Gliomas are tumors that arise from glial cells – cells that are not directly involved with brain function, but nourish and protect neurons. They are predominantly found in the brain, but can also affect the spinal cord. Gliomas are characterized by grades, depending on the type of tumor and other tumor characteristics:
Low grade gliomas are well-differentiated, slower growing, less aggressive, and patients usually have a better prognosis for treatment.
High grade gliomas are undifferentiated, fast growing and can invade adjacent tissues, and carry a worse prognosis.
There are three main types of Gliomas:
Astrocytomas may occur in any age group but are most common between ages 40-60. They are found in males to females in a 2:1 ratio. Astrocytomas may occur nearly anywhere in the brain, and symptoms may include seizures, movement disorder, personality change, headache, vomiting, and loss of consciousness. Symptoms usually develop over several weeks, months, or years depending on the malignancy of the tumor. CT and MRI scans can identify tumor location and brain biopsy is necessary to determine type of tumor. Treatment options include a combination of the following:
Surgery, where as much tumor as possible is removed.
Radiotherapy, which is often used in conjunction with surgery after removal of tumor to prevent tumor regrowth and spread.
Prognosis depends on malignancy and location of the tumor. For High-Grade astrocytoma, extensive tumor resection extends average survival by only 1 or 2 months. Radiotherapy can extend mean survival period for another 3-4 months. Therefore, the median survival rate for astrocytoma patients that undergo tumor removal surgery and radiotherapy is typically 9-10 months. For Low-Grade astrocytoma, especially in those with well defined tumors, the median survival rate ranges from 2-4 years depending on type and location of tumor. Radiotherapy can also extend survival.
Oligodendrogliomas occur in patients 30-50 years of age and are usually found in the frontal lobes. The tumor margins are usually well-defined and the rate of growth is variable. Management is similar to that of astrocytoma with prognosis depending on tumor grade and malignancy.
Ependymomas originate from cells lining the ventricular cavities – which are fluid filled spaces in the brain. Most arise in the 4th ventricle and usually in children. Ependymomas can be low-grade or malignant and may spread through CSF pathways. In 4th ventricle Ependymomas, symptoms usually include increased intracranial pressure from CSF obstruction and vomiting.
The aim of the surgery is to completely remove the tumor. 5-year survival rates range from 20-50%.