Hypofractionated stereotactic radiotherapy for intracranial meningioma: a systematic review

Long-term follow-up in high-grade meningioma and outcome analysis

Objectives

The determinants of progression-free survival (PFS) and overall survival (OS) for higher-grade meningiomas have not been clearly established and to summarize the long-term clinical outcome for patients with grade 2 or 3 meningioma and assess the PFS and OS factors.

Materials and Methods

The study included all individuals, who had undergone surgical removal of cerebral meningiomas between 2005 and 2020 and whose histological results suggested a World Health Organization (WHO) grade 2 or grade 3 diseases. Kaplan-Meier curves are plotted to examine tumor control and OS after the follow-up. The reverse Wald logistic regression and Mantel-Cox test were used in multivariate analysis for tumor recurrence and mortality.

Results

There were 94 individuals enrolled with 82 having WHO grade 2 tumors and 12 having WHO grade 3 lesions. Gross total resection of the tumor was present in 73 patients (78%), and adjuvant radiotherapy (RT) was administered to 43 (45.7%) individuals. During the course of the study, 17 patients died. The WHO grade of the tumor, the extent of resection, and the absence of bone involvement were all independent predictors of better survival in a multivariate analysis. Furthermore, whereas adjuvant RT after surgery enhanced survival, it was not statistically significant (hazard ratios [95% confidence interval CI] = 1.91 [0.15-23.52] [P = 0.61]).

Conclusion

The degree of tumor excision is the strongest predictor of PFS and OS. In the event of a recurrence, rather than opting for upfront radiation, a second surgery with the goal of maximum safe resection should be performed.

Evidence-based clinical recommendations for hypofractionated radiotherapy: exploring efficacy and safety - Part 1. Brain and head and neck

Advances in radiotherapy (RT) techniques, including intensity-modulated RT and image-guided RT, have allowed hypofractionation, increasing the fraction size over the conventional dose of 1.8-2.0 Gy. Hypofractionation offers advantages such as shorter treatment times, improved compliance, and under specific conditions, particularly in tumors with a low α/β ratio, higher efficacy. It was initially explored for use in RT for prostate cancer and adjuvant RT for breast cancer, and its application has been extended to various other malignancies. Hypofractionated RT (HFRT) may also be effective in patients who are unable to undergo conventional treatment owing to poor performance status, comorbidities, or old age. The treatment of brain tumors with HFRT is relatively common because brain stereotactic radiosurgery has been performed for over two decades. However, re-irradiation of recurrent lesions and treatment of elderly or frail patients are areas under investigation. HFRT for head and neck cancer has not been widely used because of concerns regarding late toxicity. Thus, we aimed to provide a comprehensive summary of the current evidence for HFRT for brain tumors and head and neck cancer and to offer practical recommendations to clinicians faced with the challenge of choosing new treatment options.

Intracranial meningiomas: an update of the 2021 World Health Organization classifications and review of management with a focus on radiation therapy

Meningiomas account for approximately one third of all primary intracranial tumors. Arising from the cells of the arachnoid mater, these neoplasms are found along meningeal surfaces within the calvarium and spinal canal. Many are discovered incidentally, and most are idiopathic, although risk factors associated with meningioma development include age, sex, prior radiation exposure, and familial genetic diseases. The World Health Organization grading system is based on histologic criteria, and are as follows: grade 1 meningiomas, a benign subtype; grade 2 meningiomas, which are of intermediately aggressive behavior and usually manifest histologic atypia; and grade 3, which demonstrate aggressive malignant behavior. Management is heavily dependent on tumor location, grade, and symptomatology. While many imaging-defined low grade appearing meningiomas are suitable for observation with serial imaging, others require aggressive management with surgery and adjuvant radiotherapy. For patients needing intervention, surgery is the optimal definitive approach with adjuvant radiation therapy guided by extent of resection, tumor grade, and location in addition to patient specific factors such as life expectancy. For grade 1 lesions, radiation can also be used as a monotherapy in the form of stereotactic radiosurgery or standard fractionated radiation therapy depending on tumor size, anatomic location, and proximity to dose-limiting organs at risk. Optimal management is paramount because of the generally long life-expectancy of patients with meningioma and the morbidity that can arise from tumor growth and recurrence as well as therapy itself.

