Subependymal Giant Cell Astrocytoma: A Surveillance, Epidemiology, and End Results Program–Based Analysis from 2004 to 2013

Benign Glioma

Benign glioma broadly refers to a heterogeneous group of slow-growing glial tumors with low proliferative rates and a more indolent clinical course. These tumors may also be described as "low-grade" glioma (LGG) and are classified as WHO grade I or II lesions according to the Classification of Tumors of the Central Nervous System (CNS) (Louis et al. in Acta Neuropathol 114:97-109, 2007). Advances in molecular genetics have improved understanding of glioma tumorigenesis, leading to the identification of common mutation profiles with significant treatment and prognostic implications. The most recent WHO 2016 classification system has introduced several notable changes in the way that gliomas are diagnosed, with a new emphasis on molecular features as key factors in differentiation (Wesseling and Capper in Neuropathol Appl Neurobiol 44:139-150, 2018). Benign gliomas have a predilection for younger patients and are among the most frequently diagnosed tumors in children and young adults (Ostrom et al. in Neuro Oncol 22:iv1-iv96, 2020). These tumors can be separated into two clinically distinct subgroups. The first group is of focal, well-circumscribed lesions that notably are not associated with an increased risk of malignant transformation. Primarily diagnosed in pediatric patients, these WHO grade I tumors may be cured with surgical resection alone (Sturm et al. in J Clin Oncol 35:2370-2377, 2017). Recurrence rates are low, and the prognosis for these patients is excellent (Ostrom et al. in Neuro Oncol 22:iv1-iv96, 2020). Diffuse gliomas are WHO grade II lesions with a more infiltrative pattern of growth and high propensity for recurrence. These tumors are primarily diagnosed in young adult patients, and classically present with seizures (Pallud et al. Brain 137:449-462, 2014). The term "benign" is a misnomer in many cases, as the natural history of these tumors is with malignant transformation and recurrence as grade III or grade IV tumors (Jooma et al. in J Neurosurg 14:356-363, 2019). For all LGG, surgery with maximal safe resection is the treatment of choice for both primary and recurrent tumors. The goal of surgery should be for gross total resection (GTR), as complete tumor removal is associated with higher rates of tumor control and seizure freedom. Chemotherapy and radiation therapy (RT), while not typically a component of first-line treatment in most cases, may be employed as adjunctive therapy in high-risk or recurrent tumors and in some select cases. The prognosis of benign gliomas varies widely; non-infiltrative tumor subtypes generally have an excellent prognosis, while diffusely infiltrative tumors, although slow-growing, are eventually fatal (Sturm et al. in J Clin Oncol 35:2370-2377, 2017). This chapter reviews the shared and unique individual features of the benign glioma including diffuse glioma, pilocytic astrocytoma and pilomyxoid astrocytoma (PMA), subependymal giant cell astrocytoma (SEGA), pleomorphic xanthoastrocytoma (PXA), subependymoma (SE), angiocentric glioma (AG), and chordoid glioma (CG). Also discussed is ganglioglioma (GG), a mixed neuronal-glial tumor that represents a notable diagnosis in the differential for other LGG (Wesseling and Capper 2018). Ependymomas of the brain and spinal cord, including major histologic subtypes, are discussed in other chapters.

Essential Management of Pediatric Brain Tumors

Brain tumors are the most common solid tumors in children and are associated with high mortality. The most common childhood brain tumors are grouped as low-grade gliomas (LGG), high grade gliomas (HGG), ependymomas, and embryonal tumors, according to the World Health Organization (WHO). Advances in molecular genetics have led to a shift from pure histopathological diagnosis to integrated diagnosis. For the first time, these new criteria were included in the WHO classification published in 2016 and has been further updated in the 2021 edition. Integrated diagnosis is based on molecular genomic similarities of the tumor subclasses, and it can better explain the differences in clinical courses of previously histopathologically identical entities. Important advances have also been made in pediatric neuro-oncology. A growing understanding of the molecular-genetic background of tumorigenesis has improved the diagnostic accuracy. Re-stratification of treatment protocols and the development of targeted therapies will significantly affect overall survival and quality of life. For some pediatric tumors, these advances have significantly improved therapeutic management and prognosis in certain tumor subgroups. Some therapeutic approaches also have serious long-term consequences. Therefore, optimized treatments are greatly needed. Here, we discuss the importance of multidisciplinary collaboration and the role of (pediatric) neurosurgery by briefly describing the most common childhood brain tumors and their currently recognized molecular subgroups.

