Glioblastoma Multiforme

(GBM; Brain Tumor; Malignant Astrocytoma)

Pronounced: GLEE-oh-blass-TOE-mah


Glioblastoma multiforme (GBM) is the most common glioma. Glioma is a type of brain tumor. This tumor starts in the glial cells. These cells help the brain work.

GBM can develop quickly. It can also come from other slower growing brain tumors. GBMs are mainly found in the middle part of the brain. But, it can also start in the the base of the brain or spinal cord.

Brain Tumor

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Cancer is when cells in the body split without control or order. They go on to form a growth or tumor. The term cancer refers to harmful growths. These growths attack nearby tissues. They also spread to the brain or spinal cord. It's not clear what causes this. It’s likely a mix of genes and the environment.

Risk Factors

Your chances of GBM are higher if you:

  • Are aged 50 years or older
  • Are White, Hispanic, or Asian
  • Have a brain tumor
  • Have rare inherited diseases such as Li-Fraumeni syndrome,or neurofibromatosis type 1
  • Were exposed to radiation
  • Worked in rubber or petroleum jobs
  • Were exposed to vinyl chloride or pesticides


Symptoms depend on the tumor's size and where it is. GBM may cause:

  • Headaches
  • Seizures
  • Problems with:
    • Walking
    • Hearing
    • Vision
    • Speech
    • Memory


The doctor will ask about your symptoms and health history. Your answers and a physical exam may point to GBM. You may also have

Imaging tests such as:

  • Imaging tests such as:
  • EEG —to test the electrical activity of the brain
  • Biopsy —a sample of the tumor is studied in a lab
  • Lumbar puncture —to test the fluid that surrounds the brain and spinal cord


Surgery is often done to confirm a diagnosis. It’s done to remove as much of the tumor as possible. In most cases, the entire tumor can’t be taken out. Other methods to treat GBM:

  • Radiation therapy—to shrink the tumor
  • Chemotherapy —to improve length and quality of life
  • Steroids—to reduce swelling in the brain
  • Antiseizure medicines
  • Pain relievers

GBM is very hard to treat and has a low survival rate. You and your family may be advised to find:

  • Support groups
  • Counseling
  • Someone to help with end of life planning
  • Hospice care


There is no way to prevent GBM since the cause is unknown.


American Brain Tumor Association
American Cancer Society


Brain Tumour Foundation of Canada
Canadian Cancer Society


Brain tumors. American Association of Neurological Surgeons. Available at:
...(Click grey area to select URL)
Accessed January 29, 2021.
General information about adult primary central nervous (CNS) tumors. National Cancer Institute website. Available at: Accessed January 29, 2021.
Glioblastoma. EBSCO DynaMed website. Available at: Accessed January 29, 2021.
Last reviewed September 2020 by EBSCO Medical Review Board Mohei Abouzied, MD, FACP
Last Updated: 1/29/2021

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