Outcomes and predictors of response to fractionated radiotherapy as primary treatment for intracranial meningiomas

Background

Surgery is the primary treatment for most meningiomas. However, primary fractionated radiotherapy (fRT) remains an option for patients with larger meningiomas in challenging anatomic locations or patients at prohibitively high surgical risk. Outcome prediction for these patients is uncertain and cannot be guided by histopathology without available tumor tissue from surgery. Therefore, we aimed to assess the clinical factors that contribute to treatment failure in a large cohort of meningiomas consecutively treated with fRT as primary therapy, with the goal of identifying predictors of response.

Methods

Patients treated with primary fRT for intracranial meningiomas from 1998 to 2017 were reviewed. Those who received primary surgical resection, radiosurgery, previous fRT, or had <6 months of clinical follow-up were excluded. We applied logistic regression and Cox regression modeling to ascertain key predictors of treatment failure, progression-free survival (PFS), and adverse events (AE) following fRT.

Results

Our cohort included 137 meningiomas, 21 of which progressed after fRT (median PFS 3.45 years). Progressive meningiomas had a larger median gross tumor volume (GTV) compared to those that remained stable (19.1 cm³ vs 9.6 cm³, p = 2.86 × 10^-2). GTV > 11.27 cm³ was independently predictive of progression and larger GTV was associated with higher risk of significant (grades 3/4) AE following fRT. Cavernous sinus and optic nerve sheath meningiomas had overall excellent outcomes post-fRT.

Conclusions

We present a large cohort of meningiomas treated with primary fRT and find GTV and anatomic location to be key predictors of outcome, adding to the complex treatment considerations for this heterogeneous disease.

Clinical Management of Supratentorial Non-Skull Base Meningiomas

Supratentorial non-skull base meningiomas are the most common primary central nervous system tumor subtype. An understanding of their pathophysiology, imaging characteristics, and clinical management options will prove of substantial value to the multi-disciplinary team which may be involved in their care. Extensive review of the broad literature on the topic is conducted. Narrowing the scope to meningiomas located in the supratentorial non-skull base anatomic location highlights nuances specific to this tumor subtype. Advances in our understanding of the natural history of the disease and how findings from both molecular pathology and neuroimaging have impacted our understanding are discussed. Clinical management and the rationale underlying specific approaches including observation, surgery, radiation, and investigational systemic therapies is covered in detail. Future directions for probable advances in the near and intermediate term are reviewed.

Hypofractionated Stereotactic Radiotherapy for the Treatment of Benign Intracranial Meningiomas: Long-Term Safety and Efficacy

Introduction: Hypofractionated stereotactic radiotherapy (hSRT) has emerged as an alternative to single-fraction stereotactic radiosurgery (SRS) and conventionally fractionated radiotherapy for the treatment of intracranial meningiomas (ICMs). However, there is a need for data showing long-term efficacy and complication rates, particularly for larger tumors in sensitive locations. Methods: A retrospective review was conducted on adult patients with ICMs seen at a tertiary care center. Eligible patients were treated with the CyberKnife platform and had a planned treatment course of 3–5 fractions from 2011–2020. The local control was assessed based on radiographic stability and the late toxicity/radionecrosis rates were recorded. Radiographic progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan–Meier method. Results: In total, 62 patients (age 26–87) with 67 treated tumors were included in this study with a median follow-up of 64.7 months. RT was delivered as the primary treatment in 62.7% of cases and for recurrence in 37.3%. The most common tumor locations were the convexity of the brain and the base of the skull. The tumor sizes ranged from 0.1–51.8 cc and the median planning target volume was 4.9 cc. The most common treatment schedule was 18 Gy in 3 fractions. The five-year PFS and OS were 85.2% and 91.0%, respectively. The late grade III/IV toxicity rate was 3.2% and the radionecrosis rate was 4.8%. Conclusions: Based on our data, hSRT remains an effective modality to treat low-grade ICMs with acceptable long-term toxicity and radionecrosis rates. hSRT should be offered to patients who are not ideal candidates for SRS while preserving the benefits of hypofractionation.

Importance of Pre-treatment Fractional Anisotropy Value in Predicting Volumetric Response in Patients with Meningioma Treated with Gamma Knife Radiosurgery

Background

The importance of pre-treatment Diffusion Tensor Imaging (DTI) parameters in determining the response to treatment after radiosurgery in patients with meningioma has not yet been clearly revealed.

