Whole brain radiation is being routinely administered to patients after craniotomy for excision of a cerebral metastasis in an attempt to destroy any residual cancer cells at the surgical site. However, the deleterious effects of whole brain radiation, such as dementia and other irreversible neurotoxicities, can become evident.
This raises the question as to whether elective postoperative whole brain radiation should be administered to patients after excision of a solitary brain metastasis. Current clinical practice, at a number of leading cancer centers, use a more focused radiation field that includes only 2-3cm beyond the periphery of the tumor site.
Many metastatic brain lesions are now being treated with stereotactic radiosurgery. In fact, some feel radiosurgery is the treatment of choice for most brain metastases. There are a number of radiation treatments for therapy (Stereotatic, Gamma-Knife, Cyber-Knife, Brachyradiation and IMRT to name a few). These treatments are focal and not diffuse.
Unlike surgery, few lesions are inaccessible to radiosurgical treatment because of their location in the brain. Also, their generally small size and relative lack of invasion into adjacent brain tissue make brain metastases ideal candidates for radiosurgery. Multiple lesions may be treated as long as they are small.
The risk of neurotoxicity from whole brain radiation is not insignificant and this approach is not indicated in patients with a solitary brain metastasis. Observation or focal radiation is a better choice in solitary metastasis patients.
Whole brain radiation can induce neurological deterioration, dementia or both. Those at increased risk for long-term radiation effects are adults over 50 years of age. However, whole brain radiation therapy has been recognized to cause considerable permanent side effects mainly in patients over 60 years of age. The side effects from whole brain radiation therapy affect up to 90% of patients in this age group. Focal radiation to the local tumor bed has been applied to patients to avoid these complications.
Aggressive treatment like surgical resection and focal radiation to the local tumor bed in patients with limited or no systemic disease can yield long-term survival. In some patients, delayed deleterious side effects of whole brain radiation therapy are particularly tragic. Within 6 months to 2 years patients can develop progressive dementia, ataxia and urinary incontinence, causing severe disability and in some, death. Delayed radiation injuries result in increased tissue pressure from edema, vascular injury leading to infarction, damage to endothelial cells and fibrinoid necrosis of small arteries and arterioles.
Previous studies on this protocol were thought to have been on the difference between surgical excision of brain tumor alone vs. surgical excision & whole brain radiation. It was a study of whole brain radiation of a brain tumor alone vs. whole brain radiation & surgical excision. The increased success had been the surgery.
Those studies convincingly showed there was no survival benefit or prolonged independence in patients who received postoperative whole brain radiation therapy. The efficacy of postoperative radiotherapy after complete surgical resection had not been established. It never mentioned the incidence of dementia, alopecia, nausea, fatigue or any other numerous side effects associated with whole brain radiation. The most interesting part of thes studies were the patients who lived the longest. Patients in the observation group who avoided neurologic deaths had an improvement in survival, justifying the recommendation that whole brain radiation therapy is not indicated following surgical resection of a solitary brain metastasis.
Had fatigue, memory loss and other adverse effects of whole brain radiation been considered, and had quality of life been measured, it might be less clear that whole brain radiation is the right choice for all patients. These patients do not remain functionally independent longer, nor do they live longer than those that have surgery alone. The standard for proving the value (improving overall survival) of whole brain radiation fell short of this criteria.
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/
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://www.upmc.com/home.htm
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/pdfs-issues/05/oncolog1-05.pdf
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