Gamma Knife surgery for low-grade astrocytomas: evaluation of long-term outcome based on a 10-year experience

Pleomorphic Xanthoastrocytoma: Multi-Institutional Evaluation of Stereotactic Radiosurgery

BACKGROUND AND OBJECTIVES

Pleomorphic xanthoastrocytoma (PXA) is a rare low-grade glial tumor primarily affecting young individuals. Surgery is the primary treatment option; however, managing residual/recurrent tumors remains uncertain. This international multi-institutional study retrospectively assessed the use of stereotactic radiosurgery (SRS) for PXA.

METHODS

A total of 36 PXA patients (53 tumors) treated at 11 institutions between 1996 and 2023 were analyzed. Data included demographics, clinical variables, SRS parameters, tumor control, and clinical outcomes. Kaplan-Meier estimates summarized the local control (LC), progression-free survival, and overall survival (OS). Secondary end points addressed adverse radiation effects and the risk of malignant transformation. Cox regression analysis was used.

RESULTS

A total of 38 tumors were grade 2, and 15 tumors were grade 3. Nine patients underwent initial gross total resection, and 10 received adjuvant therapy. The main reason for SRS was residual tumors (41.5%). The median follow-up was 34 months (range, 2-324 months). LC was achieved in 77.4% of tumors, with 6-month, 1-year, and 2-year LC estimates at 86.7%, 82.3%, and 77.8%, respectively. Younger age at SRS (hazard ratios [HR] 3.164), absence of peritumoral edema (HR 4.685), and higher marginal dose (HR 6.190) were significantly associated with better LC. OS estimates at 1, 2, and 5 years were 86%, 74%, and 49.3%, respectively, with a median OS of 44 months. Four patients died due to disease progression. Radiological adverse radiation effects included edema (n = 8) and hemorrhagic change (n = 1). One grade 3 PXA transformed into glioblastoma 13 months after SRS.

CONCLUSION

SRS offers promising outcomes for PXA management, providing effective LC, reasonable progression-free survival, and minimal adverse events.

Subependymal Giant Cell Astrocytoma Apoplexy: A Case Report and Systematic Review

Subependymal giant cell astrocytoma (SEGA) is the most common intracranial tumor in tuberous sclerosis (TS) patients. The tumor generally localizes in the proximity of Monro's foramen; as it grows, it subsequently causes hydrocephalus and increases intracranial pressure (ICP). However, acute symptoms of increased ICP due to intratumoral bleeding rarely manifest in SEGA patients. We present a 27-year-old male with TS who presented due to hemorrhagic complications of SEGA with intratumoral bleeding and vitreous orbital hemorrhage. We then conducted a systematic review with four databases (PubMed, Web of Science, Google Scholar, and Cochrane) to identify similar cases using the following keywords: "Subependymal giant cell astrocytoma," "Hemorrhage," "Haemorrhage," and "Bleeding." Our review identified 12 articles reporting 14 cases of hemorrhagic complications of SEGA in addition to our case report. The median age of diagnosis was 21 (range 5-79) years with unequal gender distribution (M:F ratio, 11:4). Headache was the most presented symptom, followed by hemiparesis, seizure, altered mental status, visual deterioration, and headache accompanied by seizure. TS was seen in most of the cases (80%). Gross total resection (GTR) was achieved in 53.5% of the patients. Regarding the clinical outcome, 66.7% had a good outcome, 20% died, and 13.3% had no report of their outcomes. No tumor recurrence was seen in the cases with a reported duration of follow-up. Catastrophic presentation of SEGA apoplexy is a rare occurrence. We present a case report with a systematic review and discuss SEGA apoplexy's possible pathophysiology and outcome.

Concise review of stereotactic irradiation for pediatric glial neoplasms: Current concepts and future directions

Brain tumors, which are among the most common solid tumors in childhood, remain a leading cause of cancer-related mortality in pediatric population. Gliomas, which may be broadly categorized as low grade glioma and high grade glioma, account for the majority of brain tumors in children. Expectant management, surgery, radiation therapy (RT), chemotherapy, targeted therapy or combinations of these modalities may be used for management of pediatric gliomas. Several patient, tumor and treatment-related characteristics including age, lesion size, grade, location, phenotypic and genotypic features, symptomatology, predicted outcomes and toxicity profile of available therapeutic options should be considered in decision making for optimal treatment. Management of pediatric gliomas poses a formidable challenge to the physicians due to concerns about treatment induced toxicity. Adverse effects of therapy may include neurological deficits, hemiparesis, dysphagia, ataxia, spasticity, endocrine sequelae, neurocognitive and communication impairment, deterioration in quality of life, adverse socioeconomic consequences, and secondary cancers. Nevertheless, improved understanding of molecular pathology and technological advancements may pave the way for progress in management of pediatric glial neoplasms. Multidisciplinary management with close collaboration of disciplines including pediatric oncology, surgery, and radiation oncology is warranted to achieve optimal therapeutic outcomes. In the context of RT, stereotactic irradiation is a viable treatment modality for several central nervous system disorders and brain tumors. Considering the importance of minimizing adverse effects of irradiation, radiosurgery has attracted great attention for clinical applications in both adults and children. Radiosurgical applications offer great potential for improving the toxicity profile of radiation delivery by focused and precise targeting of well-defined tumors under stereotactic immobilization and image guidance. Herein, we provide a concise review of stereotactic irradiation for pediatric glial neoplasms in light of the literature.

