Treatment modalities and outcomes for asymptomatic meningiomas

Gamma knife radiosurgery as primary management for intracranial meningioma identified as growing on serial imaging

Gamma knife radiosurgery (GKRS) has emerged as a highly effective therapeutic modality for the management of intracranial meningiomas. However, the role of GKRS in treating growing meningiomas detected during active surveillance remains unclear. This study seeks to investigate the long-term outcomes of GKRS treatment for growing meningiomas. A retrospective analysis was conducted on patients who underwent GKRS as the primary treatment for growing meningiomas between 2004 and 2021. Growing meningiomas were defined as those exhibiting a > 10% increase in tumor volume (TV) compared to the previous imaging. Fifty-nine patients who received GKRS as their initial treatment were included, with a minimum follow-up period of 12 months. Comprehensive clinical, radiological, and procedural data were analyzed. Serial TV assessments were performed for all tumors before and after GKRS. Tumor progression and regression were defined as a > 10% increase or decrease in TV, respectively, compared to the pretreatment image. At a median follow-up of 41 months (range 15-197 months), TV was unchanged in 16 patients (27.1%), decreased in 41 patients (69.5%), and increased in 2 patients (3.4%). Multivariate analysis revealed that both TV (cm3) (hazard ratio [HR], 1.107; 95% confidence interval [CI], 1.002-1.222; P = .045) and volume growing rate (%/yr) (HR, 1.013; 95% CI, 1.000-1.025; P = .04) significantly correlated with tumor progression. Eleven patients (18.6%) experienced new or worsening symptoms. In multivariate analysis, factor predicting new or worsening neurological function was preexisting calcification (HR, 5.297; 95% CI, 1.328-21.124; P = .018). GKRS demonstrates a promising level of tumor control with minimal risk of neurological deterioration when applied to growing meningiomas. These findings provide compelling support for considering GKRS as a valuable therapeutic option following an initial period of active surveillance for these tumors.

Incidental Meningiomas: Potential Predictors of Growth and Current State of Management

The rise in availability of neuroimaging has led to an increase in incidentally discovered meningiomas. These tumors are typically asymptomatic and tend to display slow growth. Treatment options include observation with serial monitoring, radiation, and surgery. Although optimal management is unclear, clinicians recommend a conservative approach, which preserves quality of life and limits unnecessary intervention. Several risk factors have been investigated for their potential utility in the development of prognostic models for risk assessment. Herein, the authors review the current literature on incidental meningiomas, focusing their discussion on potential predictive factors for tumor growth and appropriate management practices.

Surgical complications and recurrence factors for asymptomatic meningiomas: a single-center retrospective study

PURPOSE

Observation is the first management option in asymptomatic meningiomas, but when an enlargement or mass effect is observed, surgery is indicated. This study is aimed at exploring risk factors for complications and recurrence after surgery for asymptomatic meningioma. We also examined the impact of preoperative tumor embolization, which is considered controversial.

METHODS

We retrospectively reviewed 109 patients with primary asymptomatic meningiomas surgically treated at our institute between April 2007 and March 2021. Patients who only had headaches as a nonspecific complaint were included in the asymptomatic group. Complications, time to recurrence, and Glasgow Outcome Scale (GOS) score were the endpoints of the study. Risk factors for complications and recurrence were explored. Moreover, the effect of the resection on nonspecific headaches was also explored.

RESULTS

The permanent postoperative complication rate related to the surgical procedure was 1.8%. Of the total, 107 patients (98.2%) with asymptomatic meningiomas who were surgically treated achieved a GOS score of 5 1 year after the operation. Preoperative headache was present in 31 patients and improved postoperatively in 21 patients. Multivariate analysis using the Cox proportional hazard model showed that preoperative tumor embolization with > 80% resolution of tumor staining (p < 0.001) was negatively related to recurrence, whereas age (p = 0.046) and Simpson grade IV resection (p = 0.041) were positively related to recurrence.

CONCLUSION

Although surgery for asymptomatic meningiomas can, in many cases, be safe, it is not free of complications Thus, surgical intervention for asymptomatic meningiomas should be considered cautiously. However, more than half the patients with headaches showed improvement. Simpson grade IV resection cases should be assessed for recurrence, and preoperative tumor embolization might be effective in controlling recurrence.

