Overview

Glioma is a type of tumor that arises from glial cells in the brain or spinal cord. Glial cells are supportive cells that provide structural and functional support to nerve cells (neurons). Gliomas are the most common primary brain tumors in adults and can vary widely in severity, ranging from slow-growing, benign forms to highly aggressive, malignant types. The classification of gliomas is based on the type of glial cell involved, including astrocytomas, oligodendrogliomas, and ependymomas. Gliomas can affect people of all ages but are more commonly diagnosed in adults. The severity and treatment options depend on the tumor’s grade, location, and molecular characteristics.

Causes

The exact causes of glioma are not fully understood, but several factors may increase the risk of developing this type of tumor:

• Genetic mutations: Changes in specific genes that regulate cell growth, such as IDH1, IDH2, and TP53, are often implicated in glioma formation.
• Age: The risk of glioma increases with age, especially between 45 and 70 years old.
• Radiation exposure: Previous exposure to ionizing radiation, especially to the head, increases the risk of brain tumors, including gliomas.
• Family history: Although rare, individuals with a family history of glioma or genetic syndromes like Li-Fraumeni syndrome or neurofibromatosis have a higher risk.
• Environmental factors: There is ongoing research into potential links between environmental exposures (such as chemicals) and gliomas, though no definitive conclusions have been made.
• Immune factors: A weakened immune system may play a role in certain brain tumors, but its role in gliomas remains under investigation.

Symptoms

Symptoms of glioma depend on the size, location, and rate of growth of the tumor. As the tumor grows, it can interfere with normal brain function and produce various neurological symptoms:

• Headaches: Frequent headaches that may worsen in the morning or with activity.
• Seizures: New onset of seizures, especially in adults, is a common symptom of glioma.
• Cognitive or personality changes: Memory issues, confusion, and changes in mood or behavior may occur.
• Muscle weakness or paralysis: Loss of strength or movement in specific parts of the body, depending on tumor location.
• Speech difficulties: Trouble speaking, finding words, or understanding language.
• Vision or hearing problems: Blurred vision, double vision, or hearing loss may be present if the tumor is near sensory areas.
• Balance and coordination issues: Difficulty walking or maintaining balance, especially with tumors in the cerebellum or brainstem.

Diagnosis

The diagnosis of glioma involves a combination of neurological evaluation, imaging studies, and tissue analysis:

• Neurological examination: A doctor checks for signs of neurological impairment, including reflexes, muscle strength, coordination, and sensory function.
• Imaging tests:
  • MRI (Magnetic Resonance Imaging): The primary imaging tool to visualize the brain and detect the presence of a tumor with high detail.
  • CT scan (Computed Tomography): May be used when MRI is not available or to quickly evaluate acute symptoms.
• Biopsy: A surgical procedure where a sample of the tumor is removed and examined under a microscope to determine the tumor type and grade.
• Molecular testing: Analysis of specific genetic mutations (such as IDH mutation, 1p/19q codeletion, MGMT methylation) helps guide treatment and predict prognosis.
• Functional MRI or PET scans: Advanced imaging techniques may be used to assess tumor activity and plan surgical interventions.

Treatment

Treatment for glioma depends on factors like tumor type, grade, size, location, and the patient’s overall health. Common treatment options include:

• Surgery: Surgical removal of the tumor is usually the first step, aiming for maximum safe resection while preserving brain function.
• Radiation therapy: High-energy radiation is used to destroy remaining cancer cells and slow tumor growth, particularly in higher-grade gliomas.
• Chemotherapy: Drugs such as temozolomide are commonly used to target and kill tumor cells, often in combination with radiation.
• Targeted therapy: Newer treatments target specific genetic mutations or pathways involved in glioma growth.
• Tumor-treating fields (TTF): A non-invasive treatment using electrical fields to disrupt cancer cell division, primarily used in glioblastoma.
• Supportive care: Corticosteroids may reduce brain swelling, and anticonvulsants help manage seizures.
• Clinical trials: Participation in clinical trials may provide access to experimental therapies for eligible patients.

Prognosis

The prognosis of glioma varies significantly based on tumor type, grade, and molecular features. Low-grade gliomas (Grade I or II) generally have a better prognosis and slower progression, with many patients living for several years after diagnosis. High-grade gliomas, such as glioblastoma (Grade IV), are more aggressive and have a poorer prognosis, with median survival typically ranging from 12 to 18 months despite treatment.

Factors that improve prognosis include younger age, complete or near-complete surgical removal, presence of favorable genetic markers (like IDH mutation), and good overall health. Advances in treatment, including targeted therapies and immunotherapy, are ongoing and offer hope for better outcomes in the future. Regular follow-up care, MRI monitoring, and supportive therapies play a crucial role in improving quality of life and managing symptoms during and after treatment.