Glioma: Types, Symptoms, Causes & Treatment

What Is Glioma?

Glioma is a type of brain tumour that develops from glial cells, the supportive cells in the brain and spinal cord. It is one of the most common primary brain tumours and can occur at any age, ranging from slow-growing, benign forms to aggressive, malignant cancers.

Glial cells play a vital role in supporting and insulating nerve cells, maintaining the environment around neurones, and aiding in nutrient transport and immune defence. Even benign gliomas can cause serious health issues due to their location. Understanding the types of glioma, its causes, and the available treatments can help you navigate this diagnosis with greater clarity and confidence.

Types of Glioma

Astrocytoma

Astrocytomas develop from star-shaped glial cells called astrocytes, which support and help maintain the blood-brain barrier. These tumours range from slow-growing (low-grade) to highly aggressive forms, with glioblastoma representing the most malignant type within this group.

Glioblastoma (GBM)

Glioblastoma (GBM) is the most aggressive type of astrocytoma and the primary malignant brain cancer in adults. It grows rapidly, invades surrounding brain tissue, and is often resistant to conventional therapies. Despite aggressive treatment, GBMs usually recur, resulting in a poor prognosis.

Oligodendroglioma

Oligodendrogliomas originate from oligodendrocytes, which produce myelin, the protective layer around nerve fibres. These tumours generally grow slowly and may be less aggressive than astrocytomas or GBMs.

Ependymoma

Ependymomas arise from ependymal cells lining the ventricles of the brain or the central canal of the spinal cord. These types of glioma tumours may block the flow of cerebrospinal fluid, leading to symptoms such as headaches, nausea, and balance problems. Ependymomas occur at any age but are more frequent in children; location varies by age (posterior fossa in children, spinal canal more often in adults).

Mixed Gliomas

Previously described as tumours with both astrocytic and oligodendroglial components, “mixed gliomas” are now rarely used as a diagnosis. With modern WHO criteria, most are classified by molecular testing as either IDH-mutant astrocytoma or oligodendroglioma (IDH-mutant and 1p/19q-codeleted).

Grades of Glioma (WHO Classification)

The 2021 WHO Classification of Tumours of the Central Nervous System (WHO CNS5) uses Arabic numerals (1 to 4) for grading tumours rather than Roman numerals to reduce confusion and to standardise grading across tumour types.

• Gliomas are divided into multiple families, including adult-type diffuse gliomas.
• Adult-type diffuse astrocytic gliomas, for example, are graded as CNS WHO grade 2, 3, or 4 based on histological and molecular features.

Grade 1 (Low Grade)

Grade 1 (Low Grade) gliomas are typically circumscribed (e.g., pilocytic astrocytoma), often seen in children and young adults, and may be cured with surgery when complete resection is feasible.

Grade 2 (Moderate)

Grade 2 gliomas are still slow-growing but show more abnormal cells under the microscope. These tumours have a greater tendency to recur and can progress to higher grades over time.

Grade 3 (Anaplastic)

Grade 3 gliomas are malignant, grow more rapidly, and are more likely to invade nearby brain tissue. They often require aggressive treatment, including surgery, radiation, and chemotherapy.

Grade 4 (Most Aggressive)

Grade 4 gliomas, such as glioblastoma, are the most aggressive and rapidly growing. They are highly malignant, infiltrate surrounding brain tissue, and are associated with the poorest prognosis, even with intensive therapy.

Symptoms of Glioma

General Symptoms

• Persistent headaches
• Nausea and vomiting
• Fatigue
• Unintentional weight loss (less common)
• Cognitive or personality changes

Neurological Symptoms

• Seizures
• Weakness or numbness in parts of the body
• Difficulty with speech or language
• Vision problems
• Problems with balance or coordination

Causes of Glioma

Genetic Mutations

Most gliomas are caused by acquired genetic mutations that affect how glial cells grow and divide. Some known mutations involve genes that regulate cell growth and repair, such as IDH1, IDH2, and TP53.

Environmental Factors

There is no strong evidence linking common environmental exposures to glioma causes or risk. Although rare, factors like exposure to high-dose ionising radiation (such as previous radiation therapy to the head) may slightly increase the risk.

Family History

A family history of glioma or other rare genetic syndromes such as neurofibromatosis, Li-Fraumeni syndrome, or Turcot syndrome may increase the risk for some individuals. However, most gliomas occur sporadically.

Risk Factors for Glioma

• Older age
• Male sex
• History of exposure to high-dose ionising radiation
• Family history of glioma or certain genetic syndromes

Complications of Glioma

• Permanent neurological deficits
• Seizures
• Hydrocephalus (buildup of fluid in the brain)
• Brain swelling (oedema)
• Cognitive impairment
• Recurrence of the tumour
• Side effects from treatment, such as infection, bleeding, or radiation necrosis.

How Glioma Is Diagnosed

1. Neurological Examination

A neurological examination assesses reflexes, muscle strength, coordination, vision, hearing, and mental status to detect functional deficits that may suggest a brain tumour.

