. A second resection and three Gamma Knife surgeries could not control progression of the enhancing mass; therefore, the authors applied BNCT based on their experience with it in the treatment of malignant gliomas. The minimum tumor dose and maximum brain tissue dose were estimated as 39.7 Gy-Eq and less than 9.0 Gy-Eq, respectively. Before BNCT the patient was mobile by wheelchair only, whereas 1 week after therapy she was able to walk. Twenty-two weeks later she underwent a second BNCT for tumor regrowth on the contralateral side, and the lesion was subsequently reduced. The tumor volume was markedly decreased from 65.6 cm3 at the time of the first BNCT to 31.8 cm3 at 26 weeks thereafter. The treatment of recurrent malignant meningioma is difficult and has been discouraging thus far. Data in the present case indicate that BNCT may be a promising treatment option for this challenging tumor.

Stereotactic radiation treatment for recurrent nonbenign meningiomas

Object

The authors analyzed the results of stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) for the treatment of recurrent meningiomas that were described at initial resection as showing aggressive, atypical, or malignant features (nonbenign).

Methods

Twenty-five patients who underwent SRS and/or SRT for nonbenign meningiomas between December 1992 and August 2004 were included. Thirteen of these patients underwent treatment for multiple primary or recurrent lesions. In all, 52 tumors were treated. All histological sections were reviewed and reclassified according to World Health Organization (WHO) 2000 guidelines as benign (Grade I), atypical (Grade II), or anaplastic (Grade III) meningiomas. The median follow-up period was 42 months.

Seventeen (68%) of the cases were reclassified as follows: WHO Grade I (five cases), Grade II (11 cases), and Grade III (one case). Malignant progression occurred in eight cases (32%) during the follow-up period; these cases were considered as a separate group. The 3-year progression-free survival (PFS) rates for the Grades I, II, and III, and malignant progression groups were 100, 83, 0, and 11%, respectively (p < 0.001). In the Grade II group, the 3-year PFS rates for patients treated with SRS and SRT were 100 and 33%, respectively (p = 0.1). After initial treatment, 22 new tumors required treatment using SRS or SRT; 17 (77%) of them occurred inside the original resection cavity. Symptomatic edema developed in one patient (4%).

Conclusions

Stereotactic radiation treatment provided effective local control of “aggressive” Grade I and Grade II meningiomas, whereas Grade III lesions were associated with poor outcome. The outcome of cases in the malignant progression group was intermediate between that of the Grade II and Grade III groups, with the lesions showing a tendency toward malignancy.

Stereotactic radiosurgery for atypical and anaplastic meningiomas

Atypical and anaplastic meningiomas frequently recur in the relatively short-term after surgery. We have followed such postoperative cases by short-interval repeated MRI and have performed stereotactic radiosurgery (SRS) for progressive tumors as a salvage therapy. The objective of this report was assessment of the degree of tumor control, the risk of complications, and the presence of variables that predict outcome in patients treated with SRS for high-grade meningiomas. We reviewed 12 high-grade meningioma patients with 30 lesions treated by Linac-based SRS at Kyoto University Hospital between 1997 and 2002. They included 10 atypical meningiomas and 2 anaplastic ones according to the WHO classification. A mean tumor volume was 4.40cc and a mean marginal dose of SRS was 18.0 Gy (12-20 Gy). After a mean follow-up period of 43.4 months (6-84 months), 13 lesions had progression tumor within the SRS field and 6 lesions had out of the SRS field. Nine of 14 lesions, which were treated by SRS with a marginal dose of less than 20 Gy, had local recurrence in the SRS field. In contrast, four of 16 lesions, which were treated with marginal dose of 20 Gy, had local recurrence in the SRS field. The marginal dose <20 Gy was a statistically significant factor for a short-term progression in high-grade meningiomas (P = 0.0139). Five-year progression-free survival ratio in lesions treated with SRS below 20 Gy and 20 Gy were 29.4% and 63.1%, respectively. In conclusion, based on our findings, we suggest that recurrent high-grade meningiomas be treated by SRS with a marginal dose exceeding 20 Gy.

Gamma-knife radiosurgery for cranial base meningiomas: experience of tumor control, clinical course, and morbidity in a follow-up of more than 8 years

OBJECTIVE

Surgical resection of cranial base meningiomas is often limited owing to involvement of crucial neural structures. Within the last 2 decades Gamma Knife radiosurgery (GKRS) has gained increasing importance as an adjunct treatment after incomplete resection and as an alternative treatment to open surgery. However, reports of long-term results are still sparse. We therefore performed this study to analyze the long-term results of GKRS treatment of cranial base meningiomas, following our previously published early follow-up experience.

METHODS

A retrospective analysis of the medical files for Gamma Knife and surgical treatments, clinicoradiological findings, and outcome was carried out focusing on tumor control, clinical course, and morbidity.

RESULTS

Between 1992 and 1995, we treated 36 patients with cranial base meningiomas using GKRS (male:female ratio, 1:5; mean age, 59 yr; range, 44-89 yr). Twenty-five patients were treated with GKRS after open surgery, and 11 patients received GKRS alone. Tumor control, neurological outcomes, and adverse effects were analyzed after a long-term follow-up period (mean, 103 mo; range, 70-133 mo) and compared with our previous results after an early follow-up period (mean, 48 mo; range, 36-76 mo). Control of tumor growth was achieved in 94% of patients. Compared with the early follow-up period, the late neuroradiological effects of GKRS on cranial base meningiomas were continuing tumor shrinkage in 11 patients (33%), stable tumor size in 20 patients (64%) and tumor progression in two meningiomas (6%). The neurological status improved in 16 patients (44%), remained stable in 19 patients (52%), and deteriorated in one patient (4%). Adverse side effects of GKRS were found only during the early follow-up period.

CONCLUSION

Our data confirm that GKRS is not only a safe and effective treatment modality for cranial base meningiomas in short-term observation, but also in a mean long-term follow-up period of more than 8 years. Tumor shrinkage and clinical improvement also continued during the longer follow-up period.