A Pathophysiological Approach to Reduce Peritumoral Edema with Gamma Knife Radiosurgery for Large Incidental Meningiomas

Background: Peritumoral edema may be a prohibitive side effect in treating large incidental meningiomas with stereotactic radiosurgery. An approach that limits peritumoral edema and achieves tumor control with SRS would be an attractive management option for large incidental meningiomas. Methods: This is a retrospective cohort study of patients with large incidental meningiomas (≥2 mL in volume and/or 2 cm in diameter) treated with gamma knife radiosurgery (GKRS) between 2000 and 2019 in Taiwan and followed up for 5 years. The outcomes of a pathophysiological approach targeting the dural feeding artery site with a higher marginal dose (18–20 Gy) to enhance vascular damage and the parenchymal margin of the tumor with a lower dose (9–11 Gy) to reduce parenchymal damage were compared with those of a conventional approach targeting the tumor center with a higher dose and tumor margin with a lower dose (12–14 Gy). Results: A total of 53 incidental meningiomas were identified, of which 23 (43.4%) were treated with a pathophysiological approach (4 cases underwent a two-stage approach) and 30 (56.7%) were treated with a conventional approach. During a median follow-up of 3.5 (range 1–5) years, tumor control was achieved in 19 (100%) incidental meningiomas that underwent a single-stage pathophysiological approach compared with 29 (96.7%) incidental meningiomas that underwent a conventional approach (log-rank test: p = 0.426). Peritumoral edema developed in zero (0%) incidental meningiomas that underwent a single stage pathophysiological approach compared to seven (23.3%) incidental meningiomas that underwent a conventional approach (log-rank test: p = 0.023). Conclusions: Treatment of large incidental meningiomas with a pathophysiological approach with GKRS achieves similar rates of tumor control and reduces the risk of peritumoral edema. GKRS with a pathophysiological approach may be a reasonable management strategy for large incidental meningiomas.

Stereotactic Radiosurgery (SRS) Induced Higher-Grade Transformation of a Benign Meningioma into Atypical Meningioma

Background

Stereotactic radiosurgery (SRS) is a widely used treatment modality for the management of meningioma. Whether used as a primary, adjuvant, or salvage procedure, SRS is a safe, less invasive, and effective modality of treatment as microsurgery. The transformation of a meningioma following radiosurgery raises a concern, and our current understanding about it is extremely limited. Only a few case reports have described meningioma dedifferentiation after SRS to a higher grade. Moreover, a relatively small number of cases have been reported in large retrospective studies with little elaboration. Case Description. We report a detailed case description of a 41-year-old man with progressive meningioma enlargement and rapid grade progression after SRS, which was histopathologically confirmed before and after SRS. We discussed the clinical presentation, radiological/histopathological features, and outcome. We also reviewed previous studies that reported the outcome and follow-up of patients diagnosed with grade I meningioma histopathologically or presumed with benign meningioma by radiological features who underwent primary or adjuvant radiosurgery.

Conclusion

The risk of progression after SRS is low, and the risk of higher-grade transformation after SRS is trivial. The early timing for recurrence and field-related radiation may favor a relationship between SRS and higher-grade transformation (causality) although transformation as a part of the natural history of the disease cannot be fully excluded. Tumor progression (treatment failure) after SRS may demonstrate a transformation, and careful, close, and long follow-up is highly recommended. Also, acknowledging that there is a low risk of early and delayed complications and a trivial risk of transformation should not preclude its use as SRS affords a high level of safety and efficiency.

Are there predilection sites for intracranial meningioma? A population-based atlas

Meningioma is the most common benign intracranial tumor and is believed to arise from arachnoid cap cells of arachnoid granulations. We sought to develop a population-based atlas from pre-treatment MRIs to explore the distribution of intracranial meningiomas and to explore risk factors for development of intracranial meningiomas in different locations. All adults (≥ 18 years old) diagnosed with intracranial meningiomas and referred to the department of neurosurgery from a defined catchment region between 2006 and 2015 were eligible for inclusion. Pre-treatment T1 contrast-enhanced MRI-weighted brain scans were used for semi-automated tumor segmentation to develop the meningioma atlas. Patient variables used in the statistical analyses included age, gender, tumor locations, WHO grade and tumor volume. A total of 602 patients with intracranial meningiomas were identified for the development of the brain tumor atlas from a wide and defined catchment region. The spatial distribution of meningioma within the brain is not uniform, and there were more tumors in the frontal region, especially parasagittally, along the anterior part of the falx, and on the skull base of the frontal and middle cranial fossa. More than 2/3 meningioma patients were females (p < 0.001) who also were more likely to have multiple meningiomas (p < 0.01), while men more often have supratentorial meningiomas (p < 0.01). Tumor location was not associated with age or WHO grade. The distribution of meningioma exhibits an anterior to posterior gradient in the brain. Distribution of meningiomas in the general population is not dependent on histopathological WHO grade, but may be gender-related.

