What it is

Glioblastoma (also called grade 4 glioblastoma or GBM) is the most common and aggressive primary tumor of the brain in adults. It arises from glial cells, the support cells of the nervous system, and grows quickly, infiltrating surrounding healthy tissue.

Because it spreads in a diffuse way, it is difficult to remove completely with surgery, which is why treatment combines several approaches. Research is advancing every year toward more personalised and effective options.

This page is educational and general. Every case is different. Your medical team is the only one who can interpret your specific situation.

Just diagnosed? Start with the calm, step-by-step guide in Minute Zero.

Symptoms

Symptoms depend on the tumor's size and location. They often appear gradually over weeks and may include:

  • Persistent or worsening headaches, often worse in the morning
  • Seizures (sometimes the first sign)
  • Nausea, vomiting or vision changes
  • Difficulty with speech, memory or concentration
  • Weakness or numbness on one side of the body, or personality changes
A new seizure, sudden severe headache or sudden neurological change needs urgent medical attention.

Diagnosis

Diagnosis usually starts with a magnetic resonance imaging (MRI) scan, which shows the tumor's location and characteristics. The definitive diagnosis comes from a biopsy or surgery, when a sample of tissue is analysed under the microscope and with molecular tests.

These molecular tests are increasingly important: they define the tumor's exact subtype and help choose the most appropriate treatment.

Biomarkers

Two markers are especially relevant in glioblastoma. Understanding them helps you follow conversations with your team:

MGMT methylation

When this gene is 'silenced' (methylated), the tumor tends to respond better to the chemotherapy temozolomide.

IDH status

Glioblastoma is, by current definition, IDH-wildtype. IDH-mutant tumors are now classified as a different type of glioma.

Treatment

Standard treatment combines several steps, adapted to each person:

  1. Surgery. The neurosurgeon removes as much tumor as is safely possible.
  2. Radiotherapy + chemotherapy. Radiation combined with temozolomide, usually over about six weeks.
  3. Maintenance chemotherapy. Further cycles of temozolomide after radiotherapy.
  4. Tumor Treating Fields (optional). A wearable device that uses alternating electric fields, added in some cases.
Clinical trials may offer access to new approaches. Ask your team whether a study is right for you, and explore our finder.

Research

The field is moving fast: immunotherapy, CAR-T cells, therapeutic vaccines, targeted drugs and liquid biopsy are all under active investigation. Many of these advances reach patients first through clinical trials.

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