Radiosurgery for intracranial meningiomas: A systematic review and meta-analysis

Predictors of salvage therapy for parasagittal meningiomas treated with primary surgery, radiosurgery, or surgery plus adjuvant radiotherapy

OBJECTIVE

Parasagittal meningiomas (PM) are treated with primary microsurgery, radiosurgery (SRS), or surgery with adjuvant radiation. We investigated predictors of tumor progression requiring salvage surgery or radiation treatment. We sought to determine whether primary treatment modality, or radiologic, histologic, and clinical variables were associated with tumor progression requiring salvage treatment.

METHODS

Retrospective study of 109 consecutive patients with PMs treated with primary surgery, radiation (RT), or surgery plus adjuvant RT (2000-2017) and minimum 5 years follow-up. Patient, radiologic, histologic, and treatment data were analyzed using standard statistical methods.

RESULTS

Median follow up was 8.5 years. Primary treatment for PM was surgery in 76 patients, radiation in 16 patients, and surgery plus adjuvant radiation in 17 patients. Forty percent of parasagittal meningiomas in our cohort required some form of salvage treatment. On univariate analysis, brain invasion (OR: 6.93, p < 0.01), WHO grade 2/3 (OR: 4.54, p < 0.01), peritumoral edema (OR: 2.81, p = 0.01), sagittal sinus invasion (OR: 6.36, p < 0.01), sagittal sinus occlusion (OR: 4.86, p < 0.01), and non-spherical shape (OR: 3.89, p < 0.01) were significantly associated with receiving salvage treatment. On multivariate analysis, superior sagittal sinus invasion (OR: 8.22, p = 0.01) and WHO grade 2&3 (OR: 7.58, p < 0.01) were independently associated with receiving salvage treatment. There was no difference in time to salvage therapy (p = 0.11) or time to progression (p = 0.43) between patients receiving primary surgery alone, RT alone, or surgery plus adjuvant RT. Patients who had initial surgery were more likely to have peritumoral edema on preoperative imaging (p = 0.01). Median tumor volume was 19.0 cm3 in patients receiving primary surgery, 5.3 cm3 for RT, and 24.4 cm3 for surgery plus adjuvant RT (p < 0.01).

CONCLUSION

Superior sagittal sinus invasion and WHO grade 2/3 are independently associated with PM progression requiring salvage therapy regardless of extent of resection or primary treatment modality. Parasagittal meningiomas have a high rate of recurrence with 80.0% of patients with WHO grade 2/3 tumors with sinus invasion requiring salvage treatment whereas only 13.6% of the WHO grade 1 tumors without sinus invasion required salvage treatment. This information is useful when counseling patients about disease management and setting expectations.

A Systematic Review Informing the Management of Symptomatic Brain Radiation Necrosis After Stereotactic Radiosurgery and International Stereotactic Radiosurgery Society Recommendations

Radiation necrosis (RN) secondary to stereotactic radiosurgery is a significant cause of morbidity. The optimal management of corticosteroid-refractory brain RN remains unclear. Our objective was to summarize the literature specific to efficacy and toxicity of treatment paradigms for patients with symptomatic corticosteroid-refractory RN and to provide consensus guidelines for grading and management of RN on behalf of the International Stereotactic Radiosurgery Society. A systematic review of articles pertaining to treatment of RN with bevacizumab, laser interstitial thermal therapy (LITT), surgical resection, or hyperbaric oxygen therapy was performed. The primary composite outcome was clinical and/or radiologic stability/improvement (ie, proportion of patients achieving improvement or stability with the given intervention). Proportions of patients achieving the primary outcome were pooled using random weighted-effects analysis but not directly compared between interventions. Twenty-one articles were included, of which only 2 were prospective studies. Thirteen reports were relevant for bevacizumab, 5 for LITT, 5 for surgical resection and 1 for hyperbaric oxygen therapy. Weighted effects analysis revealed that bevacizumab had a pooled symptom improvement/stability rate of 86% (95% CI 77%-92%), pooled T2 imaging improvement/stability rate of 93% (95% CI 87%-98%), and pooled T1 postcontrast improvement/stability rate of 94% (95% CI 87%-98%). Subgroup analysis showed a statistically significant improvement favoring treatment with low-dose (below median, ≤7.5 mg/kg every 3 weeks) versus high-dose bevacizumab with regards to symptom improvement/stability rate (P = .02) but not for radiologic T1 or T2 changes. The pooled T1 postcontrast improvement/stability rate for LITT was 88% (95% CI 82%-93%), and pooled symptom improvement/stability rate for surgery was 89% (95% CI 81%-96%). Toxicity was inconsistently reported but was generally low for all treatment paradigms. Corticosteroid-refractory RN that does not require urgent surgical intervention, with sufficient noninvasive diagnostic testing that favors RN, can be treated medically with bevacizumab in carefully selected patients as a strong recommendation. The role of LITT is evolving as a less invasive image guided surgical modality; however, the overall evidence for each modality is of low quality. Prospective head-to-head comparisons are needed to evaluate the relative efficacy and toxicity profile among treatment approaches.

Evaluation of inverse treatment planning for gamma knife radiosurgery using fMRI brain activation maps as organs at risk

BACKGROUND

Stereotactic radiosurgery (SRS) can be an effective primary or adjuvant treatment option for intracranial tumors. However, it carries risks of various radiation toxicities, which can lead to functional deficits for the patients. Current inverse planning algorithms for SRS provide an efficient way for sparing organs at risk (OARs) by setting maximum radiation dose constraints in the treatment planning process.

