Prostate Cancer Trial: Two Radiotherapy Sessions as Effective as Five

A new study presented at the ESTRO 2026 conference has found that just two high-dose radiotherapy sessions may be as safe and effective as the standard five for men with localized prostate cancer.

The HERMES study randomly assigned 46 patients into two groups: 24 received the standard five doses over two weeks, while 22 received just two doses over eight days. All patients were treated with MRI-guided radiotherapy for maximum precision.

"The study showed that two-session treatment is feasible and safe, with side effects comparable to the five-session standard."
— Dr. Sian Cooper, The Royal Marsden and ICR

Side Effects: Mild and Similar Between Groups

• Moderate urinary side effects (increased frequency or urgency) occurred in about 25% of patients in both groups between 6 months and 2 years after treatment.
• No severe urinary or bowel side effects were observed in either group.
• Notably, no patients in the two-session group reported any bowel side effects at all.
• Quality of life changes were minimal and comparable across both arms.

A Potential New Standard of Care?

Radiotherapy is a standard curative treatment for prostate cancer, with five sessions currently being the norm in many countries. While MRI-guided machines are still limited, they are becoming more widely available.

Reducing the number of sessions offers significant benefits for both patients and healthcare systems—including greater convenience, lower costs, and reduced hospital visits.

"The results suggest that two high-dose sessions can be effective and convenient, potentially shaping a new standard of care."
— Prof. Matthias Guckenberger, ESTRO President (not involved in the study)