2. Imaging Tests

• Magnetic resonance imaging (MRI)
• Computed tomography (CT) scan
• Magnetic resonance spectroscopy (MRS)
• Positron emission tomography (PET) scan

3. Biopsy

A biopsy involves removing a sample of tumour tissue for examination under a microscope to determine the type and grade, which guides glioma treatment decisions.

4. Molecular Testing

Molecular testing analyses tumour tissue for specific genetic mutations and molecular markers (such as IDH mutations, 1p/19q codeletion, and MGMT promoter methylation) to refine diagnosis and select targeted therapies.

Treatment for Glioma

Surgery

Surgery is often the first-line treatment for glioma, aiming to remove as much of the tumour as safely possible. Complete removal may not be feasible if the tumour is near critical brain areas.

Radiation Therapy

Radiation therapy uses high-energy rays to destroy tumour cells, often as an adjunct to surgery or for inoperable tumours. Techniques include external beam radiation, IMRT, proton therapy, and stereotactic radiosurgery.

Chemotherapy

Chemotherapy for brain tumours involves drugs (commonly temozolomide) that kill or slow cancer cell growth. It may be combined with radiation or used for tumours that recur or cannot be surgically removed.

Targeted Therapy

Targeted therapies focus on specific molecular changes in tumour cells. For example, IDH inhibitors (e.g., vorasidenib) may be used in appropriately selected IDH-mutant diffuse gliomas based on indication and availability.

Clinical Trials

Clinical trials test new treatments, such as immunotherapy, novel targeted agents, and tumour-treating fields (TTFields). Patients are encouraged to discuss participation with their healthcare team.

Living with Glioma: Supportive Care

• Medications to control seizures
• Steroids for brain swelling
• Pain management
• Cognitive and psychological support
• Physical, occupational, and speech therapy
• Nutritional support
• Palliative care services for symptom management

Prognosis and Survival Rate

Prognosis depends on tumour type, grade, location, age, and overall health. Low-grade gliomas have better outcomes, especially if completely removed, while high-grade gliomas (especially glioblastoma) have a median survival of 12–18 months despite aggressive treatment. Survival rates continue to improve with advances in therapy and supportive care.

Prevention of Glioma

• Avoid unnecessary exposure to ionising radiation.
• There is no proven way to prevent most gliomas. For people with hereditary syndromes, management focuses on counselling, surveillance, and addressing complications early.
• No proven lifestyle measures to prevent most gliomas

When to See a Doctor

• Persistent or severe headaches
• New or worsening seizures
• Unexplained neurological or brain tumour symptoms (weakness, vision loss, speech difficulty)
• Changes in personality or mental status
• Symptoms that worsen over time

Conclusion

Receiving a glioma diagnosis can feel overwhelming, but understanding the types of glioma and the available treatment options is an important first step in navigating this journey. If you or a loved one is experiencing persistent symptoms or has been diagnosed with a glioma, working closely with a trusted healthcare team to develop a personalised treatment plan is essential.

At Metropolis Healthcare, we are here to support you and your family with accurate pathology testing and comprehensive health checkup services. With over 220 laboratories and 4,600 service centres across India, we ensure timely and reliable testing wherever you are. With our commitment to accuracy, quality, and personalised care, we help you take proactive steps to prioritise your family’s health with confidence.

FAQs

1. Is glioma cancerous?

Gliomas can be cancerous, depending on their type and grade. Many grade 1 circumscribed gliomas are non-malignant, but most diffuse gliomas — even at lower grades (grade 2) — are considered malignant because they infiltrate brain tissue and can progress. High-grade gliomas (especially glioblastoma) are malignant, aggressive, and can grow and spread rapidly.

2. What is the difference between glioma and glioblastoma?

Glioblastoma is a specific type of glioma, representing the most aggressive and malignant form of astrocytoma. While all glioblastomas are gliomas, not all gliomas are glioblastomas.

3. Can glioma be cured?

The likelihood of curing a glioma depends on several factors, including the tumour's type, grade, and location, and the patient's age and overall health. Low-grade gliomas have a better chance of being cured, especially if they can be completely removed through surgery.

4. How fast do gliomas grow?

Growth rates vary by type and patient. Low-grade gliomas often grow slowly over years, whereas high-grade gliomas (such as glioblastoma) can progress rapidly, sometimes within weeks. This is why early detection and prompt treatment are so important.

5. What is the life expectancy for someone with glioma?

Patients with low-grade gliomas generally have a better prognosis, with median survival ranging from several years to decades. However, those with high-grade gliomas, especially glioblastoma, have a poorer prognosis, with a median survival of 12–18 months despite aggressive treatment.

References

• https://pmc.ncbi.nlm.nih.gov/articles/PMC8328013/
• https://my.clevelandclinic.org/health/diseases/21969-glioma
• https://www.hopkinsmedicine.org/health/conditions-and-diseases/glioma
• https://www.pathologyoutlines.com/topic/cnstumorwhograding.html