Potential stereotactic radiosurgery targets
for metastatic brain tumors.

The most common indication for stereotactic radiosurgery (SRS) has become the treatment of patients with metastatic tumors to the brain. The single biggest controversy has been the relative roles of SRS and whole brain radiation therapy (WBRT), the prior mainstay for metastatic tumor treatment — and, some say, still the “gold standard” against which other methods must be compared.

Evidence-based medicine principles have become increasingly integrated into neurosurgical practice and education. The American Association of Neurological Surgeons/Congress of Neurological Surgeons (AANS/CNS) Joint Guidelines Committee (JGC) was created to support these efforts and recently approved a series of guidelines directed at the management of central nervous system metastatic disease. Included within this larger work, recommendations specifically addressing the role of radiosurgery for CNS metastatic disease were enumerated. The JCG methodology dictates that a specific question be addressed, which for SRS was:

“Should patients with newly-diagnosed metastatic brain tumors undergo stereotactic radiosurgery compared with other treatment modalities?”

Based on a literature review of more than 16,000 articles, a series of recommendations were made. The following two were made at the highest level (i.e. Level 1 is the highest degree of medical certainty):

SRS Plus WBRT Versus WBRT Alone

Level 1: Single-dose SRS along with WBRT leads to significantly longer patient survival compared with WBRT alone for patients with single metastatic brain tumors who have a KPS ≥70.

Level 1: Single-dose SRS along with WBRT is superior in terms of local tumor control and maintaining functional status when compared to WBRT alone for patients with 1-4 metastatic brain tumors who have a KPS ≥70.

In addition to these high-level recommendations, recommendations based on Class II and Class III data supported the role of SRS in essentially every situation examined.

Key issues targeted for future investigation include better defining the role of SRS in improving outcome and in maintaining neuro-cognitive function.

Now that SRS has been firmly established as having a role in the management of CNS metastatic disease, it is time to begin to examine the impact of these recommendations both from a clinical and economic point of view. As a group we need to collect the outcome date in order to support the continued and expanded use of SRS. In the era of “pay for performance,” evidence-based guidelines will allow a physician influenced coherent model of resource allocation to be pursued. Organized prospective data collection is essential to begin to understand the scope of SRS in neurosurgical practice. The AANS could provide the database infrastructure to collect registry data on SRS patients in order to capture the demographics. Coupled with validated and uniform outcome measures, this database could provide an excellent foundation for translational research as well as a methodology for analyzing economic impact and cost-effectiveness. Neurosurgeons need to take the lead in guiding the future of SRS in our metastatic cancer patients. The creation of the guidelines supported by organized neurosurgery is a good start. Now is the time to push for better outcome data and better economic modeling, and neurosurgery should lead the way.

Steven N. Kalkanis, MD, FAANS, is co-director of the Hermelin Brain Tumor Center and director of neurosurgical oncology at Henry Ford Health System in Detroit. He also was the lead author on the recently published national clinical practice guidelines for brain metastases sponsored by the AANS, the CNS and the Joint Section on Tumors, and is chair of the Guidelines Subcommittee of the Tumor Section. Timothy Ryken, MD, MS, FAANS, FACS, is a neurosurgeon and chair of the Iowa Spine and Brain Institute in Waterloo, Iowa. He holds a master’s degree in Clinical Epidemiology, and is chair-elect of the American Association of Neurological Surgeons and Congress of Neurological Surgery Joint Guidelines Committee. Dr. Ryken maintains an active clinical and translational research program, and lectures extensively on central nervous system tumor management. The authors reported no conflicts for disclosure.

Reference:

1). Linskey ME, Andrews DW, Asher AL, Burri SH, Kondziolka D, Robinson PD, Ammirati M, Cobbs CS, Gaspar LE, Loeffler JS, McDermott M, Mehta MP, Mikkelsen T, Olson JJ, Paleologos NA, Patchell RA, Ryken TC, Kalkanis SN. The role of stereotactic radiosurgery in the management of patients with newly diagnosed brain metastases: a systematic review and evidence-based clinical practice guideline. J Neurooncol. 2010 Jan; 96(1):45-68.