A tumor in the brain can be a primary tumor--meaning it originated in the brain--or a secondary tumor. Secondary tumors originate somewhere else in the body, such as the lung or breast, and spread to the brain through the blood stream or lymph system. These metastasized cancer cells establish themselves in the brain and continue to grow. Twenty to 40 percent of cancer patients diagnosed with a primary cancer will develop a secondary cancer in the brain. In fact, these metastasized brain tumors account for the majority of brain malignancies.
Chemotherapy, conventional radiation and surgery are all possible treatment options for brain cancer. However, brain cancer patients, especially those with metastasized tumors, have another treatment option called stereotactic radiosurgery. The medical instrument for this treatment is the Gamma Knife.
The name Gamma Knife is a misnomer: there is no knife blade. Instead, the "blades" are tiny rays of radiation beams. Gamma rays are high-energy photons emitted by radioactive substances. They have shorter wavelengths than radiation used in traditional radiography. The stereotactic part of the name refers to its precise positioning in a three-dimensional space.
During Gamma Knife surgery, the patient wears a helmet with tiny holes through which radiation beams--about the thickness of a strand of hair--pass into the brain. The physician completely immobilizes the patient's head to ensure the aim of the radiation beams is accurate. The radiation beams converge upon the tumor and react on a molecular level with the cancer cells to stop them from reproducing. This kills the cancer.
Gamma Knife surgery is widely used and can treat tumors in patients who otherwise would be untreatable or who are at high risk for surgery. It is highly effective and extensively studied.
The Gamma Knife offers many benefits to brain cancer patients, including:
- Physicians administer a single dose of radiation, minimizing patients' total radiation exposure.
- Gamma Knife surgery is non-invasive; there's no incision so patients experience little discomfort, minimal risk and few side effects.
- It's effective. The Gamma Knife successfully treats specific tumors more than 85 percent of the time, and controls benign brain tumors more than 95 percent of the time.
- It's precise, damaging only the tumor cells and sparing nearby brain tissue.
Sources
http://www.irsa.org/gamma_knife.html
http://www.mayoclinic.org/stereotactic-radiosurgery/gamma-knife.html
http://www.livingwithbrainmets.org/
