Stereotactic radiosurgery (SRS) in the modern management of patients with brain metastases

// Hany Soliman 1 , Sunit Das 2 , David A. Larson 3 and Arjun Sahgal 1,2 1 Department of Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada 2 Division of Neurosurgery, St. Michaels Hospital, University of Toronto, Toronto, ON, Canada 3 Department of Radiation Oncology, University of California San Francisco, San Francisco, CA, USA Correspondence to: Hany Soliman, email: // Keywords : stereotactic radiosurgery, brain metastases, whole brain radiation, targeted therapy Received : October 19, 2015 Accepted : January 13, 2016 Published : February 02, 2016 Abstract Stereotactic radiosurgery (SRS) is an established non-invasive ablative therapy for brain metastases. Early clinical trials with SRS proved that tumor control rates are superior to whole brain radiotherapy (WBRT) alone. As a result, WBRT plus SRS was widely adopted for patients with a limited number of brain metastases (“limited number” customarily means 1-4). Subsequent trials focused on answering whether WBRT upfront was necessary at all. Based on current randomized controlled trials (RCTs) and meta-analyses comparing SRS alone to SRS plus WBRT, adjuvant WBRT results in better intracranial control; however, at the expense of neurocognitive functioning and quality of life. These adverse effects of WBRT may also negatively impact on survival in younger patients. Based on the results of these studies, treatment has shifted to SRS alone in patients with a limited number of metastases. Additionally, RCTs are evaluating the role of SRS alone in patients with >4 brain metastases. New developments in SRS include fractionated SRS for large tumors and the integration of SRS with targeted systemic therapies that cross the blood brain barrier and/or stimulate an immune response. We present in this review the current high level evidence and rationale supporting SRS as the standard of care for patients with limited brain metastases, and emerging applications of SRS.