Early versus delayed postoperative radiotherapy for treatment of low-grade gliomas

BACKGROUND

This is an update of the review originally published in 2011 and first updated in 2015. In most people with low-grade gliomas (LGG), the primary treatment regimen remains a combination of surgery followed by postoperative radiotherapy. However, the optimal timing of radiotherapy is controversial. It is unclear whether to use radiotherapy in the early postoperative period, or whether radiotherapy should be delayed until tumour progression occurs.

OBJECTIVES

To assess the effects of early postoperative radiotherapy versus radiotherapy delayed until tumour progression for low-grade intracranial gliomas in people who had initial biopsy or surgical resection.

SEARCH METHODS

Original searches were run up to September 2014. An updated literature search from September 2014 through November 2019 was performed on the following electronic databases: the Cochrane Central Register of Controlled Trials (CENTRAL; 2019, Issue 11), MEDLINE via Ovid (September 2014 to November week 2 2019), and Embase via Ovid (September 2014 to 2019 week 46) to identify trials for inclusion in this Cochrane review update.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared early versus delayed radiotherapy following biopsy or surgical resection for the treatment of people with newly diagnosed intracranial LGG (astrocytoma, oligodendroglioma, mixed oligoastrocytoma, astroblastoma, xanthoastrocytoma, or ganglioglioma). Radiotherapy may include conformal external beam radiotherapy (EBRT) with linear accelerator or cobalt-60 sources, intensity-modulated radiotherapy (IMRT), or stereotactic radiosurgery (SRS).

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed the trials for inclusion and risk of bias, and extracted study data. We resolved any differences between review authors by discussion. Adverse effects were also extracted from the study report. We performed meta-analyses using a random-effects model with inverse variance weighting.

MAIN RESULTS

We included one large, multi-institutional, prospective RCT, involving 311 participants; the risk of bias in this study was unclear. This study found that early postoperative radiotherapy was associated with an increase in time to progression compared to observation (and delayed radiotherapy upon disease progression) for people with LGG but did not significantly improve overall survival (OS). The median progression-free survival (PFS) was 5.3 years in the early radiotherapy group and 3.4 years in the delayed radiotherapy group (hazard ratio (HR) 0.59, 95% confidence interval (CI) 0.45 to 0.77; P < 0.0001; 311 participants; 1 trial; low-quality evidence). The median OS in the early radiotherapy group was 7.4 years, while the delayed radiotherapy group experienced a median overall survival of 7.2 years (HR 0.97, 95% CI 0.71 to 1.33; P = 0.872; 311 participants; 1 trial; low-quality evidence). The total dose of radiotherapy given was 54 Gy; five fractions of 1.8 Gy per week were given for six weeks. Adverse effects following radiotherapy consisted of skin reactions, otitis media, mild headache, nausea, and vomiting. Rescue therapy was provided to 65% of the participants randomised to delayed radiotherapy. People in both cohorts who were free from tumour progression showed no differences in cognitive deficit, focal deficit, performance status, and headache after one year. However, participants randomised to the early radiotherapy group experienced significantly fewer seizures than participants in the delayed postoperative radiotherapy group at one year (25% versus 41%, P = 0.0329, respectively).

AUTHORS' CONCLUSIONS

Given the high risk of bias in the included study, the results of this analysis must be interpreted with caution. Early radiation therapy was associated with the following adverse effects: skin reactions, otitis media, mild headache, nausea, and vomiting. People with LGG who underwent early radiotherapy showed an increase in time to progression compared with people who were observed and had radiotherapy at the time of progression. There was no significant difference in overall survival between people who had early versus delayed radiotherapy; however, this finding may be due to the effectiveness of rescue therapy with radiation in the control arm. People who underwent early radiation had better seizure control at one year than people who underwent delayed radiation. There were no cases of radiation-induced malignant transformation of LGG. However, it remained unclear whether there were differences in memory, executive function, cognitive function, or quality of life between the two groups since these measures were not evaluated.

