What is a glioma?
Malignant Brain Tumors (Gliomas such as astrocytoma, oligodendroglioma, glioblastoma)
A Glioma is a brain tumor that originates in the glial cells, which are the supportive, non-neural cell structures that provide energy and nutrients to the brain’s nerve cells. There are four different types of glial cells:
- Astrocyte
- Oligodendrocyte
- Microglia
- Ependymal cells
The Gliomas are subdivided into two types:
- Astrocytoma tumors: Astrocytomas (less malignant), anaplastic astrocytomas (WHO grade III), and glioblastomas (WHO grade IV – most malignant). Astrocytomas can progress over time to more malignant forms, including glioblastoma multiforme.
- Oligodendroglial tumors: Vary from low grade to highly malignant. Some primary brain tumors are composed of both astrocytic and oligodendrocytic tumors. These are called mixed gliomas.
(Note: WHO refers to World Health Organization tumor grade classification)
What are the symptoms of a glial tumor?
Symptoms of a Glioma are directly related to their location in the brain and include:
- Headache
- Seizures
- Motor weakness
- Gait instability
- Confusion
- Mental status changes
- Nausea & vomiting
How is a Glioma diagnosed?
A computerized tomography (CT) or magnetic resonance imaging (MRI) is used to identify a potential glioma. Surgical biopsy confirms the diagnosis.
What are the treatment options?
Treatment options are dependent upon the type of glial tumor and its aggressiveness. The World Health Organization (WHO) has created a grading system that is confirmed by a pathologist after a biopsy or resection of the tumor has been performed.
WHO Grade I
Pilocytic astrocytoma: Usually occurs in children, but can occur in adults. Grade I tumors are usually slow growing and benign in nature. Treatment options usually include:
- Observation – If the tumor is small and not causing any problems, following the patient with regularly scheduled MRI or CT scans is a viable course of action.
- Surgery – In most cases, surgery is the treatment of choice. A complete resection (removal of all visible portions of tumor) can result in a curative outcome for the patient. This is only possible if the surgery can be done safely without the risk of causing further neurological deficits.
- Radiotherapy – Radiation therapy can be utilized if the tumor cannot be surgically resected. This may occur, for example, when the tumor is located in a part of the brain that cannot be accessed without further harm to the patient. Sometimes radiotherapy is also utilized after a tumor has been surgically resected, as a means of assuring the destruction of any microscopic tumor cells that might remain following surgery.
WHO Grade II
Low-grade Glioma: This category includes astrocytoma, oligodendroglioma, and mixed oligoastroctyoma. Grade II gliomas are more infiltrative (invasive) in nature and often recur and/or evolve into a more aggressive, higher grade of Glioma. Treatment options usually include:
- Observation - If the tumor is located in an area of the brain that precludes surgical resection or is in a high risk area that might cause further neurological deficits, observation with regularly scheduled imaging is a viable course of action. Some low grade tumors may never increase in size, but most will grow or transform to a more aggressive, higher grade of glioma.
- Surgery - In most cases, a surgical resection is the treatment of choice and can result in curative outcome for the patient. Surgery is recommended only if it can be performed safely without the risk of causing further neurological deficits.
Radiotherapy – Radiation can be utilized either after the tumor has been surgically resected or in cases in which surgery was not an option. - Chemotherapy – Can be utilized if the tumor recurs. Temodar (temozolomide) is an oral chemotherapy drug that is most often prescribed for gliomas.
WHO Grade III
This grade of Glioma is considered malignant and aggressive, and includes anaplastic astrocytoma, anaplastic oligodendroglioma, and anaplastic mixed oligoastrocytoma. These tumors are usually faster growing than the lower grades. Because this tumor has tentacle-like projections that invade brain tissue, it is often difficult to obtain a complete resection of the tumor.
- Observation – Not usually an option as this grade of Glioma is malignant with rapid growth.
- Surgery – Obtaining maximum tumor removal is preferred if the tumor can be removed without causing further neurological impairment.
- Radiotherapy – Recommended in the post-operative setting with multiple treatments (fractions) over several weeks.
- Chemotherapy – Temozolomide (Temodar), an oral chemotherapy agent usually administered in combination with radiotherapy and for several months after radiotherapy.
WHO Grade IV
Glioblastoma Multiforme (GBM) is a malignant Glioma and is the most common and aggressive of the malignant, primary brain tumors. A GBM usually grows at a rapid pace, spreading into various portions of the brain. Because this tumor has tentacle-like projections that invade brain tissue, it is often difficult to obtain a complete resection of the tumor. It is common for this disease to recur at some point following treatment, requiring additional surgery or clinical trials.
- Observation - Not usually an option as this grade of glioma is malignant with rapid growth.
- Surgery - Obtaining maximum tumor removal is preferred if tumor can be removed without causing further neurological impairment.
- Radiotherapy – Recommended in the post-operative setting with multiple treatments (fractions) over several weeks.
- Chemotherapy – Temozolomide (Temodar), an oral chemotherapy agent usually administered in combination with radiotherapy and after radiotherapy for several months.
- Clinical Trials – Due to the aggressive nature of this disease, new investigative treatments are often being developed and tested.
Learn more about NeuroTexas Institute’s Brain Tumor Program.
Information from the National Institutes of Health, November 2008