Many people will have heard of the prostate specific antigen test (or more commonly PSA test) for prostate cancer, but do you know just what it is and whether or not it is something which you should consider having?

The PSA test was considered a major breakthrough when it was approved for use by the FDA in the mid 1980s and today it remains one of the best tests available for detecting the possible presence of prostate cancer.

PSA testing is quick and easy as it is a simple blood test looking for the presence in the blood of a specific protein produced by the prostate gland. In a normal prostate gland the quantity of this protein produces a level in the blood of about 4 nanograms per milliliter and this is assigned a normal PSA score of 4. As with most things of course this level will vary from one individual to another and so a slightly higher or lower level is not necessarily an indication of a problem and many men will have a normal PSA score of as high as 8 or 9.

In the presence of cancer production of this protein rises and, as the cancer progresses, so the level of the prostate specific protein in the blood increases. Accordingly, once a PSA score reaches 10 your doctor will want to monitor PSA levels carefully as this is an initial indicator of a possible developing problem. If your PSA score continues to rise then additional and more specific tests will normally be recommended. As an indicator, a PSA score of 50 is considered to be very high and the level at which not only is the presence of cancer very likely, but such cancer will probably have already spread beyond the prostate gland itself.

Prostate specific antigens appear in two forms within the blood. In the first form antigens attach themselves to the blood proteins, while in the other the antigens are simply free floating. Today it is possible to test for both by measuring the total amount of PSA in the blood and by measuring only free PSA in the blood. Being able to separate out the two different forms of PSA is thought by many doctors to produce a more accurate test and in a study published in the Journal of the American Medical Association in 1995 it was said that the ability to measure free PSA had led to a twenty percent fall in the number of unnecessary follow-up tests following PSA tests.

Perhaps the biggest controversy today is not over whether men should undergo regular (annual) PSA testing which almost all physicians today recommend, but at what age such testing should begin.

Both The American Cancer Society and The American Urological Association recommend testing for all men over the age of 50 and testing for men in 'at risk' categories from the age of 40 onwards. There are several 'at risk' categories, the most important of which is men with a family history of prostate cancer.

Unfortunately, these recommendations probably have more to do with resources and cost than with anything else and it is not uncommon for men to develop prostate cancer in their forties, or even in their thirties. So, where do we go from here?

Well, this must of course be a personal decision but an increasing number of men are now asking to be tested at quite young ages (typically when they reach 40) to provide a benchmark and then decide on the frequency of follow-up testing depending on their initial result. For example, if a 40 year old man has a normal initial PSA score of 4 then he may decide to leave further testing for 2 or 3 years. However, if his initial test score comes in at 8, he may decide to have a follow-up after six months and, if it remains the same or has fallen, to then have tests annually.

When you start testing and how often you have follow-up testing is very much a personal decision to be taken in consultation with your physician. What is important is that every man should be tested regularly and you should not put off testing for too long.