Prostate cancer screening: where are we now?
Prostate cancer is the most common cancer in UK males. Every day, about 140 men are told they have it. Every year, about 12,000 men die. These are huge numbers. Breast screening for women was introduced in the UK back in 1988. Why don’t we have something similar for prostates?
What is the prostate?
An organ only men have, the prostate helps nourish sperm and aid fertility. It sits below the bladder and above the base of the penis, between the pubic bone and the rectum and encircles the urethra (the tube through which urine passes from the bladder). About the size and shape of a walnut, it generally gets larger as men age. Sometimes, this growth becomes cancerous.
Is prostate cancer on the rise?
Throughout this century, total deaths from prostate cancer in the UK have been rising, hitting record highs.
This is partly because men are living longer. As a result, the age-standardised mortality rate for the disease - which takes this increased longevity into account - has, generally, been decreasing. However, it’s still above breast cancer (it was below it until 1990) and it is not decreasing as quickly. In 2018, prostate cancer killed more people than breast cancer for the first time. This is because breast screening works.
So why don’t we already screen for prostate cancer?
Traditionally there have been two main prostate tests in the medic’s armoury: the DRE and the PSA.
- The DRE - or digital rectal examination - involves nothing more or less than the doctor sticking a finger up your bottom to feel the size and texture of your prostate.
- The PSA (prostate-specific antigen) was discovered in 1979. It is a particular protein in the blood that is associated with prostate cancer and can be measured with a simple blood test.
Both tests, especially if they’re repeated over time, can help a health care professional to get a rough idea of what’s going on with your prostate but neither have been accurate enough predictors on their own or in tandem to roll out to all men. (Only 1 in 4 men with a raised PSA level have prostate cancer.)
Indeed, the evidence, according to the European Association of Urology (EAU), suggests that since the introduction of PSA testing in the 1980s, there has been considerable over-diagnosis. Lives have certainly been saved but many others have been damaged with unnecessary procedures for cancers that didn’t exist or, if they did, were not doing any real harm.
How has the PSA test caused over-diagnosis?
As with many blood tests, both false positive and false negative results can occur. PSA may be high in some other prostate conditions which are not cancer such as benign prostatic enlargement or prostatitis. PSA can also be elevated by a urinary tract infection or even vigorous sex or cycling.
Moreover, prostate cancer does not always need active treatment. Medics distinguish between ‘tigers’ (cancers which grow quickly and can kill) and ‘pussycats’ (which don’t and won't). The PSA cannot distinguish.
Cancer diagnosis is usually determined with a biopsy whereby a sample of the potentially cancerous body tissue is removed and examined. In the case of prostate cancer, collecting this tissue has usually required access up the backside through the rectum. These biopsies are not pleasant. It can be difficult to access the potentially cancerous area and infection is not unusual. On the basis of PSA testing, many men have had biopsies they didn’t need. Some have even had cancer treatment they didn’t need with the resultant impact on quality of life including urinary incontinence and erectile dysfunction.
In 2012, the United States Preventive Services Task Force which makes recommendations on preventive health interventions in the USA recommended against PSA-based screening for prostate cancer. In 2020, the United Kingdom National Screening Committee also recommended against whole-population prostate cancer screening.
So what’s new?
There’s no new test available - not yet anyway. But by using a combination of existing diagnostic tools including the PSA test, the EAU is now recommending what they call a ‘risk-adapted approach for the early detection of prostate cancer’. The approach’s algorithm could form the basis of a national screening programme.
It works roughly like this:
- having discussed the pros and cons, a PSA test should be offered to those at higher risk of significant prostate cancer. These groups are: all men over 50; those men over 45 with a family history of prostate cancer or who are of African descent; and those men over 40 who have the gene variant BRCA2.
- following the test, men with low to moderate PSA (less than 3 ng/ml) need nothing more beyond perhaps being retested after 2-5 years depending on their age and PSA score.
- men with a high PSA will have a risk assessment based on family history, prostate volume (measured using a simple ultrasound scan similar to those used in pregnancy), PSA density (the relationship between the total PSA score and the prostate volume), urinary symptoms and other risk factors. (EAU calculate that by this process about a third of men with a high PSA will be identified as at low risk - less than a 1 in 8 chance of having cancer - meaning they too need no further interventions at this stage.)
- those still at intermediate or high risk following the risk assessment will have a multi-parametric Magnetic Resonance Imaging (mpMRI) scan. This now routine scan uses magnetic fields and radio waves to generate detailed images of the prostate. These images are then scored on the likelihood of cancer being present (called a PIRADS score). On this basis, over half of men who have had an mpMRI will have a low PIRADS score requiring no further interventions.
