Prostate cancer can be treated with fewer, higher doses of radiation, trial finds

People with intermediate risk, localised prostate cancer can be treated as effectively using fewer and higher doses of radiation therapy, a study has found.

Results from the Prostate Advances in Comparative Evidence (PACE-B) trial published in the New England Journal of Medicine found that higher doses of radiotherapy delivered over five treatment sessions can treat prostate cancer just as effectively as lower doses delivered over several weeks.

Higher doses of radiotherapy cut treatment times by 75 per cent in localised prostate cancer patients, while maintaining high cure rates, it said.

Comparative study

Research from The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, London built on previously reported data, and showed that stereotactic body radiotherapy (SBRT) performed as well as standard radiotherapy treatment for people whose prostate cancer had not spread.

PACE-B investigated whether SBRT was worse than conventional radiation for treating people with intermediate risk, localised prostate cancer. 

It tested whether patients remained free of biochemical clinical failure (BCF), defined as an increase in prostate specific antigen (PSA) levels, distant metastases or other evidence the cancer was returning, or death from prostate cancer. 

Those treated with SBRT had a BCF-event free rate of 95.8 per cent compared to 94.6 per cent for those treated with conventional radiotherapy five years following treatment.

SBRT vs IMRT

SBRT, which can be delivered on a CyberKnife or standard radiotherapy machines, allows clinicians to target tumours with higher precision than standard radiotherapy. 

This approach uses advanced imaging and treatment planning techniques to minimise damage to surrounding healthy tissue. 

It delivers five high doses of radiation to patients over one to two weeks, compared to standard Intensity-Modulated Radiation Therapy, 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 a month.

Side effects were relatively low in both groups. 

At five years post-treatment, 26.9 per cent of patients who received SBRT experienced grade two or higher side effects affecting the genital or urinary organs, such as urinary frequency and urgency, compared to 18.3 per cent in the conventional group. 

The cumulative incidence of late grade two or higher gastrointestinal effects was 10.7 per cent in patients who received SBRT, and 10.2 per cent in the conventional group. At five years, 29.1 per cent of men treated with conventional radiotherapy and 26.4 per cent of men receiving SBRT reported erectile dysfunction.

'Smarter, better and kinder'

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 is 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 per cent,’ 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.” 

The PACE-B trial was funded by Accuray, sponsored by The Royal Marsden, coordinated by the 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. 

PACE is an umbrella of trials supported by funding from The Royal Marsden Cancer Charity. The CyberKnife at The Royal Marsden was funded by The Royal Marsden Cancer Charity.

(Image: Professor Nicholas van As, via the Royal Marsden(