Glioblastomas are the most common high grade (cancerous) primary brain tumour in adults. They can also occur, rarely, in children. Glioblastomas belong to a group of brain tumours known as gliomas, as they grow from a type of brain cell called a glial cell.

Glioblastoma is the more common name for a type of brain tumour called a grade 4 astrocytoma. They are fast growing and likely to spread. You may also hear them called glioblastoma multiforme, GBM or GBM4.

There are different types of glioblastoma:

  • Primary - this means the tumour first appeared as a grade 4 glioblastoma (GBM)
  • Secondary - this means the tumour developed from a lower grade astrocytoma

What causes glioblastoma?

There is nothing you could have done, or avoided doing, that would have caused you to develop a brain tumour.

As with most brain tumours, why glioblastomas begin to grow is not known. The Brain Tumour Charity is funding research into possible causes, focussed around our genes.

How brain tumours are formed

Our genes control the way our cells grow and divide. Mutations (changes) in our genes can cause this process to go wrong, resulting in the cells growing uncontrollably and forming a tumour. These changes are often the result of a mistake being made when the cell copies its DNA before dividing.

Research, including that funded by The Brain Tumour Charity, is gradually discovering which genes are involved in which tumours.

This research is starting to be used (and may be able to be used more accurately in the future) to predict how people may respond to certain treatments and also the length of their overall survival (prognosis).

Learn more about how and why brain tumours form.

How are glioblastomas treated?

The best treatment currently is surgery to remove as much of the tumour as possible, followed by chemoradiation. This is a combination of chemotherapy and radiotherapy.

Glioblastoma are 'diffuse', meaning they have threadlike tendrils that extend into other parts of the brain making it difficult to remove it all. The chemoradiation is needed to target those cells which cannot be removed by surgery.

Generally, it involves radiotherapy given over a period of weeks alongside rounds of the chemotherapy drug temozolomide (TMZ). TMZ is also usually taken for a further 6 months after the radiotherapy has finished.

Before surgery, you might like to ask about the possibility of biobanking a sample of tissue from your tumour. This may enable you to take part in clinical trials in the future and also have any relevant genetic (biomarker) tests.


Learn about the types of surgery you may have and why surgery is not possible for everyone.


Learn how radiotherapy uses controlled doses of high energy beams to destroy GBM tumour cells.


Find our how chemotherapy drugs destroy GBM tumour cells by disturbing their growth.


A chemotherapy drug used to treat glioblastoma - discover how it’s taken and its side-effects.

Effectiveness of treatment

Unfortunately glioblastomas are aggressive tumours and often appear resistant to treatment. This is probably due to the fact that the cells within the tumour are not all of the same type. This is known as 'heterogeneity'. This means that treatments will kill off some types of cell within the glioblastoma, but leave others, which can then continue to grow.

However, some of the research into the genes, which play a role in glioblastoma (GBM) development and growth, are starting to give us information about who may respond better to certain treatments. For example biomarker tests, such as:

  • MGMT gene methylation test
    This shows how likely you are to respond to the chemotherapy drug, temozolomide.
  • Mutations in the IDH-1 and TERT gene
    These mutations are associated with effects on overall survival.

Many centres routinely test for these gene mutations, but if your hospital does not and you would like to have a test, ask your neuro-oncologist for information and advice about whether you are suitable.

Emerging treatments

Tumour Treating Fields (TTF)

Also known as Optune®, TTF is a relatively new, non-invasive technique for adults with glioblastoma. It uses alternating electrical fields, delivered via a set of adhesive patches worn like a skull cap, to disrupt tumour cell division, or cause cell death. This helps to prevent the tumour from growing or spreading so quickly.

It's not currently available through the NHS.

For more information, see our TTF webpage


Immunotherapy, which uses substances to enhance or subdue your immune system to help your body fight the tumour, is also showing some promise, such as the cancer vaccine DCVax®.

DCVax®-L is a personalised cancer vaccine that is made from each patient's own dendritic cells. (Dendritic cells are a type of immune cell that help the body's immune system recognise and attack tumour cells.)

In May 2018, interim results from a clinical trial showed increased overall survival for patients with glioblastoma. However, as of June 2018, it's not currently available on the NHS, and the trial, though ongoing, is not recruiting any more people. It may be possible to access it privately and you may have to go abroad for the initial treatment. You will need to have a sample of your tumour flash frozen. Speak to your healthcare team if you are interested.

For more information, see our webpages on immunotherapy, on dendritic cell vaccines (of which DCVax is one type), and our news article about DCVax®.

Research is ongoing to find the keys to tumour progression in glioblastomas.

What is the prognosis?

Information about prognosis can be difficult to receive - some people do not want to know, whilst others do. There is no wrong or right answer as to whether or when to receive such information.

We've here to help you cope with a brain tumour diagnosis.


Information about the prognosis (likely outcome) for specific types of brain tumour.

You're not alone

We offer a wide range of inclusive and accessible services for everyone affected by a brain tumour.

Living with a brain tumour

Get information to help and support you in dealing with this life-changing event in the best way possible.

Page last reviewed: 06/2018
Next review due: 06/2021

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