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Glioma is a type of brain tumour that occurs in glial cells, which support nerve cells (neurons) in the brain. These tumours mostly develop in the largest regions of the brain (cerebral hemispheres) responsible for functions such as cognition, emotion, movement and speech. However, gliomas can also occur in other brain areas, including:
Symptoms will differ depending on the brain area affected.
Gliomas are cancerous (malignant) and can be graded based on the type of glial cells affected and their aggressiveness. Knowing the grade of a glioma helps determine the type of treatment and progression of the tumour.
Gliomas can be graded into three primary types based on the origin and function of the tumour cells. In general, the higher the grade, the more aggressive the tumour:
Astrocytomas develop from star-shaped glial cells called astrocytes and are categorised into four grades:
Ependymomas originate from ependymal cells that line the brain ventricles and spinal cord canal. They are less common in adults and account for 2-3% of primary brain tumours. Ependymomas are graded as follows:
Oligodendrogliomas arise from oligodendrocytes, cells that produce the layer covering nerve cells (myelin sheath). They are divided into:
Knowing the grade of a glioma helps determine the type of treatment and progression of the tumour.
The symptoms of gliomas may differ widely depending on the size and location of the tumour in the brain and spinal cord. Different brain and spinal structures may be affected, leading to symptoms that reflect the tumour's location.
Common signs and symptoms associated with gliomas include:
Diagnosing gliomas based solely on symptoms can be challenging, as these symptoms do not confirm the presence of a glioma. Seek medical advice if the symptoms listed above persist or worsen.
For example, if you have a headache that lasts more than 15 days, you should see a doctor for a thorough medical check-up. Early detection and appropriate medical intervention are crucial to manage gliomas.
The causes of glioma are not clear and risk factors such as age and genes cannot be controlled. If there is a family history of brain tumour, consider regular medical check-ups or consult a doctor about genetic counselling.
The exact causes of most gliomas are not fully understood, but research suggests they may begin when genetic changes occur in the brain or spinal cord cells. These changes lead to abnormal cell growth and tumour formation, with some gliomas eventually becoming cancerous and invade healthy cells.
Several factors have been identified as risk factors for glioma:
The risk of developing gliomas increases with age and is most common in adults between ages 45 and 65. However, certain types, like high-grade gliomas, are more frequently diagnosed in children and young adults.
A small percentage (about 5%) of brain tumour cases are due to inherited genetic conditions, such as:
Certain chemicals or substances in work environments have been linked to an increased risk of glioma. For example, being exposed to vinyl chloride may increase the risk of developing gliomas, although no clear evidence has been established.
While many of the risk factors associated with glioma cannot be controlled, understanding them can help with early detection and treatment.
When symptoms could be a sign of a brain tumour, a detailed medical history and neurological examination will be taken.
Imaging is used to diagnose a brain tumour, and includes:
Other types of imaging may be needed, such as:
These tests help to detect and pinpoint the tumour's size, location and how close it is to parts of the brain that control key functions such as language. The test results will help a neurosurgeon, a doctor who specialises in the diagnosis and surgical treatment of neurological conditions, to plan for the management of the tumour.
To determine tumour type, a biopsy is often recommended. During a biopsy, tissue samples are taken from the tumour and examined under a microscope for a more accurate understanding of the tumour's cell structure and features.
The primary goal of managing brain tumours is to remove as much cancerous tissue while maintaining the surrounding brain structures.
Treatment involves a multidisciplinary team of specialists, including neurosurgeons, neurologists, neuroradiologist, neuropathologists, oncologists, nurse clinicians and allied health professionals (therapists, social workers, psychologists, dieticians) who work together to develop a management plan personalised to the patient's needs and tumour profile.
Treatment depends on the tumour's size, location, grade, sub-type, how much was removed for testing and the patient's general health. For gliomas graded 2 to 4, treatment often aims to control the tumour's growth or relieve symptoms, but it is unable to cure the tumour.
Treatment approaches include:
Patients are regularly monitored to track the progression of the tumour. This approach is suitable for patients with slow-growing tumours that do not present symptoms, where the potential risks of any procedure may outweigh the benefits.
Surgical removal of the tumour is often the initial treatment for glioma. The amount of cancerous tissue to be removed depends on the tumour's grade and location. Complete removal may not always be possible, especially if the tumour is near critical brain regions responsible for functions such as breathing. In these cases, the goal is to remove as much of the tumour as possible while keeping brain function intact. Other surgical techniques, such as imaging and brain mapping, help surgeons during the tumour removal process.
Some may undergo an awake craniotomy, a surgery that is performed while the patient is conscious and able to respond to simple instructions, but unable to feel any pain. An awake craniotomy reduces the risk of damage to critical brain regions close to the tumour.
The risk of surgery depends on multiple factors including the patient's age, medical history and location of the tumour. These risks may include infection, bleeding, seizures, paralysis and coma.
Radiation therapy is commonly used either as a treatment on its own or together with surgery and chemotherapy. External Beam Radiation Therapy (EBRT) directs high-energy particles such as x-rays, photons, or protons to target and destroy glioma cells. Radiation therapy aims to shrink tumours, prevent them from growing, and reduce the likelihood of recurrence.
Depending on the size and spread of the tumour, and the patient's overall health condition, radiation therapy may be given five days a week for three to six weeks. The first session will usually start within six weeks of the surgery, depending on how well the surgical wound has healed. Prior to radiation therapy, the patient would need to go for a simulation CT scan. During the session, a plastic shell will also be custom made for each patient. This shell will help to hold the head and neck in position during therapy.
Your doctor will discuss potential side-effects and how to cope with them before radiation therapy is started. Short-term side effects of radiation therapy can include fatigue, headaches, hair loss and scalp irritation. Longer term side effects may vary depending on your treatment.
Chemotherapy involves the use of drugs to stop cancer cells from multiplying. Drugs are delivered throughout the body via the bloodstream (systemic chemotherapy), targeting the primary tumour and potential tumours that have spread to other parts of the body.
Alternatively, a dissolvable wafer may be placed at the tumour site after surgery, allowing the chemotherapy to target the remaining cancer cells. This targeted approach minimises side effects while improving treatment results.
The most common form of chemotherapy for high-grade glioma is Temozolomide, however this medication is only effective in certain sub-types of glioma. Temozolomide is a capsule to be taken orally. The standard treatment is to start Temozolomide at the same time as radiation therapy followed by another six cycles of chemotherapy given over six months.
Side effects of Temozolomide include fatigue, nausea, liver injury, constipation, decreased white blood cell count or platelet count.
