Studies Show that RapidArc® Radiosurgery is a Viable, Time Efficient Way to Treat Multiple Brain Metastases | Varian

Studies Show that RapidArc® Radiosurgery is a Viable, Time Efficient Way to Treat Multiple Brain Metastases

PALO ALTO, Calif., June 5, 2015 /en-gb/en-gb/en-gb/PRNewswire/en-gb/en-gb/en-gb/ -- Treating multiple brain metastases with single isocenter RapidArc® radiosurgery—a technique for treating several tumors at once rather than one at a time—can deliver results that are equal or comparable to other types of radiosurgery, according to research teams from the University of California, San Diego (UCSD), the University of Birmingham, Alabama (UAB), and other institutions.

RapidArc Radiosurgery, which is a term for volumetric modulated arc radiosurgery delivered using a medical linear accelerator (linac) from Varian Medical Systems (NYSE: VAR), can also be completed in substantially less time, researchers report.  One reason for the speed are the properties of the Varian beam-shaping device, called a multileaf collimator, which features 120 narrow slats that can slide in and out and past each other to produce multiple apertures of virtually any shape, making it possible to target more than one tumor at a time during a treatment.  Cone-based and cobalt-based systems like Cyberknife® and Gamma Knife® are generally limited to targeting one tumor at a time.

In a single-center, retrospective review of 15 patients with multiple brain metastases who were treated with RapidArc radiosurgery between 2009 and 2011, researchers from UCSD noted local tumor control and overall survival rates that were equal or comparable to conventional radiosurgery approaches.  The study, published online prior to print in Neurosurgery, reports that no toxicity above grade 2 was observed.1

"Our clinical experience with Rapid Arc Radiosurgery is that it reduced treatment time while accurately conforming the radiation plan to the intended targets," said Clark C. Chen, MD, PhD, chief of stereotactic radiosurgery and vice-chairman of academic affairs, UCSD neurosurgery. "Each treatment of multiple brain metastases in our study was completed in under eight minutes.  Reduced treatment time not only optimizes efficiency of institutional work-flow but, more importantly, maximizes patient comfort and the treatment experience."

At the annual meeting of the American Association of Neurological Surgeons (AANS) last month, a poster presentation by Evan Thomas, MD, PhD, from the University of Alabama, Birmingham (UAB), reported on a retrospective review of 34 patients with multiple metastases treated with RapidArc Radiosurgery between 2010 and 2014.2  As described in their Neurosurgery article last year, the UAB team follows a particular planning approach for RapidArc treatments that incorporates the use of non-coplanar arcs to maximize the number of treatment angles, along with key optimization criteria that minimize the amount of low dose "spill" reaching normal brain tissues during treatment.3

"Preliminary results indicated that the toxicity profile associated with these treatments is similar to other modalities, including multi-isocenter approaches, such as Gamma Knife and Cyberknife," Thomas said.  "We saw no Grade 4 or 5 toxicity.  Grade 3 toxicity occurred in one patient.  Grade 2 toxicity occurred in eight patients, consisting mainly of headaches that responded well to steroids.  In this patient population, the likelihood of toxicity was mainly associated with previous cranial irradiation treatments and the volume of tissue being irradiated."

Thomas will take part in two presentations about the UAB approach to RapidArc Radiosurgery at the International Stereotactic Radiosurgery Society (ISRS) Congress in Yokohama, Japan next week.4 One will cover a case study wherein RapidArc Radiosurgery was used on five separate occasions to treat a single patient for multiple brain metastases that recurred (Abstract O-59).  The second will demonstrate the feasibility of treating numerous (i.e. 15) brain metastases with RapidArc Radiosurgery using Varian's TrueBeam® STx system (Abstract O-48).  "Because such treatments can be delivered very quickly, in less than 20 minutes, and with great accuracy, some may find the technique preferable to whole brain radiotherapy or Gamma Knife radiosurgery," Thomas said.