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What is glioblastoma?

A glioblastoma is the most common and most aggressive cancerous primary brain tumour (a tumour that starts in the brain). These tumours are made up of different cell types, the most common being astrocytes (a star-shaped glial cell of the nervous system). Glioblastomas are usually highly cancerous because the cells reproduce quickly and have a large network of blood vessels supporting them.

Most of these tumours are in the brain hemispheres but they can develop in other parts of the brain and spinal cord.

Like many brain tumour types, the exact cause of glioblastoma is not known.

How many people get glioblastomas?

The rate of glioblastoma is about 2 to 3 per 100,000 people in Canada, the United States and Europe. At Sunnybrook, we treat around 250 patients with glioblastoma each year.

Glioblastomas account for about 15 per cent of all primary brain tumours, and about 60-75 per cent of all astrocytomas (tumours that start in the astrocytes). This type of tumour is more common in older individuals and more common in men than women.

What are the symptoms of glioblastomas?

A patient's symptoms depend on the location of his/her tumour. Some common symptoms include:

  • Headache: This is the most common symptom. It is caused by an increased pressure in the brain
  • Weakness on the left or right side of the body
  • Nausea
  • Seizure
  • Memory difficulties
  • Personality changes
  • Vomiting

Sometimes the tumour starts producing symptoms quickly, but on occasion, there are no symptoms until it reaches a larger size.

What are the types of glioblastomas?

There are two types of glioblastomas.

Learn more about the different types of glioblastoma

The American Brain Tumour Association cites two types of glioblastomas. These include:

Primary, or “de novo”

These tumours tend to form and make their presence known quickly. This is the most common form of glioblastoma; it is very aggressive.


These tumours have a longer, somewhat slower growth history, but still are very aggressive. They may begin as lower-grade tumours, which eventually become higher grade. They tend to be found in people 45 and younger, and represent about 10 per cent of glioblastomas.

Treatment / Standard of care

At Sunnybrook, glioblastoma patients are treated at our Odette Cancer Centre.

Patients at the Odette Cancer Centre are treated by a comprehensive, interdisciplinary care team, which, depending on your care needs, includes: neurosurgeons, radiation oncologists, neuro-oncologists, neuropathologists, psychiatrists, social workers and nurses.

Learn more about how we treat glioblastoma

Depending on your individual case, your glioblastoma care plan may include:


The first treatment step is surgery, to remove as much as the tumour as possible. This is done using advanced image-guided techniques (such as MRI, ultrasound, X-ray). During this surgery, the patient is awake (sometimes sedated) to allow intraoperative mapping.

Surgery is almost always followed by secondary treatment, such as radiation and/or chemotherapy. This is because glioblastomas infiltrate into the brain, making it difficult to completely remove the whole tumour during surgery.

Radiation & Chemotherapy

After surgery, a patient is treated with intensity-modulated radiation therapy, an advanced type of radiation. This treatment is combined with chemotherapy.

Clinical trials

Patients may also enroll in clinical trials, which test new approaches at treating glioblastomas.

Glioblastoma is a difficult cancer to treat. Some reasons include:

  • The tumour cells are very resistant to conventional therapies
  • The brain is susceptible to damage due to conventional therapy
  • The brain has a very limited capacity to repair itself
  • Many drugs cannot cross the blood-brain barrier to act on the tumour.


Sunnybrook researchers are investigating new ways to treat patients with glioblastomas.

Breaching the blood-brain barrier

In late 2015, Sunnybrook researchers breached the blood-brain barrier, effectively delivering medication directly to a patient’s brain tumour for the first time in history. Researchers are investigating ways they could use this technology to treat patients with glioblastoma. Learn more about the Blood-Brain Barrier »

Intravenous gene therapy

Researchers are looking at ways to use IV-delivered gene therapy to attack tumour-associated blood vessels.

Surgical techniques

Researchers are combining surgery with the injection of a modified, tumour-killing virus.

» Learn more about the ways Sunnybrook researchers are advancing treatment for glioblastoma