What is brain cancer?*
Brain cancer is an abnormal growth of cells in the brain, resulting in a collection of cells called a brain tumor. If the abnormal cells were originally brain cells that started to grow uncontrollably, it is a primary brain tumor. If the abnormal cells originated in another part of the body, such as the lung or breast, and were carried to the brain by the blood or other body fluid, then the cancer is considered a metastatic brain tumor.
- Primary brain tumors
There are many types of primary brain tumor, including meningiomas, pituitary adenomas, schwannomas and gliomas, which are divided into astrocytomas, ependymomas, medulloblastomas and oligodendrogliomas. Each primary brain tumor is categorized based on the type of normal brain cell from which it originated, and has its own unique characteristics and growth patterns. Gliomas account for 40 percent of all primary brain tumors, and it is common for them to spread from the brain to other parts of the body. The most aggressive type of glioma is called glioblastoma multiforme.
- Metastatic brain tumors
The cells that form metastatic brain tumors travel to the brain from other parts of the body through the bloodstream, along nerves or within the fluid surrounding the spinal cord and the brain. These cells most commonly originate in tumors within the lung, breast, skin or colon, and are deposited in the brain where they grow into a tumor.
Both primary and metastatic brain tumors can be very dangerous because they can compress sensitive brain tissue and nerves within the head, causing patients to experience symptoms such as vision loss, hearing loss, difficulties with balance, pain or seizures. As these tumors grow larger, they can be life-threatening because they disrupt critical parts of the brain that are responsible for breathing and other basic life functions.
How is brain cancer detected?
Patients with brain tumors may have symptoms such as headaches, seizures and other neurological problems. Because many of these symptoms are not unique to brain tumors, it is difficult to make a diagnosis without some type of imaging study. Diagnosis often involves visualization of the brain tumor by a physician using tools such as positron emission tomography-computed tomography (PET-CT), computed tomography (CT) scan or magnetic resonance imaging (MRI). Once the diagnosis has been made, more tests may be necessary to identify the specific type of tumor and determine the proper treatment for the patient.
How it is treated?
Combinations of several types of treatment are often required to fight brain cancer. These treatments are described below.
For solitary tumors that are not near the brain’s most critical structures, such as those involved in vision or regulation of breathing, the most common treatment option is surgery to remove the tumor. Surgery is used for primary brain tumors as well as for solitary brain metastases and benign tumors. Surgery is often followed by whole-brain radiation therapy or partial-brain radiation techniques to eliminate any microscopic bits of the tumor. In some cases, malignant brain tumors can be treated in combination with chemotherapy for greater effect.
Chemotherapy medication is delivered orally or through an IV. It affects both normal tissue and the cancer cells, so patients may experience side effects, such as severe nausea and vomiting, infections, fatigue and weight loss. Chemotherapy is typically given to a patient in combination with other types of brain cancer treatment. For example, it may be given after whole-brain radiation therapy to target both the metastatic tumors in the brain and the tissues outside the brain that originally produced the cancer cells.
- Radiation therapy
If the patient suffers from multiple tumors, as is often the case with metastatic brain cancer, treatment is often whole-brain radiation therapy. Whole-brain radiation treatment typically requires 20 to 40 sessions over four to six weeks and is applied to the entire brain, including both the tumor(s) and normal tissue. The normal brain tissue is not as susceptible to small doses of radiation as the tumor cells, so the extended courses of whole-brain radiation therapy result in minimal destruction of normal brain cells for the patient.
For a patient with a limited number of tumors in his or her brain, radiosurgery is another option.
During the past 25 to 30 years, radiosurgery has emerged as an alternative to surgery. Unlike conventional radiation therapy, during which small doses of radiation are delivered over weeks and months, radiosurgery can treat a tumor in one to five sessions by delivering a high dose of radiation with extreme accuracy.
During radiosurgery, hundreds of narrow radiation beams are delivered from different angles, all intersecting at the tumor. This treatment allows the tumor to be attacked by a high dose of radiation without damaging surrounding sensitive brain tissue. To be effective and safe, radiosurgery must be accurate. To achieve this accuracy, some radiosurgery devices, such as the Gamma Knife®, require that a rigid stereotactic frame be affixed to a patient’s head so the system can pinpoint the exact location of a tumor. The frame is screwed into a patient’s skull after local anesthesia is given. Many patients find the frame to be uncomfortable and painful. In addition, if multiple treatment sessions are required, a patient may have to be hospitalized with the frame in place for several days until the treatment is complete.
Other radiosurgery devices, such as the CyberKnife® Robotic Radiosurgery System, improve on other radiosurgery techniques by eliminating the need for stereotactic frames. As a result, the CyberKnife System enables doctors to achieve a high level of accuracy in a non-invasive manner and allows patients to be treated on an outpatient basis. Learn more about CyberKnife for brain cancer treatment.
*Source material drawn from www.cyberknife.com. Please refer to that website for a complete listing of references used in the original information sections.
CyberKnife® is a registered trademark of Accuray Incorporated.
Leksell Gamma Knife® is a registered trademark of Elekta Instruments, Inc.