by Kimberly Allen, RN
Gliomas are a group of primary brain tumors. Gliomas are the most common malignant brain tumors accounting for 80% of all malignant brain tumors. Though gliomas can occur at any age they are more common in adults than children. Gliomas also tend to develop in men slightly mote often than in women and are also more common in Caucasians than African Americans. Prior radiation therapy is the only currently known risk factor.
Gliomas develop in the glial cells. The glial cells are non-neuronal cells that form the myline that protects the neurons and nerves in the central nervous system. There are three specific types of glial cells in which gliomas can develop, astrocytes, ependymal cells and oligodendrocytes. The type of glioma a person has depends on the type of cell that it originates from. The American Cancer Society recognizes three types of gliomas, though many doctors consider a fourth type as a mixed type involving more than one type of cell.
Astrocytomas originate in the astrocytes. Astrocytomas account for 35% of all brain tumors. Astrocytes play a significant role in maintaining the blood-brain barrier as well as provide nutrients to nerve tissue and assist in repairing damage don to the brain and/or spinal cord after a traumatic injury. Because astrocytes are so plentiful in the brain these types of gliomas are usually fast growing and spread throughout the brain tissue making them nearly impossible to cure.
Oligodendrogliomas originate in the oligodendrocytes. The main function of the oligodendrocytes is creating the myline sheath that protects the nerves of the central nervous system. Oligodendrogliomas account for approximately 4% of all brain tumors. Though this type of glioma tends to grow slower than astrocytomas it spread throughout the brain in the same fashion making treatment difficult and complex.
Ependymomas are gliomas that form from the ependymal cells and accounts for approximately 2% of all brain tumors. Ependymal cells are the cells that make up the lining of the ventricles in the brain and spinal cord as well as assists in the production of cerebral spinal fluid. This type of glioma not only does not spread throughout the brain tissue like the others it also rarely spreads to other areas outside the brain. Some of these can even be cured with surgery. However, this type also has a significant risk of recurrence.
In addition to being classified by the type of cell involved gliomas are also classified by grade. The World Health Organization grading system is the most commonly used grading system. It is comprised of grades I thru IV. Grades I and II are considered low grade tumors they tend to be benign and slow growing. Brain tumors that are classified as low grade tend to have better survival rates. Grades III and IV are considered high grade tumors. High grade tumors are always malignant and spread quickly. These tumors are much more difficult to treat and the survival rates are much lower.
Because treatment of gliomas is so difficult and survival rates so low doctors have been investigating new ways of treating them. Not only are they making adjustments in current treatments they are also developing new techniques for administering treatments. For example, doctors have developed a technique that delivers the chemotherapy directly to the site of the tumor. They have also developed similar techniques that allow radiation therapy to be delivered in a similar manor. Other techniques being tried include antiangiogenisis which is stopping the blood supply to the tumor to prevent it from growing and without a blood supply it will also shrink and die. Researchers are also studying the ability of our body’s immune system to fight these tumors by developing a vaccine using the persons own tumor cells and then vaccinating them with it. This has been found to stimulate the production of white blood cells which are needed to fight any type of foreign invasion. So far this is showing significant promise in study groups.
Receiving a diagnosis of a glioma doesn’t have to mean a death sentence anymore. There are numerous cancer facilities across the country that are trying and using the latest treatments available improving survival rates.