The UCLA Metastatic Brain Tumor Program treats metastatic disease focally so as to spare normal brain tissue and function. Focal treatment allows retreatment of local and new recurrences (whole brain radiation is once and done, cannot be used again). UCLA is equipped with X-knife and Novalis to treat tumors of all sizes and shapes. For patients with a large number of small brain metastases (more than 5), they offer whole brain radiotherapy.
http://neurosurgery.ucla.edu/Programs/BrainTumor/Metastatic_
As reported in MD Anderson's OncoLog, in the past the only treatment for multiple metastases was whole brain radiation, which on its own had little effect on survival. There are now a variety of effective treatment modalities for people who have fewer than four tumors. Dr. Jeffrey Weinberg at the Department of Neurosurgery at MD Anderson has said "with a small, finite number of tumors, it may be better to treat the individual brain tumors themselves rather than the whole brain." Anderson is equipped with Linac Linear Accelerator. The critical idea is to focally treat all tumors.
http://www2.mdanderson.org/depts/oncolog/articles/05/1-jan/1
The results of a study at the University of Pittsburgh School of Medicine reported that treating four or more brain tumors in a single radiosurgery session resulted in improved survival compared to whole brain radiation therapy alone. Patients underwent Gamma-Knife radiosurgery and the results indicate that treating four or more brain tumors with radiosurgery is safe and effective and translates into a survival benefit for patients.
http://newsbureau.upmc.com/UPCI/GammaKnifeStudy2005.htm
Sometimes, symptoms of brain damage appear many months or years after radiation therapy, a condition called late-delayed radiation damage (radiation necrosis or radiation encephalopathy). Radiation necrosis may result from the death of tumor cells and associated reaction in surrounding normal brain or may result from the necrosis of normal brain tissue surrounding the previously treated metastatic brain tumor. Such reactions tend to occur more frequently in larger lesions (either primary brain tumors or metastatic tumors). Radiation necrosis has been estimated to occur in 20% to 25% of patients treated for these tumors. Some studies say it can develop in at least 40% of patients irradiated for neoplasms following large volume or whole brain radiation and possibly 3% to 9% of patients irradiated focally for brain tumors that developed clinically detectable focal radiation necrosis. In the production of radiation necrosis, the dose and time over which it is given is important, however, the exact amounts that produce such damage cannot be stated.
Late effects of whole brain radiation can include abnormalities of cognition (thinking ability) as well as abnormalities of hormone production. The hypothalamus is the part of the brain that controls pituitary function. The pituitary makes hormones that control production of sex hormones, thyroid hormone, cortisol. Both the pituitary and the hypothalamus will be irradiated if whole brain radiation occurs. Damage to these structures can cause disturbances of personality, libido, thirst, appetite, sleep and other symptoms as well. Psychiatric symptoms can be a prominent part of the clinical picture presented when radiation necrosis occurs.
Again, whole brain radiation is the most damaging of all types of radiation treatments and causes the most severe side effects in the long run to patients. In the past, patients who were candidates for whole brain radiation were selected because they were thought to have limited survival times of less than 1-2 years and other technology did not exist. Today, many physicians question the use of whole brain radiation in most cases as one-session radiosurgery treatment can be repeated for original tumors or used for additional tumors with little or no side effects from radiation to healthy tissues. Increasingly, major studies and research have shown that the benefits of radiosurgery can be as effective as whole brain radiation without the side effects.
Of course, surgical excision is the gold standard of treatment for surgically accessible lesions. Many studies in the medical literature clearly demonstrate the efficacy and superiority of surgical resection followed by radiation over radiation therapy as a first-line treatment for metastatic brain tumors. Doctors at UCLA and MD Anderson say that even for patients with up to four metastases, surgical excision of all intracranial disease has been shown to provide the long survival with good quality of life, and has the same prognosis as someone who has only one brain tumor.