Glioma is a broad category of brain and spinal cord tumors that come from glial cells, the main brain cells that can develop into tumors.
The symptoms, prognosis, and treatment of a malignant glioma depend on the person’s age, the exact type of tumor, and the location of the tumor within the brain. These tumors tend to grow and infiltrate into the normal brain tissue, which makes surgical removal very difficult -- or sometimes impossible -- and complicates treatment.
There is no defined staging system for childhood central nervous system atypical teratoid/rhabdoid tumor (AT/RT). Patients are classified as having newly diagnosed or recurrent disease with or without neuraxis dissemination.
The risk of these brain tumors increases with age, beginning at 20 and reaching a peak at ages 75 to 84. Usually low-grade versions of gliomas can occur in children. Brain tumors are slightly more likely to occur in males.
The only risk factor for malignant gliomas is prior radiation to the brain. Family history accounts for less than 5% of causes for developing these tumors. Some genetic disorders increase the risk of development of these tumors in children but rarely in adults.
There are no lifestyle risk factors associated with malignant gliomas. This includes alcohol, cigarette smoking, or cell phone use.
Are There Different Types of Gliomas?
While about 42% of all brain tumors, even benign tumors, are gliomas, 77% of malignant brain tumors are gliomas.
Gliomas are named based on the specific type of glioma, or brain cell, affected. According to the American Cancer Society, there are three types of gliomas, including astrocytomas, oligodendrogliomas, and ependymomas. (A fourth type of glioma, contains more than one type of cell so is not a true glioma.)
Ependymomas make up less than 2% of all brain tumors. These tumors come from the ependymal cells and because they do not spread into the normal brain tissue, some ependymomas can be cured by surgery. They rarely spread outside the brain. But they do have a high risk of local recurrence and thus are considered malignant.
Astrocytomas make up about 35% of all brain tumors and start in brain cells called astrocytes. Most of these brain tumors cannot be cured because they spread all through the normal brain tissue. Astrocytomas are usually classified as low grade, intermediate grade, or high grade, depending on criteria used by a doctor examining the biopsy under a microscope. Tumors that are low grade grow the slowest. Intermediate-grade astrocytomas grow at a moderate rate, while the highest grade, called glioblastomas, the most common adult malignant brain tumor, are fast growing.
Oligodendrogliomas make up about 4% of all brain tumors. These tumors spread in a similar manner to astrocytomas and usually cannot be cured with surgery. However, these tumors may be slow growing. With time, they may transform into a higher glade glioma.
What Are the Symptoms of a Glioma?
Symptoms of a glioma are similar to those produced by other malignant brain tumors and depend on the area of the brain affected. The most common symptom is headache -- affecting about half of all people with a brain tumor. Other symptoms can include seizures, memory loss, physical weakness, loss of muscle control, visual symptoms, language problems, cognitive decline, and personality changes. These symptoms may change, according to which part of the brain is affected.
Symptoms may worsen or change as the tumor continues to grow and destroys brain cells, compresses parts of the brain, and causes swelling in the brain and pressure in the skull.