Intracranial meningioma surveillance using volumetrics from T2-weighted MRI

BACKGROUND AND PURPOSE

The gold standard for imaging of meningiomas is MRI with gadolinium-based contrast agent. Due to increased costs, time, and uncertain chronic effects of gadolinium exposure, use of noncontrast T2-weighted imaging (T2WI) in lieu of contrast-enhanced MRI has been an increasing focus of research across various diagnostic scenarios. The purpose of this study was to evaluate the diagnostic accuracy of T2WI in detecting changes in meningioma tumor volume.

METHODS

Imaging and clinical data were reviewed for 82 consecutive patients undergoing MR-surveillance of intracranial meningioma. Using volumetric-T2WI, two neuroradiologists independently calculated tumor volumes. Measurements were compared to a baseline study contrast-enhanced T1 tumor volume. Using contrast-enhanced sequences as the reference standard, statistical analysis was performed to determine the accuracy of T2WI in detecting changes of meningioma volume.

RESULTS

Using only T2WI, readers detected meningioma volume change ≥ 20% in 19/82 patients and volume change <20% in 63/82 patients. Reader accuracy for detecting change in tumor volume on T2WI ≥ 20% was 0.85, sensitivity 0.65, specificity 0.93, positive predictive value (PPV) 0.79, and negative predictive value (NPV) 0.87. For meningiomas >1 ml, reader accuracy for detecting change in tumor volume on T2WI ≥20% was 0.90, sensitivity 0.78, specificity 0.95, PPV 0.88, and NPV 0.91. Change in tumor volume on T2WI ≥20% was detected with 100% accuracy for posterior fossa meningiomas. Inter-reader agreement for all meningiomas was moderate (κ = 0.45) improving to substantial agreement (κ = 0.77) with tumor volumes >1 ml.

CONCLUSION

Volumetric-T2WI detects changes in meningioma volume with comparable accuracy to gold standard T1 postcontrast imaging, particularly with higher tumor volumes and posterior fossa locations.

An International Multicenter Matched Cohort Analysis of Incidental Meningioma Progression During Active Surveillance or After Stereotactic Radiosurgery: The IMPASSE Study

BACKGROUND

The optimal management of patients with an incidental meningiomas remains unclear. The aim of this study was to characterize the radiologic and neurological outcomes of expectant and SRS management of asymptomatic meningioma patients.

METHODS

Using data from 14 centers across 10 countries, the study compares SRS outcomes to active surveillance of asymptomatic meningiomas. Local tumor control of asymptomatic meningiomas and development of new neurological deficits attributable to the tumor were evaluated in the SRS and conservatively managed groups.

RESULTS

In unmatched cohorts, 727 meningioma patients underwent SRS and were followed for a mean of 57.2 months. In the conservatively managed cohort, 388 patients were followed for a mean of 43.5 months. Tumor control was 99.0% of SRS and 64.2% of conservatively managed patients (p<0.001; OR 56.860 (95%CI 26.253-123.150))). New neurological deficits were 2.5% in the SRS and 2.8% of conservatively managed patients (p=0.764; OR 0.890 (95% CI 0.416-1.904)). After 1:1 propensity matching for patient age, tumor volume, location, and imaging follow-up, tumor control in the SRS and conservatively managed cohorts was 99.4% and 62.1%, respectively (p<0.001; OR 94.461 (95% CI 23.082-386.568)). In matched cohorts, new neurological deficits were noted in 2.3% of SRS treated and 3.2% of conservatively managed patients (p=0.475; OR 0.700 (95% CI 0.263-1.863)).

CONCLUSIONS

SRS affords superior radiologic tumor control compared to active surveillance without increasing the risk of neurological deficits in asymptomatic meningioma patients. While SRS and active surveillance are reasonable options, SRS appears to alter the natural history of asymptomatic meningiomas including tumor progression in the majority of patients treated.

Stereotactic Radiosurgery for Intracranial Noncavernous Sinus Benign Meningioma: International Stereotactic Radiosurgery Society Systematic Review, Meta-Analysis and Practice Guideline

BACKGROUND

Stereotactic radiosurgery (SRS) for benign intracranial meningiomas is an established treatment.

OBJECTIVE

To summarize the literature and provide evidence-based practice guidelines on behalf of the International Stereotactic Radiosurgery Society (ISRS).

METHODS

Articles in English specific to SRS for benign intracranial meningioma, published from January 1964 to April 2018, were systematically reviewed. Three electronic databases, PubMed, EMBASE, and the Cochrane Central Register, were searched.

RESULTS

Out of the 2844 studies identified, 305 had a full text evaluation and 27 studies met the criteria to be included in this analysis. All but one were retrospective studies. The 10-yr local control (LC) rate ranged from 71% to 100%. The 10-yr progression-free-survival rate ranged from 55% to 97%. The prescription dose ranged typically between 12 and 15 Gy, delivered in a single fraction. Toxicity rate was generally low.

