Plenary Presentation at The ASTRO Meeting by TGH Cancer Institute Member Dr. Rodney Ellis Demonstrated That Short-course Radiation Improves Quality of Life for Men with Prostate Cancer Without Compromising Outcomes

Phase III trial presented at ASTRO in San Francisco finds five-treatment regimen poised to become new standard of care.

 

SAN FRANCISCO, September 29, 2025 — Men with intermediate-risk prostate cancer can receive a complete course of radiation in just five treatments — rather than the typical 20 to 28 — while maintaining excellent cancer control and improving quality of life, according to results of an international phase III trial conducted by Dr. Rodney J. Ellis.

The principal investigator of the trial, Ellis is a radiation oncologist and physician-scientist at the Tampa General Cancer Institute, Tampa General Hospital and serves as director of Clinical Research, Department of Radiation Oncology; and professor of Radiation Oncology, USF Health Morsani College of Medicine.

He presented the study results today (Monday, Sept. 29, 2025) in a plenary session at the American Society for Radiation Oncology (ASTRO) Annual Meeting.

The NRG Oncology GU-005 trial is among the first large, international Phase III randomized trials directly comparing stereotactic body radiotherapy (SBRT) with a longer course of moderately hypofractionated IMRT for men with localized, intermediate-risk prostate cancer, with co-primary endpoints of disease-free survival and patient-reported outcomes.

A total of 698 patients in six countries were randomly selected to receive either SBRT, delivered in five highly targeted treatments over two weeks, or IMRT, delivered in the standard 20 to 28 sessions over four to six weeks.

Two years after treatment, men treated with SBRT reported less decline in bowel function as part of the primary endpoint as well as secondary gains in sexual function and fewer problems with urinary control. Specifically:

• Bowel/rectal toxicity: Fewer SBRT patients reported clinically meaningful declines in bowel quality of life at two years (35% vs. 44% p=0.034)
• Sexual function: SBRT patients reported less decline in function at one year (34.3 % vs. 43.9%, p=0.026).
• Urinary incontinence: SBRT patients had significantly better scores at two years (25.9% vs. 34.7%, p=0.023).

Three years after treatment, both groups maintained high rates of disease-free survival (88.6% with SBRT vs. 92.1% with MH-IMRT). Overall survival was similarly high (91% vs. 94%).

“We demonstrated that patients treated with SBRT had fewer problems with urinary incontinence, better preservation of sexual function and significantly less rectal toxicity compared to those receiving longer-course radiation,” Ellis said. “Equally important, the cancer outcomes were nearly identical between SBRT and IMRT in the previously published PACE-B trial at five years. These combined findings will likely change the standard of care for prostate cancer.”

“This study reflects exactly the kind of research portfolio we continue to build at Tampa General in partnership with the USF Health Morsani College of Medicine: rigorous, care-defining clinical trials that translate into tangible benefits for patients,” said Dr. Eduardo M. Sotomayor, vice president and executive director, TGH Cancer Institute. “That combination of scientific precision and patient impact is at the heart of our Cancer Institute’s strategy to advance the latest research and improve care and treatment for individuals with cancer.”

Prostate cancer is the most common solid tumor in men and intermediate-risk prostate cancer accounts for a substantial proportion of new prostate cancer diagnoses in the United States. Each year, tens of thousands of men could be eligible for the five-treatment course, which reduces treatment time by more than 80% compared to traditional regimens.

“For patients, this means less time away from work and family, fewer side effects and a treatment that is just as effective as what we’ve done for decades,” Ellis said. “Knowing that we can both control the cancer and better preserve overall bowel function with additional improvements seen for both urinary and sexual function makes this a clear win for patients.”

The trial provides insight into the biological trade-offs of treatment. While disease-free survival rates were similar, SBRT patients had a slightly higher rate of biochemical recurrence at three years (8% vs. 4%). Ellis emphasized that longer follow-up is needed to determine whether this difference reflects transient PSA “bounces” commonly seen after SBRT, rather than true cancer recurrence.

Pace-B gave a slightly higher total prostate dose and at 5 years showed SBRT was non-inferior to 5 to 8 weeks of daily IMRT, but with slightly higher bowel toxicity. GU-005 shows that careful planning and daily delivery can overcome the risk for toxicity and may benefit from focal targeted dose escalation to the regions of the prostate shown theoretically to harbor higher burden of disease. Current studies and routine clinical practices already are offering patients this option.

How it works

SBRT uses advanced imaging, fiducial markers and daily image guidance to deliver high doses of radiation directly to the prostate and, when possible, the portion of the prostate with the cancerous lesion. With such millimeter precision, this treatment reduces exposure of nearby organs such as the rectum and bladder. The precise radiation targeting allows SBRT to complete treatment in just five sessions, compared with several weeks of daily therapy with IMRT.

“The precision of modern SBRT is what makes this possible,” Ellis explained. “By using daily imaging and careful dose constraints, we can safely escalate the dose to the tumor while protecting bowel and bladder function. Fewer doses mean fewer trips to the hospital and is one reason patients do better — not just in terms of convenience, but also quality of life.”

Context and Next Steps

Until now, evidence supporting SBRT came largely from smaller, single-institution studies and the recent international PACE-B trial, which established non-inferiority but reported somewhat higher toxicity. By contrast, GU-005 showed lower rates of bowel and urinary side effects, likely due to stricter protocol requirements such as mandatory MRI fusion and daily image guidance.

“These results will accelerate the shift toward five-treatment SBRT for many men with localized, intermediate-risk prostate cancer,” said Dr. Abraham Schwarzberg, executive vice president; chief of Oncology; president, Tampa General Provider Network, Tampa General Hospital and co-vice president, Clinical & Translational Research, TGH | USF Health Office of Clinical Research.

“The evidence is clear that we can shorten therapy, improve important aspects of quality of life and preserve outcomes — exactly the kind of change that patients value,” Schwarzberg continued. “It also underscores the importance of our academic partnerships: By aligning Tampa General’s clinical depth with USF Health Morsani College of Medicine, we are able to bring leading-edge protocols to our region and move the standard of care forward.”

“With GU-005 and PACE-B together, we now have definitive, phase III evidence that five-treatment SBRT is safe, effective — and in many cases superior to longer regimens,” Ellis said. “This will move forward recognition of SBRT as the preferred approach, and I expect it will quickly become the standard of care.”

Attribution to the American Society for Radiation Oncology (ASTRO) Annual Meeting is requested in all coverage.

 

Study/Presentation Details

Abstract LBA 01: NRG-GU005: Phase III trial of SBRT vs. hypofractionated IMRT for intermediate-risk prostate cancer

Plenary Session: Monday, September 29, 2025, 2:06-2:16 p.m. Pacific Time, Walter E. Washington Convention Center, San Francisco

ClinicalTrials.gov Identifier: NCT03367702