New prostate cancer test could save thousands from unnecessary surgery

Aug 10 2005

Doctors at present lack a test that can distinguish fast-developing tumours that need urgent attention from slow-growing ones that are not a threat and need only watching, and as a result many men have operations that can leave them impotent and incontinent for prostate tumours that would never have killed them.

Now a new technique developed by British scientists from the Institute of Cancer Research in London, appears to be an ingenious method of identifying "markers" that could be used to make this distinction.

If successful the technique could prevent thousands of men undergoing unnecessary radical surgery.

Professor Colin Cooper says it is amazing that the discovery was not thought of before.

In order to identify prostate tumours samples are taken from the tumour using a biopsy needle which removes a cylinder of tissue a centimetre or two long and a millimetre or so in diameter.

A pathologist then examines the tissue under a microscope.

Professor Cooper says, of the many markers, one is a protein made by a gene they discovered last year, called E2F3, which is linked to aggressive tumours.

Apparently the time to test for markers is immediately after the biopsy is taken, so the problem comes down to finding a way to use a small fragment of tissue for many simultaneous tests, and by simply turning the biopsy through 90 degrees, and taking a series of slices across it, they were able to get thousands of slices.

The first use of the technique will be in research.

The team will take 60 samples from many biopsy samples over the years, that the Institute has collected of both lethal and harmless tumours.

They will then examine them for marker proteins such as E2F3.

The idea is that the tests will establish a series of markers that can be used to distinguish the tumours and is expected to take two years.

The key markers will then be used to characterise newly taken biopsies from new patients, using the same microarrays, in order to predict with far greater certainty whether a tumour is dangerous or harmless.

Prostate cancer is the most common form of cancer among men in Britain, with more than 30,000 case diagnosed every year. Of that number almost 10,000 men will die from it.

The prevalence of the disease rises sharply with age, and autopsies of men who have died of other causes have revealed that by their 80s, 40 per cent of men have prostate cancer, but most will die from other causes, unaware they even have it.

Although screening for the presence of a protein called Prostate Specific Antigen (PSA) in the blood can give some indication of the presence of cancer, it gives no real measure of its severity.

A positive PSA test is usually followed by a biopsy, but this is not as informative as doctors would like.

Though PSA testing is much commoner in the U.S., where as a result far more prostate cancers are detected, mortality is the same as in the UK, showing how ineffective PSA screening is.

An increased risk of prostate cancer has been linked to age, family background, and diet.

Apparently those of African and Caribbean origin have the highest risk, and men from the Far East and Asia the lowest.

The study can be seen in the online version of British Journal of Cancer.