- men with an intermediate or high PIRADS score will have a biopsy. Biopsies today are better targeted and preferably transperineal which means the prostate is accessed via the perineum, the area of skin between scrotum and anus. Sampling via this route is more accurate and there is much less risk of infection. Some of these biopsies will lead to a prostate cancer diagnosis but even among this group of men it is estimated that about a quarter will require no immediate treatment beyond ‘active surveillance’ (ie regular appointments to monitor the prostate).
- In total, it is estimated that of the men who have an mpMRI scan, about one third will have prostate cancer. Three quarters of these will need active treatment.
Will this algorithm eliminate over-treatment?
All screening processes lead to some degree of over-diagnosis. Over time the algorithm can be tweaked to reduce over-treatment to a minimum. For example, the time between tests can be adjusted or a more sophisticated risk-assessment adopted or additional genetic biomarkers used as they become available and affordable.
The EAU believe that the approach will maximise quality of life for men since those with insignificant cancer will avoid any further investigation or treatment (or undergo active surveillance) while those with significant cancer will be diagnosed earlier with less impact on quality of life than later diagnosis.
The EU has set up and is funding five pilot centres in Lithuania, Poland, Spain (2) and Ireland where, from April 2023, a screening programme based on this algorithm will be trialled. Centres are encouraged to tweak and fine tune the algorithm. The incidence of prostate cancer varies across Europe - rates are generally far higher in the north than the sunnier south - so the appropriate algorithm may well vary from country to country.
Professor Hendrik Van Poppel, who leads on policy for the EAU, says he expects to see prostate cancer screening throughout the EU from about 2027, once the aforementioned three year project (called PRAISE-U) has shown its feasibility and cost-effectiveness.
In the UK, the oncology section of the British Association of Urological Surgeons voted against a prostate screening programme as recently as November 2022. However, the men’s health charity CHAPS and the umbrella organisation Tackle Prostate Cancer are currently running a screening project along the lines of the EAU’s suggested approach. CHAPS has just completed its first full year running a screening programme and has screened just over 3,000 men - 9% have had an abnormal PSA. (CHAPS are keen to talk to any organisation who would like to join its programme.)
Meanwhile, leading men’s health organisations including Prostate Cancer UK and the Men’s Health Forum - both of whom have historically opposed PSA-based prostate cancer screening for the reasons outlined in this article - are reconsidering their positions in the light of the new developments.
Clearly, something needs to change. The latest Prostate Cancer National Audit for England and Wales found that 17% of men diagnosed in 1920-21 had cancer that had already spread elsewhere in their body (metastatic) compared to 13% the previous year. In part the result of Covid-19 delaying appointments, this is a significant increase of nearly a third.
Moreover, there is a serious north-south divide in the UK when it comes to prostate cancer detection. In Scotland, one man in three (35%) is detected too late for the cancer to be cured. In London, it is far lower at one in eight (12.5%)
Is screening expensive?
Treating advanced prostate cancer is extremely expensive and the quality of life for men whose cancer is detected late is also highly compromised. The EAU puts the cost of treating a single male with advanced prostate cancer at about €300,000, most of it in easing the very poor quality of the last two to four years of life. On the other hand, a PSA test costs about €10-15, an mpMRI scan around €150 and treatment for early-detected significant prostate cancer about €10-15,000.
Professor van Poppel notes that availability of and clinician expertise in mpMRI could be an economical obstacle. But, he says, it 'looks as if the much cheaper and shorter bi-parametric MRI would be as good as the mpMRI in the screening setting.'
Breast cancer screening is generally considered cost-effective for the NHS. The EAU say says that risk-stratified, organised prostate cancer screening based on its algorithm would be cost-effective, certainly if it is costed using quality-adjusted life years (QALY), the standard academic measurement of how well a particular medical treatment will lengthen and/or improve a patient’s life.
Will men do it?
That’s the big question. Several regions of Sweden already offer screening but, according to Professor Van Poppel, only about 45% of men take the opportunity. He says: 'men are confused about prostate health, quality of life, sexual health and are not willing to be exposed to investigations that could find something interfering' But, he believes, 'this figure will increase overtime and when policy makers and healthcare providers are able to better inform the general population, both the healthy males and their partners.'
Will prostate cancer continue to kill in such large numbers? The choice is ours.
Date of last review 06/01/23
Date of next review 06/01/26
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