Radiosurgery, Tumor-Tracking Advancements Reduce Treatment Time for Cancer, Enhance Precision of Treatment

John B. Fiveash, MD, professor of radiation oncology, and Richard Popple, PhD, associate professor of medical physics at the University of Alabama at Birmingham (UAB; USA), detailed clinical experiences using RapidArc radiosurgery on a TrueBeam STx system developed by Varian.

Drawing on their experience planning and delivering some 435 courses of treatment for prostate, head and neck, brain, spine, lung, liver, and pancreatic cancer, Dr. Fiveash and Dr. Popple described the potential benefits of the high intensity mode on TrueBeam STx, which makes it possible to deliver dose more quickly than conventional dose delivery methods, and may reduce the amount of radiation scatter than can reach surrounding healthy tissues during treatment.

“The TrueBeam STx machine allows radiosurgery to be completed in a dramatically short time frame,” said Dr. Fiveash, who is also the interim associate director for clinical research at the UAB Comprehensive Cancer Center. “In many cases, these procedures can be scheduled to fit into a normal radiotherapy treatment time slot.”

The UAB clinicians also described their experiences using TrueBeam to deliver RapidArc radiosurgery, a fast, accurate strategy to targeting cancer with carefully shaped high-energy beams during one or more continuous rotations of the treatment machine around the patient. “RapidArc Radiosurgery enables us to deliver a highly conformal dose to a tumor, using multiple partial non-coplanar arcs,” Dr. Fiveash said, describing an approach to radiosurgery that increases the number of beam angles used, thereby minimizing the dose to surrounding healthy tissues.

In another Varian-sponsored workshop, Constantine A. Mantz, MD, chief medical officer at 21st Century Oncology (Fort Myers, FL, USA), presented preliminary findings from a prospective phase II study showing that low-risk prostate cancer patients treated with radiosurgery using Calypso real-time tracking technology had favorable health-related quality of life scores and minimal toxicities. The study evaluated 84 patients who received treatment between January 2007 and January 2011. Patients received five treatments, on alternating days, each at 8.0 Gy. Patients completed a quality of life questionnaire before and after treatment. Follow-up data were collected from patients three, six, and nine months, as well as one, two, and three years’ post-treatment.

Dr. Mantz emphasized that real-time tumor tracking is proving to be an important tool for decreasing treatment margins during SBRT for prostate cancer, which is vital in limiting side effects. “Based on 36 months’ worth of follow up data, our prostate cancer trial is showing that real-time tumor tracking with SBRT [stereotactic body radiation therapy, a form of radiosurgery targeting tumors in the body] appears to have clinically significant benefits in decreasing acute toxicity, as well as improving quality of life and biochemical outcomes. The Calypso real-time tracking technology enables us to deliver increased doses of radiation accurately to the tumor and minimize exposure of surrounding healthy tissues. These are the fundamental goals when treating prostate cancer.”

“Radiosurgery is poised to make a big difference in how cancer is treated,” said Tim Guertin, president and CEO of Varian Medical Systems, a major cosponsor of the meeting, in an address he made during one of the general sessions. “As the technology has advanced, radiosurgery utilization has been steadily rising over the last decade because clinicians are seeing--and publishing about--real benefits to patients.”

Varian’s TrueBeam machine and RapidArc Radiosurgery were also the focus of two of the meeting’s scientific sessions. Corey Zankowski, PhD, vice president of product management at Varian, collaborated with Sonia Dieterich, PhD, clinical associate professor and chief of physics at the department of radiation oncology, Stanford University Medical Center (Stanford, CA, USA), to detail the ways in which Varian’s TrueBeam and TrueBeam STx platforms have been optimized for radiosurgical procedures. In a following session, they reviewed the technical and clinical advantages of RapidArc Radiosurgery, summarizing the literature as well as Stanford’s clinical experience using this modality to treat brain, spine, lung, gastrointestinal, and genitourinary cancer.

“The applications, technologies, and methodologies in the field of radiosurgery have been developing rapidly over the last 10 years,” said Kolleen Kennedy, president of Varian’s oncology systems business. “We commend The Radiosurgery Society for its efforts to meet the need for continual learning in this field. The Society put together a stellar and comprehensive program with world-class clinical thought leaders who presented on a wide spectrum of topics over a period of three days. Varian was pleased to be the leading sponsor of this important meeting.”

Related Links:
Varian Medical Systems
University of Alabama at Birmingham
Stanford University Medical Center