What is the PSA test?

The prostate specific antigen (PSA) test is used to screen for problems with the prostate. It measures how much of the protein called PSA is in your blood. It’s normal for some PSA to enter the blood. However, a large amount can sometimes be a sign of prostate cancer. PSA levels can also be high for reasons other than cancer, such as infections, prolonged exercise and ejaculation. So having a raised PSA level does not mean you definitely have prostate cancer.

Men in the UK are not routinely offered a PSA test, as it is not considered to be completely reliable. Two out of three men with a raised PSA level will not have prostate cancer detected in a biopsy.

There are some possible advantages and disadvantages to consider before making a decision about the PSA test. For example, the PSA test may detect prostate cancer early, but an inaccurate PSA test may lead to further tests that you don’t need.

There’s no right or wrong answer when it comes to deciding whether to have a PSA test. With the help of your doctor and this information, you can make the decision that’s right for you.

What the test involves

The PSA test is a blood test. PSA (prostate specific antigen) is a protein made by the prostate gland, which naturally leaks out into the blood. The PSA test measures the level of PSA in your blood. Sometimes a raised PSA level can be a sign of prostate cancer. More often it’s caused by something less serious like BPH or prostatitis. A single PSA test can’t show whether a prostate cancer is present, or whether it’s slow or fast-growing.

The level of PSA can also be raised by:

  • infections
  • prostate biopsies (PSA should not be tested until three months after a biopsy)
  • having a urinary catheter (a tube to drain urine)
  • prostate or bladder surgery (PSA should not be tested until three months after surgery)
  • prolonged exercise, such as long-distance running or cycling, which may raise PSA for up to 48 hours
  • ejaculation – this may raise PSA for up to 48–72 hours.

Some drugs such as finasteride (Proscar®), which are given to help with urinary symptoms caused by an enlarged prostate gland, can lower the level of PSA in the blood, so this needs to be taken into account. It’s important to tell your healthcare professional (GP or nurse practitioner) about any medicines you are taking before having the test.

How reliable is the PSA test?

There are still questions about how reliable PSA testing is.

The PSA test is not a test for prostate cancer. It's a test for abnormalities of the prostate, one of which may be cancer.

Two out of three men with a raised PSA level will not have any cancer cells in their prostate biopsy, while up to one in five men with prostate cancer will have a normal PSA result.

Screening for prostate cancer

In the UK, there is currently no screening programme for prostate cancer. This is because we still don’t know how reliable the PSA test is and there isn’t another reliable test. Research suggests that while the lives of some men could be saved by PSA screening, many more men would be unnecessarily treated for cancers that would never cause serious harm. This is called over-diagnosis or over-treatment.

However, this doesn’t mean that you can’t have a PSA test. The Department of Health has said that any man over 50 who would like the PSA test, even if they don’t have any symptoms, can contact their GP or nurse practitioner who will then discuss the advantages and disadvantages of the test with them.

If the man decides he would like to go ahead with the PSA test then his GP will arrange it for him. Alternatively, there are self-test PSA kits available for a small charge from pharmacies or online. There are potential problems with these tests and they should be used with caution.

If you have any worrying symptoms or concerns, discuss them with your GP or nurse practitioner.

Advantages and disadvantages of having the PSA test

Before deciding whether to have a PSA test you may want to think about some of the possible advantages and disadvantages. You can also discuss these with your GP or nurse practitioner.

Possible advantages:

  • It could reassure you if the test is normal
  • It can help to find cancers before any symptoms develop
  • Treatment in the early stages could help you live longer and avoid the complications of cancer (although there is no good research evidence for this).

Possible disadvantages:

  • It could read normal when there is cancer in the prostate, and falsely reassure you that all is well
  • It could lead to anxiety, even if you don't have cancer
  • It could lead to a biopsy, even if you don't have cancer
  • If you do have cancer, the test can't tell you if it's likely to cause problems in the future
  • Treatment of early prostate cancers may not help you live longer
  • Treatments for early prostate cancer have risks and may cause side effects that can affect your quality of life.

Questions to help you decide

To help you make your decision, try answering these questions:

  • What would you choose to do if your PSA level is found to be high?
  • What would you do if further tests find that you have an early prostate cancer?
  • What difference will it make for you to know?

If you can answer these three questions, focusing on what is really important to you, you will be able to make a decision about the PSA test that’s best for you.

Deciding whether or not to have a PSA test can be very difficult and we hope that this information has helped you. If you have further questions, contact your GP. You can also call our cancer support specialists (0808 808 00 00) who can discuss the options with you and send you more information.

Back to PSA test

The prostate gland

The prostate gland produces semen and a protein called prostate specific antigen (PSA), needed for ejaculation.

Your PSA test results and what happens next

Your PSA test results will help your doctor decide if you need further tests.