Description and Location
Glioblastoma multiforme (GBM) is the most common and deadliest of malignant primary brain tumors in adults and is one of a group of tumors referred to as gliomas.
Classified as a Grade IV (most serious) astrocytoma, GBM develops from the lineage of star-shaped glial cells, called astrocytes, that support nerve cells.
GBM develops primarily in the cerebral hemispheres but can develop in other parts of the brain, brainstem, or spinal cord.
Because of its lethalness, GBM was selected as the first brain tumor to be sequenced as part of The Cancer Genome Atlas (TCGA Website), a national effort to map the genomes of the many types of cancer. In this effort, researchers discovered that GBM has four distinct genetic subtypes that respond differently to aggressive therapies, making treatment extremely difficult and challenging. Parallel research Parallel research at Johns Hopkins University also contributed to the expansion of genomic information on GBM.
Characteristics:
- Can be composed of several different cell types
- Can develop directly or evolve from lower grade astrocytoma or oligodendroglioma
- Most common in older individuals and more common in men than women
- Less common in children
- Median survival rate of ~15 months; 5-year survival rate of ~4%
- The cause is unknown, but increasingly research is pointing toward genetic mutations
Incidence
The incidence, or the number of new diagnoses made annually is 2 to 3 per 100,000 people in the United States and Europe. GBM accounts for 12% to 15% of all intracranial tumors and 50% to 60% of astrocytic tumors.
Treatment
Standard treatment is surgery, followed by radiation therapy or combined radiation therapy and chemotherapy. If inoperable, then radiation or radiation/chemotherapy can be administered.
Treatment requires effective teamwork from neurosurgeons, neuro-oncologists, radiation oncologists, physician assistants, social workers, psychologists, and nurses. A supportive family environment is also helpful.
Surgery
GBM’s capacity to wildly invade and infiltrate normal surrounding brain tissue makes complete resection impossible. However, improvements in neuroimaging have helped to make better distinctions between tumor types and between tumor and normal cells.
Radiation
After surgery, radiation therapy is used to kill leftover tumor cells and try and prevent recurrence.
Chemotherapies, an Alkylating Agent, and a Medical Device
(identified by generic names)
Temozolomide
FDA-approved in 2005 for treatment of adult patients with newly diagnosed GBM
Bevacizumab
FDA-approved in 2009 for treatment of patients with recurrent GBM and prior treatment
Prolifeprosan 20 with Carmustine Implant
FDA-approved in 1997 for treatment of initial occurrence GBM in 1997as an alkylating agent that is surgically implanted as a wafer after surgical resection and allows for drug delivery directly to the tumor site
TTF Device
FDA-approved in 2011 approved as a medical device for adult patients with recurrent GBM after surgery and chemotherapy treatment to deliver electric tumor-treating fields to the brain to physically break up the tumor cell membranes
Ongoing Research and Clinical Trials
Clinical Trials
A number of clinical trials are being conducted to search for GBM treatments. The National Cancer Institute maintains a website that lists these trials:
The trials involve many types of therapy, including immunotherapy, antiangiogenic therapy, gene and viral therapy, cancer stem cell therapy, and targeted therapy (personalized medicine).
