PSA testing for prostate cancer
Prostate-specific antigen (PSA) is a protein produced by prostate cancer cells. A blood test, the PSA test, measures the level of PSA and may help to detect early prostate cancer.
This video provides an introduction to the PSA test.
The information in this video was correct as of 1 July 2013.
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Men in the UK are not routinely offered PSA tests to screen for prostate cancer. There are many reasons for this:
The PSA test is not completely reliable. For every 100 men with a raised PSA level, only about 30 will have prostate cancer detected in a biopsy. This is called a false-positive result. Also, approximately 15% of men with a normal PSA
level will have prostate cancer. This is known as a false negative result.
The amount of PSA in the blood can be high for reasons other than prostate cancer.
If the PSA level is high a man may need further tests such as a biopsy, which can be painful and lead to blood in the urine, the semen or bowel motions. In a few men the biopsy can lead to infection of the prostate gland, which can be difficult to get rid of. In 5-10% of men the biopsy will not show cancer even if it is present.
Many small prostate cancers detected by PSA screening would never grow enough to cause any symptoms at all during a man’s lifetime.
Many prostate cancers grow very slowly and the side effects from treatment (radiotherapy or surgery) may be worse than the effects of the prostate cancer. If the tests show there is an early cancer it can be difficult to decide whether or not to have treatment.
Research hasn’t yet shown whether finding and treating prostate cancer early gives an improvement in survival. This can make it difficult to decide whether to have a test. Your doctors and nurses will be aware of this difficulty and can discuss it with you.
Men who don’t have symptoms but would like to have a PSA test should discuss it with their GP, who can give them all the necessary information and arrange the blood test if they would still like to have it.
In most men with advanced prostate cancer the PSA level will be raised. Once the cancer has been treated the level of PSA will fall. Measuring PSA levels can help to assess the cancer and see how well treatment is working.