PURPOSE

We propose using activation maps from functional MRI (fMRI) to map the eloquent regions of the brain and define functional OARs (fOARs) for Gamma Knife SRS treatment planning.

METHODS

We implemented a pipeline for analyzing patient fMRI data, generating fOARs from the resulting activation maps, and loading them onto the GammaPlan treatment planning software. We used the Lightning inverse planner to generate multiple treatment plans from open MRI data of five subjects, and evaluated the effects of incorporating the proposed fOARs.

RESULTS

The Lightning optimizer designs treatment plans with high conformity to the specified parameters. Setting maximum dose constraints on fOARs successfully limits the radiation dose incident on them, but can have a negative impact on treatment plan quality metrics. By masking out fOAR voxels surrounding the tumor target it is possible to achieve high quality treatment plans while controlling the radiation dose on fOARs.

CONCLUSIONS

The proposed method can effectively reduce the radiation dose incident on the eloquent brain areas during Gamma Knife SRS of brain 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.

Long Term Outcome and Quality of Life of Intracranial Meningioma Patients Treated with Pencil Beam Scanning Proton Therapy

The aim of this study was to assess the clinical outcome, including QoL, of patients with intracranial meningiomas WHO grade 1-3 who were treated with Pencil Beam Scanning Proton Therapy (PBS PT) between 1997 and 2022. Two hundred patients (median age 50.4 years, 70% WHO grade 1) were analyzed. Acute and late side effects were classified according to CTCAE version 5.0. Time to event data were calculated. QoL was assessed descriptively by the EORTC-QLQ-C30 and BN20 questionnaires. With a median follow-up of 65 months (range: 3.8-260.8 months) the 5 year OS was 95.7% and 81.8% for WHO grade 1 and grade 2/3, respectively (p < 0.001). Twenty (10%) local failures were observed. Failures occurred significantly (p < 0.001) more frequent in WHO grade 2 or 3 meningioma (WHO grade 1: n = 7, WHO grade 2/3: n = 13), in patients with multiple meningiomas (p = 0.005), in male patients (p = 0.005), and when PT was initiated not as upfront therapy (p = 0.011). There were no high-grade toxicities in the majority (n = 176; 88%) of patients. QoL was assessed for 83 (41.5%) patients and for those patients PT did not impacted QoL negatively during the follow-up. In summary, we observed very few local recurrences of meningiomas after PBS PT, a stable QoL, and a low rate of high-grade toxicity.

Efficacy and Safety of Primary Stereotactic Radiosurgery in Patients With Intraventricular Meningiomas

Purpose

Primary stereotactic radiosurgery for intraventricular meningiomas remains controversial owing to the potential for life-threatening peritumoral edema and lack of long-term follow-up data. We review the literature and present the largest series to assess efficacy and safety of primary stereotactic radiosurgery.

Methods and Materials

A systematic review of the literature for primary stereotactic radiosurgery for intraventricular meningiomas was conducted. The retrospective series presented here comprised 33 patients who received primary stereotactic radiosurgery between 1999 and 2015 for a radiologically detected intraventricular meningioma. Demographic, diagnostic, and therapeutic data were extracted from medical records, imaging, and treatment-planning systems. Both standalone and pooled analysis were performed.

Results

The mean patient age was 53 years, and 24 patients (73%) were female. The median Karnofsky performance status pretreatment was 80 (range, 60-100). The majority of lesions were located in the lateral ventricles (n = 32; 97%). The mean tumor volume was 8.7 cm³ (range, 0.6-44.55 cm³). The mean delivered dose was 1390.9 cGy. Complete imaging follow-up data were available for 21 patients (64%). Of those, 14 (67%) showed partial or marginal response, 7 (33%) had stable disease, and no patient progressed per Response Assessment in Neuro-Oncology criteria. On last follow-up, 32 patients (97%) had significant improvement in performance status and a decrease in pretreatment symptoms. No high-grade Common Terminology Criteria for Adverse Events (version 5.0) toxicity was observed with the dose range employed.

Conclusions

Primary stereotactic radiosurgery for intraventricular meningiomas shows excellent treatment efficacy and low toxicity in patients with a long follow-up period. The best therapeutic algorithm remains to be established leveraging further clinical investigation.

Hypofractionated Radiosurgery for Large or in Critical-Site Intracranial Meningioma: Results of a Phase 2 Prospective Study

PURPOSE

Radiosurgery is a well-known, safe, and effective technique used in the treatment of intracranial meningiomas. However, single-fraction radiosurgery can lead to high toxicity rates when large-volume or critically located lesions are targeted. Multisession-also called hypofractionated-radiosurgery (hypo-RS) might overcome these limitations. Accordingly, we carried out a prospective phase 2 trial, aiming to establish whether a fractionated RS schedule of 25 Gy in 5 fractions would be safe and effective in treating large (≥ 3 cm) and/or critically located (<3 mm from critical structures) grade 1 intracranial meningiomas. The main aim was to evaluate the safety of hypo-RS in terms of absence of adverse events. The secondary aim was to evaluate tumor response in terms of local control, defined as stability or reduction of lesion volume.

