Research team launches clinical trial looking at adaptive radiotherapy for the postoperative treatment of cervical and endometrial cancer
China’s First Ethos Therapy™ system
In January of 2022, Peking Union Medical College Hospital (PUMCH) became the first treatment center in China to install Varian’s Ethos Therapy™ system for adaptive radiotherapy (ART).
Between February and July of that year, the system was commissioned as the clinical team participated in a robust educational program of simulations, structured exercises, on-site training, and seminars with ART experts from the United States and Australia.
“Adaptive radiotherapy involves transformation of the radiotherapy treatment process,” explains Prof. Fuquan Zhang, MD, Professor and Director of the Department of Radiotherapy Oncology at PUMCH. “With conventional treatment, we assume that the initial treatment plan—based on target contours created at one point in time—can cover an entire course of treatment over 25-30 fractions. In our online adaptive treatment workflow, we adjust the plan—and the contours—every day according to changes in the size, shape, and location of the patient’s tumor and neighboring organs.”
Making these adjustments each day, he points out, meant that the clinical team members’ roles had to change. The radiation oncology department at PUMCH set up a specialized group of physicians, medical physicists, therapists, and doctoral students to carry out online ART treatments.
“There are greater requirements for the radiotherapy team with online adaptive treatment,” says Prof. Zhang. “They must complete the contouring, planning, QA, and confirmations safely and rapidly each day, and carry out the treatment delivery for each fraction.”
Prof. Zhang and his team have focused primarily on using their Ethos system for treatment of cervical, bladder, prostate, rectal, and other pelvic cancers. They are also using the system to deliver conventional image-guided radiotherapy (IGRT) for the treatment of head and neck, lung, abdominal, and pelvic tumors.
“In the future, as the applications of Ethos Therapy evolve, we will consider how we can use it for adaptation of stereotactic body radiotherapy treatments,” says Prof. Zhang.
When it comes to the value of Ethos adaptive radiotherapy, Prof. Zhang cited the potential for enabling quick adaptation to interfractional changes, improved target coverage, reduction of dose to normal tissues, reduction of toxicities and side effects, and improved quality of life for patients.
“In the future, scientific research may reveal more potential benefits, as we study the biological effects of ART, simulation-less radiotherapy processes, the use of multi-modality imaging, and the impacts of target margin reduction and dose escalation,” Prof. Zhang predicts.
Looking at adaptive radiotherapy for the postoperative treatment of cervical and endometrial cancer
In January 2023—exactly one year after the PUMCH Ethos system was installed—Prof. Zhang and his colleagues received approval for a clinical trial (NCT05682950) that involves using the Ethos system for iterative cone-beam computed tomography (iCBCT)-guided adaptive radiotherapy, to investigate the extent and value of margin reduction in the postoperative treatment of endometrial and cervical cancer.
“Variations in bladder and rectal anatomy are the biggest challenge in pelvic cancer radiotherapy, and can sometimes lead to poor target coverage,” says Prof. Zhang, who is serving as trial chair. “We already see the great potential of Ethos ART in cervical cancer; it has helped us to address these challenges very well. We believe this trial will further verify its clinical advantages.”
The trial—a prospective phase II clinical trial—is expected to enroll 15 patients, who cumulatively will receive an anticipated total of more than 380 radiotherapy fractions. The primary outcome will look at the dose coverage of the target volumes as compared with the planning tumor volumes. The study’s secondary outcomes encompass: 1) treatment safety as assessed by dose to organs at risk, 2) acute toxicity measurements, 3) target and organs-at-risk contouring accuracy, and 4) adaptive time data capturing time from first iCBCT to selection of the optimal plan.
“Ethos is enabling us to provide more accurate treatments for cervical cancer,” added Junfang Yan, MD, another key member of the trial team. “It has the impressive ability to enable precise treatment of large targets, even with complicated inter- and intra-fractional anatomical variations.”
In preparation for the trial, Guangyu Wang, MD, another researcher working with Professor Zhang, analyzed data from the first 24 patients who received Ethos ART treatment at PUMCH. He found that adapted plans were selected for delivery more than 95% of the time. In addition, target coverage with the adaptive plans increased by 3-7% compared with non-adapted plans. In terms of efficiency, the average adaptive session for treatment of pelvic cancers took less than 16 minutes. These positive findings led the clinical team at PUMCH to launch their trial quickly, within just five months of treating their first Ethos ART patients.
“There are more than 1,500 patients with cervical or endometrial cancer treated in our department every year,” commented Professor Zhang. “We hope to reduce the gastrointestinal discomfort and other toxicities, such as diarrhea, chronic anemia, etc., that often accompany radiotherapy to this part of the body. And we believe that Ethos will show its value in treating other cancers as clinical trials such as this one are launched around the world.”
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