Published: 13 March 2023
Men with localised prostate cancer who are actively monitored have the same high survival rates after 15 years as men who are treated with radiotherapy or surgery, finds NIHR-funded research.
Latest findings from the ProtecT trial were presented at the European Association of Urology (EAU) Congress in Milan. The trial's 15 year clinical findings and 12 year patient reported outcomes are published in the New England Journal of Medicine (NEJM) and NEJM Evidence respectively.
Researchers at the universities of Oxford and Bristol led the trial. It is the longest running study of its kind and took place at nine UK centres. 97% of the men taking part in the trial survived 15 years after diagnosis, regardless of what treatment they received.
Active monitoring
Prostate cancer is very common in older men, but it often grows very slowly and may never cause a problem in a man’s lifetime. Men taking part in this trial had been diagnosed with prostate cancer that hadn’t spread beyond the prostate gland (localised).
Active monitoring involves regular tests to check on cancer. Men being monitored were more likely to see their prostate cancer grow or spread compared to those receiving radiotherapy or surgery. But this did not reduce their likelihood of survival.
Radiotherapy and surgery for prostate cancer can cause side effects such as incontinence and impotence. The trial found that the negative impacts of radiotherapy and surgery on urinary and sexual function persist much longer than previously thought – for up to 12 years for some men.
The trial results show treatment decisions for low and intermediate risk localised prostate cancer do not need to be rushed, researchers say.
Professor Freddie Hamdy, trial Chief Investigator, from the University of Oxford, said: “It’s clear that, unlike many other cancers, a diagnosis of prostate cancer should not be a cause for panic or rushed decision making.
“Patients and clinicians can and should take their time to weigh up the benefits and possible harms of different treatments in the knowledge that this will not adversely affect their survival.”
Long term evidence
Between 1999-2009 researchers randomised 1,643 UK men aged 50-69 years diagnosed with localised prostate cancer after a blood test. 545 underwent active monitoring, 553 radical prostatectomy (removal of the prostate) and 545 radical radiotherapy.
97% of the men survived 15 years after diagnosis. This was irrespective of their treatment. Around a quarter on active monitoring still hadn’t needed any invasive treatment for their cancer after that time.
Patients from all three groups reported similar quality of life. This included their general mental and physical health. But the negative effects of surgery or radiotherapy on urinary, bowel and sexual function persisted for up to 12 years.
The study's previous 10 year results had found those receiving active monitoring were twice as likely to see their cancer progress or spread than the other two groups. The assumption had been that this might lead to a lower survival rate for men on active monitoring long term. But these new results show this isn’t the case. Survival rates are high across all groups.
Options and priorities
Commenting further on the results, Professor Hamdy added: “This is very good news. Most men with localised prostate cancer are likely to live for a long time, whether or not they receive invasive treatment and whether or not their disease has spread, so a quick decision for treatment is not necessary and could cause harm.
“It’s also now clear that a small group of men with aggressive disease are unable to benefit from any of the current treatments, however early these are given. We need to both improve our ability to identify these cases and our ability to treat them.”
Co-investigator, Professor Jenny Donovan, from the University of Bristol, said: “Patients and doctors now have the necessary information on the long-lasting side effects of treatments to better understand the trade-offs between their benefits and harms. Survival no longer needs to be considered when deciding on treatment – as that’s the same for all three options. Now men diagnosed with localised prostate cancer can use their own values and priorities when making the difficult decisions about which treatment to choose.”
The trial has also highlighted flaws in current methods to predict which prostate cancers are likely to grow quickly and spread. Initially, all those recruited to the trial were diagnosed with localised cancer and 77% of them were deemed low risk. A reassessment using more modern methods showed that a far greater number would now be considered intermediate-risk – and in around 30% of men, the disease had spread beyond the prostate already.
This means that the participants in the study had higher grade and stage disease than was initially thought.
The trial was funded by NIHR’s Health Technology Assessment (HTA) Programme.