METHODS AND MATERIALS

We prospectively enrolled patients with diagnoses of grade 1 meningiomas, large size and/or critically located lesions, either histologically diagnosed or imaging defined. Additional inclusion criteria were signed informed consent, an age of ≥18 years, and Karnofsky Performance Status ≥70.

RESULTS

Between 2011 and 2016, 178 patients were consecutively enrolled. The median follow-up was 53 months (range, 4-101 months). Overall, the toxicity rate was 12.7% (21 of 166 patients). At a 5-year minimum follow-up, the patients' toxicity rates were 11.7 % (9 of 77 patients). Symptom evaluation at both 3-year and last follow-up showed an improvement in most of the patients. Five-year local tumor control was 97% (95% confidence interval, 92%-99%).

CONCLUSIONS

Hypo-RS schedule of 25 Gy in 5 fractions is a well-tolerated option in the treatment of large-volume and/or critically located benign meningiomas. Early results suggest favorable local control, although longer-term follow-up is needed.

Stereotactic Therapies for Meningiomas

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

Outcomes after gamma knife radiosurgery for intraventricular meningiomas

BACKGROUND

Intraventricular meningiomas (IVMs) are rare tumors with considerable treatment-associated morbidity due to their challenging location. Treatment with stereotactic radiosurgery (SRS) is sparsely reported in the literature. We describe our experience over the last 35 years using Gamma knife radiosurgery (GKRS) for IVMs.

METHODS

We retrospectively reviewed the GKRS database identifying 2501 meningiomas treated at the University of Pittsburgh Medical Center over the last 35 years. Nineteen patients with (12 males, mean age = 53.2 years, range 14-84) 20 IVMs were identified. Headache was the most frequent presenting symptom (N = 12), and the trigone of the lateral ventricle was the most common location (N = 18). The median tumor volume was 4.8 cc (range, 0.8-17). The median margin dose was 14 Gy (range, 12-25) delivered at 50% isodose line.

RESULTS

At a median follow-up of 63.1 months (range, 6-322.4) symptom control was achieved in 18 (94.7%) patients. The overall progression-free survival (PFS) was 95% at 5 years, and 85% at 10-years. After Log-rank test, patients who underwent GKRS within 12 months after diagnosis (vs. ≥ 12 months, X²: 4.455, p = 0.035), patients treated with primary GKRS without prior biopsy (vs. prior biopsy, X²: 4.000, p = 0.046), and patients with WHO grade I meningioma (vs. WHO II, X²: 9.000, p = 0.003) had a longer PFS. Imaging showed peritumoral edema in seven cases at a median of 10.5 (range, 6.13-24.3) months after GKRS. Only three of these patients were symptomatic and were successfully managed with oral medications. Cox´s regression revealed that a V12Gy ≥ 10 cc [HR: 10.09 (95% CI: 2.11-48.21), p = 0.004], and tumor volume ≥ 8 cc [HR: 5.87 (95% CI: 1.28-26.97), p = 0.023] were associated with a higher risk of peritumoral edema.

CONCLUSION

GKRS is an effective and safe management option for intraventricular meningiomas. Early GKRS should be considered as a primary management modality for small and medium sized IVM and adjuvant management for residual IVMs.

Radiation of meningioma dural tail may not improve tumor control rates

Introduction

Dural tails are thickened contrast-enhancing portions of dura associated with some meningiomas. Prior studies have demonstrated the presence of tumor cells within the dural tail, however their inclusion in radiation treatment fields remains controversial. We evaluated the role of including the dural tail when treating a meningioma with stereotactic radiation and the impact on tumor recurrence.

Methods

This is a retrospective, single-institution, cohort study of patients with intracranial World Health Organization (WHO) grade 1 meningioma and identified dural tail who were treated with stereotactic radiosurgery (SRS) or fractionated stereotactic radiotherapy (FSRT) from January 2012 to December 2018. SRS and FSRT subgroups were categorized based on coverage or non-coverage of the dural tail by the radiation fields, as determined independently by a radiation oncologist and a neurosurgeon. Demographics, tumor characteristics, radiation plans, and outcomes were evaluated. High grade tumors were analyzed separately.

Results

A total of 187 WHO grade 1 tumors from 177 patients were included in the study (median age: 62 years, median follow-up: 40 months, 78.1% female) with 104 receiving SRS and 83 receiving FSRT. The dural tail was covered in 141 (75.4%) of treatment plans. There was no difference in recurrence rates (RR) or time to recurrence (TTR) between non-coverage or coverage of dural tails (RR: 2.2% vs 3.5%, P = 1.0; TTR: 34 vs 36 months, P = 1.00). There was no difference in the rate of radiation side effects between dural tail coverage or non-coverage groups. These associations remained stable when SRS and FSRT subgroups were considered separately, as well as in a high grade cohort of 16 tumors.

Conclusion

Inclusion of the dural tail in the SRS or FSRT volumes for meningioma treatment does not seem to reduce recurrence rate. Improved understanding of dural tail pathophysiology, tumor grade, tumor spread, and radiation response is needed to better predict the response of meningiomas to radiotherapy.

