What Is Glioblastoma?
Glioblastoma, formerly referred to as glioblastoma multiforme, is a type of brain cancer that develops from glial cells. Glial cells provide support, nourishment, and repair for cells of the central nervous system (the brain and spinal cord). Glioblastomas frequently arise from a type of glial cell known as the astrocyte, named for its star-like shape. Astrocytomas have four grades (Grade I through IV). Glioblastoma is an aggressive Grade IV astrocytoma.
What Causes Glioblastoma?
As with many types of tumors, abnormal replication cannot be controlled by the body’s natural defense system. Cells divide too rapidly and form large collections of non-working cells (tumors). Why this happens is not yet clear. We do know that certain rare genetic conditions (neurofibromatosis type 1, Turcot syndrome, and Li Fraumeni syndrome) increase the risk of tumors such as glioblastoma. Ionizing radiation (the kind produced by certain medical imaging studies and nuclear weapons) and occupational exposure to mercury, arsenic, and petroleum products may increase the lifetime risk of developing glioblastoma.
Can Stress Cause Glioblastoma?
Evidence on whether stress can cause glioblastoma is mixed, but stress hormones may act on tumors to make them worse. It is possible that the body may have more difficulty detecting and correcting tumor cells during stressful times due to a compromised immune system; however, more studies are needed to draw any concrete conclusions regarding stress and glioblastoma susceptibility.
Who Is Likely to Get Glioblastoma?
Glioblastoma is the most common primary brain tumor among adults. About 3 new cases of glioblastoma arise for every 100,000 people per year. Men are more likely to develop glioblastoma than women.
Is Glioblastoma Hereditary?
Glioblastomas are not known to be hereditary, although a family history of glioblastoma may increase lifetime risk.
Signs and symptoms of glioblastoma are highly dependent on the location of the tumor. Symptoms can occur rapidly, often causing patients to seek evaluation. Examples of symptoms include:
- Personality changes
- Memory difficulties
- Vision changes
- Balance problems
- Speech difficulties
- Nausea and vomiting
- One-sided weakness
How Is Glioblastoma Diagnosed?
A comprehensive medical history and physical examination will help physicians rule out potential causes of presenting symptoms. If your doctor suspects a brain tumor, a thorough neurological examination with an emphasis on identifying neurological changes will be conducted. Your doctor will also evaluate cranial nerves (nerves arising from the brain that control vision, hearing, eye and facial muscle movement, sensation to the face, etc.). The doctor will also evaluate muscle strength, balance, and coordination.
Computed tomography (CT) scans and magnetic resonance imaging (MRI) are valuable tools for identifying tumors within the brain and spinal cord. Dye is often injected in the veins to help visualize certain aspects of the tumor that may not otherwise be readily apparent. Glioblastomas commonly have characteristic appearances on imaging. In certain cases, a biopsy may be necessary to determine specific tumor characteristics, which will help select the most appropriate treatment strategy.
Figure 1: A right frontal glioblastoma is shown in this MRI.
Is Glioblastoma Aggressive?
This type of cancer is unfortunately highly aggressive and invasive. Glioblastoma often grows rapidly and infiltrates healthy brain tissue outside of the boundaries seen on routine imaging studies. This makes total removal of a glioblastoma almost impossible and is associated with a high risk of tumor returning in the future.
Figure 2: Gliomas (left) infiltrate the normal brain as compared to other tumors such as meningiomas (right) that displace the normal brain.
- Surgery through a craniotomy, when appropriate, may improve overall survival; however, surgery should not cause any neurological change to compromise the patient’s quality of life.
- Chemotherapy is typically started about 2 weeks after the procedure.
- Temodar (temozolomide), an oral medication, is the most common form of chemotherapy prescribed for glioblastoma. It binds to the tumor’s DNA in order to slow down the tumor from reproducing and to trigger tumor cell death. It is administered during the radiation therapy phase and later for maintenance.
- BiCNU (carmustine) is an intravenous medication that blocks DNA, RNA, and protein synthesis in the tumor.
- Avastin (bevacizumab), an oral medication, aims to inhibit the blood supply to the tumor.
- Gleostine (lomustine) is given in conjunction with bevacizumab, to improve its effect.
- Radiation is also used to slow down tumor growth by targeting the tumor cells that have infiltrated normal brain tissue and are not removable safely via surgery.
- Using external beam radiation therapy, multiple therapy sessions (10-30) target the tumor cells but protect the normal cells.
What Is the Prognosis of Glioblastoma?
If glioblastoma is left untreated, patients live an average of 3 to 4 months after diagnosis. The average survival time with treatment is unfortunately 12-18 months and about 25% of the patients suffering from glioblastoma survive more than one year after diagnosis. Only 5% of patients survive more than 5 years.
Survival is dependent upon several factors, including location of the tumor, how much of it can be removed via surgery safely without damaging healthy tissue, response to chemotherapy and/or radiation, and patient’s age and general health. Long-term survivors have been reported so all hope should not be lost. Your care should be discussed with your physician, since each case is unique.
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