Results of a new trial of a protocol for treating localized prostate cancer was due to be presented to The American Society for Radiation Oncology (ASTRO) Annual Meeting on Monday. These show (that for suitable patients) the number of doses of radiation required can safely be reduced from the standard regimen of 20 lower doses of radiation to 5 using higher doses. In the USA, treatments can involve as many as 40 lower doses. (Emphasis mine)
The phase III randomised trial found that stereotactic body radiotherapy (SBRT) performed as well as standard radiotherapy treatment for people whose prostate cancer had not spread, demonstrating a 96% chance of no disease progression within five years, compared to 95% for conventional radiation.
SBRT, which can be delivered on a CyberKnife or standard radiotherapy machines, 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, which delivers more moderate doses over a much 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, researchers enrolled 874 people who preferred radiation treatment or were unsuitable for surgery. Patients 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.
The significance of this finding is not lost on one of the leads in the trial, Professor Nicholas van As with The Institute of Cancer Research, London, who is also a senior doctor at the Royal Marsden Hospital NHS Trust.
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.
The speed of the treatment has impressed one of the patients in the trial who is cancer-free after 9 years,
Alistair Kennedy-Rose, 64, from the West Midlands, was diagnosed with prostate cancer in 2014 after a blood test which showed his prostate-specific antigen (PSA) levels were raised.
"I had no symptoms at all so it was a shock to find I had cancer," he told the BBC.
He was treated at the Royal Marsden as part of the trial using Cyberknife, a robotic radiotherapy machine, and had all five sessions in the same week and did not receive hormone therapy.
"The treatment was pretty easy. There were no side effects and it was all over very quickly, allowing me to continue living my life to the full," he said.
"I was treated so rapidly it's hard to come to terms with the fact that I ever had cancer."
This is quite separate from the economic benefits, for the patient fewer visits and less time off work and for the healthcare provider in terms of radiotherapists’ time and costs of the extra sessions. Britain’s National Institute for Health and Care Excellence (NICE) guidelines are the recommendations for the treatment of different disease within the National Health Service. The last guidelines for prostate cancer were issued in 2019*. This new evidence is likely to mean that they will be revised in light of this new research and thus the protocol should spread very quickly throughout the UK.
*You should note that the recommendations are based on quality of life as well as efficacy of treatment. In the case of slowly progressing prostate cancer, it is often the case that the patient will die of other diseases or just old age before any cancer proves fatal. Treatment on the other hand can be invasive and have distressing side-effects. For this reason patients are often advised to not have radical treatment like surgery or radiotherapy but to be regularly monitored or adopt “watchful waiting”. This is much more common in the UK than in the US. One reason could be the amounts that US hospitals are able to charge for the different approaches. This could also be responsible for the almost double the number of sessions of conventional radiotherapy as could the US fear of litigation.