Comparison of Active Surveillance to Stereotactic Radiosurgery for the Management of Patients with an Incidental Frontobasal Meningioma-A Sub-Analysis of the IMPASSE Study

Meningioma is a common incidental finding, and clinical course varies based on anatomical location. The aim of this sub-analysis of the IMPASSE study was to compare the outcomes of patients with an incidental frontobasal meningioma who underwent active surveillance to those who underwent upfront stereotactic radiosurgery (SRS). Data were retrospectively collected from 14 centres. The active surveillance (n = 28) and SRS (n = 84) cohorts were compared unmatched and matched for age, sex, and duration of follow-up (n = 25 each). The study endpoints included tumor progression, new symptom development, and need for further intervention. Tumor progression occurred in 52.0% and 0% of the matched active surveillance and SRS cohorts, respectively (p < 0.001). Five patients (6.0%) treated with SRS developed treatment related symptoms compared to none in the active monitoring cohort (p = 0.329). No patients in the matched cohorts developed symptoms attributable to treatment. Three patients managed with active surveillance (10.7%, unmatched; 12.0%, matched) underwent an intervention for tumor growth with no persistent side effects after treatment. No patients subject to SRS underwent further treatment. Active monitoring and SRS confer a similarly low risk of symptom development. Upfront treatment with SRS improves imaging-defined tumor control. Active surveillance and SRS are acceptable treatment options for incidental frontobasal meningioma.

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.

Stereotactic Radiosurgery for Olfactory Groove Meningiomas: An International, Multicenter Study

BACKGROUND

Stereotactic radiosurgery (SRS) is increasingly considered for selected olfactory groove meningiomas (OGMs).

OBJECTIVE

To investigate the safety and efficacy of SRS for OGMs.

METHODS

From 20 institutions participating in the International Radiosurgery Research Foundation, we pooled patients who underwent SRS for histologically confirmed or radiologically suspected WHO grade I OGMs and were followed for 6 mo or more after the SRS.

RESULTS

In total, 278 (median age 57 yr) patients underwent SRS for histologically confirmed (29%) or radiologically suspected (71%) WHO grade I OGMs Median treatment volume was 4.60 cm3 (range: 0.12-27.3 cm3), median prescription dose was 12 Gy, and median dose to the olfactory nerve was 11.20 Gy. During median post-SRS imaging follow-up of 39 mo (range: 6-240 mo), 43% of patients had partial or marginal response, 54% of patients had stable disease, and 3% of patients experienced progression. During median post-SRS clinical follow-up of 51 mo (range: 6-240 mo), 36 (13%) patients experienced clinical and/or radiological adverse radiation events (AREs). Elevated risk of AREs was associated with larger OGM volume (P = .009) and pre-SRS peritumoral T2/fluid-attenuated inversion-recovery signal abnormalities (P < .001). After the SRS, olfaction remained stable, improved, or deteriorated in 90%, 8%, and 2% of patients, respectively. Complete post-SRS anosmia was predicted by partial/complete anosmia before the SRS (odds ratio [OR] = 83.125; 95% CI [24.589-281.01], P < .001) and prior resection of OGM (OR = 3.919; 95% CI [1.713-8.970], P = .001).

CONCLUSION

SRS is associated with durable local control of the majority of OGM patients with acceptable safety profile. SRS allows preservation or improvement of olfactory function in the majority of OGM patients.

Long term follow up in 183 high grade meningioma: A single institutional experience

INTRODUCTION

Meningiomas are usually considered benign lesions, however a proportion of them shows a more aggressive behavior, defined high-grade meningiomas (HGM). Effective medical treatments are lacking, especially at the time of recurrence.

METHODS

Through a retrospective analysis, we examined epidemiological, diagnostic, therapeutic, recurrence information and survival data of HGM treated at our institution between 2010 and 2018.

RESULTS

183 patients (105 females and 78 males), with median age of 58 years (25-88), were included; 168 were atypical, 12 anaplastic, 3 rhabdoid. Overall, m-PFS was 4.2 years, and m-OS was 10.3 years. Gross-total resection had a 5-year survival rate of 95% compared with subtotal/partial resection (86% and 67%) (p = 0.002). Higher expression of Ki-67/MIB-1 seems associated with higher risk of death (HR:1.06 with 95% CI, 1.00-1.12, p = 0.03). No statistically significant differences were seen in survival between the group managed with a wait-and-see strategy vs the group treated with RT while a difference on PFS was seen (4.1 years vs 5.2 years p = 0.03). After second recurrence, the most employed treatments were systemic therapies with a very limited effect on disease control.

CONCLUSIONS

Data confirmed the aggressive behavior of HGM. The extent of resection seems to correlate with a favorable outcome regardless histological subtypes. The role of RT remains controversial, with no statistically significant impact on OS but a possible role on PFS. Recurrent HGM remains the real challenge, to date no chemotherapies are able to achieve disease control. Future research should focus on biological/molecular predictors in order to achieve a patient-tailored treatment.

Sphenoid wing meningiomas

Meningiomas that arise from the dura along the sphenoid wing can occur in globoid or en plaque forms. Radiographically they can be defined as occurring in the medial, middle, or lateral portions of the sphenoid wing. The medial group carries the highest neurologic risk for surgical treatment, while the hyperostosing en plaque type is the most difficult to remove completely because of orbital and bone involvement. This chapter addresses the clinical presentation and surgical treatment of sphenoid wing meningiomas with an emphasis on the most recent results from the literature.

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.

Intraoperative MRI for the microsurgical resection of meningiomas close to eloquent areas or dural sinuses: patient series

BACKGROUND

Meningiomas are the most commonly encountered nonglial primary intracranial tumors. The authors report on the usefulness of intraoperative magnetic resonance imaging (iMRI) during microsurgical resection of meningiomas located close to eloquent areas or dural sinuses and on the feasibility of further radiation therapy.

