Glioblastomas, also known as glioblastoma multiforme (GBMs), are a relatively common type of glioma, which develop from the glial (or supportive) cells in the central nervous system (CNS). More specifically, they develop from a type of glial cell called astrocytes, a star-shaped cell that has a variety of functions, including regulating blood flow and regulating and maintaining synapses. Glioblastomas are classified as a high-grade astrocytoma. 

The brain is a complex organ that is responsible for controlling all functions of the body. It has five main portions: the cerebrum, cerebellum, brainstem, pituitary gland, and hypothalamus. The cerebrum is the biggest part of the brain, and consists of the frontal, parietal, temporal, and occipital lobes. This part of the brain is responsible for voluntary movement, intelligence, and memory, and is often where glioblastomas develop. The cerebellum is a small part of the brain located at the back of the head, and regulates posture and balance. The brainstem is a small, stalk-like structure towards the bottom of the brain that connects the brain to the spinal cord.  It regulates many vital bodily processes, such as swallowing, breathing, and heart rate. The pituitary gland is a pea sized organ located behind the eyes, and is responsible for the production and secretion of hormones in the body. The hypothalamus is located deep within the brain, and has many important functions, such as producing and secreting different hormones, regulating temperature, and controlling appetite. 

The spinal cord is a long, thin, tubular structure that extends down from the brainstem to the lower back. It is made of nerve tissue, and is surrounded by the bones of the spine (vertebrae). The spinal cord is responsible for transmitting nerve signals from the brain to the body, and vice versa. It has motor functions (such as voluntary movement), sensory functions (such as pressure, touch, temperature, and pain), and autonomous functions (such as regulating digestion, heart rate, and blood pressure). 

Glioblastomas are more common in males, and tend to develop between the ages of 50-80. However, anyone can develop this disease.

Variants of Glioblastoma

There are three primary variants of glioblastoma, which are classified by their cellular appearance under the microscope.

Giant Cell Glioblastoma

Giant cell glioblastomas are a rare form of glioblastomas that are categorised by large malignant cells under the microscope. It was previously referred to as a monstrocellular tumour due to the large cells. These tumours are often non-aggressive, and often has a better prognosis than other types of glioblastomas

Gliosarcoma

Gliosarcomas are a rare form of glioblastoma that contains elements of glial cells and sarcomas, which are traditionally cancers arising from bone and soft tissue. They are generally found along the surface of the brain, but can also develop along the spinal cord. Gliosarcomas are often aggressive, and may not have as good of a prognosis as other types of glioblastomas.

Epithelioid Glioblastoma

Epithelioid glioblastomas are a rare form of glioblastoma that contain epithelial cells, which are cells that line organs. They are generally found in the cerebrum, however they can develop in other locations. Epithelioid glioblastomas are often very aggressive, and may not have as good of a prognosis as other types of glioblastomas.

Treatment 

When cancers are detected, they are staged and graded based on size, metastasis (whether the cancer has spread to other parts of the body), and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you. However, brain cancers are rarely staged, as they rarely spread to other parts of the body. Instead, they are generally graded from I-IV. 

Glioblastomas and their variants are considered to be grade IV tumours, as the tumour cells appear very abnormal under the microscope and grow rapidly.

Once your tumour has been graded, your doctor may recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you. 

Treatment is dependent on several factors, including location, age, stage of disease and overall health.

Treatment options for glioblastomas may include:

• Surgery to remove as much of the tumour as possible.
• Radiation therapy.
• Chemotherapy.
• Tumour treating fields (TTF) therapy.
• Targeted therapy.
• Immunotherapy.
• Clinical trials.
• Palliative care. 

For more information on the treatment options, please refer to the Rare Cancers Australia treatment options page. 

Risk factors 

Although it is a relatively common type of tumour, it is not clear what the risk factors of glioblastomas are.

Early symptoms 

Glioblastomas may appear asymptomatic in the early stages of disease. As the tumour progresses, some of the following symptoms may appear:

• Headaches (commonly in the morning, and may go away after vomiting). 
• Nausea and/or vomiting.
• Difficulties with vision, hearing, and/or speaking. 
• Loss of balance.
• Difficulties walking.
• Fainting.
• Worsening handwriting and speaking skills. 
• Weakness or changes in one side of the body.
• Fatigue.
• Changes in energy levels.
• Changes in personality and behaviour.
• Seizures.
• Unexplained weight loss/loss of appetite. 

Not everyone with the symptoms above will have cancer, but see your general practitioner (GP) if you are concerned. 

Diagnosis/diagnosing 

If your doctor suspects you have a glioblastoma, they may order the following tests to confirm the diagnosis and refer you to a specialist for treatment.

Physical examination

Your doctor will collect your overall medical history, as well as your current symptoms. Following this, they may examine your body to check for any abnormalities.

Neurological examination

A neurological examination assesses sensory and motor functions, and can generally be done in your GPs office. The doctor may check your vision, hearing, balance, coordination, strength and reflexes, depending on the signs and symptoms you have described. Any problem that is detected in this exam can help determine which portion of the CNS needs further investigation.

Imaging & blood tests

The doctor will take images of your body using magnetic resonance imaging (MRI), a computed tomography scan (CT scan), x-rays, bone scan and/or positron emission tomography (PET scan), depending on where it is suspected the cancer is. The doctor may also look at other parts of the body and looks for signs of metastasis. Additionally, a blood test may be taken to assess your overall health and help guide treatment decisions.

Biopsy

Once the location of the cancer has been identified, the doctor will perform a biopsy to remove a section of tissue using a needle. This may be done during a surgery, or by a stereotactic needle biopsy.

Prognosis (Certain factors affect the prognosis and treatment options) 

Unfortunately, the prognosis for glioblastomas remain very poor. While it is not possible to predict the exact course of the disease, your doctor may be able to give you a general idea based on the rate and depth of tumour growth, susceptibility to treatment, age, overall fitness, and medical history. It is very important to discuss your individual circumstances with your doctor to better understand your prognosis.

References 

• Cedars-Sinai
• Mayo Clinic
• Radiopaedia

^{Some references are to overseas websites. There may be references to drugs and clinical trials that are not available here in Australia.}