A recent BBC investigation questioned the accuracy of prostate-specific antigen (PSA) self-tests - rapid at-home tests for men worried about prostate cancer. The BBC analysed five of these tests using one blood sample and found varying results: one positive, three negative, and one unreadable.
Author
- Dipa Kamdar
Senior Lecturer in Pharmacy Practice, Kingston University
PSA blood tests measures levels of PSA, a protein produced by the prostate gland. All men have some PSA in their blood but a raised level can suggest a problem with the prostate, including cancer.
In the UK, prostate cancer is the most common cancer in men . One in eight men will be diagnosed with prostate cancer during their lifetime.
Unlike many other cancers, there is no national screening programme for prostate cancer and the NHS doesn't offer routine PSA testing . But anyone who has a prostate and is over 50 years old - or over 45 and from a high-risk group - can request PSA testing on the NHS. A doctor may also request testing if they think a patient has prostate cancer symptoms or want to monitor a diagnosed prostate condition.
A faster and potentially more convenient alternative is self-testing. Currently, anyone over the age of 18 can buy a PSA self-testing kit for home use. With no proactive NHS screening programme, home testing is on the rise to catch prostate cancer early - even before there are any symptoms. By catching fast-growing cancers early, treatment can prevent them from spreading and causing serious problems.
As with COVID self-testing, the PSA home kits use test cassettes. You use a lancet (small needle) to prick your finger to get a few drops of blood, put the blood into a pipette and then drip this on to the test cassette along with a buffer solution. Depending on the test kit, a positive or negative result is displayed in five-to-ten minutes.
This might sound convenient, but some users find the detailed instructions for home PSA tests difficult to follow, which can lead to errors. A review found the information provided with self-tests is generally inadequate.
But as the BBC report showed, even when used correctly, PSA home tests can give varying results.
Not a cancer test
Positive tests or high PSA levels may cause men to worry unnecessarily. PSA tests are not blood tests for prostate cancer, and a PSA test can neither diagnose nor rule out prostate cancer. Rather, higher levels of PSA indicate a potential problem with the prostate.
In many men, this could be caused by a benign prostatic hyperplasia - an enlarged prostate. This is a non-cancerous condition affecting 8% of men in their fifties, where the prostate gland grows larger. It can cause urinary problems, such as difficulty in starting pee, a weak urine stream and frequent or urgent urination. The likelihood of developing an enlarged prostate increases with age .
An inflamed prostate (prostatitis) can also cause raised PSA , as can urine infections - and even vigorous exercise and sexual activity.
In some cases, rapid home tests can give a false negative result, offering false reassurance for users who should go on to have further tests for cancer.
Another drawback of home-testing kits is that there is no medical professional to refer a test user for further checks or to help interpret results. For example, a normal PSA level doesn't mean the person testing is cancer-free: PSA levels can be normal even in someone with prostate cancer.
Tests are not a GP substitute
While rapid at-home PSA tests can be unreliable, other types of PSA self-testing kit allow you to collect the blood sample in a small tube, then send it to a laboratory for testing. Getting these results can take a few days but can offer a more detailed PSA value, compared with rapid at-home tests. But again, these lab tests can neither diagnose nor rule out prostate cancer.
Whatever the method of testing, high PSA levels should be followed up with a doctor who can order more tests and scans to check for cancer.
Many men might find the Prostate Cancer UK online risk checker useful. It asks three main questions about age, ethnicity and family history.
The older a man is, the higher their risk of prostate cancer. Men of black ethnic heritage have double the chance of developing prostate cancer, while those with a close relative - father or brother - who has had prostate cancer are also at increased risk.
The online risk checker also provides useful resources, information to take to the doctor, and contact details for specialist nurses.
If a man is experiencing any symptoms of prostate problems, falls into a higher risk group, has genetic risk factors, has a positive PSA home-test, or just has concerns about prostate cancer, it's always best to check with the doctor - they can provide more support, information and further testing.
Dipa Kamdar does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.