OBSERVATIONS

Six patients benefited from this approach. The mean follow-up period after surgery was 3.3 (median 3.2, range 2.1–4.6) years. Five patients had no postoperative neurological deficit, of whom two with preoperative motor deficit completely recovered. One patient with preoperative left inferior limb deficit partially recovered. The mean interval between surgery and radiation therapy was 15.8 (median 16.9, range 1.4–40.5) months. Additional radiation therapy was required in five cases after surgery. The mean preoperative tumor volume was 38.7 (median 27.5, range 8.6–75.6) mL. The mean postoperative tumor volume was 1.2 (median 0.8, range 0–4.3) mL. At the last follow-up, all tumors were controlled.

LESSONS

The use of iMRI was particularly helpful to (1) decide on additional tumor resection according to iMRI findings during the surgical procedure; (2) evaluate the residual tumor volume at the end of the surgery; and (3) judge the need for further radiation and, in particular, the feasibility of single-fraction radiosurgery.

Stereotactic radiosurgery for treating meningiomas eligible for complete resection

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Value of KI-67/MIB-1 labeling index and simpson grading system to predict the recurrence of who grade I intracranial meningiomas compared to who grade II

Simpson grading of resection has been used as a predictor of intracranial meningioma (IM) recurrence. Histopathological findings, like the Ki-67/MIB-1 labeling index, may be useful in the assessment risk of recurrence. Our objective was to analyze the predictive value of meningioma recurrence using both parameters. We retrospectively studied 322 consecutive patients with histopathological diagnosis of IM WHO grade I and 43 patients with IM WHO grade II in a 13-year period. Multivariate survival analysis was performed. In the WHO grade I IM group, recurrence was observed in 28 patients (8.69%). The Cox regression model for WHO grade I IM, provided a significative hazard ratio (HR) for Ki-67/MIB-1 index ≥3 (HR = 36.35, p < 0.001) and Simpson's grading resection, grade II (HR = 2.03, p = 0.045), grade III (HR = 3.41, p = 0.034) and grade IV (HR = 19.75, p ≥ 0.001). In the WHO grade II IM group, recurrence was observed in 10 patients (23.25%). The Cox regression model for WHO grade II IM, provided a significative hazard ratio (HR) for Ki-67/MIB-1 index ≥3% (HR = 1.66, p < 0.001) and Simpson's grading resection grade III (HR = 3.96, p = 0.027). The Kaplan-Meier survival curve showed a similar distribution of survival between WHO grade I IM with Ki-67/MIB-1 ≥3% and WHO grade II IM. In WHO grade I meningiomas, the Ki-67/MIB-1 index and Simpson grading were both independent predictors of recurrence. A similar management protocol should be advisable for WHO grade I with Ki-67/MIB-1 ≥3% and WHO grade II meningiomas.

Long-term apparent diffusion coefficient value changes in patients undergoing radiosurgical treatment of meningiomas

PURPOSE

A noninvasive method to predict the progress or treatment response of meningiomas is desirable to improve the tumor management. Studies showed that apparent diffusion coefficient (ADC) pretreatment values can predict treatment response in brain tumors. The aim of this study was to analyze changes of intratumoral ADC values in patients with meningiomas undergoing conservative or radiosurgery.

METHOD

MR images of 51 patients with diagnose of meningiomas were retrospectively reviewed. Twenty-five patients undergoing conservative or radiosurgery treatment, respectively, were included in the study. The follow-up data ranged between 1 and 10 years. Based on ROI analysis, the mean ADC values, ADC_10%min, and ADC_90%max were evaluated at different time points during follow-up.

RESULTS

Baseline ADC values in between both groups were similar. The ADC_mean values, ADC_10%min, and ADC_90%max within the different groups did not show any significant changes during the follow-up times in the untreated (ADC_mean over 10 years period: 0.87 ± 0.05 × 10^-3 mm²/s) and radiosurgically treated (ADC_mean over 4 years period: 1.02 ± 0.12 × 10^-3 mm²/s) group. However, statistically significant difference was observed when comparing the ADC_mean and ADC_90%max values of untreated with radiosurgically treated (p < 0.0001) meningiomas. Also, ADC_10%min revealed statistically significant difference between the untreated and the radiosurgery group (p < 0.05).

CONCLUSIONS

ADC values in conservatively managed meningiomas remain stable during the follow-up. However, meningiomas undergoing radiosurgery reveal significant change of the mean ADC values over time, suggesting that ADC may reflect a change in the biological behavior of the tumor. These observations might suggest the value of ADC changes as an indicator of treatment response.

ESTRO ACROP guideline for target volume delineation of skull base tumors

BACKGROUND AND PURPOSE

For skull base tumors, target definition is the key to safe high-dose treatments because surrounding normal tissues are very sensitive to radiation. In the present work we established a joint ESTRO ACROP guideline for the target volume definition of skull base tumors.

