Prostate Specific Antigen (PSA) Testing

The PSA test is a blood test that measures the amount of prostate-specific antigen (PSA, a protein made by cells in the prostate gland) in the blood. It’s normal for all people with a prostate - including men, trans women and some non-binary people - to have some PSA in their blood.  

Elevated levels of PSA could potentially indicate prostate cancer, which is why it’s used as one of the first-line investigations for men with symptoms. However, elevated PSA levels could also be due to several factors that do not indicate cancer such as age or a urinary tract infection (UTI) [1]. Cancer could also be present without increased PSA levels [2].  

Before offering a PSA test, health professionals should discuss the benefits and limitations of the test, as outlined below.  

The UK National Screening Committee (UK NSC) does not recommend using the PSA test in screening for prostate cancer [3]. This is largely due to the limitations in the accuracy of the test and the associated harms, as outlined below. At present there isn’t enough evidence to show that screening using the PSA test or other tests like MRI (alone or in combination with PSA testing), improves prostate cancer outcomes.  

For more information on why the PSA test isn’t used to screen for prostate cancer, read our blog.  

What to do if an asymptomatic man requests a PSA test 

Even though there’s no screening programme for prostate cancer, men without symptoms may request a PSA test. Before completing a test for someone without symptoms, you should discuss the key considerations for PSA testing with them - as noted below. 

The NHS Prostate Cancer Risk Management Programme (PCRMP) also provides GPs and primary care professionals with information to counsel asymptomatic men aged 50 and over who ask about PSA testing for prostate cancer. 

Before offering a PSA test to patients, health professionals should make sure they are aware of the key considerations below so they can make an informed choice. 

• A raised PSA level can help detect prostate cancer that is aggressive or likely to progress earlier so that there are better treatment options.   

However the PSA test also has several limitations:  

• It may suggest some men have prostate cancer when they don’t (a false positive result). As noted by NICE, around 75% of people with a raised PSA do not have prostate cancer [1]. This may lead to unnecessary and potentially invasive investigations, such as MRI or prostate biopsy, which carry their own risks. 

• It can miss aggressive cancer (a false negative result). As noted by NICE, around 15% of people with a normal PSA may have prostate cancer [1,2].

• The test may find slow-growing tumours which are common and may not be the cause of the symptoms experienced or shorten life. Some men who are tested may therefore face unnecessary diagnosis (overdiagnosis) of prostate cancer, as well as associated anxiety, medical tests, and unnecessary treatments (overtreatment) with adverse effects [4].   

Watch CRUK GP, Dr Joe Mays, discuss the benefits and limitations of PSA testing and the importance of discussing these with your patients (video recorded November 2022) 

Note: Elevated PSA levels can be a result of other factors. Check if the patient has or has had an active or recent urine infection (UTI) or a prostate biopsy in the past 6 weeks, and/or has ejaculated or done vigorous exercise in the last 48 hours. 

The diagnostic pathway for prostate cancer has changed in recent years. For example, multiparametric MRI (mpMRI) is used to assess the need for a biopsy in most areas across the UK. 

There’s some evidence to suggest mpMRI can better detect prostate cancers that need treatment (eg clinically significant prostate cancers) [8]. This could help mitigate some of the risks associated with the PSA test.  However, more research is needed to determine if the benefits of MRI sufficiently reduce the risk of harm associated with PSA testing.  

Research is ongoing to optimise the pathway. Researchers are exploring the following: 

• How to optimise the PSA test. For example by combining it with other patient factors or test results (eg free PSA or PSA volume) 

• The role of risk prediction models, including genetic risk scores to inform how likely a person is to develop prostate cancer  

• the use of AI to support current diagnostics 

• Screening for prostate cancer using newer diagnostic technology (eg TRANSFORM trial)  

• The potential of urinary biomarkers 

Resources for health professionals:  

• GP guide to recognition and referral of prostate cancer (UK)  

• GP guide to recognition and referral of prostate cancer (Scotland)  

• Prostate cancer statistics 

• "Can prostate cancer screening with the PSA help to save lives?" (April 2024) 

• "Overdiagnosis: when finding cancer can do more harm than good" (March 2018)  

Resources for patients:  

• Prostate cancer webpages  

• What is the PSA test webpage 

• Prostate cancer awareness leaflet