Stereotactic Radiotherapy with Fractionation for the Lesions in and Around the Brainstem and Optic Nerve

Purpose

Among the components of the central nervous system, the optic nerve and the brainstem are considered to be the eloquent structures that are sensitive to stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT). SRS or SRT with fractionation in areas adjacent to these tissues is both promising and challenging.

Materials and methods

To clarify the precise dose distribution achievable with fractionation in and around the optic nerve and brainstem, theoretical simulations were performed, based on the biological effective dose (BED).

Results

These simulations clearly showed that the doses to the optic nerve and brainstem can be adjusted using fractionation, meaning that the prescribed doses to the surrounding brain tissue can be reduced. Conversely doses to the lesions themselves can be increased by fractionation, while maintaining a stable dose to normal optic nerve and brainstem tissue.

Single-session Gamma Knife radiosurgery for optic pathway/hypothalamic gliomas

OBJECTIVE Because of their critical and central location, it is deemed necessary to fractionate when considering irradiating optic pathway/hypothalamic gliomas. Stereotactic fractionated radiotherapy is considered safer when dealing with gliomas in this location. In this study, the safety and efficacy of single-session stereotactic radiosurgery for optic pathway/hypothalamic gliomas were reviewed. METHODS Between December 2004 and June 2014, 22 patients with optic pathway/hypothalamic gliomas were treated by single-session Gamma Knife radiosurgery. Twenty patients were available for follow-up for a minimum of 1 year after treatment. The patients were 5 to 43 years (median 16 years) of age. The tumor volume was 0.15 to 18.2 cm³ (median 3.1 cm³). The prescription dose ranged from 8 to 14 Gy (median 11.5 Gy). RESULTS The mean follow-up period was 43 months. Five tumors involved the optic nerve only, and 15 tumors involved the chiasm/hypothalamus. Two patients died during the follow-up period. The tumors shrank in 12 cases, remained stable in 6 cases, and progressed in 2 cases, thereby making the tumor control rate 90%. Vision remained stable in 12 cases, improved in 6 cases, and worsened in 2 cases in which there was tumor progression. Progression-free survival was 83% at 3 years. CONCLUSIONS The initial results indicate that single-session Gamma Knife radiosurgery is a safe and effective treatment option for optic pathway/hypothalamic gliomas.

Transamniotic stem cell therapy: a novel strategy for the prenatal management of congenital anomalies

Transamniotic stem cell therapy, or TRASCET, is an emerging therapeutic concept for the management of congenital anomalies based on the augmentation of the biological role of select populations of stem cells that already occur in the amniotic fluid, for targeted therapeutic benefit. Amniotic fluid-derived mesenchymal stem cells (afMSCs) have a central role in the enhanced ability of the fetus to repair tissue damage. This germane recent finding constitutes the biological foundation for the use of afMSCs in TRASCET. It has been shown experimentally that simple intra-amniotic delivery of afMSCs in large numbers can either elicit the repair, or significantly mitigate the effects associated with major congenital anomalies by boosting the activity that these cells normally have. For example, TRASCET can induce partial or complete coverage of experimental spina bifida by promoting the local formation of host-derived skin, thus protecting the spinal cord from further damage. In another example, it can significantly alleviate the bowel damage associated with gastroschisis, one of the most common major abdominal wall defects. Other applications involving different congenital anomalies and/or other stem cells present in the amniotic fluid in diseased pregnancies are currently under investigation in this freshly evolving facet of fetal stem cell therapy.

Subependymal Giant Cell Astrocytoma Presenting with Tumoral Bleeding: A Case Report

We report a rare case of subependymal giant cell astrocytoma (SEGA) associated with tumoral bleeding in a pediatric patient without tuberous sclerosis complex (TSC). A 10-year-old girl presented with a 2-week history of an increasingly aggravating headache. Brain magnetic resonance imaging revealed an approximately 3.6-cm, well-defined, heterogeneously enhancing mass with multistage hemorrhages on the right-sided foramen of Monro. The tumor was completely resected using a transcallosal approach. Intraoperatively, the mass presented as a gray-colored firm tumor associated with acute and subacute hemorrhages. The origin of the mass was identified as the ventricular septum adjacent to the foramen of Monro. A pathological analysis revealed pleomorphic multinucleated eosinophilic tumor cells with abundant cytoplasm. These cells showed positive staining for the glial fibrillary acidic protein and S100 protein. A diagnosis of SEGA was established. The patient recovered without any neurological symptoms. There was no evidence of TSC. The radiological follow-up showed no recurrence for 2 years. This was a case of SEGA with intratumoral hemorrhage, for which a favorable outcome was achieved, without any neurological deficit after tumoral resection.