MATERIAL AND METHODS

A comprehensive literature search was conducted in PubMed using various combinations of the following medical subjects headings (MeSH) and free-text words: "radiation therapy" or "stereotactic radiosurgery" or "proton therapy" or "particle beam therapy" and "skull base neoplasms" "pituitary neoplasms", "meningioma", "craniopharyngioma", "chordoma", "chondrosarcoma", "acoustic neuroma/vestibular schwannoma", "organs at risk", "gross tumor volume", "clinical tumor volume", "planning tumor volume", "target volume", "target delineation", "dose constraints". The ACROP committee identified sixteen European experts in close interaction with the ESTRO clinical committee who analyzed and discussed the body of evidence concerning target delineation.

RESULTS

All experts agree that magnetic resonance (MR) images with high three-dimensional spatial accuracy and tissue-contrast definition, both T2-weighted and volumetric T1-weighted sequences, are required to improve target delineation. In detail, several key issues were identified and discussed: i) radiation techniques and immobilization, ii) imaging techniques and target delineation, and iii) technical aspects of radiation treatments including planning techniques and dose-fractionation schedules. Specific target delineation issues with regard to different skull base tumors, including pituitary adenomas, meningiomas, craniopharyngiomas, acoustic neuromas, chordomas and chondrosarcomas are presented.

CONCLUSIONS

This ESTRO ACROP guideline achieved detailed recommendations on target volume definition for skull base tumors, as well as comprehensive advice about imaging modalities and radiation techniques.

Clinical outcomes of fractionated stereotactic radiosurgery in treating perioptic meningiomas and schwannomas: A single-institutional experience

Application of radiosurgery to the newly diagnosed or post-operative residual perioptic lesions has been proved to improve tumor control. However, risk of vision injury induced by radiosurgery may increase substantially if the radiation dose is too high or tumor is close to the optic apparatus. The purpose of this study was to evaluate the safety and the effectiveness of fractionated stereotactic radiosurgery (FSRS) for perioptic tumors. We retrospectively analyzed 60 consecutive patients with 53 meningiomas and 7 schwannomas treated with FSRS between October 2007 and February 2020. We administered a marginal dose of 6-7 Gy (mean 6.8 Gy) per fraction and delivered 3 fractions in 3 consecutive days. The median tumor volume was 6.31 cm³ (range 0.3-58.23 cm³). The mean minimum lesion-optic distance (MLOD) is 0.85 mm (range 0-3 mm). After mean follow-up period of 69.6 months (range 6.82-156.32 months; median 58.9 months), the tumor control rates at 1, 3, 5, 8 and 13 years were 98.3%, 93.4%, 90.60%, 88.4% and 88.4%, respectively. Four out of the 60 tumors (6.7%) experienced a transient volume increase after FSRS. None of the patients developed visual impairment related to radiation induced optic neuropathy (RION) after FSRS. In conclusion, FSRS offers an alternative treatment option in treating perioptic meningiomas and schwannomas with acceptable tumor control rates and good visual preservation in the present study.

Glioblastoma multiforme as a secondary malignancy following stereotactic radiosurgery of a meningioma: case report

The documentation and exact incidence of stereotactic radiosurgery (SRS)-induced neoplasia is not well understood, with most literature restricted to single case reports and single-center retrospective reviews. The authors present a rare case of radiosurgery-induced glioblastoma multiforme (GBM) following radiosurgical treatment of a meningioma. A 74-year-old patient with a sporadic meningioma underwent radiosurgery following surgical removal of a WHO grade II meningioma. Eighteen months later she presented with seizures, and MRI revealed an intraaxial tumor, which was resected and proven to be a glioblastoma. As far as the authors are aware, this case represents the third case of GBM following SRS for a meningioma. This report serves to increase the awareness of this possible complication following SRS. The possibility of this rare complication should be explained to patients when obtaining their consent for radiosurgery.

Racial and socioeconomic correlates of treatment and survival among patients with meningioma: a population-based study

BACKGROUND

Though meningioma is the most common primary brain tumor, there is a paucity of epidemiologic studies investigating disparities in treatment and patient outcomes. Therefore, we sought to explore how sociodemographic factors are associated with rates of gross total resection (GTR) and radiotherapy as well as survival.

METHODS

The National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database was queried to identify adult patients with meningioma diagnosed between 2005 and 2015. Socioeconomic status (SES) was determined using a validated composite index in which patients were stratified into tertiles and quintiles. Multivariable logistic regression and Cox proportional hazards analyses were used to identify predictors of treatment and survival, respectively.

RESULTS

71,098 patients met our inclusion criteria. Low SES quintile was associated with reduced odds of receiving GTR (OR 0.76, 95% CI 0.69-0.83, p < 0.0001) and radiotherapy (OR 0.83, 95% CI 0.76-0.91, p < 0.0001) as well as worse survival (HR 1.48, 95% CI 1.41-1.56) as compared to the highest SES quintile. Black patients had reduced odds of GTR (OR 0.74, 95% CI 0.67-0.71, p < 0.0001) and worse survival (HR 1.23, 95% CI 1.18-1.29, p < 0.0001) as compared to white patients.

CONCLUSIONS

This national study of patients with meningioma found socioeconomic status and race to be independent inverse correlates of likelihood of GTR, radiotherapy, and survival. Limited access to care may underlie these disparities in part, and future studies are warranted to identify specific causes for these findings.

