A national prostate cancer screening programme in the UK could prevent one in six deaths from the disease, new research claims.
Scientists at University College London (UCL) are proposing ‘more targeted’ check-ups for those at higher risk of the disease based on their age and genetic profile.
Results of their modelling study suggest a programme that first involves taking samples of the blood or saliva in the search for genetic ‘biomarkers’ could prevent up to 16 per cent of prostate cancer deaths.
Unlike for breast and cervical cancer, in the UK, there is no national screening programme for prostate cancer, because until now, it has not been proved that the benefits would outweigh the risks.
Prostate cancer is the most common form of cancer in men with around 130 new cases diagnosed in the UK every day and more than 10,000 men a year dying as a result of the disease.
Researchers at University College London (UCL) are proposing ‘more targeted’ check-ups for those at higher risk of the disease based on their age and genetic profile. Pictured, prostate cancer cells (stock image)
WHAT IS A PSA TEST?
There is no universal screening for prostate cancer, but many men opt for a prostate-specific antigen (PSA) blood test.
PSA is a protein produced by the prostate, and concentrations in the blood often increase if someone has prostate cancer.
But there are other reasons why PSA levels may be raised, such as a benign growth or an infection or inflammation. And in some people with cancer, levels are not raised at all.
If high PSA levels are detected, men can be referred for a biopsy, during which up to 20 samples of tissue are taken from the prostate to be examined.
But as biopsies sample only about one per cent of the gland, there is a 30 per cent chance that the cancer could be missed. Biopsies are also carried out with a needle, carrying a small risk of infection afterwards.
‘Prostate cancer is a leading cause of death from cancer amongst men, but there is no screening programme because the harms of screening are considered to outweigh the benefits,’ said study author Dr Tom Callender at UCL.
‘However those at higher genetic risk are more likely to benefit from screening and less likely to be harmed.’
Currently, men suspected of having prostate cancer can opt for a prostate specific antigen (PSA) test, which requires a blood sample.
The PSA test was previously the only test men would have to detect the presence of prostate cancer.
But PSA ‘is not perfect’, as the NHS puts it, and does not accurately distinguish between dangerous cancers and harmless ones.
This can lead to problems of under-diagnosis, meaning aggressive life-threatening cancers are missed, and over-diagnosis, leading to both unnecessary operations and missed cancers that are harmful.
At present, some 12,000 men die each year from prostate cancer – compared to around 11,000 for breast cancer – and over the course of the last decade the number of deaths has overtaken that of breast cancer.
While breast cancer screening is routinely offered to women from 50 years, there is no equivalent screening programme for prostate cancer.
As of 2019, National Institute of Clinical Excellence (NICE) guidelines advise all men with a positive PSA result have an MRI scan (which uses strong magnetic fields and radio waves to produce detailed images of the inside of the body) before a biopsy.
A biopsy, which is an invasive procedure, uses thin needles to take small samples of tissue from the prostate.
This extra step of having an MRI scan has been shown to better distinguish and increase detection of aggressive cancers whilst reducing over-diagnosis and unnecessary treatment of insignificant cancers.
Prostate cancer is the most common form of cancer in men with around 130 new cases diagnosed in the UK every day and more than 10,000 men a year dying as a result of the disease. However, unlike breast and cervical cancer there is currently no national screening programme for this disease in the UK (stock image)
POLYGENIC RISK SCORES
Many people have an illness, or several illnesses, that are affected by changes in either one or many of their genes, frequently coupled with environmental factors.
Researchers are studying these changes to understand the role that genetics plays in diseases across different populations.
A ‘polygenic risk score’ is one way by which people can learn about their risk of developing a disease, based on the total number of changes related to the disease.
Source: National Human Genome Research Institute
Building on this, researchers say recently discovered genetic markers that predict prostate cancer risk – known as a polygenic risk score – could also complement a PSA test and MRI scan.
This polygenic test, which is not yet widely available, uses a sample of blood or saliva from the mouth to assess the numerous genetic variants.
It can identify individuals with high-risk prostate cancer genes (biomarkers) and help predict when an individual is likely to start to benefit from screening.
For their study, researchers created a hypothetical cohort of 4.5 million men, representing the number of men aged 55 to 69 in England.
They simulated the health outcomes of introducing two potential screening programmes into this population – age-based and risk-tailored.
An age-based screening programme would see all men aged between 55 and 69 receive a PSA test every four years, and if the test was positive this would be followed by MRI and, if required, a biopsy.
Meanwhile, the risk-tailored pathway would see men screened if their risk – determined by both their age and polygenic risk score – reached a certain threshold.
