Radiotherapy for prostate cancer can be safely delivered in two sessions rather than five, according to new data presented at the congress of the European Society for Radiotherapy and Oncology (ESTRO).

In the trial, patients who received two radiotherapy doses experienced no bowel side effects over two years’ follow-up and showed similar rates of urinary side effects to those who received the same dose over five sessions.

Patients treated with the shorter course reported similar quality of life two years later and experienced little to no difference in the overall rate of side effects.

“This study suggests that delivering patients’ treatment in fewer, higher doses is both effective in treating the cancer and has minimal impact on the side effects that patients might experience,” said Dr Sian Cooper, Clinical Research Fellow at The Royal Marsden NHS Foundation Trust, who presented the results at ESTRO 2026.

“For patients, a two-session treatment course is more convenient with fewer hospital visits and clear benefits for work, family life, and travel,” she added.

“For clinicians and hospitals, fewer sessions mean faster treatment pathways and improved efficiency, allowing patients to receive the right treatment more quickly.”

In the HERMES trial, 46 patients with prostate cancer were randomised to receive radiotherapy in five sessions over two weeks (n=24) or the same dose but in two sessions over eight days (n=22), with all treatment delivered using the MR Linac system which uses MRI to deliver highly precise targeting.

In the period six months to two years after treatment, around one in four patients in both groups experienced moderate urinary side effects at some point, such as increased frequency or urgency.

No patients in either group experienced severe urinary or bowel side effects, and there were no instances of bowel side effects in the two-session group.

At two years’ follow-up, patients reported minimal change in their quality of life, with minimal or no differences in the rate of side effects seen in both groups.

“Limiting treatment to two doses is more convenient for patients, who would need fewer hospital visits, making it easier for those who live far from radiotherapy centres to complete their treatment,” said ESTRO President, Professor Matthias Guckenberger, from University Hospital Zurich, Switzerland, who was not involved in the research.

“It is reassuring for patients to know that potential side effects are not affected by a more condensed treatment plan,” he noted.

“It can also reduce the associated costs for hospitals and treatment centres,” he added.