Radiosurgery for Brain Metastases
Many types of cancer can spread to the brain. Previously by the time cancer was found in the brain, prognosis was known to be poor. Without treatment, patients with brain metastases would only be expected to survive at most 1-2 months. Surgery and radiation therapy including radiosurgery has significantly improved the duration of survival in patients in whom disease in the rest of the body is controlled.
The symptoms of brain metastases can include headache and vomiting, seizures, weakness or numbness in the arm, leg or face, loss of vision or confusion. Since brain metastases can now be effectively treated, it is also possible that patients with cancers that commonly spread to the brain (including melanoma, lung cancer, breast cancer and renal cancer) may undergo screening MRIs periodically to detect brain metastases before they cause symptoms.
Treatment options available for brain metastases include open surgery, whole brain radiation therapy and radiosurgery. Open surgery is helpful when there is a single large metastasis in an accessible region of the brain. It is not used when there are multiple metastases or where the tumors are located in surgically inaccessible regions such as motor cortex, thalamus and brainstem. In these situations, whole brain radiation therapy (WBRT) is helpful and has been shown to increase average survival to 4 months. WBRT is the standard delivery of radiation to the whole brain. While it is able to treat all the brain tumor cells, the normal brain cells also receive the same dose of radiation. Its use can therefore be associated with the possible development of permanent radiation-induced dementia and hearing and vision impairment in those patients with good long-term survival. WBRT is traditionally offered one time only as the side effects of radiation on brain cells are cumulative and a second round of WBRT is usually only offered in palliative settings. WBRT is also much less effective in the long-term control of melanoma and renal cancer when compared with breast and lung cancer.
Traditionally, radiosurgery was therefore reserved for the treatment of patients with brain metastases who were either unable to tolerate surgery or those with multiple tumors who had previously undergone WBRT. The addition of radiosurgery to the armamentarium of tools for treating cancer has increased the average survival of patients to 8 months. Radiosurgery can be used to treat multiple tumors in the same treatment session and can be repeated multiple times for new lesions as they develop. Additionally radiosurgery is equally effective in the treatment of melanoma, renal cell cancer, lung and breast cancer. Most cancer patients tolerate radiosurgery very well and unlike with WBRT, chemotherapy regimens rarely need to be significantly altered to undergo radiosurgery. Given the effectiveness and versatility of radiosurgery, many patients are now choosing to have radiosurgery as their first line of treatment for brain metastases, thus reserving the option of WBRT if needed in the future.