Glioblastoma (GBM) is a fast-growing brain tumor that is composed mainly of star-shaped cells called astrocytes. It is among the most common primary brain tumors in adults. GBM rarely spreads to other parts of the body, but it can spread within the brain and spinal cord. Each tumor is unique, and its molecular profile (such as MGMT and IDH) helps your care team understand how it may respond to treatment.
This pathway is typical, not prescriptive. Your care team will tailor it to your situation.
Appointment checklist
Bring all imaging (MRI) on a disk or with access details
Write down all medications and supplements you take
You can bring a close person to help listen and take notes
Prepare a list of questions in advance
Ask whether a second opinion is appropriate
Useful care-team questions
What is the tumor's molecular profile (MGMT, IDH) and what does it mean?
What treatment options are available, and what is the goal of each?
What are the potential risks and side effects?
Are there clinical trials I should consider?
What can I expect during recovery?
What support services are available to me and my family?
Other approaches you may hear about
You may come across complementary approaches and treatments outside standard care. We help you understand what has been studied, what remains uncertain, and what questions to ask your care team.
Being included here does not mean an approach is effective, safe, or suitable for you. Before starting a diet, supplement, or other intervention, discuss possible risks and interactions with your care team. Do not stop or delay prescribed treatment based on this information.
The 2021 WHO Classification of CNS Tumors (Louis et al., Neuro-Oncology 2021) is the current international standard for diagnosis and classification of brain tumors.
What remains uncertain
The classification system is updated periodically. Your pathology report may use terms from the current or previous edition. Ask your care team which edition was used and what it means for your case.
Defines glioblastoma as a diffuse astrocytic glioma, IDH-wildtype, WHO grade 4. Separates it from IDH-mutant astrocytoma. Retires the term "glioblastoma multiforme".
Questions to ask your care team
Which WHO classification edition was used for my diagnosis? Is my tumor IDH-wildtype or IDH-mutant? What grade is it?
The Cancer Genome Atlas (Brennan et al., Cell 2013) characterized the genomic landscape of glioblastoma and identified EGFR amplification as a hallmark of the classical subtype.
What remains uncertain
EGFR amplification is a diagnostic marker, not a treatment target in current standard care. Targeted therapies against EGFR have not yet shown clear benefit in glioblastoma.
A biomarker is a measurable indicator. Having or not having it does not by itself determine your prognosis or treatment — discuss what it means for your situation with your care team.
Killela et al. (PNAS 2013) identified TERT promoter mutations as frequent in gliomas, and the WHO 2021 classification lists them as a defining feature of glioblastoma.
What remains uncertain
TERT promoter mutation is a diagnostic marker. It does not currently guide a specific treatment decision in standard care.
A biomarker is a measurable indicator. Having or not having it does not by itself determine your prognosis or treatment — discuss what it means for your situation with your care team.
Hegi et al. (N Engl J Med 2005) showed that MGMT promoter methylation predicts benefit from temozolomide in glioblastoma. The WHO 2021 classification recognizes MGMT methylation as an important molecular marker.
What remains uncertain
MGMT methylation is a predictive marker, not a guarantee. Treatment decisions are made by your care team based on multiple factors, not this single test result.
A biomarker is a measurable indicator. Having or not having it does not by itself determine your prognosis or treatment — discuss what it means for your situation with your care team.
Yan et al. (N Engl J Med 2009) identified IDH1 and IDH2 mutations in gliomas. The WHO 2021 classification uses IDH status as the primary molecular divider between glioblastoma and astrocytoma.
What remains uncertain
IDH1 and IDH2 are distinct genes. Your report should specify which one (if either) is mutated. If your report does not mention IDH testing, ask whether it was done.
Identified IDH1 and IDH2 mutations in gliomas, establishing IDH as a key molecular marker.
Questions to ask your care team
Was my tumor tested for IDH1 and IDH2 mutations? What was the result? Does this mean my diagnosis is glioblastoma (IDH-wildtype) or astrocytoma (IDH-mutant)?
What you can check now
IDH testing is usually part of the standard pathology workup. Check your pathology report or ask your care team.
A biomarker is a measurable indicator. Having or not having it does not by itself determine your prognosis or treatment — discuss what it means for your situation with your care team.
Both sources are reviews that summarize existing research and propose analysis frameworks. Neither reports new clinical trial results or patient outcomes.
What remains uncertain
The reviews highlight that standardization, prospective validation, and integration into clinical workflows are still needed. The sources do not describe liquid biopsy as part of routine care for glioblastoma.
Questions to ask your care team
Is liquid biopsy currently used in the standard care plan for my specific case? What are the limitations or potential risks if we consider this testing? Is there a research study available that I might be eligible for?
The 2021 WHO Classification of Tumors of the Central Nervous System defines oligodendroglioma by the combination of an IDH mutation and a 1p/19q codeletion. The clinical importance of this marker for treatment response is being verified against primary trial sources.
What remains uncertain
The 1p/19q codeletion is determined by molecular testing. If your report does not mention it, ask whether it was tested.