For patients with recurrent retroperitoneal sarcomas that cannot be treated surgically, treatment choices are limited. These tumors can grow in the abdomen adjacent to vital organs or enmeshed within the bowel. Given their radioresistant nature, they require high doses of radiation that risk damaging healthy nearby tissue. Once patients have undergone an initial radiation course, doctors are often left with no safe radiation treatment option.
But a pilot study from Fox Chase Cancer Center, presented at the American Society for Radiation Oncology (ASTRO) 2025 Annual Meeting, offers patients and physicians new options. Researchers found that using computed tomography (CT)-adaptive stereotactic body radiation therapy (CTA-SBRT) can make repeat radiation not only possible, but safe. The study also underscores the promise this new therapy offers for many different types of cancer. It was presented by Lubas et al at the meeting (Abstract 2164).
A New Option for Patients With Recurrent Disease
The study was conducted by Maryanne J. Lubas, DO, a fifth-year radiation oncology resident at Fox Chase, under the leadership of Rebecca Shulman, MD, Assistant Professor in the Department of Radiation Oncology. Their team reviewed the cases of five patients treated with adaptive re-irradiation between April 2024 and January 2025.
At each treatment, the team prepared two plans: a standard one created in advance and a second adaptive plan built from same-day imaging. Every session, the adaptive plan proved to be the better choice.
“These patients often face a difficult situation,” Dr. Lubas explained. “With adaptive therapy, we’ve shown it’s possible to move beyond short-term palliative intent and aim for long-term control of disease.”
Study Highlights at a Glance
- Radiation to the small intestine was reduced by 21% with the adaptive plan, while tumor doses rose by 7.7%.
- Patients treated with the adaptive regimen experienced no serious complications and no emergency surgeries.
- Quality of life was preserved; patients maintained normal bowel and bladder function.
- Each treatment session was re-optimized in real time.
At the center of this progress is the Ethos cone-beam CT adaptive system, which uses imaging and artificial intelligence software to re-optimize each plan while the patient is already receiving treatment. Together, these innovations make it possible to closely track tumors during treatment.
Traditional radiation therapy relies on a single plan designed before treatment begins. That plan never changes, even as a patient’s anatomy shifts during weeks of care. Adaptive therapy, however, creates a new plan for every radiation session.
“Adaptive radiation therapy takes us one step further,” said Eric M. Horwitz, MD, FABS, FASTRO, Chair of the Department of Radiation Oncology at Fox Chase and the Lewis Katz School of Medicine at Temple University. “We can now adjust not just the position of the patient, but the actual treatment plan itself in real time, giving a large dose of radiation to the cancer while protecting healthy cells.”
Disclosure: For full disclosures of the study authors, visit amportal.astro.org.