CONCLUSION

The current literature supporting SRS for benign intracranial meningioma lacks level I and II evidence. However, when summarizing the large number of level III studies, it is clear that SRS can be recommended as an effective evidence-based treatment option (recommendation level II) for grade 1 meningioma.

Spatial mechanistic modeling for prediction of the growth of asymptomatic meningiomas

BACKGROUND AND OBJECTIVE

Mathematical modeling of tumor growth draws interest from the medical community as they have the potential to improve patients' care and the use of public health resources. The main objectives of this work are to model the growth of meningiomas - slow-growing benign tumors requiring extended imaging follow-up - and to predict tumor volume and shape at a later desired time using only two times examinations.

METHODS

We develop two variants of a 3D partial differential system of equations (PDE) which yield after a spatial integration systems of ordinary differential equations (ODE) that relate tumor volume with time. Estimation of models parameters is a crucial step to obtain a personalized model for a patient that can be used for descriptive or predictive purposes. As PDE and ODE systems share the same parameters, they are both estimated by fitting the ODE systems to the tumor volumes obtained from MRI examinations acquired at different times. A population approach allows to compensate for sparse sampling times and measurement uncertainties by constraining the variability of the parameters in the population.

RESULTS

Description capabilities of the models are investigated in 39 patients with benign asymptomatic meningiomas who had had at least three surveillance MRI examinations. The two models can fit to the data accurately and more realistically than a naive linear regression. Prediction performances are validated for 33 patients using a population approach. Mean relative errors in volume predictions are less than 10% with ODE systems versus 12.5% with the naive linear model using only two times examinations. Concerning the shape, the mean Sørensen-Dice coefficients are 85% with the PDE systems in a subset of 10 representative patients.

CONCLUSIONS

Our strategy - based on personalization of mathematical model - provides a good insight on meningioma growth and may help decide whether to extend the follow-up or to treat the tumor.

Initial Gamma Knife Radiosurgery for Large or Documented Growth Asymptomatic Meningiomas: Long-Term Results From a 27-Year Experience

Objective

The aims of this study were to investigate the long-term outcomes of initial Gamma Knife radiosurgery (GKRS) for large (≥20 mm) or documented growth asymptomatic meningiomas.

Design and Methods

This was a single-center retrospective study. Fifty-nine patients with large (≥20 mm) or documented growth asymptomatic meningiomas undergoing initial GKRS were enrolled. The median age was 56 (range, 27–83) years. The median time of follow-up was 66.8 (range, 24.6–245.6) months, and the median tumor margin dose was 13.0 Gy (range, 11.6–22.0 Gy).

Results

Tumors shrunk in 35 patients (59.3%) and remained stable in 23 (39.0%). One patient (1.7%) experienced radiological progression at 54 months after GKRS. The PFS was 100%, 97%, and 97% at 3, 5, and 10 years, respectively. Nine patients (15.3%) occurred new neurological symptoms or signs at a median time of 8.1 (range, 3.0–81.6) months. The symptom PFS was 90% and 78% at 5 and 10 years, respectively. Fifteen patients (25.4%) occurred peritumoral edema (PTE) at a median time of 7.2 (range, 2.0–81.6) months. One patient underwent surgical resection for severe PTE. In univariate and multivariate analysis, Only tumor size (≥25 mm) and maximum dose (≥34 Gy) were significantly associated with PTE [hazard ratio (HR)= 3.461, 95% confidence interval (CI)=1.157-10.356, p=0.026 and HR=3.067, 95% CI=1.068-8.809, P=0.037, respectively].

Conclusions

In this study, initial GKRS can provide a high tumor control rate as well as an acceptable rate of complications in large or documented growth asymptomatic meningiomas. GKRS may be an alternative initial treatment for asymptomatic meningiomas.

Indications and outcome in surgically treated asymptomatic meningiomas: a single-center case-control study

BACKGROUND

Many meningiomas are detected incidentally and remain asymptomatic until intervention. The goal of this study was to describe the management and outcome in this group of surgically treated asymptomatic meningiomas.

METHODS

From 2004 to 2017, 45 patients with asymptomatic meningioma were surgically treated at Sahlgrenska University Hospital, and their medical records and imaging data were analyzed. The asymptomatic cases were matched with symptomatic ones with respect to age at diagnosis, location, WHO (World Health Organization) grade, and Simpson grade.

RESULTS

Time from diagnosis to surgery differed between the asymptomatic and symptomatic patients (8.6 vs. 1.3 months; p < 0.001). Of symptomatic patients, 32.6% still used anti-epileptic drugs > 1 year after surgery, compared with 7.7% of the asymptomatic (p = 0.003). Thirty-day complication rate was significantly higher among the asymptomatic cases (35.6% vs. 24.4%; 0.001), as well as the proportion of older asymptomatic individuals (> 70 years) experiencing postoperative complication compared with symptomatic patients of the same age group.

