The PSA (prostate specific antigen) blood test can help monitor prostate cancer. It is often used to try to detect prostate cancer, but that is not recommended by most health authorities.
What is being tested?
The prostate is part of the male reproductive system, and produces the protein PSA. PSA is released into semen but some also enters the bloodstream.
High levels of PSA can be caused by prostate cancer, but they are usually caused by other conditions.
Do I need the PSA test?
It is important to know whether you have symptoms suggesting there might be cancer, or if you are otherwise healthy and it would be a screening test.
If you have prostate cancer
If you have been diagnosed with prostate cancer, the PSA test can help monitor your condition. When the levels go up, this suggests the cancer is growing. When they go down, this suggests it might be shrinking.
If you have symptoms
If you have prostate symptoms, you might be asked to have a PSA test. It might help point your doctor in certain directions, but it doesn’t diagnose prostate cancer. The only way to do that is with a biopsy.
If this is a screening test
The PSA test is not very accurate for screening men without symptoms. High PSA levels can be due to many things, and cancer is just one of them. And a man with prostate cancer can have a normal PSA level.
As there are a range of risks and potential benefits of PSA testing, talk to your doctor to help make an informed decision.
How to prepare for this test
You may be asked to avoid ejaculation and vigorous physical activity that can affect the prostate (such as bicycle riding) in the 2 days before the test.
Understanding your results
It is important to note that PSA is not a test specifically for prostate cancer. A raised PSA level can indicate the possibility of cancer, but can also be caused by many other conditions. PSA levels also increase in all men with age.
The PSA test can provide false positive (raised PSA levels but no prostate cancer) and sometimes false negative (low or normal PSA levels, but prostate cancer is present) results.
The PSA test also cannot differentiate between slow-growing prostate cancer (that would not cause harm) and cancer that will cause harm.
For all of these reasons, it is important to talk to your doctor about your results.
About PSA testing
About blood testing
Visit our ‘Guide to blood testing’ to learn more about blood tests in general with information such as:
- what to consider before having the test
- what happens during a blood test
- results accuracy
- blood tests cost.
Last reviewed: September 2016