Cerebellar Astrocytomas are tumors that develop from star-shaped brain cells called astrocytes and grow in the area of the brain called the cerebellum, responsible for complex motor functions like coordination and balance. Cerebellar astrocytomas usually grow slowly and do not usually spread (also known as metastasize) to other parts of the brain or body.
The cause of cerebellar astrocytomas is not known, but tumors in the cerebellum tend to occur in very young children. In fact, 19% of all childhood tumors are cerebellar astrocytomas.
A brain tumor can produce neurologic symptoms by putting pressure on important structures within the brain. As a tumor grows and takes up more space within the skull, it causes swelling inside the brain. Since the skull has a limited amount of space inside it, a tumor does not have to grow substantially to increase pressure and cause symptoms.
Most common symptoms include:
- Headaches, especially at night and early in the morning.
- Severe lethargy/exhaustion
- Confusion and disorientation
Less common symptoms include:
- Numbness or weakness of an arm or a leg
- Vision loss, blurriness or double-vision
- Speech difficulty
- Memory loss
- Impaired judgment
Diagnosing A Cerebellar Astrocytoma
Imaging studies performed by a brain specialist (also known as neurologist) are the most effective way to locate and diagnose a cerebellar 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. Cerebellar astrocytomas are most often Grade I tumors and rarely progress. If the tumors grow at all, they typically grow very slowly.
- 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.
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, cerebellar astrocytomas are typically treated by three methods: observation, surgery and/or radiation. In many cases, the best approach is to observe a low-grade cerebellar astrocytoma over time with regular MRI scans, opting for surgery only if and when the tumor begins to show signs of growth. With complete surgical removal, these tumors rarely return and long-term outcome is usually very good. While focused radiation therapy may be used if a cerebellar astrocytoma grows (or re-grows after surgery), neither radiation nor chemotherapy is typically considered a front-line 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 cerebellar 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 cerebellar 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 meningiomas 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.
Although focused radiation therapy may be used if a tumor progresses or recurs, neither radiation nor chemotherapy is typically considered a front-line therapy.