The clinical and paraclinical manifestations of tuberous sclerosis complex in children

Tuberous sclerosis complex (TSC) is an autosomal-dominant, multi-system, neurocutaneous disorder characterized by hamartomas in multiple organs. This study aimed to evaluate the clinical and paraclinical manifestations of children with TSC. The clinical and paraclinical characteristics of 79 children with TSC were evaluated and the possible correlations between the factors were calculated. Among the studied children which composed of 41 females (51.9%) and 38 males (48.1%), skin manifestations as hypopigmented macules as well as the brain involvement as cortical tubers in all (100%) cases, seizure in 74 (93.7%), and sub-ependymal nodules in 73 (92.4%) patients were the most common findings. The renal angiomyolipoma was diagnosed in 36 (70.6%) out of 51 patients. Subependymal giant cell astrocytoma in 25 (3/54%) out of 46 patients, retinal hamartoma in 15 (42.9%) out of 35 patients, and cardiac rhabdomyoma in 17 (41.3%) out of 46 patients were diagnosed. Furthermore, 50 (63.3%) out of 79 patients had psychological disorders that had a significant correlation with the prevalence of seizures (p = 0.002). Given the multi-systemic involvement of TSC, it is necessary that all organs of the patients even without any related clinical symptom or sign be examined regularly for proper therapeutic intervention and prevent disease progression. The growth of hamartomas in the brain and kidneys can be life-threatening; therefore, these organs have more importance to be regularly followed up and examined.

[Tuberous sclerosis system: A review]

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder that affects different organs and caused by loss-of-function mutations in one of two genes: TSC1 or TSC2. TSC1 or TSC2 gene mutation lead to dysfunction of hamartin or tuberin, respectively. Hamartin and tuberin form a protein complex that helps regulate cellular proliferation. These proteins form a complex that constitutively inhibits the mammalian target of rapamycin (mTOR) signaling pathway, leading to permanent activation of mTOR signaling within all TSC-associated lesions. Major features of TSC include tumors of the brain, skin, heart, lungs and kidneys, seizures and TSC-associated neuropsychiatric disorders, which can include autism spectrum disorder and cognitive disability. These disorders are usually diagnosed in children and adults. Specific guidelines for diagnosis, surveillance, and management have been proposed by the International Tuberous Sclerosis Complex Consensus Group. Several randomized controlled trials led to regulatory approval of the use of mTOR inhibitors for the treatment of renal angiomyolipomas, brain subependymal giant cell astrocytomas, refractory epilepsy and pulmonary lymphangioleiomyomatosis.

Trends in survival and treatment of SEGA: National Cancer Database Analysis

Background

SEGA is a rare, slow-growing CNS neoplasm that has historically been treated by surgical resection. However, the advent of a mammalian target of rapamycin complex-1 inhibitor, everolimus, has shown promising results in recent clinical trials. We sought to provide an analysis of epidemiological and survival risk factors in this rare tumor entity, while comparing trends in surgical management before and after introduction of everolimus in SEGAs.

Methods

Patients with SEGA were queried from the National Cancer Database between 2004 and 2015. Standard statistical analysis was conducted to assess variables associated with the odds of performing surgery and survival, while controlling for confounding variables.

Results

A total of 460 patients were diagnosed with SEGA. Multivariable analysis of survival demonstrated that increased age was associated with decreased survival (HR, 1.05; P < .0001). Multivariable analysis of surgery showed increased age (odds ratio [OR], 1.02, P = .04) and tumor size 20 mm or larger (OR, 9.52-16.75, P < .0001 for all) to be associated with higher odds of performing surgery. The use of radiotherapy (OR, 0.12, P = .008) or chemotherapy (OR, 0.21, P = .008) was associated with lower odds of surgery. A comparison of surgical rates between 2004 and 2010 and 2011 and 2015 was found to be significantly different, with a lower rate of surgery seen after 2011 (60.63% vs 48.06%, P = .007).

Conclusion

Our analysis of SEGAs demonstrated that age was the only variable affecting overall survival. Surgical resection was performed in older patients with larger tumors (> 20 mm) as a primary mode of treatment, without chemoradiotherapy. Expectedly, rates of surgical resection were found to have decreased since 2011, after FDA approval of everolimus for SEGA treatment.