Brain tumors almost never form from neurons, because the neurons intrinsically lack the ability to divide and grow, which is a key part of cancer. Instead, many brain tumors come from cells that support and nourish the neurons. These cells, called glial cells, can form tumors called gliomas, which can cause brain damage and even invade the brain tissue.
Types
There are six different kinds of glial cells, the National Brian Tumor Society explains, and only some of them commonly form gliomas. The most common type of glioma is derived from astrocytes, making it an astrocytoma. Gliomas can also arise in the brain stem, the cells of the ependyma (the tissue that makes cerebrospinal fluid), oligodendrocytes (which surround neurons with a protective sheath) and the optic nerve.
Grading
Gliomas are often classified according to their grade, which describes the invasiveness of the cells. The grading scale for glioma goes from I to IV, with IV being the most aggressive kind of cancer. Grading is often based in part by the appearance of the cancer cells under the microscope; cells that are more similar to healthy cells are given a low grade, whereas highly abnormal cells (also called anaplastic cells) are of a higher grade. Gliomas can also be classified, according to the American Brian Tumor Association, based on whether they have spread to other parts of the brain and body.
Symptoms
The symptoms of a glioma, according to the Mayo Clinic, can vary depending on the location and rate of growth of the tumor. Some common symptoms, however, include headaches, dizziness, and sudden nausea and vomiting. Patients may also experience problems with their senses, including vision and auditory problems. Confusion, changes in personality and seizures can also be caused by a glioma.
Diagnosis
Patients who are suspected of having a glioma are normally given a full physical and neurological exam to check for any abnormalities or dysfunction within the nervous system. The American Cancer Society explains that gliomas (and other brain tumors) can also be detected on an MRI or CT scan. Although these imaging tests can detect masses in the brain, a biopsy is necessary to definitively diagnose a glioma.
Treatment
In many cases, the Mayo Clinic explains, the first-line treatment for a glioma is surgical removal of as much as the cancer as possible. Radiation treatment can also be used; this approach uses high energy X-ray beams that are directed at the cancer cells, damaging and killing them. Chemotherapy, which uses medications that poison cancerous cells, can also be used to treat gliomas. The Mayo Clinic also notes that some new therapies, called targeted therapies, attack cancer cells in novel ways. Angiogenesis inhibitors, such as bevacizumab, work to keep brain tumors from making new blood vessels, causing them to die from lack of oxygen.