Objective

This study was conducted to determine tumor volume changes in terms of radiological response in patients with meningioma treated with Gamma Knife Radiosurgery (GKR) and to analyze the relationship between Total Tumor Volume (TTV) and Diffusion Tensor Imaging (DTI) parameters. In addition, we investigated whether the response to treatment can be predicted by pre-radiosurgery DTI findings.

Methods

Fifty-four patients were assessed using MRI and DTI before and after GKR. Mean Diffusivity (MD), Fractional Anisotropy (FA), Radial Diffusivity (RD), and TTV of tumour were determined. Patients with 10% or more decrease in TTV after GKR were classified as group 1 and those with less than 10% decrease in volume or increase in volume were considered group 2. The relationships between MD, RD, and FA values and TTV were investigated.

Results

A decrease of 46.34% in TTV was detected in group 1 after GKR, while TTV increased by 42.91% in group 2. The lowest pre-treatment FA value was detected in group 1. In addition, after GKR, FA values showed a significant increase in group 1. MD and RD values increased in both groups after radiosurgery. There was a negative correlation between pre-treatment FA, RD, and MD values after radiosurgery.

Conclusion

Detection of low FA values due to the poor fiber content in meningioma before radiosurgery may be a guide in predicting the response to treatment. Further studies are required to have a better understanding of the relationship between pre- and post-treatment follow-up FA values and tumor volume in determining the efficacy of GKR in patients with meningioma.

Brain Invasion in Meningioma-A Prognostic Potential Worth Exploring

Most meningiomas are slow growing tumors arising from the arachnoid cap cells and can be cured by surgical resection or radiation therapy in selected cases. However, recurrent and aggressive cases are also quite common and challenging to treat due to no established treatment alternatives. Assessment of the risk of recurrence is therefore of utmost importance and several prognostic clinical and molecular markers have been established. Additionally, the identification of invasive growth of meningioma cells into CNS tissue was demonstrated to lead to a higher risk of recurrence and was therefore integrated into the WHO classification of CNS tumors. However, the evidence for its prognostic impact has been questioned in subsequent studies and its exclusion from the next WHO classification proposed. We were recently able to show the prognostic impact of CNS invasion in a large comprehensive retrospective meningioma cohort including other established prognostic factors. In this review we discuss the growing experiences that have been gained on this matter, with a focus on the currently nonuniform histopathological assessment, imaging characteristics and intraoperative sampling as well as the overall outlook on the future role of this potential prognostic factor.

Advances in Multidisciplinary Management of Skull Base Meningiomas

The surgical management of Skull Base Meningiomas (SBMs) has radically changed over the last two decades. Extensive surgery for patients with SBMs represents the mainstream treatment; however, it is often challenging due to narrow surgical corridors and proximity to critical neurovascular structures. Novel surgical technologies, including three-dimensional (3D) preoperative imaging, neuromonitoring, and surgical instruments, have gradually facilitated the surgical resectability of SBMs, reducing postoperative morbidity. Total removal is not always feasible considering a risky tumor location and invasion of surrounding structures and brain parenchyma. In recent years, the use of primary or adjuvant stereotactic radiosurgery (SRS) has progressively increased due to its safety and efficacy in the control of grade I and II meningiomas, especially for small to moderate size lesions. Patients with WHO grade SBMs receiving subtotal surgery can be monitored over time with surveillance imaging. Postoperative management remains highly controversial for grade II meningiomas, and depends on the presence of residual disease, with optional upfront adjuvant radiation therapy or close surveillance imaging in cases with total resection. Adjuvant radiation is strongly recommended in patients with grade III tumors. Although the currently available chemotherapy or targeted therapies available have a low efficacy, the molecular profiling of SBMs has shown genetic alterations that could be potentially targeted with novel tailored treatments. This multidisciplinary review provides an update on the advances in surgical technology, postoperative management and molecular profile of SBMs.

Multiplatform Radiosurgery for Intracranial Meningiomas and Dose to the Dural Tail

Introduction

Meningiomas are extra-axial central nervous system tumors. Complete resection is often curative with macroscopically complete removal of the tumor, excision of its dural attachment, and any abnormal bone. Radiosurgery is also an option for high-risk patients or in patients with surgically residual disease. Dural tail is a typical radiological sign on contrast-enhanced MRI; it can contain tumor cells or be a reaction due to vascular congestion and edema. Radiosurgical planning treatment varies regarding the identification and coverage of the dural tail. This study aimed to retrospectively analyze a series of 143 patients with WHO Grade I meningiomas treated with different radiosurgical platforms, and dosing parameters focused on planning and dose delivery to the dural tail.

