Astrocytomas are the most common form of glioma, originating from star-shaped brain cells called astrocytes. They can grow anywhere in the brain but are most commonly found in the cerebrum, the largest part of the brain responsible for higher brain functions like memory, speech, movement and sensory function.
While a definitive cause of astrocytomas is unknown, they are found in both children and adults. Genetics may play a role in development, especially in children with neurofibromatosis (a genetically-inherited disorder in which nerve tissue grows tumors).
Diagnostic An Astrocytoma
Imaging studies performed by a brain specialist (also known as neurologist) are the most effective way to locate and diagnose an astrocytoma. They can include an MRI (Magnetic Resonance Imaging), CT Scan (Computed Tomography) and chest X-Ray. A biopsy – or piece or tissue removed from the tumor itself – may also be necessary to determine the type of tumor.
• MRI (Magnetic Resonance Imaging): A non-invasive scan that reveals detailed images of the brain and its surrounding nerves and tissue.
• CT Scan (Computed Tomography): While a surefire diagnosis comes from an MRI, a CT scan can also help identify the exact location and size of the tumor. A CT scan uses X-rays to make detailed images of structures inside the body.
• Chest X-Ray: A chest X-ray may be taken to see if the tumor has spread – or metastasized – from the brain to other parts of the body (or vice versa). However, X-rays are much less sensitive and are used less often to diagnose a brain tumor.
Brain tumors are categorized on four-level scale developed by the World Health Organization. Grade I tumors are the least aggressive, while Grade IV are the most aggressive. Astrocytomas can occur as Grade III and Grade IV tumors at the outset. Many, however, arise from pre-existing Grade II astrocytomas that progress to a higher grade in four to five years.
• Grade I: These tumors have slow-growing cells that appear similar to normal brain cells.
• Grade II: Cells of Grade II tumors grow relatively slowly but show signs of change. They are typically considered “pre-cancerous,” as the tumor’s cells may begin to move into neighboring healthy brain tissue. If they are surgically removed, the tumor may return as a higher-grade.
• Grade III: The cells of Grade III tumors lack the structure and function of normal cells. They actively reproduce and can grow into neighboring healthy tissue. Again, if they are surgically removed it is not uncommon for the tumor to return as a higher-grade.
• Grade IV: Grade IV tumors are made up of the most aggressive, rapidly reproducing abnormal cells. These cells reproduce so quickly because they are able to form new blood vessels that support their aggressive growth. Grade IV astrocytomas are also known as Glioblastoma Multiforme, the most aggressive type of brain tumor.
Treatment & Risks
Each patient and astrocytoma tumor is unique and requires a team of specialists that work together to develop a customized treatment plan. Depending on the location and size of the tumor, your personalized team may include one or more of the following specialists:
• Neuro-oncologist: A physician specializing in brain cancer.
• Neuropathologist: A physician specializing in diseases of the brain and spinal cord with the ability to make a definitive diagnosis of brain tumors.
• Neurosurgeon: A physician trained in surgery on the nervous system, especially the spine and the brain.
• Radiation oncologist: A physician specializing in the treatment of cancer patients, using radiation therapy as the main method of treatment.
Depending on the grade of the tumor, astrocytomas are typically treated by three methods: observation, surgery and/or radiation. Because astrocytomas can grow very slowly, lower-grade tumors may need nothing more than close observation. Others will be removed surgically and have little if any effect on longevity and quality of life. Higher-grade astrocytomas are surgically removed when possible, followed by a treatment regimen of chemotherapy and/or radiation therapy.
1. Observation: Because astrocytomas can grow very slowly, lower-grade tumors may need nothing more than close observation. A physician will monitor any activity of the tumor through regular MRI scans. If the tumor shows signs of growth, it may be treated with surgery or radiation.
2. Surgery: The goal of surgery is to remove as much of the tumor as possible while minimizing damage to healthy brain tissue. The location and size of the tumor will determine how much of it, if any, can be removed. Removal of the tumor reduces the pressure within the brain, improving symptoms. If the entire tumor cannot be removed, the smaller, remaining area will be treated by radiation.
3. Radiation: In certain situations, complete surgical removal of the astrocytoma may not be an option. For example, the neurosurgical team may need to leave part of the tumor in place to avoid damage to a vital structure and the possibility of serious or life-threatening consequences. In these cases radiation may be an appropriate treatment, either alone or following surgery. Cedars-Sinai’s treatment teams have several state-of-the-art focused radiation options. For astrocytomas, the Gamma Knife® is an extremely precise, fixed system that uses up to 201 separate beams of radiation converging at a single point. The Trilogy™ System provides highly focused, image-guided radiotherapy and radiosurgery for treating astrocytomas and other lesions that are in close proximity to the spinal cord or other vital structures. The goal of either approach is to bombard the tumor with a destructive dose of radiation while minimizing damage to healthy tissue.
General symptoms of an astrocytoma tumor are a result of growing pressure inside the skull.
Most common symptoms include:
• Mental status changes
Less common symptoms (occurring in one in four patients) include:
• Personality changes
• Impaired mental cognition