The role of radiotherapy in the management of patients with diffuse low grade glioma: A systematic review and evidence-based clinical practice guideline

QUESTIONS

(1) What is the optimal role of external beam radiotherapy in the management of adult patients with newly diagnosed low-grade glioma (LGG) in terms of improving outcome (i.e., survival, complications, seizure control or other reported outcomes of interest)? (2) Which radiation strategies (dose, timing, fractionation, stereotactic radiation, brachytherapy, chemotherapy) improve outcomes compared to standard external beam radiation therapy in the initial management of low grade gliomas in adults? (3) Do specific factors (e.g., age, volume, extent of resection, genetic subtype) identify subgroups with better outcomes following radiation therapy than the general population of adults with newly diagnosed low-grade gliomas?

TARGET POPULATION

These recommendations apply to adults with newly diagnosed diffuse LGG.

RECOMMENDATIONS

OUTCOMES IN ADULT PATIENTS WITH NEWLY DIAGNOSED LOW GRADE GLIOMA TREATED WITH RADIOTHERAPY: Level I Radiotherapy is recommended in the management of newly diagnosed low-grade glioma in adults to prolong progression free survival, irrespective of extent of resection. Level II Radiotherapy is recommended in the management of newly diagnosed low grade glioma in adults as an equivalent alternative to observation in preserving cognitive function, irrespective of extent of resection. Level III Radiotherapy is recommended in the management of newly diagnosed low grade glioma in adults to improve seizure control in patients with epilepsy and subtotal resection. Level III Radiotherapy is recommended in the management of newly diagnosed low-grade glioma in adults to prolong overall survival in patients with subtotal resection. Level III Consideration of the risk of radiation induced morbidity, including cognitive decline, imaging abnormalities, metabolic dysfunction and malignant transformation, is recommended when the delivery of radiotherapy is selected in the management of newly diagnosed low-grade glioma in adults. STRATEGIES OF RADIOTHERAPY IN ADULT PATIENTS WITH NEWLY DIAGNOSED LOW GRADE GLIOMA: Level I Lower dose radiotherapy is recommended as an equivalent alternative to higher dose immediate postoperative radiotherapy (45-50.4 vs. 59.4-64.8 Gy) in the management of newly diagnosed low-grade glioma in adults with reduced toxicity. Level III Delaying radiotherapy until recurrence or progression is recommended as an equivalent alternative to immediate postoperative radiotherapy in the management of newly diagnosed low-grade glioma in adults but may result in shorter time to progression. Level III The addition of chemotherapy to radiotherapy is not recommended over whole brain radiotherapy alone in the management of low-grade glioma, as it provides no additional survival benefit. Level III Limited-field radiotherapy is recommended over whole brain radiotherapy in the management of low-grade glioma. Level III Either stereotactic radiosurgery or brachytherapy are recommended as acceptable alternatives to external radiotherapy in selected patients. PROGNOSTIC FACTORS IN ADULT PATIENTS WITH NEWLY DIAGNOSED LOW GRADE GLIOMA TREATED WITH RADIOTHERAPY: Level II It is recommended that age greater than 40 years, astrocytic pathology, diameter greater than 6 cm, tumor crossing the midline and preoperative neurological deficit be considered as negative prognostic indicators when predicting overall survival in adult low grade glioma patients treated with radiotherapy. Level II It is recommended that smaller tumor size, extent of surgical resection and higher mini-mental status exam be considered as positive prognostic indicators when predicting overall survival and progression free survival in patients in adult low grade glioma patients treated with radiotherapy. Level III It is recommended that seizures at presentation, presence of oligodendroglial histological component and 1p19q deletion (along with additional relevant factors-see Table 1) be considered as positive prognostic indicators when predicting response to radiotherapy in adults with low grade gliomas. Level III It is recommended that increasing age, decreasing performance status, decreasing cognition, presence of astrocytic histological component (along with additional relevant factors (see Tables 1, 2) be considered as negative prognostic indicators when predicting response to radiotherapy.

Gamma Knife treatment of low-grade gliomas in children

BACKGROUND

Low-grade gliomas have good overall survival rates in pediatric patients compared to adults. There are some case series that reported the effectiveness and safety of Gamma Knife radiosurgery, yet they are limited in number of patients. We aimed to review the relevant literature for pediatric low-grade glial tumors treated with stereotactic radiosurgery, specifically Gamma Knife radiosurgery, and to present an exemplary case.