CONCLUSION

As expected, asymptomatic cases had smaller tumors and waited longer for surgery. Surprisingly, complication rate was significantly higher among asymptomatic cases compared with their symptomatic control. Taken into account that many asymptomatic tumors are removed surgically due to patient's wish, one might suggest a more restrictive approach, especially in the elderly.

Treatment Outcomes of Incidental Intracranial Meningiomas: Results from the IMPACT Cohort

BACKGROUND

Incidental findings such as meningioma are becoming increasingly prevalent. There is no consensus on the optimal management of these patients. The aim of this study was to examine the outcomes of patients diagnosed with an incidental meningioma who were treated with surgery or radiotherapy.

METHODS

Single-center retrospective cohort study of adult patients diagnosed with an incidental intracranial meningioma (2007-2015). Outcomes recorded were postintervention morbidity, histopathologic diagnosis, and treatment response.

RESULTS

Out of 441 patients, 44 underwent treatment. Median age at intervention was 56.1 years (interquartile range [IQR], 49.6-66.5); patients included 35 women and 9 men. The main indication for imaging was headache (25.9%). Median meningioma volume was 4.55 cm³ (IQR, 1.91-8.61), and the commonest location was convexity (47.7%). Six patients underwent surgery at initial diagnosis. Thirty-eight had intervention (34 with surgery and 4 with radiotherapy) after a median active monitoring duration of 24 months (IQR, 11.8-42.0). Indications for treatment were radiologic progression (n = 26), symptom development (n = 6), and patient preference (n = 12). Pathology revealed World Health Organization (WHO) grade 1 meningioma in 36 patients and WHO grade 2 in 4 patients. The risk of postoperative surgical and medical morbidity requiring treatment was 25%. Early and late moderate adverse events limiting activities of daily living occurred in 28.6% of patients treated with radiotherapy. Recurrence rate after surgery was 2.5%. All meningiomas regressed or remained radiologically stable after radiotherapy.

CONCLUSIONS

The morbidity after treatment of incidental intracranial meningioma is not negligible. Considering most operated tumors are WHO grade 1, treatment should be reserved for those manifesting symptoms or demonstrating substantial growth on radiologic surveillance.

Natural History of Meningiomas: Review with Meta-analyses

Observation has been a mainstay in asymptomatic meningiomas, but it may increase the risk associated with treatment due to tumor enlargement and the aging of patients. Understanding the natural course of meningiomas is important to provide appropriate treatment. The majority of previous studies investigated factors related to their growth, but failed to demonstrate their relationship with symptomatic progression (sympP) because of its rarity. We reviewed and meta-analyzed 27 studies that investigated natural courses in asymptomatic or untreated meningiomas to find clinico-radiological factors predictive of radiological progression (radioP), growth speed, and sympP. In results of time-growth analysis, two-thirds of meningiomas showed radioP defined by a volume criterion and the rate approached a plateau at 4-5 years. In growth curve analyses, about half of incidental meningiomas presented decelerating or no growth, while less than one-quarter of them grew exponentially. RadioP, growth speed [annual volume change (AVC) or relative growth rate], and sympP each had different factors related to them. Younger age, non-calcification, and high intensity on T2-weighted image were related to radioP and rapid growth speed, but not to sympP. Tumors in males and those of larger size were likely to be symptomatic in the meta-analysis. AVC (≥2.1 cm³/year) was the strongest indicator of sympP. Apart from perifocal edema, radiological features at up-front imaging may not be useful for predicting sympP. This may be due to dynamic changes of those radiological markers in the long term. Quantified tumor size and growth speed, especially AVC, are important markers for deciding on treatment.

Multisession radiosurgery for intracranial meningioma treatment: study protocol of a single arm, monocenter, prospective trial

Background

Single session radiosurgery represents a widely accepted treatment for intracranial meningiomas. However, this approach could involve a high risk of treatment-related complications when applied to large volume lesions. In these cases and for those not suitable for surgical resection, radiosurgery in multisession setting could represents a viable option. The literature results are reassuring in terms of correlated adverse events as well as in terms of tumor control. However, no prospective long-term results are available. In this scenario, we design a prospective monocentric phase II study, in order to verify the safety of a multisession radiosurgery schedule delivering 25 Gy in 5 daily fractions.

