UAB Radiation Oncology Team Compares Conventional Volumetric Modulated Arc Therapy with HyperArc radiotherapy
- Report covers nearly 700 patients treated over a 30-month period with single-isocenter stereotactic radiosurgery (SRS) delivered on a Varian Edge® system and addressing some 2,000 targets.
- All targets were treated using a 0 mm (i.e., no) margin (PTV=GTV), which is the gold standard of care for radiosurgical procedures
- HyperArc® high-definition radiotherapy gets high scores for quality, ease of planning, and workflow efficiency.
Clinical researchers at the University of Alabama at Birmingham (UAB) Department of Radiation Oncology have long studied diverse approaches to the treatment of multiple brain metastases, comparing different methods of planning and delivering these complex treatments. From their work in the mid-2010s comparing RapidArc® radiotherapy with Gamma Knife®1 to a more recent report, which compares manual and HyperArc approaches to VMAT, the UAB researchers have amassed useful information to help clinical teams sort through the technology options for offering single-isocenter radiosurgery using linear accelerator systems like Varian’s Edge.
In late 2017, UAB became the first center in the U.S. to offer HyperArc® high-definition radiotherapy for complex radiosurgical procedures. At that time, John Fiveash, MD, Professor and Senior Vice Chair for Academic Programs in the Department of Radiation Oncology at UAB, said: “Our radiosurgery program treats more than 300 patients per year and has evolved to treat metastatic disease. HyperArc planning automates much of the radiosurgery treatment planning strategies that we have implemented at UAB by offering standardized treatment planning and delivery that leads to greater efficiency and higher quality with a decreased dependence on the expertise of the planner.”
Fast forward to 2021. By this time, the UAB researchers had considerable experience with both approaches to VMAT and had accrued enough data to report on their transition from manual to automated planning and delivery with HyperArc, including the clinical, dosimetric, and quality assurance results associated with the two approaches.2
They found that HyperArc produces high-quality radiosurgery plans where the gross target volume (GTV) is made equal to the planning target volume, meaning that tumors are treated with a margin of zero. The HyperArc plans are at least as good as conventional (i.e., manually generated) VMAT plans, while being easier and more efficient both to plan AND to deliver. In addition, the UAB team found that a less experienced planner can produce high-quality SRS plans using HyperArc, even for patients with more than ten targets.
“The use of a single-isocenter technique for multiple targets with no PTV margin did not compromise clinical outcomes, and one-year local control for treated targets remained congruent with historical series,” the authors concluded.
The research team also noted that, while all plan-quality metrics were the same for both manual VMAT and HyperArc automated techniques, there was a “modest improvement in the gradient index for the automated plans,” and that the HyperArc plans “agreed modestly better with the treatment planning system.”
The study drew its conclusions based on comparisons between two sets of patients that comprised “the largest clinical experience to date, to our knowledge, comparing manual planning with a new automated platform designed to standardize and simplify radiosurgery planning and delivery processes,” i.e., HyperArc:
|MODALITY||# of Patients||# of Targets|
|Conventional (manually generated) VMAT plans||
A subset of the HyperArc patients—107 with 377 metastases—were evaluated for local control and toxicity. These patients received either a single fraction of 18 to 20 Gy, or 5 fractions of 6 Gy each. The local tumor control rate was 90.1 percent for the overall population (both groups). After seven months of follow-up, grade 3 seizures occurred in 3 patients. There were no grade 4 or 5 events. (Toxicity was scored according to the Common Terminology Criteria for Adverse Events, version 5, with a focus on grade 3 or higher events).
“The UAB study represents the largest cohort of brain targets and patients ever reported by a single institution,” said Raymond Schulz, Director, Global Radiosurgery Programs in the Office of Medical Affairs at Varian. “Any time we can offer clinicians a way to deliver high quality radiosurgery treatment consistently and efficiently, patients and clinics benefit. This study shows that HyperArc can provide both favorable patient outcomes as well as an expedited workflow for the clinic.”
The information captured herein represents the genuine experience of the attributed individuals and may not necessarily represent the views of Varian or the above-referenced institution. Individuals were not compensated for their participation. Radiation treatment may not be appropriate for all cancers. Individual results may vary. For more information, please visit www.varian.com/safety.
Some of the study authors disclose the following relationships with Varian: Dr Popple reports grants and personal fees from Varian outside the scope of the study reported on here. Dr Thomas reports honoraria for educational sessions from Varian during the conduct of the study and grants from Varian Medical Systems outside the study. Dr Willey reports grants and personal fees from Varian outside the study. Dr Cardan reports personal fees from Varian Medical Systems outside the study and has a patent (20160166856) pending to Varian and a patent (10073438) issued to Varian. Dr Covington reports nonfinancial support from Varian outside the study. Dr Fiveash reports grants from Varian Medical Systems, outside the study.
1 Thomas EM, Popple RA, Xingen W et al. Comparison of Plan Quality and Delivery Time Between Volumetric Arc Therapy (RapidArc) and Gamma Knife Radiosurgery for Multiple Cranial Metastases, Neurosurgery, 75:4, October 2014, pages 409–418.
2 Popple RA, Brown MH, Thomas EM et al. Transition From Manual to Automated Planning and Delivery of Volumetric Modulated Arc Therapy Stereotactic Radiosurgery: Clinical, Dosimetric, and Quality Assurance Results, Practical Radiation Oncology, 11:2, March 2021, pages E163-E171.