The scenario generating the most benefits, the researchers found, would be to screen men with a 3.5 per cent risk of getting prostate cancer over the next 10 years – that is, roughly half of all men aged 55 to 69 – as part of the risk-tailored pathway.
Such a programme could prevent up to 16 per cent of prostate cancer deaths – about one in six – and reduce overdiagnosis by 27 per cent.
POTENTIAL NATIONAL SCREENING PROGRAMME
1. Polygenic test
Those men that are over a 3.5 per cent 10-year risk, as indicated by the results of the polygenic test, start screening with…
2. PSA test
Once every four years
If PSA blood test comes back positive, they have a…
If MRI is positive…
4. A biopsy to finally diagnose those with cancer
Essentially, prostate cancer screening is the PSA blood test with MRI and a biopsy used for diagnosis.
But the eligibility for screening is determined after a polygenic test.
Study author Dr Thomas Callender, also at UCL, explained to MailOnline what this could mean for a national screening programme.
‘All men would have their polygenic risk assessed – this could be via a cheek swab or blood test, at any age but most likely 50, when the screening programme might start,’ he said.
‘Depending on their polygenic profile and their age – as age is also a risk for prostate cancer – a man would then be invited for screening when their 10-year risk of prostate cancer hit a threshold – i.e they had a 3.5 per cent chance of getting prostate cancer in the next 10 years.’
Screening men at this threshold (3.5 per cent) would also be more cost-effective than screening all men aged 55 to 69.
Following the age-based screening pathway – where all men aged between 55 and 69 would be screened once every four years – would result in the most prostate cancer deaths prevented (20 per cent).
However, risk-based screening would prevent nearly as many deaths (16 per cent) whilst reducing over-diagnosed harmless cancers by up to 70 per cent (depending on the risk threshold used) and the number of biopsies needed by about a third.
‘Screening for prostate cancer – which could save between 16 per cent and 20 per cent of prostate cancer deaths – might be possible with targeted screening using genetic risk and MRI as part of the diagnostic pathway,’ said study co-author, Professor Mark Emberton at UCL.
‘This paves the way for further clinical trials to study the real-world implementation of such a screening programme.’
Simon Grieveson, head of research funding at Prostate Cancer UK, welcomed the findings.
He said: ‘We desperately need an effective screening programme for prostate cancer to help stop so many men dying from this disease.
‘This really interesting study models the potential benefits and harms of possible screening approaches, in particular exploring the use of blood tests in combination with MRI scans to target testing towards men who are genetically predisposed to prostate cancer.
‘We now need to test this approach in a real world setting in a large scale clinical trial before we can say with any certainty whether or not it could form the basis of a national screening programme.
‘Finding a suitable and effective screening programme for men is a top priority for Prostate Cancer UK and we’re continuing to invest in research to make this a reality as soon as possible.’
The study has been published in JAMA Network Open.
WHAT IS PROSTATE CANCER?
How many people does it kill?
Prostate cancer became a bigger killer than breast cancer for the first time, official statistics revealed last year.
More than 11,800 men a year – or one every 45 minutes – are now killed by the disease in Britain, compared with about 11,400 women dying of breast cancer.
It means prostate cancer is behind only lung and bowel in terms of how many people it kills in Britain. In the US, the disease kills 26,000 each year.
Despite this, it receives less than half the research funding of breast cancer – while treatments for the disease are trailing at least a decade behind.
How quickly does it develop?
Prostate cancer usually develops slowly, so there may be no signs someone has it for many years, according to the NHS.
If the cancer is at an early stage and not causing symptoms, a policy of ‘watchful waiting’ or ‘active surveillance’ may be adopted.
Some patients can be cured if the disease is treated in the early stages.
But if it diagnosed at a later stage, when it has spread, then it becomes terminal and treatment revolves around relieving symptoms.
Thousands of men are put off seeking a diagnosis because of the known side effects from treatment, including erectile dysfunction.
Tests and treatment
Tests for prostate cancer are haphazard, with accurate tools only just beginning to emerge.
There is no national prostate screening programme as for years the tests have been too inaccurate.
Doctors struggle to distinguish between aggressive and less serious tumours, making it hard to decide on treatment.
Men over 50 are eligible for a ‘PSA’ blood test which gives doctors a rough idea of whether a patient is at risk.
But it is unreliable. Patients who get a positive result are usually given a biopsy which is also not foolproof.
Scientists are unsure as to what causes prostate cancer, but age, obesity and a lack of exercise are known risks.
Anyone with any concerns can speak to Prostate Cancer UK’s specialist nurses on 0800 074 8383 or visit prostatecanceruk.org