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

Stereotactic Radiotherapy for Parasagittal and Parafalcine Meningiomas: Patient Selection and Special Considerations

Treatment options for intracranial meningiomas are surgical resection alone, surgery followed by adjuvant radiation therapy (RT), or exclusive RT. Parasagittal and parafalcine meningiomas are a subgroup of meningeal disease located close to the vascular structures. Considering the frequent venous invasion, a complete resection is not possible in the majority of cases, and even if a Simpson Grade I resection can be performed, the risk of recurrence is relevant. To date, few studies are focused on parasagittal and parafalcine meningiomas. Because of their specific related issues, particular considerations on decision-making process, outcome, and toxicity follow-up are mandatory. In fact, parasagittal and parafalcine meningiomas require a clear-cut radiological assessment, as well as a tailored toxicity risk evaluation. Moreover, similarly to other meningioma sites, also for parasagittal and parafalcine ones, a standardization of local control, toxicity, and quality of life evaluation is needed in order to lead to a pooled analysis of the results. In this context, our aim was to review the literature data regarding the role of both single-session and multisession radiosurgery (RS), and stereotactic radiotherapy (SRT) for parasagittal and parafalcine meningioma management, summarizing available data on safety and efficacy. It was also discussed how RS and SRT can be performed in a setting of evolving views concerning the treatment paradigm of the parasagittal and parafalcine meningiomas.

Intraventricular meningiomas frequently harbor NF2 mutations but lack common genetic alterations in TRAF7, AKT1, SMO, KLF4, PIK3CA, and TERT

Intraventricular meningiomas (IVMs) account for less than 5% of all intracranial meningiomas; hence their molecular phenotype remains unknown. In this study, we were interested whether genetic alterations in IVMs differ from meningiomas in other locations and analyzed our institutional series with respect to clinical and molecular characteristics. A total of 25 patients with surgical removal of an IVM at our department between 1986 and 2018 were identified from our institutional database. Median progression-free survival (PFS) was 79 months (range of 2–319 months) and PFS at 5 years was 86%. Corresponding tumor tissue was available for 18 patients including one matching recurrence and was subjected to targeted panel sequencing of 130 selected genes frequently mutated in brain cancers by applying a custom hybrid capture approach on a NextSeq500 instrument. Loss of chromosome 22q and 1p occurred frequently in 89 and 44% of cases. Deleterious NF2 mutations were found in 44% of IVMs (n = 8/18). In non-NF2-mutated IVMs, previously reported genetic alterations including TRAF7, AKT1, SMO, KLF4, PIK3CA, and TERT were lacking, suggesting alternative genes in the pathogenesis of non-NF2 IVMs. In silico analysis revealed possible damaging mutations of APC, GABRA6, GSE1, KDR, and two SMO missense mutations differing from previously reported ones. Interestingly, all WHO°II IVMs (n = 3) harbored SMARCB1 and SMARCA4 mutations, indicating a role of the SWI/SNF chromatin remodeling complex in aggressive IVMs.

Neuroimaging for Radiation Therapy of Brain Tumors

Delineating the gross tumor volume (GTV) is a core task within radiation treatment planning. GTVs must be precisely defined irrespective of the region involved, but even more so in a sensitive area such as the brain. As precision medicine cannot exist without precision imaging, the current article aims to discuss the various imaging modalities employed in the radiation treatment planning of brain tumors.Gliomas, meningiomas, and paragangliomas are some of the most challenging tumors and the advancement in diagnostic imaging can significantly contribute to their delineation. For gliomas, irradiation based on multiparametric magnetic resonance imaging (MRI) and amino-acid positron emission tomography (PET)/computed tomography (CT) may have a higher sensitivity and specificity, which could lead to a better sparing of organs at risk and help distinguish between tumor, edema, and radiogenic alterations. Meningiomas and paragangliomas are often associated with a good prognosis. Therefore, GTV delineation according to MRI and somatostatin receptor ligand-PET/CT plays an essential role in sparing sensitive structures and maintaining a good quality of life for these patients.The combination of multiparametric MRI and PET/CT (possibly in the form of PET/MRI) presently appears to be the optimal approach for target volume delineation. The comparative efficacy of these imaging modalities has to be further evaluated in prospective trials.

Factors Associated with Treatment Failure and Radiosurgery-Related Edema in WHO Grade 1 and 2 Meningioma Patients Receiving Gamma Knife Radiosurgery

BACKGROUND

Before the advent of radiosurgery, neurosurgical treatment of meningiomas typically involved gross total resection of the mass whenever surgery was deemed possible. Over the past 4 decades, though, Gamma Knife radiosurgery (GKRS) has proved to be an effective, minimally invasive means to control the growth of these tumors. However, the variables associated with treatment failure (regrowth or clinical progression) after GKRS and GKRS-related complications, such as cerebral edema, are less well understood.

METHODS

We retrospectively collected data between 2009 and 2018 for patients who underwent GKRS for meningiomas. After data collection, we performed univariate and multivariable modeling of the factors that predict treatment failure and cerebral edema after GKRS. Hazard ratios (HR) and P values were determined for these variables.

RESULTS

Fifty-two patients were included our analysis. The majority of patients were female (38/52,73%), and nearly all patients presented with a suspected or confirmed World Health Organization grade 1 meningioma (48/52, 92%). The median tumor volume was 3.49 cc (range, 0.22-20.11 cc). Evidence of meningioma progression after treatment developed in 5 patients (10%), with a median time to continued tumor growth of 5.9 months (range, 2.7-18.3 months). In multivariable analysis, patients in whom treatment failed were more likely to be male (HR = 8.42, P = 0.045) and to present with larger tumor volumes (HR = 1.27, P = 0.011). In addition, 5 patients (10%) experienced treatment-related cerebral edema. On univariate analysis, patients who experienced cerebral edema were more likely present with larger tumors (HR = 1.16, P = 0.028).

