Higher doses of radiotherapy cut treatment time by up to 75 per cent in localised prostate cancer patients, while maintaining high cure rates

People with low to medium-risk, localised prostate cancer can be treated as effectively using fewer and higher doses of radiation therapy delivered over five treatment sessions as they can with lower doses delivered over several weeks, according to researchers from The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, London.

Findings from the PACE B (Prostate Advances in Comparative Evidence) study will be presented on Monday 2 October at The American Society for Radiation Oncology (ASTRO) Annual Meeting.

The phase III randomised trial found that stereotactic body radiotherapy (SBRT) performed as well as standard radiotherapy treatment for people whose prostate cancer was considered low to medium risk and had not spread beyond the prostate. Both radiotherapy schedules kept cancer under control in most patients. Five years after entering the study, cancer remained under control, with no recurrence or worsening, in 96 per cent of patients who had SBRT compared to 95 per cent of patients who had conventional radiation.

Sub-millimetre precision

SBRT allows clinicians to target tumours to sub-millimetre precision. This approach uses advanced imaging and treatment planning techniques to deliver radiation with pinpoint accuracy, minimizing damage to surrounding healthy tissue. It delivers five high doses of radiation to patients over one to two weeks, compared to standard radiotherapy (Intensity-modulated radiation therapy, or IMRT), which delivers more moderate doses over a longer period of time - usually around 20 sessions for patients in the UK, which can take up to one month.

Drawing from 38 centres across the UK, Ireland and Canada, PACE B researchers enrolled 874 people with low to medium risk prostate cancer who preferred radiation treatment or were unsuitable for surgery.

Participants were randomly assigned to receive either SBRT, consisting of five doses over one to two weeks, or standard radiation consisting of 20 doses over four weeks or 39 doses over 7.5 weeks. None of the patients received hormonal therapy.

Side effects were low in both groups. At five years post-treatment, 5.5 per cent of patients who received SBRT experienced grade 2 or higher side effects affecting the genital or urinary organs, compared to 3.2 per cent in the conventional group. Only one person in each group experienced grade 2 or higher gastrointestinal side effects. Grade 2 side effects can be bothersome, and may affect daily activity, but they require little to no medical treatment.

'I've been able to live my life to the full'

Alistair Kennedy-Rose, 64, from the West Midlands was diagnosed with prostate cancer in 2014 at his local hospital following a blood test which revealed his prostate-specific antigen (PSA) levels were raised. Alistair was referred to The Royal Marsden and, after being recruited to the PACE-B trial, was treated with SBRT via CyberKnife.

He said: “When I was diagnosed I had no symptoms at all, so it came as quite a shock. There can be a lot of anxiety following a cancer diagnosis, but just ten days after I was referred to the Royal Marsden, I started SBRT. I still find it unbelievable that five days later I finished my treatment, for something as serious as a cancer diagnosis it was incredibly easy. I haven’t had any side effects and I’ve been able to live my life to the full. I can’t thank The Royal Marsden enough for what they have done for me.”

Chief Investigator Professor Nicholas van As, Medical Director and Consultant Clinical Oncologist at The Royal Marsden NHS Foundation Trust, and Professor in Precision Prostate Radiotherapy at The Institute of Cancer Research, London, said:  

“At The Royal Marsden and the ICR, we are focused on developing smarter, better and kinder treatments for patients across the UK and internationally. Standard radiation treatment is already highly effective and is very well tolerated in people with localised prostate cancer but for a healthcare system and for patients, to have this treatment delivered just as effectively in five days as opposed to four weeks has hugely significant.

“To be able to sit with a patient and say, ‘We can treat you with a low toxicity treatment in five days, and your chance of keeping the cancer at bay for five years is 96%,’ is a very positive conversation to have. We expect our trial to be practice changing and people with intermediate risk prostate cancer should be given the option of SBRT as an alternative to conventional radiation or prostate surgery.”

Deliver treatment in a fraction of the standard time

Professor Emma Hall, Co-Director of the Clinical Trials and Statistics Unit at The Institute of Cancer Research, London, which is managing the PACE-B trial said:

"It's fantastic that advances in radiotherapy mean we can now give patients treatment in a fraction of the standard time. This is a game-changer for patients – meaning they receive a highly-effective cancer treatment while spending less time in hospital and travelling to appointments."

"It's another example of how the rapidly advancing field of radiotherapy can improve patients' lives."

The PACE-B trial was funded by Accuray, sponsored by The Royal Marsden, coordinated by the Cancer Research UK-funded Clinical Trials and Statistics Unit at The Institute of Cancer Research (ICR-CTSU) and endorsed by Cancer Research UK. ICR-CTSU receives core programme support from Cancer Research UK and is accredited by the UKCRC.

The ICR has an extenstive programme of research that aims find new ways to defeat prostate cancer. Find out more about exciting research areas that have the potential to revolutionise prostate cancer treatment in years to come.

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