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Paper Abstract

Pediatric Astrocytoma

Overview

An astrocytoma is a type of brain tumor. It forms in small star shaped cells called astrocytes, a type of glial cell. Astrocytoma accounts also for about half of all brain tumors in children. It may be found in the brain, spinal cord, or other nervous system tissues such as peripheral nerves and eye muscles. An astrocytoma is usually low grade, meaning it is a slow-growing tumor but it should be watched carefully because it could turn into a faster-growing tumor. Most brain tumors are caused by abnormal genes or chromosomes. Some chemicals may play a part in gene changes. Many children with CNS tumors have successful treatment, but sometimes their tumor cannot be controlled or cured, this is called an advanced or terminal tumor.

Indian perspective

In India, the most frequent central nervous tumors were astrocytoma (47.3%), MB (11.4%), craniopharyngioma (9.7%), and ependymal tumors (4.8%), and nerve sheath tumors (4.1%) according to 2016 research. The incidence of central nervous system (CNS) tumors in India ranges from 5 to 10 per 100,000 population with an increasing trend and accounts for 2% of malignancies. The most common tumor is astrocytoma (34.7%) followed by MB and supratentorial PNETs (22.4%) and craniopharyngioma. Most of the astrocytic tumors were reported to be low grade commonly pilocytic astrocytoma and subependymal giant cell astrocytoma. This was found to be comparable to data from Western countries or other Asian countries.

Diagnosis

An astrocytoma can be either asymptomatic (usually in the early stages) or symptomatic. The generalized clinical signs include headache, nausea, and vomiting. While the focal signs (which are due to regional brain tissue damage) comprise defects in vision, hearing, and speech. High-grade astrocytomas (WHO Grades–III&IV) show rapid progression of symptoms (few weeks). Headache from CNS tumors is mostly tension-type, bifrontal (both sides of the forehead), constant and dull. Low-grade astrocytomas typically present with seizures. ECF obstruction leads to an increase in the intracranial pressure (ICP). The classic triad of increased ICP includes headache, nausea, and papilledema (swelling in the nerve of the eye). ICP signs in infants comprise an enlarged head with prominent scalp veins. The typical signs of a brain tumor include mental confusion, learning impairment, disturbed vision, seizures, and ataxia (poor muscular control). Astrocytoma is often associated with other diseases, such as Li Fraumeni syndrome (Tp53 syndrome), Turcot Lynch syndrome (DNS mismatch repair loss), and Neurofibromatosis (NF) type 1 & 2, and Tuberous Sclerosis Complex (TSC).

The laboratory investigations required are baseline blood tests such as complete blood picture (CBC), prothrombin time (PT), and activated partial thromboplastin time (aPTT).

Neuroimaging mainly Magnetic Resonance Imaging (MRI) with contrast (gadolinium) is the preferred imaging modality for diagnosing astrocytoma. Astrocytomas appear hyperintense on T2 MRI and isointense/hypointense on T1 MRI. The appearance of new enhancement in a previously non-enhancing lesion indicates tumor progression. 

Histology (study of cell features) has long been the gold standard of diagnosis, classification, and prognostic prediction for astrocytomas. The histologic examination is carried out with biopsy (either open or 3 dimensional image-guided stereotactic) and/or histochemistry (immunohistochemistry, light electron microscopy, or cytogenic analysis).

Quality of life

A study that was conducted based on the surveillance, epidemiology, and end results (SEER) database for the period 1999-2010, to analyze the overall survival (OS) related to radiation therapy and EOR in patients with astrocytoma, found an improvement in OS during that decade. They reported a median survival of 5-8 years, 3 years, and 12-18 months in patients with WHO grade II, III, and IV astrocytoma, respectively, and that gross total resection is typically curative for WHO grade I astrocytoma. This study also reported that EOR and post-surgical residual volume of the tumor are independent determinants of HRQL.  The estimated disease burden on HRQL in patients with malignant astrocytomas reported that these symptoms – fatigue, uncertainty or anxiety about the future, motor difficulties, drowsiness, communication difficulties, and headache were experienced by >50% of the patients. Additionally, patients with recurrent glioblastoma multiformat reported >50% frequency for visual problems and pain. Radiotherapy and the ongoing corticosteroid therapy could be the cause of prolonged fatigue in these patients. Thus, it can be concluded that high-grade astrocytomas have a significant negative impact on HRQL post-treatment, especially when recurrent, while low-grade tumors are associated with a relatively better HRQL. Therapy or counseling has proved successful in improving or maintaining HRQL in patients with astrocytoma, even though it cannot significantly improve their OS.

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