Methods

Patients diagnosed with large and/or near to critical structures, intracranial meningiomas have been treated by means of multisession radiosurgery in both exclusive and postoperative settings. The primary study aim is safety that has been being prospectively scored based on international scales, including NCI Common Toxicity criteria, version 4.03, Barrow Neurological Institute pain intensity score, Barrow Neurological Institute facial numbness score and House-Brackmann Facial Nerve Grading System for qualitative analysis. Secondary aim is treatment efficacy in terms of local control that has been being assessed on volumetric analysis.

Discussion

This is the first prospective phase II trial on multisession radiosurgery for large and/or near to critical structures intracranial meningiomas. If positive results will be found, this study could represent the starting point for a phase III trial exploring the role of multisession radiosurgery in the exclusive and postoperative radiation therapy treatment of intracranial meningiomas.

Trial registration

Trial registration: clinicaltrials.gov platform (Multisession Radiosurgery in Large Meningiomas –MuRaLM- identifier NCT02974127). Registered: November 28, 2016. Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT02974127?term=radiosurgery&cond=Intracranial+Meningioma&draw=2&rank=1

A practical predictor of the growth potential of benign meningiomas: Hypointensity of surface layer in T2-weighted magnetic resonance imaging

BACKGROUND

Accurate evaluation of proliferative potential is particularly important in the clinical management of individual patients with meningiomas. We introduce a new feature in the parenchyma of meningioma, namely, hypointensity of the surface layer (HSL), on T2-weighted MR images and compare it with a cellular proliferation index and growth speed.

MATERIALS AND METHODS

We retrospectively analyzed the records of consecutive patients with WHO grade I meningiomas in two institutes: an operated group with 124 meningiomas resected in one institute, and an observed group with 89 meningiomas monitored without surgery in the other. Proliferative potential was evaluated using the MIB-1 labeling index (MIB-1 LI) for the operated group and using the relative growth rate on serial MR images for the observed group.

RESULTS

In the operated group, 60 (48.4%) meningiomas exhibited HSL. HSL-positive meningiomas were significantly smaller in size and more often calcified than HSL-negative ones. Univariate analysis showed that HSL negativity, large size, no calcification, and surrounding brain edema were significantly associated with high MIB-1 LI (p < 0.05). Multivariate analysis demonstrated that only HSL was significantly related to MIB-1 LI (p = 0.001). HSL did not correlate with tumor recurrence after resection. In the observed group, 43 (48.3%) meningiomas exhibited HSL and they presented a significantly slow relative growth rate.

CONCLUSIONS

HSL is a simple and new radiological feature indicative of low proliferative potential and a low risk of enlargement of meningiomas. The presence or absence of HSL may serve as a key parameter for the selection of aggressive treatment or active observation.

A National Consensus Survey for Current Practice in Brain Tumor Management II: Diffuse Midline Glioma and Meningioma

Background

The Guideline Working Group of the Korean Society for Neuro-Oncology (KSNO) conducted a nationwide questionnaire survey for diverse queries faced in the treatment of brain tumors. As part II of the survey, the aim of this study is to evaluate the national patterns of clinical practice for patients with diffuse midline glioma and meningioma.

Methods

A web-based survey was sent to all members of the KSNO by email. The survey included 4 questions of diffuse midline glioma and 6 questions of meningioma (including 2 case scenarios). All questions were developed by consensus of the Guideline Working Group.

Results

In the survey about diffuse midline glioma, 76% respondents performed histologic confirmation to identify H3K27M mutation on immunohistochemical staining or sequencing methods. For treatment of diffuse midline glioma, respondents preferred concurrent chemoradiotherapy with temozolomide (TMZ) and adjuvant TMZ (63.8%) than radiotherapy alone (34.0%). In the survey about meningioma, respondents prefer wait-and-see policy for the asymptomatic small meningioma without peritumoral edema. However, a greater number of respondents had chosen surgical resection as the first choice for all large size meningiomas without exception, and small size meningiomas with either peritumoral edema or eloquent location. There was no single opinion with major consensus on long-term follow-up plans for asymptomatic meningioma with observation policy. As many as 68.1% of respondents answered that they would not add any adjuvant therapies for World Health Organization grade II meningiomas if the tumor was totally resected including dura.

Conclusion

The survey demonstrates the prevailing clinical practice patterns for patients with diffuse midline glioma and meningioma among members of the KSNO. This information provides a point of reference for establishing a practical guideline in the management of diffuse midline glioma and meningioma.

Treatment of Asymptomatic Meningioma With Gamma Knife Radiosurgery: Long-Term Follow-up With Volumetric Assessment and Clinical Outcome

BACKGROUND

Some patients are diagnosed with asymptomatic meningioma(s) after undergoing a screening CT and MRI for minor ailments or postresection.

OBJECTIVE

To help clinicians in decision making for treatment of asymptomatic meningiomas.