Methods

From February 2011 to July 2020, 143 patients with histologically confirmed or radiologically assumed WHO Grade I meningiomas were treated using rotating gamma-ray Infini™ (Gamma [MASEP Medical Science Technology Development Co., Shenzhen, China]), TomoTherapy® (Tomo [Accuray Inc., Sunnyvale, CA]), and CyberKnife® (CK [Accuray Inc.]). All plans were retrospectively reviewed to establish the maximum distance (MaxDis) from the prescription dose to the end of the dural tail and the minimum dose at the dural tail (MinDoseT) at this point. We also established the midpoint distance (MPDis) from the prescription dose to MaxDis and the dose at this point (MPDose). Plans were further distinguished when the physician intended to cover the dural tail versus when not. Patients and tumor response were assessed by imaging and clinical and phone call evaluations.

Results

Of the 143 patients, 81 were treated using Gamma, 34 using Tomo, and 28 using CK. Eighty patients were eligible for follow-up, of whom 58 (72.5%) had an unmistakable dural tail sign. Median follow-up was 1,118 days (range 189-3,496), mean age was 54.5 (range 19-90), and 61 were women, and 19 were men. Overall tumor volume was 6.5 cc (range 0.2-59); mean tumor volumes by different platforms were 2.4, 9.45, and 8 cc; dose prescribed and mean tumor coverage were 14 Gy and 92%, 14.5 Gy and 95%, and 14 Gy and 95.75% with Gamma, Tomo, and CK, respectively. The dural tail was drawn and planned with an attempt to treat in 18 patients (31%); the mean MaxDis, MinDoseT, MPDis, and MPDose were 9.0 mm, 2 Gy, 4.5 mm, and 10.6 Gy, respectively. At last follow-up, tumor control was achieved in 96% of patients for the whole series, and there were no statistical variations regarding tumor volume, dose, conformality, or control when stereotactic radiosurgery was used to cover the dural tail versus when it was not (p=0.105). One patient experienced a Grade 4 Radiation Therapy Oncology Group toxicity as an adverse radiation effect that required surgery, and 11 (7.6%) experienced a Grade 1 toxicity.

Conclusions

This is our preliminary report regarding the efficacy of radiosurgery for meningiomas using diverse platforms at three years of follow-up; the results regarding tumor control are in accordance with the published literature as of this writing. A conscious pursuit of the dural tail with the prescription dose has not proven to provide better tumor control than not doing so - even small areas of the tumor uncovered by the prescription dose did not alter tumor control at current follow-up. The doses delivered to these uncovered areas are quite significant; further follow-up is necessary to validate these findings.

Short Course Hypofractionated Radiotherapy for Frail or Elderly Patients With Meningioma

Purpose/Objective(s)

The incidence of intracranial meningiomas increases with age. The standard of care treatment is complete surgical excision, followed by radiation therapy (RT) if indicated. However, six weeks of RT can be challenging for elderly or frail patients. The purpose of this study was to determine if short course RT is safe and effective in elderly patients with meningioma.

Materials/Methods

We performed a retrospective analysis of patients with meningioma treated with short course beam RT (5-15 fractions) at a single institution. Seventeen patients (94%) received 4005 cGy over 15 fractions and one patient (6%) received 2500 cGy over five fractions. Study endpoints were treatment toxicity (edema), progression-free (PFS) and overall survival (OS).

Results

Eighteen patients with histologically proven (n = 12) or radiologically presumed meningioma (n = 6, presumed grade I) were identified. Median age at treatment was 85 years (66-95 years). There were eight, eight and two patients with grade I, II and III tumours, respectively. Eight patients (44%) had radiologic edema prior to RT. Six (33%) required dexamethasone treatment during RT and the dose was increased during RT for two patients. Fourteen patients had reduced or no edema post-RT and 13 patients had stable or improving symptoms post-RT. Six patients had disease progression (five in-field, one out-of-field). Median PFS was 3.3 and 0.9 years for grade I and II/III tumours, respectively (p = 0.014). Median OS was 3.3 and 2.5 years for grade I and II/III tumours, respectively (p = 0.12).

Conclusion

Short course RT for elderly patients with meningioma is well-tolerated and can offer disease control for some patients, particularly those with grade I tumours.

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