CASE DESCRIPTION

A 6-year-old boy was admitted to clinic due to head trauma. He was alert, cooperative, and had no obvious motor or sensorial deficit. A head CT scan depicted a hypodense zone at the right caudate nucleus. The brain magnetic resonance imaging (MRI) depicted a mass lesion at the same location. A stereotactic biopsy was performed. Histopathological diagnosis was low-grade astrocytoma (grade II, World Health Organization (WHO) classification, 2007). Gamma Knife radiosurgery was applied to the tumor bed. Tumor volume was 21.85 cm(3). Fourteen gray was given to 50% isodose segment of the lesion (maximal dose of 28 Gy). The tumor has disappeared totally in 4 months, and the patient was tumor-free 21 months after the initial treatment.

DISCUSSION AND CONCLUSION

The presented literature review represents mostly single-center experiences with different patient and treatment characteristics. Accordingly, a mean/median margin dose of 11.3-15 Gy with Gamma Knife radiosurgery (GKRS) is successful in treatment of pediatric and adult low-grade glial tumor patients. However, prospective studies with a large cohort of pediatric patients should be conducted to make a more comprehensive conclusion for effectiveness and safety of GKRS in pediatric low-grade glial tumors.

Early versus delayed postoperative radiotherapy for treatment of low-grade gliomas

BACKGROUND

In most people with low-grade gliomas (LGG), the primary treatment regimen remains a combination of surgery followed by postoperative radiotherapy. However, the optimal timing of radiotherapy is controversial. It is unclear whether to use radiotherapy in the early postoperative period, or whether radiotherapy should be delayed until tumour progression occurs.

OBJECTIVES

To assess the effects of early postoperative radiotherapy versus radiotherapy delayed until tumour progression for low-grade intracranial gliomas in people who had initial biopsy or surgical resection.

SEARCH METHODS

We searched up to September 2014 the following electronic databases: the Cochrane Register of Controlled Trials (CENTRAL, Issue 8, 2014), MEDLINE (1948 to Aug week 3, 2014), and EMBASE (1980 to Aug week 3, 2014) to identify trials for inclusion in this Cochrane review.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared early versus delayed radiotherapy following biopsy or surgical resection for the treatment of people with newly diagnosed intracranial LGG (astrocytoma, oligodendroglioma, mixed oligoastrocytoma, astroblastoma, xanthoastrocytoma, or ganglioglioma). Radiotherapy may include conformal external beam radiotherapy (EBRT) with linear accelerator or cobalt-60 sources, intensity-modulated radiotherapy (IMRT), or stereotactic radiosurgery (SRS).

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed the trials for inclusion and risk of bias, and extracted study data. We resolved any differences between review authors by discussion. Adverse effects were also extracted from the study report. We performed meta-analyses using a random-effects model with inverse variance weighting.

MAIN RESULTS

We included one large, multi-institutional, prospective RCT, involving 311 participants; the risk of bias in this study was unclear. This study found that early postoperative radiotherapy is associated with an increase in time to progression compared to observation (and delayed radiotherapy upon disease progression) for people with LGG but does not significantly improve overall survival (OS). The median progression-free survival (PFS) was 5.3 years in the early radiotherapy group and 3.4 years in the delayed radiotherapy group (hazard ratio (HR) 0.59, 95% confidence interval (CI) 0.45 to 0.77; P value < 0.0001; 311 participants; 1 trail; low quality evidence). The median OS in the early radiotherapy group was 7.4 years, while the delayed radiotherapy group experienced a median overall survival of 7.2 years (HR 0.97, 95% CI 0.71 to 1.33; P value = 0.872; 311 participants; 1 trail; low quality evidence). The total dose of radiotherapy given was 54 Gy; five fractions of 1.8 Gy per week were given for six weeks. Adverse effects following radiotherapy consisted of skin reactions, otitis media, mild headache, nausea, and vomiting. Rescue therapy was provided to 65% of the participants randomised to delayed radiotherapy. People in both cohorts who were free from tumour progression showed no differences in cognitive deficit, focal deficit, performance status, and headache after one year. However, participants randomised to the early radiotherapy group experienced significantly fewer seizures than participants in the delayed postoperative radiotherapy group at one year (25% versus 41%, P value = 0.0329, respectively).

AUTHORS' CONCLUSIONS

Given the high risk of bias in the included study, the results of this analysis must be interpreted with caution. Early radiation therapy was associated with the following adverse effects: skin reactions, otitis media, mild headache, nausea, and vomiting. People with LGG who undergo early radiotherapy showed an increase in time to progression compared with people who were observed and had radiotherapy at the time of progression. There was no significant difference in overall survival between people who had early versus delayed radiotherapy; however, this finding may be due to the effectiveness of rescue therapy with radiation in the control arm. People who underwent early radiation had better seizure control at one year than people who underwent delayed radiation. There were no cases of radiation-induced malignant transformation of LGG. However, it remains unclear whether there are differences in memory, executive function, cognitive function, or quality of life between the two groups since these measures were not evaluated.

