Targeted radiotherapy helps some men with advanced prostate cancer avoid chemotherapy for longer

A combination of radiotherapy and hormone therapy could give some men with advanced cancer more time before they need to move onto chemotherapy.

For men who are starting to run out of treatment options, pushing back the start of chemotherapy could mean more time with their loved ones – and more time without the side effects that often come with chemotherapy.

The findings come from a trial called TRAP (targeting hormone resistant metastases with radiotherapy), funded by us and led by a team at the Institute of Cancer Research.

Targeting tumours that have become resistant

The TRAP trial recruited men whose cancer had just begun to grow again, despite being on the hormone therapies abiraterone or enzalutamide. Normally, this would be taken as a sign that the cancer has become resistant to the treatment, and that the man should start chemotherapy.

However, the team behind TRAP believes that for some men, only some tumours become resistant and, if we treat those cells with radiotherapy, the rest of the cancer will still respond to hormone therapy.

The team tested this theory using a newer kind of radiotherapy that delivers very precise, very intense doses of radiation to cancer cells.

Called stereotactic body radiotherapy (SBRT), this type of radiotherapy uses multiple focused beams of radiation that cross over at the point where the tumour is. This means it can deliver a bigger dose of radiation to the cancer cells, and a much lower dose to the surrounding areas – reducing the risk of side effects.

The men were given five or six treatments of SBRT, and continued to take enzalutamide or abiraterone as normal.

On average, men on the trial got an extra six months before their prostate cancer began to progress again – and more than 40 per cent of the men still hadn’t seen their prostate cancer progress after 12 months.

The combination treatment is now being tested further in a follow-up trial called STAR-TRAP, also funded by us, that could change the way we treat advanced prostate cancer for men across the UK.

Great promise for men with advanced prostate cancer

Simon Grieveson, our Assistant Director of Research, said: “Radiotherapy can be an extremely effective treatment for men with early stage, localised prostate cancer, but we funded the TRAP trial to explore the use of radiotherapy in men whose cancer had spread to other parts of the body.

“These really exciting results suggest that targeting radiotherapy to the sites where the cancer has spread can delay further progression of the disease and the need for subsequent treatments, such as chemotherapy.

“While these results offer great promise for men with advanced prostate cancer who are starting to run out of treatment options, this now needs to be tested in a larger randomised study, and we are funding the STAR-TRAP trial to do just that.”

Dr Alison Tree, consultant clinical oncologist at The Royal Marsden NHS Foundation Trust, Honorary Reader at The Institute of Cancer Research and Chief Investigator of the TRAP trial, said: “These initial results could be fantastic news for advanced prostate cancer patients.

“Currently, treatment options for men with advanced prostate cancer are limited, however I hope that after we have conducted larger studies to confirm our findings, we will see this change and we will be able to treat these patients very differently, using radiotherapy as standard to target drug-resistant parts of the cancer.

“Radiotherapy is well tolerated and significant side effects are rare, so we hope this treatment will in the future delay the need for chemotherapy, protecting quality of life for longer.”