Detecting prostate cancer: why we need more research

Prostate cancer has recently become the most common cancer in the UK, and it accounts for 14% of all cancer deaths in males (2017 – 2019). While treatment for prostate cancer has improved over time, and survival has tripled in the last 50 years in the UK, prostate cancer remains one of the most challenging topics in public health. Detecting and treating prostate cancer has rightly been in the spotlight recently, and we wanted to unpack why it remains such a challenge and highlight our current position on the matter.

It’s a cancer that affects more than 55,000 men every year in the UK as well as trans women and non-binary people with a prostate. But current technology and tests still don’t provide us with effective ways to diagnose the disease early. The issues surrounding prostate cancer are incredibly complex and in some cases can leave more questions than answers. Science and innovation continue to try to improve how we diagnose and treat prostate cancer, but we still need to better understand how to diagnose it accurately at an early stage, who is at the greatest risk of dying from it, and the best way to treat it – all of which relies on research.

In this article we set out why we believe there are currently no easy solutions to prostate cancer early diagnosis, and what we’re doing at Cancer Research UK to change that. For more detail on each section, you can read our prostate cancer technical briefing.

What is the PSA test and why is it not an effective test?

Currently, the first investigation for men with symptoms of prostate cancer is known as the PSA test. This test measures the level of prostate specific antigen (PSA) in the blood – this is a protein all men with a prostate have. High levels of PSA in the blood can be a sign of prostate cancer. But as men get older, the level of this protein in their blood also increases naturally. PSA levels may also rise after recent exercise, ejaculation or infection. So high PSA levels do not always mean someone has prostate cancer.

Although the PSA test helps to detect some cancers, it is considered a very unreliable test. Evidence has shown that it can miss some prostate cancers (false negatives); it can indicate that people need to have further tests who don’t have prostate cancer (false positives); and it can increase the chance of overdiagnosis – which we elaborate on below. These are the risks of PSA testing, and they must be carefully considered alongside the potential benefits.

Men without symptoms of prostate cancer can request a PSA test from their GP, but the test’s limitations are still present. Many research trials (including Cancer Research UK-funded research) have tried to establish if using the PSA test for screening men without symptoms can save lives from prostate cancer – this is the main benefit of a screening test. However, these studies have limitations and often use different methods, which makes it hard to compare results between trials. Some studies show a reduction in deaths among those who were screened versus those who were not screened, whereas others show no difference between the groups.

Overall, we believe we need more research and innovation to develop a better, more accurate test for prostate cancer for both men with symptoms and men without. Some of the research we’re funding in this area includes new blood, urine and genetic tests to improve early diagnosis.

What is overdiagnosis and why is it a risk?

To add to the complexity, prostate cancer can act very differently from person to person. Some prostate cancers grow fast and spread quickly, while others grow slowly. Some of these cancers grow so slowly (or not at all) that if they went undetected, they wouldn’t ever cause any problems, and the person wouldn’t be harmed by their cancer if it was left untreated. Unfortunately, it’s not yet possible to tell accurately which early-stage prostate cancers are likely to progress and require treatment versus ones that are unlikely to progress.

When these harmless cancers are found, sometimes through a specific test or as incidental findings as a result of other medical tests, they are said to be ‘overdiagnosed’.

Overdiagnosis is concerning as it can lead to something called overtreatment. Because we can’t yet differentiate well enough between slow growing tumours and aggressive tumours, everyone is usually offered the same care – for prostate cancer this is usually surveillance or treatment. This means that in some cases, men are unnecessarily treated for a cancer that would never have harmed them – this is overtreatment. Some of these men will then suffer the side effects of a treatment that they didn’t need, such as erectile dysfunction (impotence) or the inability to control their bladder (incontinence). On top of these physical effects, a cancer diagnosis also comes with wide-ranging emotional impacts.

Why is there no screening programme for prostate cancer?

Cancer screening is for apparently healthy people and aims to find cancers early, before they cause symptoms, when they are easier to treat. In the UK, recommendations for cancer screening are made by an independent body of experts called the UK National Screening Committee (UK NSC) who make their recommendations based on a thorough assessment of the current evidence.

Every few years, the UK NSC review and assess the evidence and recommend if a new screening programme should be introduced or if any updates are needed to current screening programmes. The last time this was done for prostate cancer was in 2020, when one of the key questions was ‘does PSA screening reduce prostate cancer mortality?’ with large studies from the UK, US and Europe included in the review. After this in-depth analysis, the UK NSC concluded PSA screening should not be introduced.

We agree with the UK NSC current position, that overall there are significant limitations to the PSA test, a clear risk of harm through overdiagnosis and overtreatment, and a need for more robust research.

Can innovations in MRI scans improve prostate cancer diagnosis?

It’s important to note here that since many of these trials took place, the UK has adapted how we diagnose prostate cancer. For example, when these trials were launched, if someone’s PSA level was high, they were normally referred for a prostate biopsy (sometimes with a digital rectal exam first). But in recent years, new MRI scans have been introduced as a triage step between PSA testing and biopsy. The greater detail of these new scans when reported by a specialist doctor, can reduce the need for prostate biopsy for some men who have high PSA levels but don’t have prostate cancer – a huge step forward for reducing the harms associated with unnecessary biopsies.

However, we still need more research on whether doing these new MRIs before a biopsy can also reduce overdiagnosis and increase prostate cancer survival. One such study is due to start this year, but it will take many years for the results of this trial to become clear. A Cancer Research UK-funded study is looking at whether a cheaper and faster approach to MRIs could be used instead.