Gamma Knife radiosurgery for low-grade tectal gliomas

BACKGROUND

Tectal gliomas are present in a critical location that makes their surgical treatment difficult. Stereotactic radiosurgery presents an attractive noninvasive treatment option. However, tectal gliomas are also commonly associated with aqueductal obstruction and consequently hydrocephalus. This necessitates some form of CSF diversion procedure before radiosurgery. The aim of the study was to assess the efficacy and safety of Gamma Knife radiosurgery for tectal gliomas.

PATIENTS AND METHODS

Between October 2002 and May 2011, 11 patients with tectal gliomas were treated with Gamma Knife radiosurgery. Five patients had pilocytic astrocytomas and six nonpilocytic astrocytomas. Ten patients presented with hydrocephalus and underwent a CSF diversion procedure [7 V-P shunt and 3 endoscopic third ventriculostomy (ETV)]. The tumor volume ranged between 1.2-14.7 cc (median 4.5 cc). The prescription dose was 11-14 Gy (median 12 Gy).

RESULTS

Patients were followed for a median of 40 months (13-114 months). Tumor control after radiosurgery was seen in all cases. In 6/11 cases, the tumors eventually disappeared after treatment. Peritumoral edema developed in 5/11 cases at an onset of 3-6 months after treatment. Transient tumor swelling was observed in four cases. Four patients developed cysts after treatment. One of these cases required aspiration and eventually disappeared, one became smaller spontaneously, and two remained stable.

CONCLUSION

Gamma Knife radiosurgery is an effective and safe technique for treatment of tectal gliomas. Tumor shrinkage or disappearance after Gamma Knife radiosurgery may preclude the need for a shunt later on.

Subependymal giant cell astrocytomas in patients with tuberous sclerosis complex: considerations for surgical or pharmacotherapeutic intervention

Tuberous sclerosis complex is a genetic disorder caused by mutations in either the TSC1 or TSC2 gene that can result in the growth of hamartomas in multiple organ systems. Subependymal giant cell astrocytomas are slow-growing brain tumors associated primarily with tuberous sclerosis complex. They are usually located in the ventricles, often near the foramen of Monro, where they can cause an obstruction if they grow too large, leading to increased intracranial pressure. Surgery to remove a tumor has been the mainstay of treatment but can be associated with postoperative morbidity and mortality. Not all tumors and/or patients are suitable for surgery. The recent development of mammalian target of rapamycin inhibitors that target the pathway affected by TSC1/TSC2 mutations offers a novel pharmacotherapeutic option for these patients. We review the timing and use of surgery versus pharmacotherapy for the treatment of subependymal giant cell astrocytoma in patients with tuberous sclerosis complex.

Subependymal giant cell astrocytoma: current concepts, management, and future directions

BACKGROUND

Subependymal giant cell astrocytoma (SEGA) is the most common central nervous system tumor in patients with tuberous sclerosis complex (TSC). SEGAs are generally benign, non-infiltrative lesions, but they can lead to intracranial hypertension, obstructive hydrocephalus, focal neurologic deficits, and even sudden death.

DISCUSSION

Surgical resection has been the standard treatment for SEGAs, and it is generally curative with complete resection. However, not all SEGAs are amenable to safe and complete resection. Gamma Knife stereotactic radiosurgery provides another treatment option as a primary or adjuvant treatment for SEGAs, but it has highly variable response effects with sporadic cases demonstrating its efficacy. Recently, biologically targeted pharmacotherapy with mammalian target of rapamycin (mTOR) inhibitors such as sirolimus and everolimus has provided a safe and efficacious treatment option for patients with SEGAs. However, SEGAs can recur few months after drug discontinuation, indicating that mTOR inhibitors may need to be continued to avoid recurrence. Further studies are needed to evaluate the advantages and adverse effects of long-term treatment with mTOR inhibitors. This review presents an overview of the current knowledge and particularly highlights the surgical and medical options of SEGAs in patients with TSC.

Pediatric low-grade gliomas: how modern biology reshapes the clinical field

Low-grade gliomas represent the most frequent brain tumors arising during childhood. They are characterized by a broad and heterogeneous group of tumors that are currently classified by the WHO according to their morphological appearance. Here we review the clinical features of these tumors, current therapeutic strategies and the recent discovery of genomic alterations characteristic to these tumors. We further explore how these recent biological findings stand to transform the treatment for these tumors and impact the diagnostic criteria for pediatric low-grade gliomas.

