A major international study provides compelling evidence that molecular profiling can safely reduce the need for radiotherapy in women with early-stage endometrial cancer while identifying those who would benefit from more intensive treatment. The PORTEC-4a trial results, presented at ESTRO 2025, mark a significant step forward in personalized cancer treatment for the most common gynecological cancer.
The randomized PORTEC-4a trial enrolled 592 women across eight European countries with high-intermediate risk endometrial cancer. Molecular testing classified tumors into risk categories, allowing treatment to be adapted accordingly. The study demonstrated that 46% of patients in the molecular profiling arm safely avoided radiotherapy without compromising cancer control.
Precision Medicine Transforms Treatment Decisions
"By using molecular profiling, we can tailor treatment to each patient's individual risk," said Anne Sophie V.M. van den Heerik, MD, 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 personalized and less invasive cancer treatment."
The molecular profiling approach examines the genetic and biological features of tumors to guide clinical decisions, helping identify which patients are most likely to benefit from radiotherapy and which can safely avoid it. This method addresses the challenge of overtreatment in high-intermediate risk patients, where the amount of treatment necessary often differs between individuals.
Improved Outcomes for High-Risk Patients
Patients with an unfavorable molecular profile received a more intensive radiation approach, with pelvic radiotherapy instead of vaginal brachytherapy. The results showed dramatically better locoregional control, with a recurrence rate of 8.4% compared to 30.5% in those who received standard treatment without molecular profiling.
The trial included patients aged at least 18 years who had received their diagnosis following total abdominal or laparoscopic hysterectomy and bilateral salpingo-oophorectomy. High-intermediate risk factors included International Federation of Gynecology and Obstetrics stage 1A grade 3 invasion, stage 1B grade 1 or 2 with lymph-vascular space invasion in patients aged at least 60 years, stage 1B grade 3, and stage 2 microscopic or grade 1 invasion.
Clinical Impact and Future Implications
"The PORTEC-4a trial is a game-changer," said Professor Matthias Guckenberger, President of ESTRO and Chairman of the Department of Radiation Oncology at the University Hospital Zürich. "This research proves that precision medicine is transforming cancer treatment. By identifying patients who have the largest benefit from radiotherapy, we can maximize its impact, improve quality of life for thousands of women worldwide, and maintain excellent cancer control."
Patients were randomized 2:1 to receive either molecular risk-profile-based treatment or standard care. Vaginal recurrence was the primary outcome, with secondary outcomes including recurrence-free and overall survival, pelvic and distant recurrence, 5-year vaginal control, adverse events, and health care costs.
The findings are particularly significant given that endometrial cancer incidence is rising globally. The PORTEC trials have played a key role in refining treatment strategies, ensuring that radiotherapy is used effectively while minimizing side effects. These results pave the way for a more personalized approach to treating endometrial cancer, ensuring that each patient receives the most effective and least invasive treatment based on their tumor biology and risk profile.