Importantly, access to these special MRIs and the specialist expertise it takes to report them varies greatly across the UK. For instance, in Wales and Northern Ireland this new best practice is not the standard approach. In other parts of the UK where they are available, it is unclear if they are being implemented in line with research evidence and whether or not they are reducing harm enough to justify PSA testing as the first step.

Is active surveillance the solution to overtreatment?

Clinical guidance does now recommend that doctors offer men with early-stage prostate cancers the choice between active surveillance and treatment, and there is some evidence that outcomes are similar for men who have radiotherapy, surgery or active surveillance for early-stage prostate cancer.

Unfortunately, many men on active surveillance live with the anxiety that their cancer will grow and spread and find themselves living with the ‘patient’ label indefinitely. It’s understandable that having cancer monitored instead of treated can cause anxiety for patients, which may lead people to instead opt for active treatment. This means we need more research into the side effects of active surveillance, and it is not yet a fix for the harms linked to overdiagnosis and overtreatment.

When it comes to advanced prostate cancers, we are funding research to find the best combination of treatments to give men with prostate cancers most likely to advance and spread the best chance of survival.

‘High-risk’ men

It has been highlighted that certain men are at higher risk of prostate cancer. For example, Black men are 2-3 times more likely to be diagnosed with prostate cancer than White men – this stark disparity is deeply concerning.

We delve deeper into the evidence on this in our technical briefing, but the key takeaway is that we need more high-quality research in this space that tries to understand the drivers of disparity in this group of people, and whether it is a result of environmental or biological factors such as genetics. While it’s possible genetics are playing a role, the environments we live in and the wider determinants of health, and inequalities in access to treatment, are probably also affecting a man’s risk of death from prostate cancer. Given how many questions remain, we need to look to research to help us find answers, before screening or awareness raising is targeted specifically at Black men. Acting now without enough evidence might inadvertently cause harms like overdiagnosis or overtreatment, to Black men, who already face other health inequalities. One of the studies we are co-funding aims to shed light on why some individuals are at greater risk of prostate cancer.

Men with a family history of prostate cancer are also at an increased risk of being diagnosed with the disease. This may be because they possess specific gene faults that can increase the risk of prostate cancer – such as faulty BRCA genes, which our scientists were instrumental in discovering. However, for many people with a family history we don’t know the underlying genetic cause. It has been suggested that increased awareness of the disease could be leading to increased PSA testing; a UK study found that PSA testing was twice as likely in men with a family history of prostate cancer. This means that the picture for prostate cancer testing in men with a family history is just as complex as for testing in Black men.

Overall, current research has not shown that the benefits of PSA testing in men with no symptoms in the general population outweighs the harms. While we know there are certain groups at increased risk of prostate cancer, there is not enough research on PSA testing in these groups. We are funding research in this area, but we want to see more research looking into this, and other tests that can more accurately diagnose prostate cancers that need treatment.

The trouble with diagnosing symptomatic prostate cancer

We have also been looking into the symptoms of prostate cancer and funding research to help us spot it earlier. Unfortunately, research so far points to early-stage prostate cancer not causing symptoms. This is because when prostate cancer is small and hasn’t spread, it isn’t big enough to cause symptoms, such as pressing on the tube that carries pee out of the body (the urethra), making men need to pee more often. Without symptoms it can be hard to spot cancer.

It’s thought that later-stage prostate cancer, that has got bigger or spread, can cause symptoms like:

• Losing weight without trying to
• Feeling tired for no reason
• Bone pain
• Changes to how often or how easily you pee
• Difficulty getting or keeping an erection
• Blood in your pee

But many of these are vague and some, like peeing more often, can also be linked to simply getting older. And since it is common for the prostate to get larger with age (known as enlarged prostate or benign prostatic hyperplasia), some people may experience these symptoms who do not have prostate cancer.

Furthermore, conditions like an enlarged prostate, or prostate cancer don’t always occur in isolation – it’s possible someone can have both at the same time. Because of the overlap in symptoms and in conditions, there’s a chance that for people with prostate-related symptoms, like the ones above, overdiagnosis could still be happening. For example, someone going to their GP with symptoms caused by an enlarged prostate might then be investigated and have a prostate cancer incidentally diagnosed. This is another area where we need more research to help us understand the symptoms of prostate cancer in more depth, so that GPs have better support to recognise and manage patients.

What is Cancer Research UK doing?

Diagnosing prostate cancer early is complicated, and there are differing views among the research and clinical communities. But we’re more committed than ever to finding solutions to these complex problems. At Cancer Research UK, we are committed to bringing about a future free from the fear of cancer. And that includes reducing the number of men dying from prostate cancer, as well as the number of men being harmed by overdiagnosis and overtreatment. Our previous research paved the way for treatments such as abiraterone – giving men with advanced prostate cancer better survival outcomes.

But there is still more left to do. We need more research so that we can better detect early prostate cancer, know which cancers need treatment, as well as developing kinder and more effective treatments so that men face less side effects. We have spent £28m on prostate cancer research over the last three years, including trials to speed up diagnosis for men with symptoms so that they can start treatment sooner, research into the best radiotherapy to stop prostate cancer spreading, as well as whether MRIs can be combined with machine learning and genomics to more accurately diagnosis prostate cancer.  

For a further in-depth analysis of the evidence on prostate cancer early diagnosis, you can read our technical briefing.

If you or anyone you know is worried about prostate cancer, you can speak to your GP.