Resection of subependymal giant cell astrocytoma guided by intraoperative magnetic resonance imaging and neuronavigation

PURPOSE

Subependymal giant cell astrocytoma (SEGA) is a rare, benign tumor that occurs mainly in children; complete resection can achieve cure. Guidance of surgery by combined intraoperative magnetic resonance imaging (iMRI) and functional neuronavigation is reported to achieve more radical resection and reduced complications. However, reports about the resection of SEGA with such guidance are rare. We report here our preliminary experience of the resection of SEGA guided by iMRI and neuronavigation, focusing on the feasibility, benefits, and pitfalls of this combination of techniques.

METHODS

We performed resection of SEGA guided by combined iMRI and functional neuronavigation in seven children. The first iMRI was performed when the surgeon believed that the tumor had been completely resected; the last iMRI was performed immediately after closure. Additional scans were performed as needed.

RESULTS

Successful resection was achieved in all seven patients using this combination of techniques. The iMRI scans detected residual tumor in three patients and a large, remote epidural hematoma in one patient. Further resection or other surgery was performed in these four patients. Complete resection was eventually achieved in all patients. There were no cases of surgery-related neurological dysfunction, except transient memory loss in one patient. No recurrence of tumor or hydrocephalus was observed in any patients during the follow-up period.

CONCLUSIONS

Resection of SEGA in children guided by combined iMRI and neuronavigation is feasible and safe. This combination of techniques enables a higher complete resection rate and reduces brain injury and other unexpected events during surgery.

Gamma knife surgery of pediatric gliomas

OBJECT

While some low-grade pediatric gliomas may be cured with resection, many patients harbor tumors that cannot be completely resected safely, are difficult to access via an open surgical approach, or recur. Gamma Knife surgery may be beneficial in the treatment of these tumors.

METHODS

The authors reviewed a consecutive series of 24 pediatric patients treated at the authors' institution between 1989 and 2011. All patients harbored tumors that were either surgically inaccessible or had evidence of residual or recurrent growth after resection. Progression-free survival was evaluated and correlated with clinical variables. Additional outcomes evaluated were clinical outcome, imaging response, and overall survival.

RESULTS

Between 1989 and 2011, 13 male and 11 female patients (median age 11 years, range 4-18 years) with gliomas were treated. Tumor pathology was pilocytic astrocytoma (WHO Grade I) in 15 patients (63%), WHO Grade II in 4 (17%), and WHO Grade III in 1 (4%). The tumor pathology was not confirmed in 4 patients (17%). The mean tumor volume at the time of treatment was 2.4 cm(3). Lesions were treated with a median maximum dose of 36 Gy, median of 3 isocenters, and median marginal dose of 15 Gy. The median duration of imaging follow-up was 74 months, and the median duration of clinical follow-up was 144 months. The tumors responded with a median decrease in volume of 71%. At last follow up, a decrease in tumor size of at least 50% was demonstrated in 18 patients (75%) and complete tumor resolution was achieved in 5 (21%). Progression-free survival at last follow-up was achieved in 20 patients (83%). Progression was documented in 4 patients (17%), with 3 patients requiring repeat resection and 1 patient dying. The initial tumor volume was significantly greater in patients with disease progression (mean volume 4.25 vs 2.0 cm(3), p < 0.001). Age, tumor pathology, tumor location, previous radiation, Karnofsky Performance Scale score, symptom duration, and target dosage did not differ significantly between the 2 groups.

CONCLUSIONS

Gamma Knife surgery can provide good clinical control of residual or recurrent gliomas in pediatric patients. Worse outcomes in the present series were associated with larger tumor volumes at the time of treatment.

Current treatment of low grade astrocytoma: a review

Through a comprehensive review of the current literature, the present article investigates several aspects of low grade astrocytomas (LGA), including prognostic factors, treatment strategies and follow-up regimes. LGA are in general relatively slow-growing primary brain tumours, but they have a very heterogeneous clinical behaviour. Several factors affect prognosis, and these include age, histological subtype, and Karnofsky Performance Score (KPS) prior to surgery. Furthermore, a number of different molecular genetic alterations have been shown to affect both the prognosis as well as the course of disease. The current literature seems to support the idea that treatment with radical tumour resection, where possible, yields better long term outcome for patients with LGA. However, adjuvant therapy is often necessary. Administering early postoperative radiotherapy to patients with partially resected LGA yields a longer period of progression-free survival, whereas patients with radically resected tumours should receive radiotherapy at the time of progression. Regarding chemotherapy, we found evidence to suggest that patients respond to both temozolomide (TMZ) and the combination of procarbazine, lomustine and vincristine (PCV). However, the response rates in patients receiving PCV seem superior to those of patients receiving TMZ. In follow-up PET scans, the tracers (18)F-FDG and MET provide high sensitivities for detection of new suspicious lesions and these tracers are furthermore effective in discriminating between tumour progression and radiation necrosis. The research into biomarkers is currently limited with regards to their applications in LGA diagnostics, and therefore further studies including larger patient populations are needed.

