In a blood test, a sample of your blood is taken via a needle and sent to a pathology lab for testing. If your GP or specialist is investigating the possibility of prostate cancer, they may suggest you have a prostate-specific antigen (PSA) test.
A PSA test is a specialised blood test that helps determine whether you may have prostate cancer. The test measures PSA, a type of protein in the prostate that helps with liquefaction of semen.
Both normal and cancerous blood cells make PSA, but high PSA levels can be associated with prostate cancer. A continuous rise in PSA levels over time may also be a sign of prostate cancer.
However, the test is not definitive. Some people with high PSA levels do not have prostate cancer, while some people with prostate cancer may even have normal PSA levels. Many other conditions, such as an enlarged or inflamed prostate, also can increase PSA levels. Therefore, determining what a high PSA score means for you can be complicated.
Importantly, a PSA test does not diagnose prostate cancer. It provides information that helps your medical team determine whether you need more tests for prostate cancer.
The only test that can, at present, definitively diagnose prostate cancer is a prostate biopsy.
Your GP or specialist may suggest a PSA test if you have:
There are few, if any, risks or side effects of having a blood test. You may develop a small bruise where the needle entered.
Some blood tests require you to fast (stop eating) 8 hours before the test. If you need to fast before your PSA test, your GP or specialist will tell you.
You must abstain from sexual activity for 24 to 48 hours prior to the blood test to avoid a misleading rise in the PSA level.
Here’s what to expect during your PSA test:
Your blood sample will be sent to a lab for testing. In a few days, the results of your test will be sent to your GP and specialist. They will contact you to discuss the results and book a follow-up appointment if necessary.
A test result that shows a high PSA level, or a rising level, may mean that there is prostate cancer. However, the result isn’t definitive: PSA levels can vary, and other factors can cause an increase. These include:
If your result is high, it’s likely that you’ll need another PSA test to confirm the result. If the PSA levels in that test are still high or rising, you may need to continue having PSA tests over time to help determine your prostate cancer risk. Alternatively, your GP or specialist may recommend you have further investigations.
These could be other kinds of tests, including urine tests, and imaging, such as ultrasounds or mpMRI. Your GP or specialist may also suggest a DRE to feel for any abnormality, such as a nodule or hard area in the prostate, that could suggest a cancer.
During a DRE the doctor will insert a gloved finger into your rectum to feel the back of your prostate and check for any hard, lumpy or abnormal areas. A DRE can’t confirm the presence of every prostate cancer, as some cancers are too small to be felt or reached, but in many cases it can help inform a diagnosis.
If these investigations suggest you could have prostate cancer, your specialist may recommend you have a prostate biopsy. A biopsy is when small samples of tissue are removed and analysed in a lab for signs of cancer.
