Glioblastomas are a fast growing type of brain tumour. They are the most common type of cancerous (malignant) brain tumour in adults.

Glioblastomas are a type of brain tumour that belongs to a group of brain tumours called gliomas.

The main treatments for glioblastomas are surgery, radiotherapy and chemotherapy.  You might have these treatments on their own, or as a combination of treatments. You might also have supportive treatments to help with your symptoms.

What are glioblastomas?

Glioblastomas develop from glial cells. Glial cells are the supporting cells of the brain and the spinal cord. There are different types of glial cells. These include astrocytes and oligodendrocytes.

 Diagram of an astrocyte - type of glial cell

Doctors use a system to group (classify) brain tumours into different groups (categories) and types. The World Health Organisation (WHO) regularly update this system. The information on this page is based on the latest WHO classification of 2021.

Doctors have changed the way they group and describe gliomas. They used to call glioblastomas ‘glioblastoma multiforme’ (GBM). Glioblastomas are now called:

  • glioblastoma, IDH wildtype

What does IDH wildtype mean?

Your doctor looks to see if there are certain gene changes in the brain tumour cells. These tests are also called biomarker or molecular studies. Your doctor uses these test results to decide what type of glioma you have. 

IDH (isocitrate dehydrogenase) is a gene. Your doctor looks for permanent changes (mutations) in the IDH gene. This helps the doctor predict the tumour's behaviour.

Your type of glioma will depend on the type of glial cell it started in. And whether there are changes in the IDH gene.

Your doctor diagnoses:

  • astrocytoma, IDH mutant - if you have changes (mutations) in the IDH gene
  • glioblastoma, IDH wildtype - if you don’t have changes in the IDH gene (the term ‘wildtype’ describes an unchanged gene)

This page is about glioblastoma, IDH wildtype.

Grades of glioblastomas

Gliomas are also put into groups according to how quickly they are likely to grow. These are called grades. 

The grade depends on how the cells look.  Generally, the more normal the cells look, the lower the grade. The more abnormal the cells look, the higher the grade. Grade also depends on genes and proteins in the tumour cells. 

All glioblastomas are grade 4. This means they are fast growing, cancerous tumours.

How common are glioblastomas?

Glioblastomas are the most common type of brain tumour. Around 32 out of every 100 primary brain tumours (around 32%) diagnosed in England between 1995 and 2017 were glioblastomas. 

These statistics are based on patients diagnosed using older WHO classification systems. The WHO system for grouping (classifying) the different types of brain tumours was updated in 2021. These changes might affect these figures.

What tests will I have?

You have tests to diagnose glioblastoma. Your doctor checks the size of the tumour and its location. This helps your doctor plan your treatment. The tests you might have include:

  • MRI scan Open a glossary item or CT scan Open a glossary item
  • a test of your neurological system (neurological examination)
  • a biopsy Open a glossary item

Tests on your tumour cells

The specialist doctor (pathologist) will do an MGMT methylation test. 

MGMT is a protein (enzyme) which can repair DNA damage caused by chemotherapy. This stops the treatment from working.

In some tumour cells, the MGMT gene is turned off because of a DNA change known as methylation. If it is turned off (methylated), this prevents the repair of any DNA damage. This means chemotherapy is more likely to work better.

The MGMT methylation test finds out if your tumour cells are:

  • methylated (high MGMT levels) – this means you might benefit from chemotherapy
  • non methylated or unmethylated (low MGMT levels) – this means you might not benefit from chemotherapy

Treatment for glioblastoma

The main treatments for glioblastoma are:

  • surgery
  • radiotherapy, which uses high energy x-rays to destroy cancer cells
  • chemotherapy, which uses cytotoxic drugs to destroy cancer cells
  • supportive treatments to help control symptoms

Your treatment plan depends on:

  • your surgery and how much tumour the surgeon removed
  • how well you are – doctors call this your performance status
  • gene changes – MGMT methylation test


Surgery is the main treatment for glioblastoma. Even if your surgeon doesn't think they can completely remove the brain tumour, they are still likely to try to remove as much as possible. This can help to slow down the progression of the tumour and relieve your symptoms.

It isn’t always possible to have surgery. It will depend on where the tumour is in your brain. It will also depend on whether you are well enough to have surgery.


You usually have radiotherapy after surgery. You might have it with chemotherapy.


You might also have a chemotherapy drug called temozolomide. This is a tablet that you take. You have it if you are well and able to care for yourself. You have temozolomide in cycles of treatment Open a glossary item. You might have temozolomide:

  • after surgery and radiotherapy (adjuvant chemotherapy)
  • at the same time as radiotherapy (chemoradiotherapy) – doctors sometimes call this concomitant therapy

Supportive care

Your healthcare team will talk to you about supportive treatments to help control your symptoms. You can have these treatments alongside surgery, chemotherapy or radiotherapy.

You might not be well enough to have treatments such as surgery or chemotherapy. Your doctor will talk to you about supportive treatments to:

  • help control seizures (fits)
  • reduce the swelling inside your brain
  • control the pain

Treatment for glioblastoma that starts to grow again

Treatment for glioblastoma can control the tumour for some time. When the tumour starts to grow again your treatment depends on several factors including:

  • what treatment you had before and when you had it
  • your symptoms
  • where the tumour is

You might have:

  • more surgery
  • more radiotherapy
  • more of the same chemotherapy, or a different sort of chemotherapy - this is called second line chemotherapy
  • treatment on a clinical trial
  • supportive care treatments

Follow up

You have regular appointments with your doctor or nurse after treatment finishes. Your doctor examines you at each appointment. They ask how you are feeling, whether you have had any symptoms or side effects, and if you are worried about anything. You might also have MRI scans on some visits.

How often you have check ups depend on your individual situation.

You might have an MRI scan every 3 to 6 months.

Coping with glioblastoma

Coping with a diagnosis of a brain tumour can be difficult, both practically and emotionally. It can be especially difficult when you have a fast growing tumour. Being well informed about the type of tumour you have, and its treatment can make it easier to cope.  

Research and clinical trials

Doctors are always trying to improve the diagnosis and treatment of brain tumours. As part of your treatment, your doctor might ask you to take part in a clinical trial. This might be to test a new treatment or look at different combinations of existing treatments.

  • The 2021 WHO Classification of Tumors of the Central Nervous System: a summary.
    D Louis and others
    Neuro Oncology, 2021 Volume 23, Issue 8, Pages 1231-1251

  • EANO guidelines on the diagnosis and treatment of diffuse gliomas of adulthood
    M Weller and others
    Nature Reviews Clinical Oncology, 2021. Volume 18, Pages 170 – 186

  • Classification and pathologic diagnosis of gliomas, glioneuronal tumors, and neuronal tumors
    D Louis and others
    UpToDate, accessed February 2023

  • Classification of adult-type diffuse gliomas: Impact of the World Health Organization 2021 update
    B Whitfield and Jason Huse
    Brain Pathology. 2022, issue 32, edition 13062

  • Initial treatment and prognosis of IDH-wildtype glioblastoma in adults
    T Batchelor
    Uptodate, accessed March 2023

  • The incidence of major subtypes of primary brain tumors in adults in England 1995-2017
    H Wanis and others
    Neuro Oncology 2021 Volume 23, issue 8, pages 1371-1382

Last reviewed: 
07 Jun 2023
Next review due: 
07 Jun 2026

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