Advances in the management of subependymal giant cell astrocytoma

BACKGROUND

Subependymal giant cell astrocytoma (SEGA) is the most common central nervous system tumor in patients with tuberous sclerosis complex (TSC). Although these lesions are generally benign and non-infiltrative, they commonly arise in the region of the foramen of Monro, where they can cause obstructive hydrocephalus and sudden death.

METHODS

Surgical resection has been, and presently remains, the standard treatment for SEGAs demonstrating serial growth on neuroimaging in the setting of symptomatic hydrocephalus or progressive ventriculomegaly.

DISCUSSION

Surgery can be curative; however, not all SEGAs are amenable to safe and complete resection. Gamma Knife stereotactic radiosurgery provides another treatment option but has highly variable response rates with limited data demonstrating its efficacy. Newer medical therapy targeting mammalian target of rapamycin (mTOR), the key protein kinase that is constitutively activated in TSC, has demonstrated promising results in recent clinical trials. In both case reports and clinical trials, treatment with mTOR inhibitors results in a significant reduction in SEGA volume and improvement or resolution of ventriculomegaly. This has led to the approval of everolimus for the treatment of SEGA in tuberous sclerosis patients who are not candidates for surgery. This review summarizes the surgical and medical management of SEGA in patients with TSC.

Fetal neurosurgery: current state of the art

Congenital CNS abnormalities have been targets for prenatal intervention since the founding of fetal surgery 30 years ago, but with historically variable results. Open fetal neurosurgery for myelomenigocele has demonstrated the most promising results of any CNS malformation. Improvements in the understanding of congenital diseases and in fetal surgical techniques have reopened the door to applying fetal surgery to other congenital CNS abnormalities. Advances in gene therapy, bioengineering and neonatal neuroprotection will aid in the future expansion of fetal neurosurgery to other CNS disorders.

Gamma Knife surgery for subependymal giant cell astrocytomas. Clinical article

OBJECT

The authors report their experience of using Gamma Knife surgery (GKS) in patients with subependymal giant cell astrocytoma (SEGA).

METHODS

Over a 20-year period, the authors identified 6 patients with SEGAs who were eligible for GKS. The median patient age was 16.5 years (range 7-55 years). In 4 patients, GKS was used as a primary management therapy. One patient underwent radiosurgery for recurrent tumors after prior resection, and in 1 patient GKS was used as an adjunct after subtotal resection. The median tumor volume at GKS was 2.75 cm(3) (range 0.7-5.9 cm(3)). A median radiation dose of 14 Gy (range 11-20 Gy) was delivered to the tumor margin.

RESULTS

The median follow-up duration was 73 months (range 42-90 months). Overall local tumor control was achieved in 4 tumors (67%) with progression-free periods of 24, 42, 57, and 66 months. Three tumors regressed and one remained unchanged. In 2 patients the tumors progressed, and in 1 of these patients the lesion was managed by repeated GKS with subsequent tumor regression. The other relatively large tumor (5.9 cm(3)) was excised 9 months after GKS. The progression-free period for all GKS-managed tumors varied from 9 to 66 months. There were no cases of hydrocephalus or GKS-related morbidity.

CONCLUSIONS

Gamma Knife surgery may be an additional minimally invasive management option for SEGA in a patient who harbors a small but progressively enlarging tumor when complete resection is not safely achievable. It may also benefit patients with a residual or recurrent tumor that has progressed after surgery.

Transplantation of human embryonic stem cells and derivatives to the chick embryo

Traditional methods of studying the differentiation of human embryonic stem cells (hESCs) include generation of embryoid bodies, induced differentiation in vitro, and transplantation to immune-deficient mice. The chick embryo is a well-studied and accessible experimental system that has been used for many years as a xenograft host for mammalian cells. Several years ago, we performed experiments transplanting colonies of hESC into organogenesis-stage chick embryos to establish a novel system for studying the developmental programs and decisions of pluripotent human cells. Fluorescent hESC were used, in order to permit identification of the hESC in living embryos. We transplanted hESC into the trunk of chick embryos, both into and instead of developing somites. Our results showed that hESC survive, migrate, and integrate into the tissues of the chick embryo. Some of the hESC differentiated and the type of embryonic microenvironment that the implanted cells were exposed to modified their differentiation. Several other laboratories have subsequently xenografted hESC-derived cells to chick embryos for evaluating their differentiation in vivo. Therefore, the hESC-chick embryo system is a useful xenograft system complementing studies in rodents and in vitro, as well as uniquely shedding light on early processes in the development of human cells in the embryonic context.