METHODS

A single center retrospective cohort study of 117 patients with 122 tumors treated with Gamma Knife radiosurgery (GKRS; Elekta AB, Stockholm, Sweden). Patients were followed with longitudinal imaging and clinical evaluations. Tumor volumetry and developments of new signs or symptoms after GKRS were the end points in the study.

RESULTS

Median patient age at GKRS was 60 yr (range 21-86 yr) with a median clinical follow-up of 53 mo (range 20-252 mo). The median pre-GKRS tumor volume was 3.6 ± 3.8 cc (±standard deviation). Tumors were treated with a median margin dose of 14 ± 2 Gy. At last follow-up, median tumor volume was 2.5 ± 3.6 cc. Radiological progression-free survival (PFS) rates were 97% and 94.4% at 5 yr and 10 yr, respectively. Clinical PFS rates were 86% and 70% at 5 yr and 10 yr, respectively. Development of neurological complications was seen in 21 (18%) patients, and 11 (52%) of them had undergone surgical resection prior to GKRS.

CONCLUSION

GKRS is a reasonable treatment strategy for asymptomatic meningiomas and compares favorably to natural history studies in terms of tumor control and neurological preservation. It results in relatively low morbidity in previously untreated meningiomas and serves as an appealing alternative treatment modality for recurrent meningiomas in asymptomatic patients.

Clinical and radiological outcomes of proactive Gamma Knife surgery for asymptomatic meningiomas compared with the natural course without intervention

OBJECTIVE

This study aimed to verify the effect of proactive Gamma Knife surgery (GKS) in the treatment of asymptomatic meningioma compared with the natural course without any therapeutic intervention.

METHODS

From January 2006 to May 2017, 354 patients newly diagnosed with asymptomatic meningioma were reviewed and categorized into GKS (n = 153) and observation (n = 201) groups. Clinical and radiological progression rates were examined, and changes in volume were analyzed.

RESULTS

Clinical progression (i.e., clinician-judged progression), combining symptomatic progression (n = 43) and clinician-judged increase in size using images routinely acquired (n = 34), occurred in 4 patients (2.6%) and 73 patients (36.3%) in the GKS and observation groups, respectively (p < 0.001). The clinical progression-free survival (PFS) rates in the GKS and observation groups were 98.7% and 64.6%, respectively, at 5 years (p < 0.001), and 92.9% and 42.7%, respectively, at 10 years (p < 0.001). The radiological tumor control rate was 94.1% in the GKS group, and radiological progression was noted in 141 patients (70.1%) in the observation group. The radiological PFS rates in the GKS and observation groups were 94.4% and 38.5%, respectively, at 5 years (p < 0.001), and 88.5% and 7.9%, respectively, at 10 years (p < 0.001). Young age, absence of calcification, peritumoral edema, and high T2 signal intensity were correlated with clinical progression in the observation group. Volumetric analysis showed that untreated tumors gradually increased in size. However, GKS-treated tumors shrank gradually, although transient volume expansion was observed in the first 6 months. Adverse events developed in 26 of the 195 GKS-treated patients (13.3%), including 1 (0.5%) major event requiring microsurgery due to severe edema after GKS. Peritumoral edema was related to the development of adverse events (p = 0.004).

CONCLUSIONS

Asymptomatic meningioma is a benign disease; however, nearly two-thirds of patients experience tumor growth and one-third of untreated patients eventually require neurosurgical interventions during watchful waiting. GKS can control tumors clinically and radiologically with high probability. Although the risk of transient adverse events exists, proactive GKS may be a reasonable treatment option when there are no comorbidities limiting life expectancy.

Incidental intracranial meningiomas: a systematic review and meta-analysis of prognostic factors and outcomes

BACKGROUND

Incidental discovery accounts for 30% of newly-diagnosed intracranial meningiomas. There is no consensus on their optimal management. This review aimed to evaluate the outcomes of different management strategies for these tumors.

METHODS

Using established systematic review methods, six databases were scanned up to September 2017. Pooled event proportions were estimated using a random effects model. Meta-regression of prognostic factors was performed using individual patient data.

RESULTS

Twenty studies (2130 patients) were included. Initial management strategies at diagnosis were: surgery (27.3%), stereotactic radiosurgery (22.0%) and active monitoring (50.7%) with a weighted mean follow-up of 49.5 months (SD = 29.3). The definition of meningioma growth and monitoring regimens varied widely impeding relevant meta-analysis. The pooled risk of symptom development in patients actively monitored was 8.1% (95% CI 2.7-16.1). Associated factors were peritumoral edema (OR 8.72 [95% CI 0.35-14.90]) and meningioma diameter ≥ 3 cm (OR 34.90 [95% CI 5.17-160.40]). The pooled proportion of intervention after a duration of active monitoring was 24.8% (95% CI 7.5-48.0). Weighted mean time-to-intervention was 24.8 months (SD = 18.2). The pooled risks of morbidity following surgery and radiosurgery, accounting for cross-over, were 11.8% (95% CI 3.7-23.5) and 32.0% (95% CI 10.6-70.5) respectively. The pooled proportion of operated meningioma being WHO grade I was 94.0% (95% CI 88.2-97.9).

