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Glioma Overview

A glioma is a type of brain tumor that develops in the central nervous system and originates from the glial cells. These cells are extremely important as they help maintain the function and health of nerve cells. But if a mutation occurs, it can lead to a brain tumor.

Gliomas can manifest in various locations, but the most common ones occur in the cerebral hemispheres, brainstem, cerebellum and spinal cord. However, the location and size of the glioma all differ from one case to the next.

Glioma by itself isn’t a very common condition, and some types are more common than others. When compared to other cancers, glioma is relatively rare. Nonetheless, it’s very important to stay educated about various kinds of cancers and tumors, which is why we’ve prepared this thorough guide. 

Glioma - Sheba Medical Center

Glioma types

Glioma is an umbrella term used for a type of brain cancer, however, there are also multiple subtypes of gliomas, which are based on the area where the tumor developed. 


Astrocytoma is a type of glioma that originates from glial cells known as astrocytes, which surround neurons, and support and protect them. They typically spread through the patient’s brain and spinal cord while blending with healthy tissues, and this makes astrocytomas very hard to remove if they’re high-grade. 

Most diagnosed gliomas are astrocytomas and these tumors can be both low-grade and high-grade. 

  • Grade 1 astrocytomas include pilocytic astrocytoma, subependymal giant cell astrocytoma (SEGA) and pleomorphic xanthoastrocytoma.
  • Grade 2 astrocytomas are diffuse astrocytomas.
  • Grade 3 astrocytomas are anaplastic astrocytomas. 
  • Grade 4 astrocytomas are glioblastomas. 

Brainstem Glioma

Brainstem gliomas, as their name suggests, develop in the patient’s brain stem. These gliomas typically grow in the middle of the brain stem, which makes them very difficult if not impossible to remove with surgery.

Brainstem gliomas can also be classified from grade 1 to grade 4, and there are two distinct types of brainstem gliomas:

  • Focal brainstem gliomas are located in just one area of the brainstem, grow slowly, and aren’t very aggressive. 
  • Diffuse intrinsic pontine gliomas (DIPG) grow all over the brainstem and its neighboring cells, they grow rapidly and are extremely aggressive. 


Ependymoma is a subtype of glioma that originates in the ependymal cells, which are cells lining the fluid-filled spaces in the brain’s cavities and the center of the spinal cord. Ependymomas are classified from grade 1 to grade 3.

  • Grade 1 and grade 2 ependymomas are low-grade tumors and they typically occur in the spinal cord. 
  • Grade 3 ependymomas are high-grade tumors and typically occur in the brain. 

Mixed Glioma

Mixed gliomas are a subtype of gliomas that develop as a result of multiple different types of glial cells mixing with one another. 

There are many different variations of mixed gliomas and they vary greatly based on how aggressive they are and how they behave. This will all depend on the specific combination of cells that mixed together, and the grading of the tumor. 


Oligodendrogliomas are a subtype of glioma that originate in oligodendrocytes, which are cells that cover the nerves and protect them. These tumors are classified as grade 2 and grade 3. 

  • Grade 2 oligodendrogliomas are low-grade tumors that grow very slowly and aren’t that aggressive but can become more aggressive as time goes by.
  • Grade 3 oligodendrogliomas, also known as anaplastic oligodendrogliomas, are high-grade tumors that grow quickly and are typically very aggressive.

Optic Glioma

Optic pathway glioma, more simply known as optic glioma, is a subtype of glioma that develops along the optic nerve, optic chiasm, or hypothalamus. The optic nerve is responsible for vision, which is why this type of glioma can often cause vision problems.

Optic gliomas are classified as grades 1,2 and 3.

  • Stage 1 optic gliomas only affect the optic nerves.
  • Stage 2 optic gliomas affect the optic chiasm.
  • Stage 3 optic gliomas affect the hypothalamus.

Glioma Symptoms

The symptoms of glioma can differ based on where exactly the tumor is located and how big it is. Some of the most common symptoms include:

The most common symptoms include:
  • The symptoms of glioma can differ based on where exactly the tumor is located and how big it is. Some of the most common symptoms include:
  • Finding it difficult to balance and walk
  • Frequent and persistent headaches
  • Vision problems
  • Frequent and severe nausea and vomiting
  • Unexplained personality changes
  • Confusion
  • Sudden seizures
  • Weight fluctuations
These symptoms might be an indication of a brain tumor, but that doesn’t have to be the case. Additionally, every case is different and not everyone will experience the same symptoms and with the same intensity.

Risk Factors Risk Factors

A risk factor is a term used to describe all of the outside factors that may indicate a person is at a greater risk of developing a certain disease or illness, in this case, glioma. While medical professionals aren’t sure what exactly causes this tumor, there are some risk factors that are directly related to a higher chance of developing glioma. These factors include:
  • Genetic conditions. Certain generic and inherited conditions make people more susceptible to developing different kinds of cancers and tumors, including gliomas. These conditions include neurofibromatosis type 1, Turcot syndrome and Li Fraumeni syndrome.
  • Family history. Even though there is still research being done on the matter and medical professionals aren’t sure whether or not gliomas are hereditary, there have been multiple cases of glioma in one family.
  • Previous exposure to radiation. People who have already been exposed to ionizing radiation in the past are much more likely to develop a brain tumor. This mostly includes people who have gone through radiation therapy in the past.
  • Age. Gliomas typically affect two age groups - young children between the ages of 5 and 8, and adults between the ages of 45 and 65. However, it is more prevalent among adults.

