Phase III trial shows molecular profiling can safely reduce radiation for women with endometrial cancer and optimise treatment for patients at a higher risk patients

(Press-News.org) Vienna, Austria – Endometrial cancer is the most common gynecological cancer in high-developed countries, most often affecting women after menopause. The majority of women are diagnosed at an early stage, when treatment outcomes are generally favorable.* For women with high-intermediate risk disease, adjuvant radiotherapy — particularly vaginal brachytherapy (a form of internal radiotherapy delivered directly to the vaginal area) — is commonly used after surgery to reduce the risk of recurrence. However, patients don’t need it equally, and some may receive more treatment than necessary, exposing them to potential side effects without added benefit. Furthermore a small subgroup of patients seem to be undertreatment when only treated with vaginal brachytherapy.

 

This has sparked growing interest in tailoring treatment using molecular profiling, a method that examines the genetic and biological features of a tumour to guide clinical decisions. It helps identify which patients are most likely to benefit from radiotherapy, and which can safely avoid it.

 

A major international study, PORTEC-4a, provides the strongest evidence yet that molecular profiling can safely reduce radiotherapy for women with early stage endometrial cancer while identifying those who would benefit from more intensive treatment. The results, presented today at ESTRO 2025, the annual congress of the European Society for Radiotherapy and Oncology (ESTRO), mark a significant step forward in personalised cancer treatment.

 

Why This Matters

 

Endometrial cancer is the most common gynaecological cancer, and its incidence is rising globally. The PORTEC trials have played a key role in refining treatment strategies, ensuring that radiotherapy is used effectively while minimising side effects. The findings from PORTEC-4a highlight:

✅ More precise treatment – Molecular profiling helps tailor radiotherapy decisions based on individual tumour characteristics.
✅ Reduced overtreatment – Nearly half of patients in the trial safely avoided radiation without compromising cancer control.
✅ Improved outcomes for patients at a higher risk of recurrence – The study suggests that patients with unfavourable tumour profiles benefit from a more intensive radiation approach.


Key Findings from PORTEC-4a

The randomised PORTEC-4a trial enrolled 592 women across eight European countries with (high-)intermediate risk endometrial cancer. Molecular testing classified tumours into risk categories, allowing treatment to be adapted accordingly:

✅ 46% of patients in the molecular-profile  arm safely avoided radiotherapy.
✅ Patients with an unfavourable molecular profile received a more intensive radiation approach, pelvic radiotherapy instead of vaginal brachytherapy and the results suggest better locoregional control, with a recurrence rate of 8.4% compared to 30.5% in those who received standard treatment without molecular profiling.

"By using molecular profiling, we can tailor treatment to each patient’s individual risk," said Dr Anne Sophie V.M. van den Heerik, lead investigator of the PORTEC-4a trial, from The Leiden University Medical Centre, The Netherlands.

"This approach allows us to safely reduce radiotherapy for many women while ensuring that those who need it receive the most effective therapy. It’s a major step towards more personalised and less invasive cancer treatment."

The findings demonstrate that nearly half of patients can be safely spared radiotherapy while maintaining excellent survival rates. Additionally, exploratory analyses suggest that patients with an unfavourable molecular profile may benefit from a more intensive radiation approach to reduce recurrence risks.
 

A Game-Changer for Precision Oncology

"The PORTEC-4a trial is a game-changer," said Prof Matthias Guckenberger, President of ESTRO, Chairman of the Department of Radiation Oncology and full Professor at the University Hospital Zurich and University of Zurich.

"This research proves that precision medicine is transforming cancer treatment. By identifying patients who have the largest benefit from radiotherapy, we can maximise its impact, improve quality of life for thousands of women worldwide, and maintain excellent cancer control."

These findings pave the way for a more personalised approach to treating endometrial cancer, ensuring that each patient receives the most effective and least invasive treatment based on their tumour biology and risk profile.

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*Source: Sources: Cancer Research UK; American Cancer Society; ESGO/ESTRO/ESP Guidelines for Endometrial Carcinoma (2021)

Abstract n° E25-5008: “PORTEC-4a; an international randomised trial of molecular profile-based adjuvant treatment for women with high-intermediate risk endometrial cancer”, presented on Monday 5 May 17 hrs (CEST), Plenary Hall.

Note: When obtaining outside comment, journalists are requested to ensure that their contacts are aware of the embargo on this release.

 

About ESTRO 2025

ESTRO 2025 brings together around 7,000 participants from over 80 countries, showcasing the latest research in clinical radiation oncology, radiobiology, medical physics, technology, and brachytherapy. Leading doctors and scientists from around the world present groundbreaking findings.

ESTRO 2025 is the annual congress of the European Society for Radiotherapy and Oncology (ESTRO), an organisation dedicated to advancing cancer treatment through radiotherapy and multimodal approaches. ESTRO promotes education, science, and research and advocates for universal access to radiotherapy. With nearly 10,000 members worldwide, it supports radiation oncology professionals and the broader oncology community in their daily practice.

For further information, embargoed press materials, or to arrange interviews with the researchers, please contact the ESTRO press office.

ESTRO Press Office
Cécile Hardon-Villard
chardon@estro.org
Mobile : +33 679 43 16 01

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