Pediatric and Adult Low-Grade Gliomas: Where Do the Differences Lie?

Abstract

Two thirds of pediatric gliomas are classified as low-grade (LGG), while in adults only around 20% of gliomas are low-grade. However, these tumors do not only differ in their incidence but also in their location, behavior and, subsequently, treatment. Pediatric LGG constitute 65% of pilocytic astrocytomas, while in adults the most commonly found histology is diffuse low-grade glioma (WHO II), which mostly occurs in eloquent regions of the brain, while its pediatric counterpart is frequently found in the infratentorial compartment. The different tumor locations require different skillsets from neurosurgeons. In adult LGG, a common practice is awake surgery, which is rarely performed on children. On the other hand, pediatric neurosurgeons are more commonly confronted with infratentorial tumors causing hydrocephalus, which more often require endoscopic or shunt procedures to restore the cerebrospinal fluid flow. In adult and pediatric LGG surgery, gross total excision is the primary treatment strategy. Only tumor recurrences or progression warrant adjuvant therapy with either chemo- or radiotherapy. In pediatric LGG, MEK inhibitors have shown promising initial results in treating recurrent LGG and several ongoing trials are investigating their role and safety. Moreover, predisposition syndromes, such as neurofibromatosis or tuberous sclerosis complex, can increase the risk of developing LGG in children, while in adults, usually no tumor growth in these syndromes is observed. In this review, we discuss and compare the differences between pediatric and adult LGG, emphasizing that pediatric LGG should not be approached and managed in the same way as adult LCG.

Medical Treatment of Pediatric Low-Grade Glioma

“…The mainstay of therapy for progressive or symptomatic pLGG is surgical resection [ 10 ]. Gross total resection (GTR) of tumors often requires no further therapy, and even subtotal resection may lead volume reduction and long-term tumor quiescence [ 8 ].…”

Epidemiological characteristics, clinical presentations, and prognoses of pediatric brain tumors: Experiences of national center for children’s health

“…It is known that brain tumors have specific site distribution and predilection age patterns. The meninges are the most common tumor site in all age groups, with meningiomas being the most common tumor histology in the 2021 CBTRUS report (1,2). However, brain tumors in the pediatric population have different epidemiological characteristics than those in the adult population.…”

Prognostic Factors of Low-Grade Gliomas in Adults

“…The low-grade gliomas are grouped by the World Health Organization (WHO) as primary tumors of the central nervous system with histopathological grade 1 and 2 [ 1 ]. This category includes both circumscribed and diffuse entities: pilocytic astrocytoma, pleomorphic xantoastrocytoma, oligodendroglioma grade 2, and astrocytoma grade 2 (diffuse astrocytoma) [ 2 , 3 ]. Their main characteristic is represented by a low proliferative index [ 1 ].…”

“…They have an increased incidence in males between 35–44 years [ 3 ]. Unlike the pediatric population, the adult population is less often affected [ 2 ].…”

“…Life expectancy is relatively good, with an average survival rate of 5.6 to 13.3 years [ 1 ]. A number of molecular and constitutional characteristics contribute to this rate: topography, topographic effects, tumor histology, patient age, type of treatment, tumor volume, and patient performance status [ 1 , 2 , 3 , 4 , 5 ]. Another aspect not to be neglected is the potential for malignant transformation of these tumors, which can vary between 25 and 72% of cases [ 6 ].…”