Glioma Diagnosis

While exhibiting symptoms and having certain risk factors could be an indication of glioma, it’s impossible to know for sure unless you go to a doctor and get a proper diagnosis. There are a couple of tests the doctor will perform to ensure they make the proper diagnosis:

  • Physical exam and medical history. During the physical examination, the doctor will talk to the patient to see whether they’re experiencing any symptoms that may be an indication of a brain tumor. As for their medical history, they will check whether the patient has any genetic conditions that weaken the immune system or present a risk factor for glioma, previous radiation exposure or a family history of brain tumors.
  • Neurological exam. As glioma and other brain tumors can lead to neurological issues, the doctor will perform a neurological exam. This exam is used to check the patient’s fine motor skills, muscle strength, speech, response to pain and simple math skills.
  • CT scan. Imaging tests are a great way to check for tumors because they give doctors a clear overview of the patient’s organs along with tissues, blood vessels, and bones. A CT scan takes 3D cross-sectional images with the use of X-rays that doctors can examine to check whether a tumor is present.
  • Magnetic resonance imaging (MRI). Another imaging test used for diagnosing tumors is an MRI, which creates images similar to the ones taken by a CT scan. However, an MRI uses magnetic forces and radiofrequency waves to take images, which is why this technique is used more frequently than CT scans as it doesn’t expose the patient to radiation.
  • Biopsy. Determining the presence of the tumor is just one part of the diagnosis because for the doctor to decide on the best treatment option, they will also need to know what type of glioma the patient suffers from. During a biopsy, a medical professional will remove a small piece of tissue from the tumor and then send it over to the laboratory where it will be examined under a microscope by a pathologist. This process will show the tumor’s cellular structure.
  • Lumbar puncture. Also known as a spinal tap, a lumbar puncture is a type of biopsy that involves removing a small amount of cerebrospinal fluid from the spinal cord and analyzing it. Just like a regular biopsy, a lumbar puncture can help determine what type of glioma the patient is suffering from, but also whether the tumor has spread to the spine.
  • Molecular testing. Each diagnosed case of glioma is different in multiple aspects, one of which is the composition of its genes and proteins. These distinctions can only be determined by molecular testing, and the results of this testing will help determine the best treatment option.

Glioma Grading

When doctors set out to determine how malignant or cancerous a tumor is, they assign it with a grade. These grades range from 1 to 4, meaning from least to most malignant. Another reason why gliomas and other tumors are graded is so doctors can determine how quickly the tumor will grow and spread.

Gliomas can be low-grade and high-grade.

Low-Grade Glioma

Grade 1 and grade 2 gliomas are considered to be low-grade gliomas. They are the least malignant, spread very slowly and have a normal structure when examined under a microscope.

Low-grade gliomas include: 

  • Astrocytoma
  • Oligodendroglioma
  • Ependymoma

All of these tumors are highly treatable and curable and often require only surgery and possibly chemotherapy. Patients with low-grade gliomas have a great outlook.

High-Grade Glioma

Grade 3 and grade 4 gliomas are considered to be high-grade gliomas. They are very malignant, spread quickly and their cells have a very abnormal structure when examined under a microscope. 

In some cases, high-grade gliomas occur completely spontaneously and sometimes a lower-grade glioma can become high-grade if left untreated for a long period of time.


Glioma Treatment

Once the doctor in charge of the patient’s case makes a diagnosis of glioma and determines its staging, they will be able to proceed with the best possible treatment.

These are all the treatment options available for glioma:

  • Surgery. Unless the tumor is located in a part of the brain that shouldn’t be operated on out of concern it may cause neurological damage, the first step in treatment will be surgery. A grade 1 glioma can often be completely removed this way, while for other grades the surgeon will be able to remove part of the tumor.
  • Radiation therapy. If surgery isn’t a viable option or if the patient needs additional treatment after surgery, one of the options is radiation therapy. During radiotherapy, a machine directs radiation through the patient’s skin until it reaches the cancerous cells and destroys them.
  • Chemotherapy. Chemotherapy is often the most frequently used treatment option for glioma. It can be administered intravenously or in pill form to get rid of the cancerous cells left over after the surgery and those that spread through the rest of the brain/spinal cord.
  • Bone marrow transplant with high dose chemotherapy. If the glioma is especially malignant and hard to treat, the doctor will administer high dose chemotherapy and perform a bone marrow transplant. The high dose chemotherapy will attack the cancerous cells very effectively but it will also greatly damage the patient’s bone marrow, which is why they will also receive a bone marrow transplant.

Targeted therapy. Unlike all the other treatment options on our list, targeted therapy only attacks the cancerous cells and doesn’t have any effect on the patient’s healthy cells. It can be given orally and intravenously and is often used when other treatment options fail.

Glioma Prognosis

The prognosis given to glioma patients greatly varies depending on a few different factors. These factors include what type of glioma the patient has, how big it is, what grade it is, where it’s located and how the patient responds to treatment.

That being said, each grade of glioma has a prognosis and 5-year survival rate of:

Grade 1 glioma – approximately 95%.

Grade 2 glioma – approximately 40-50%.

Grade 3 glioma – approximately 25-30%.

Grade 4 glioma – approximately 5-10%.

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