Clinical Academic Radiotherapy Group (Huddart)

Men with localised prostate cancer could benefit from a shorter course of radiotherapy, after new research data shows that just two higher-dose treatments are as safe as a standard five-session regimen, with no increase in side effects. 

The findings from the HERMES study, led by The Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust were presented at the Congress of the European Society for Radiotherapy and Oncology (ESTRO) in Stockholm. 

MRI-guided radiotherapy

Radiotherapy is one of the main curative treatments for localised prostate cancer.  Many hospitals currently treat patients for localised disease with five sessions delivered over two weeks. The HERMES study - managed by The Institute of Cancer Research (ICR) Clinical Trials and Statistics Unit (ICR-CTSU) - investigated whether the same effective overall dose could be safely delivered in two sessions, over an eight-day period, using advanced MRI-guided technology. 

The HERMES trial recruited 46 men with localised prostate cancer, 24 patients received a five-session course over two weeks, while 22 received an equivalent dose delivered in two sessions over eight days. All treatment on the trial was delivered using a state-of-the-art MR Linac system, which combines MRI imaging with radiotherapy delivery to enable highly precise targeting of the prostate, while protecting surrounding healthy tissue. 

The Royal Marsden together with the ICR, was the first in the UK to treat patients with the MR Linac in 2018.The MR Linac was funded by a £10 million grant from the Medical Research Council to the ICR and supported by The Royal Marsden Cancer Charity. 

No impact on side effects

Researchers set out to determine whether delivering the equivalent dose in just two sessions could be safe and feasible, while also assessing its impact on side effects such as urinary and bowel function. The results show that the approach is both feasible and safe, with no increase in side effects compared with a standard five-session schedule. Larger studies are now needed to confirm this finding.  

Around one in four patients in both groups experienced moderate urinary side effects, such as increased frequency or urgency, at some point between six months and two years after treatment. No severe urinary or bowel side effects were reported in either group. Bowel side effects were very low overall, with no moderate side effects in the two-session group, although some mild side effects were observed in the two-session group. After two years, patients reported minimal changes in quality of life, with no meaningful difference between the two treatment approaches. Overall, condensing treatment into two sessions had no impact on patient side effects. 

Damien Garland, 64, a delivery driver from London, was diagnosed with prostate cancer in 2023 and joined the HERMES trial at The Royal Marsden.  

“When I was told I had cancer, I was terrified. I lost my dad to cancer when I was a child, so I thought I was going to die. 

"I was told I wouldn’t need surgery and would instead have radiotherapy and hormone treatment. I’ve had a few side effects from the hormone therapy, but I went through the radiotherapy without pain or side effects. I can honestly say I haven’t had a bad day; my life didn’t stop in the way I thought it would. 

"My cancer has remained in remission, I’m still working, and I enjoy staying active and going for walks with my partner. I consider myself extremely lucky."

'Allowing patients to receive the right treatment more quickly'

Dr Sian Cooper, Clinical Research Fellow at The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, London, said: 

“Radiotherapy is one of the main treatments used to cure localised prostate cancer and until recently it was thought that delivering multiple treatments over a longer period was most effective. 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. 

“For patients, a two-session treatment course is more convenient with fewer hospital visits and clear benefits for work, family life, and travel. For clinicians and hospitals, fewer sessions mean faster treatment pathways and improved efficiency, allowing patients to receive the right treatment more quickly.” 

'Smarter, kinder treatments'

Professor Emma Hall, Director of the Clinical Trials and Statistics Unit at The Institute of Cancer Research, London, which managed the trial, said:

“Being able to treat cancer with fewer, higher doses of radiotherapy means patients can spend less time in hospital and travelling to appointments. It’s an example of how the ICR, in partnership with the Royal Marsden, is developing smarter, kinder treatments, and it builds on decades of research we have led to transform radiotherapy into the highly targeted, personalised treatment that it is today.

“Earlier this year, the ICR was awarded the Queen Elizabeth Prize for Education to recognise the worldwide impact of our research advances in radiotherapy. This recognition reflects our commitment to innovation, collaboration, and ensuring that scientific discovery delivers real- benefit for patients around the world."