What is the PSA test?  

PSA (Prostate Specific Antigen) is an enzyme (a protein) substance made by the prostate gland. It is made by both normal cells and cancer cells (if present), and is secreted into the seminal fluid to keep it liquid. A small amount of PSA continually leaks from the prostate gland into the blood stream. Cancer cells produce more PSA than normal cells, and when prostate cancer cells multiply, more PSA spills into the blood. The PSA test measures the level of PSA in the blood.

Thus a raised PSA can be an early indication of prostate cancer. But other conditions, such as benign (non-cancerous) enlargement of the prostate, inflammation or infection, can also cause a rise in PSA, a 'false positive'. And it is also possible to have cancer but have a 'normal' PSA result; this is called a 'false negative'. 

Although men did not know much about the PSA test, some of those we talked to knew what PSA stood for and could explain why the test is done. 

Explains what PSA stands for and why the test is done.

Suggests that if a man has urinary symptoms a PSA test is a useful way to start investigations.

But many other men seemed confused and expressed misunderstanding. One man, for example, suggested that too much PSA allowed the cancer to grow, and he said it was important to 'kill the amount of PSA manufactured by the prostate gland'. Some men found it hard to explain what a rise in PSA level in the blood might indicate, and others didn't know what the letters PSA meant. 

The PSA test is available in the National Health Service. A small sample of blood is taken from the arm. This is usually done in a GP's surgery or in a hospital clinic. The men we interviewed stressed that it was just like any other 'normal' blood test, but there are advantages and disadvantages of having the test and GPs have been told to inform men about the possible benefits and drawbacks of having a test before proceeding (see other 'Talking about' sections).

For him the PSA test was no problem whatsoever; he went to work five minutes later.

Says the PSA test is a normal blood test but is concerned about possible false positive results.

His GP was reluctant to do the PSA test but finally agreed after explaining that the test isn't very accurate.

A digital rectal examination is often seen as an important part of the prostate examination. Because a rectal examination may raise the PSA level and lead to a false reading a PSA test should not be done immediately after it. Some other factors, such as ejaculation, can also affect the PSA level in the blood, making it appear abnormally raised. It is not clear whether or not vigorous exercise, such as cycling, affects the PSA level, but doctors had told some men to avoid such activity just before their PSA test. 

The doctor at the hospital told him not to ride a bicycle just before his PSA test.

The GP told him to avoid sex and vigorous exercise before his PSA test.

Some medicines may also affect the PSA result. One man had heard that herbal remedies such as saw palmetto, which is sometimes used for benign prostate enlargement, could artificially 'dampen' the PSA level.

Suggests that some drugs and herbal remedies may lower the PSA level in the blood.

In future other more accurate ways to diagnose prostate cancer may be developed, perhaps by measuring levels of 'free PSA', not attached to other proteins, and levels of 'bound PSA' (complexed PSA or cPSA) which is attached to another protein. Men who do not have cancer are thought to have higher levels of free PSA than men with cancer. Several clinical trials have now been done to see whether cPSA measurements are more reliable in diagnosing prostate cancer than the usual PSA test, but so far the results of these studies are conflicting (see information from Cancerbackup).   

Researchers in the USA have recently identified another protein, which they have called EPCA [early prostate cancer antigen]. They suggest that testing for this protein may be a better way of diagnosing prostate cancer, but this is new research which needs confirmation. One man spoke enthusiastically about this new research.

He is adamant that the PSA test gives men a chance of surviving prostate cancer and mentions a new test.

Some men gave reasons for having the test while others explained why they had decided not to have one. The men we talked to also explained how they decided whether or not to have the test (see 'Talking about - Deciding whether or not to have the PSA test').