CONCLUSIONS

Increasing meningioma size and male gender predispose to meningioma progression after treatment with GKRS. Increasing tumor size also predicts the development of postradiosurgery cerebral edema.

Linear Accelerator-Based Radiosurgery of Grade I Intracranial Meningiomas

Objective

To determine the local control rate and complication rate in the treatment of grade I intracranial meningiomas.

Methods

A retrospective study was performed of patients with grade I meningioma who received radiosurgery with a dedicated linear accelerator from January 2002 to August 2012 with a minimum follow-up of 2 years. We performed descriptive statistics, logistic regression, and progression-free survival analysis through a Kaplan-Meier curve.

Results

Seventy-five patients with 78 grade I meningiomas received radiosurgery, 39 underwent surgery plus adjuvant radiosurgery, and 36 only radiosurgery. The follow-up median time was 68 months (range, 35–120 months). The tumor control rate was 93%, the 5-year progression-free survival was 92% (95% confidence interval, 77%–98%). Acute toxicity was 2.6%, and grade 1–2 late toxicity was 26.6%. Postradiosurgery edema was the main late morbidity. Age >55 years was the only significant factor for attaining a response >75%. The background of surgery before radiosurgery was the only significant prognostic factor for showing edema (odds ratio 5.78 [95% confidence interval, 2.14–15.64]).

Conclusions

The local control rate attained in our series is similar to that reported in other series worldwide; the acute toxicity rate was low and late toxicity was moderate.

Multisession radiosurgery for perioptic meningiomas: medium-to-long term results from a CyberKnife cooperative study

PURPOSE

Most recent literature has confirmed the efficacy of single-session radiosurgery (sRS) in the treatment of intracranial meningioma. Unfortunately, sRS is not always applicable due to large tumor volume and the proximity of the tumor to critical structures. When sRS is not recommended, multi-session radiosurgery (mRS) can be the solution. The best treatment schedule for mRS, however, is not well established. The aim of the present retrospective study is to validate the effectiveness of one approach, 25 Gy delivered in 5 fractions in 5 consecutive days, to treat skull base meningiomas.

METHODS

This is a retrospective multicenter study. Patients with an anterior or a medium skull base meningioma that could not be treated by sRS due to large volume or proximity to the anterior optic pathways (AOPs) underwent 5-fraction mRS. Only patients with at least 36 months follow-up were included in the analysis. Local control and visual outcomes were investigated.

RESULTS

One-hundred-sixty-seven patients were included in the analysis. One-hundred-one patients underwent RS as a primary indication and 66 were treated after a previous surgery. The median follow-up period was 51 months (range 36-129 months). Progression-free survival at 3, 5 and 8 years were, respectively, 98%, 94% and 90%. Excluding the progressive disease patients, the visual worsening rate was 3.7%. The 42% of the patients with a pre-treatment visual deficit experienced improvement in vision.

CONCLUSION

25 Gy delivered in 5 fractions is an effective modality for meningiomas that are near the AOP or are too large to be treated by sRS. The treatment schedule controlled the tumors while sparing visual function.

Long-Term Clinical Outcomes of Pencil Beam Scanning Proton Therapy for Benign and Non-benign Intracranial Meningiomas

PURPOSE

To assess and report long-term clinical outcomes regarding local control, overall survival, and toxicity-free survival after pencil beam scanning proton therapy for intracranial meningiomas at a single institution.

PATIENTS AND METHODS

Ninety-six patients (male/female, 29/67; median age 52.8 years) with intracranial meningiomas (World Health Organization [WHO] grade 1, n=61 [63.5%]; WHO grade 2, n=33 [34.4%]; WHO grade 3, n=2 [2.1%]) were treated with pencil beam scanning proton therapy (n=53 [55.2%] at diagnosis, n=17 [17.7%] at recurrence, and n=26 [27.1%] for tumor progression). Median gross tumor volume before PBSPT was 21.4 cm³ (range, 0.0-546.5 cm³), with a median planning target volume of 123.4 cm³ (range, 4.6-1142.0 cm³). Median duration of follow-up was 56.9 months (range, 12.1-207.2 months). Late toxicity was graded according to the Common Terminology Criteria for Adverse Events, version 4.0.

RESULTS

Thirteen failures (14%) (male/female, 6/7) were observed, of which the majority (n=9, 69%) were of non-benign histology. The 5-year actuarial local control and overall survival were 86.4% and 88.2%, respectively. Five-year grade ≥3 toxicity-free survival was 89.1%. On univariate analysis, local control was worse for patients with higher WHO grade (P≤.001), those treated after at least 1 recurrence (P=.006), those with non-skull base tumor location (P=.014), and males (P=.032). Significant prognosticators for 5-year overall survival were local control (P≤.001), age (P=.002), and timing of proton therapy (initial vs recurrence) (P=.002).

CONCLUSIONS

Pencil beam scanning proton therapy is an effective and safe treatment for patients with intracranial meningiomas, resulting in high local control rates with limited toxicity. Up-front radiation likely results in improved outcomes and should be considered, especially for patients with non-benign tumors and/or for those with incomplete resections.