Glioblastoma Multiforme

Glioblastoma, also known as glioblastoma multiforme, GBM, or a grade 4 astrocytoma, is one of the most common and aggressive types of brain tumors, causing about 50% of all gliomas. 

What Are the Symptoms of GBM?

While GBM typically occurs after age 50, it may occur in younger people as well, causing headaches, seizures, and focal neurological problems such as speech difficulty or cognitive changes.

  Other symptoms of glioblastoma include weakness, numbness, vision changes, and personality changes.  These symptoms vary depending on the tumor size and location.

How Quickly Does GBM Progress?

The cancerous cells of GBM spread quickly.  The tumor spreads insidiously through the brain without a clear border, making it difficult if not impossible to completely remove surgically.  The average time from first symptoms to death is approximately a year, though this varies somewhat between individuals.  About 25 percent of people may survive for two years or more with treatment. 

What Causes GBM?

Glioblastoma multiforme, like all tumors, result from inappropriate cell division.  In this case, glial cells that normally surround and protect the nerve cells of the brain multiply without restraint.  This results from alterations in how the genes in the cells are expressed—for example, cells may have amplified gene expression in areas such as epidermal growth factor receptor (EGFR) or a loss of a tumor suppressor gene such as PTEN.

  Other mutations include MDM2 and the RB gene. 

How Do Doctors Recognize GBM?

If a patient has symptoms that are suspicious, doctors will usually order a neuroimaging test such as an MRI scan of the brain.  On MRI, a GBM has an irregular appearance, often with a central area of dead tissue or hemorrhage, and a bright area around the tumor that enhances with gadolinium contrast.

 This abnormality may press on other brain structures and distort the normal structure of the brain.   

While other things may have this appearance on MRI, a concerned physician will likely attempt to arrange for a neurosurgeon to take a piece of this unusual tissue out of the brain.  The tissue can be evaluated under a microscope, where it will show a high number of dividing cells in a characteristic “pseudopalisading” pattern, meaning the cells seem lined up.  This is likely related to cell death, as their formation is adjacent to areas of dead tissue seen in GBM under the microscope.   

How Can GBM be Treated?

GBM is aggressive and resists most treatments.  Often the goal of these treatments is more about reducing symptoms and prolonging life rather than completely curing the disease. 

Treatment for glioblastoma multiforme usually includes three components:

  • Surgery—Doctors remove as much tumor as they can without hurting healthy areas of the brain.
  • Chemotherapy—medicines are given to try to target the tumor cells.    Temozolamide or a combination of procarbazine, lomustine and vincristine are some of the more common treatments. 
  • Radiation therapy—radiation delivered to the brain can kill some of the cancer cells.  This usually involves administering the radiation in a beam to just one part of the brain rather than irradiating the entire brain as is more common for some metastatic tumors. 

After all of these treatments, people who have had GBM are followed to see if the tumor returns.  Most of the time, the GBM comes back.  At that time, further treatment may be advised on a case-by case basis.  Because GBM is so aggressive and because available treatments can have serious side effects, the management of this cancer is very personal, and involves working closely with a neurological specialist as well as a neurosurgeon.

Sources: 

A Omuro, LM DeAngelis: Glioblastoma and other malignant gliomas: a clinical review. JAMA : the journal of the American Medical Association. (2013) 310:1842-1850.

H Ropper, MA Samuels. Adams and Victor's Principles of Neurology, 9th ed: The McGraw-Hill Companies, Inc., 2009.

Continue Reading