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Glioblastoma (GB)

Tumour Group:
WHO Grade:
Grade IV
The incidence of glioblastoma (GB), also known as glioblastoma multiforme, is 4 per 100,000 people in Canada according to the Brain Tumour Registry of Canada*. GB accounts for 12-15% of all intracranial tumours and 50-60% of astrocytic tumours. GBMs increase in frequency with age and affect more men than women.
Typical Age Range:
GBs may manifest at any age, but mostly affect adults with a peak incidence between 45 and 75 years of age. Only 3% of childhood brain tumours are glioblastomas.

Tumour Characteristics

  • GB is the most common and most aggressive malignant primary brain tumour. These tumours contain various cell types, the most common being astrocytes.
  • Most of these tumours occur in the cerebral hemispheres but can develop less commonly in other parts of the brain such as the cerebellum, brainstem or spinal cord. The cells of these tumours grow quickly, are not well defined, and can spread throughout the brain.
  • Can develop directly or evolve from a lower grade glioma (secondary GB).
  • Less common in children.


Common symptoms include, but are not necessarily limited to:

  • Headache: The most common symptom, it's caused by an increased pressure in the brain
  • Weakness in the arms or legs
  • Decreased sensation
  • Nausea and/or vomiting
  • Unsteadiness
  • Seizure
  • Progressive memory decline
  • Personality deficit
  • Decreased level of consciousness
  • The kind of symptoms produced depends highly on the location of the tumour, more so than on its pathological properties. The tumour can start producing symptoms quickly, but occasionally is an asymptomatic condition until it reaches a larger size.

Treatment/Standard of Care

It is very difficult to treat glioblastoma due to several factors:

  • 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.

The first treatment step is surgery to remove as much tumour as possible. Surgery is almost always followed by radiation. Glioblastoma’s capacity to extensively invade and infiltrate normal surrounding brain tissue makes complete resection impossible. The goal of surgery is to de-bulk — a surgical procedure with the goal of decreasing the mass effect of a tumour by removing dead tissue or a portion of the tumour. However, improvements in neuroimaging have helped make better distinctions between tumour types and between tumour and normal tissue.


After surgery, radiation therapy is used to treat any residual visible tumour on imaging and any microscopic tumour cells in the surrounding region in an attempt to prevent recurrence.


Chemotherapy is often given at the same time as radiation, and often given alone after the combination of chemotherapy and radiotherapy is completed. In children, chemotherapy may be used to delay the need for radiotherapy.


A prognosis is an estimate of the likely progress of a disease after a diagnosis, based on an average patient group. Since every person is different, please take time to talk with your health care team about how this information applies to you.

By clicking on 'expand', a statistic on the prognosis for Glioblastoma (GB) will be shown.