CONCLUSION

The management of incidental meningioma varies widely. Most patients who clinically or radiologically progressed did so within 5 years of diagnosis. Intervention at diagnosis may lead to unnecessary overtreatment. Prospective data is needed to develop a risk calculator to better inform management strategies.

Incidental Meningiomas: Management in the Neuroimaging Era

The number of patient imaging studies has increased because of precautious physicians ordering scans when a vague symptom is presented; subsequently, the number of incidental meningiomas detected has increased as well. These brain tumors do not present with related symptoms and are usually small. MRI and computed tomographic scans most frequently capture incidental meningiomas. Incidental meningiomas are managed with observation, radiation, and surgical resection. Ultimately, a conservative approach is recommended, such as observing an incidental meningioma and then only radiating if the tumor displays growth, whereas a surgical approach is to be used only when proven necessary.

Clinical features and treatment outcome of chordoid meningiomas in a single institute

Objective

Meningioma is the second most common primary central nervous system neoplasm. In contrast, chordoid meningioma is rare; due to the paucity of cases, little is known about its clinical features or treatment outcomes. The objectives of this study were to describe the clinical characteristics and outcomes for patients with chordoid meningioma.

Methods

In total, 16 patients, with newly diagnosed chordoid meningioma who underwent surgical excision between 1999 and 2012 were included. We retrospectively evaluated the medical records, radiological findings, and pathological findings. The median follow-up period was 56.5 (range, 3-170) months. The MIB-1 labeling index ranged from 1 to 26.60% (median, 5.04).

Results

Simpson grade I, II, and III resections were performed in four, nine, and three patients, respectively. The overall recurrence rate was 37.5%. Overall progression-free survival (PFS) after resection was 94.7 months (95% CI=62.9-126.6). Of the 4 patients with Simpson grade I resection, recurrence occurred in one patient. Among the Simpson grade II and III resection groups, eight patients underwent adjuvant radiation therapy and they showed significantly longer PFS (121 months, 95% CI=82.1-159.9) than the patients who underwent surgery alone (40.5 months, 95% CI=9.6-71.3) by the log-rank test (p<0.05).

Conclusion

Chordoid meningiomas are difficult to manage and have a high rate of recurrence. Complete resection of the tumor is a key determinant of better outcomes. Adjuvant radiation therapy is recommended, eparticulary when Simpson grade I resection was not achieved.

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 surgery for the treatment of patients with asymptomatic meningiomas

OBJECT

Increasingly, meningiomas are detected incidentally, prior to symptom development. While these lesions are traditionally managed conservatively until symptoms develop or lesion growth occurs, it is conceivable that patients at high risk for symptom development may benefit from earlier intervention prior to the appearance of symptoms. However, little research has been performed to determine whether Gamma Knife surgery (GKS) can alter the rate of symptom development in such patients.

METHODS

A retrospective case study was performed by screening the University of Virginia GKS database for patients treated for asymptomatic meningiomas. From the patient's medical records, pertinent demographic and treatment information was obtained. Yearly follow-up MRI had been performed to assess tumor control and detect signs of radiation-induced injury. Clinical follow-up via neurological examination had been performed to assess symptom development.

RESULTS

Forty-two patients, 33 females (78.6%) and 9 males (21.4%), with 42 asymptomatic meningiomas were included in the analysis. The median age at GKS was 53 years. The most common lesion location was the cerebral convexities (10 lesions [23.8%]), and the median lesion size was 4.0 ml. The median duration of imaging and clinical follow-ups was 59 and 76 months, respectively. During the follow-up period, 1 tumor (2.4%) increased in size, 2 patients (4.8%) demonstrated symptoms, and 1 patient (2.4%) exhibited possible signs of radiation-induced injury. Thus, actuarial tumor control rates were 100%, 95.7%, and 95.7% for 2, 5, and 10 years, respectively. Actuarial symptom control at 5 and 10 years was 97% and 93.1%, respectively. Overall progression-free survival was 91.1% and 77.8% at 5 and 10 years, respectively.

CONCLUSIONS

Compared with published rates of symptom development in patients with untreated meningiomas, results in this study indicated that patients with asymptomatic lesions may benefit from prophylactic radiosurgery prior to the appearance of symptoms. Additionally, GKS is a treatment option that offers low morbidity.