General Information about Brain Tumors
Primary brain tumors are tumors that originate in the brain. Brain tumors can be benign (non-cancerous) or malignant (cancerous). Benign brain tumors can grow and compress nearby structures of the brain but rarely spread into other parts of the body. Malignant brain tumors are likely to grow quickly and spread into other parts of the central nervous system including the spinal canal. There are several types of brain tumors, which include gliomas, meningiomas, pituitary adenomas, and nerve sheath tumors. These types of cancers originate in the brain, and are not to be confused with metastatic cancer. Metastatic cancer is one that has spread from the primary site of origin, or where it started, into different parts of the brain.
Facts about Brain Tumors
- Represent roughly 1.5% of all newly diagnosed cancers.
- Overall cognitive ability may be affected depending on which lobe of the brain contains the cancer. For examples: Gliomas arise from the glial cells and are the most common form of brain and CNS (Central Nervous System) tumors. Gliomas make up approximately half of all brain tumors and are classified by the cell type, grade, and location of the disease. The most common types of gliomas are oligodendrogliomas, ependymomas, and astrocytomas.
- Frontal lobe - Behavioral and cognitive decline
- Temporal lobe - Memory or visual field defects, aphasia (inability to speak), seizures, and hemiparesis (partial paralysis)
- Parietal lobe - Sensory seizures. Motor dysfunctions that the patient may not recognize
- Meningiomas are the second most common of all brain tumors and account for roughly 20% of all brain tumors. Meningiomas are generally slow growing and produce very little symptoms throughout a patient's life. Only a very small percentage of these tumors are malignant.
- Pituitary adenomas are benign lesions that originate in the pituitary gland. These tumors make up for approximately 15% of all brain tumor patients. They can be hormone secreting or non-hormone secreting. If they grow they can compress the optic chiasm leading to visual problems.
Signs and Symptons of Brain Tumors
General symptoms are related to the area of the brain that is affected and can include:
- Vomiting due to intracranial pressure
- Papilledema (edema of the optic disk)
- Cognitive and behavioral changes
- 50% of patients present with headaches
Helpful Terms Regarding Brain Tumors and the Central Nervous System
- Blood-brain barrier (BBB) - The barrier system that hinders the penetration of some substances into the brain and cerebrospinal fluid. The BBB exists between the vascular system and the brain. Its purpose is to protect the brain from potentially toxic compounds.
- Cerebellum - Part of the brain that is responsible for the coordination of voluntary muscular movements.
- Cerebrospinal fluid (CSF) - The fluid that flows through and protects the brain and spinal canal.
- Cerebrum - The largest part of the brain and consists of two hemispheres (left and right). The functions of the cerebrum include interpretation of sensory impulses and voluntary muscular activities. It is the center for memory, learning, reasoning, judgment, intelligence, and emotions.
- Debulking - A surgical procedure used to reduce tumor size, reduce tumor burden, and increase the opportunity to obtain a pathologic diagnosis.
- Edema - Excessive accumulation of fluid in a tissue, producing swelling.
- Frontal lobe - Front part of the cerebral hemisphere.
- Intracranial pressure (ICP) - Increased pressure in the brain resulting in headaches, nausea, and vomiting.
Treatment of Common Brain Tumor
Treatment of choice for most gliomas is dependent on the location, grade of malignancy, and its histology. Treatment often includes a combined approach between surgery, radiation therapy, and sometimes chemotherapy. Surgical removal of the tumor is typically the first line of treatment with post-operative chemotherapy or radiation therapy depending on the findings from surgery.
Meningiomas can be initially observed if their growth is very slow. However for certain tumors that are growing and near critical structures (such as cranial nerves), earlier treatment may help preserve neurologic function. Tumors requiring treatment are typically treated with surgical removal and/or radiation therapy.
These tumors are mostly treated with medication but can also be surgically removed. Radiation therapy also can be used to treat these tumors. It is important that patients with these tumors are evaluated by an endocrinologist to correct any hormone abnormalities.
Metastatic brain cancers are tumors that have spread from another organ system in the body. These patients are considered Stage 4. These tumors are more common than primary brain tumors. Metastatic brain cancer most commonly originates from lung, breast, and melanoma. A majority of these patients present with multiple lesions throughout the brain and can be treated with surgery or radiation therapy.
Role of Radiation Therapy in Managing CNS and Brain Tumors
Radiation therapy can be used to help manage both primary brain tumors and secondary brain tumors. Post-operative radiation can be used on tumors that require additional treatment for residual disease. Radiation therapy is commonly used to treat brain tumors in difficult surgical locations or for patients who are medically unfit to undergo surgery.
Metastatic brain tumors often present with multiple small lesions throughout the brain and are often too complex to be removed with surgery. For this reason, radiation to the whole brain is often performed to treat the multiple lesions throughout the cranium.
The image to the left shows the treatment field with MLC to protect healthy tissue.
Frequently Asked Questions
Q: What are the side effects of radiation to the brain?
A: Patients can experience some hair loss which may be permanent. They can also have headaches and fatigue. Your physician may start you on a steroid medication to decrease the swelling in the brain during radiation. Long term, patients may experience mild to moderate temporary memory problems depending on what part of the brain receives radiation. Patients also occasionally experience transient taste changes. If you have seizures you may need to take anti-seizure medication.
Q: How do we know the tumor is being properly radiated?
A: We are able to use MRI images and fuse them with our planning CT images. This forms a map where we can outline exactly where the disease in the brain is located, allowing us to target the tumor precisely. We can also use this map to make sure critical structures in the brain do not receive too much radiation.
Q: What diet should I be on during radiation treatments?
A: There are usually no diet restrictions with radiation to the brain.