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Prostate test may spare thousands from surgery
By Nigel Hawkes, Health Editor

A TECHNIQUE developed by British scientists could save many men from needless operations for prostate cancer.
At present, doctors 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.

As a result many men have operations that can leave them impotent and incontinent to deal with prostate tumours that would never have killed them.

Now scientists from the Institute of Cancer Research in Sutton, Southwest London, have developed an ingenious method to identify “markers” that could be used to make this distinction. Success could prevent thousands of men undergoing radical surgery when it is not necessary.

Professor Colin Cooper said: “The most amazing thing about the discovery is that nobody has thought of it before. We have been suffering a collective mental block.”

Prostate tumours are identified from samples taken from the tumour using a biopsy needle. The hollow needle removes a cylinder of tissue a centimetre or two long and a millimetre or so in diameter.

The biopsy tissue is fixed in formalin and then laid flat on a paraffin block. The pathologist then takes slices along the line of the needle, stains them and examines them under a microscope. The biopsy specimens are so thin that only a few slices can be taken for each one.

“There are lots of potential markers we would like to test for,” Professor Cooper said. “One is a protein made by a gene we discovered last year, called E2F3, which is linked to aggressive tumours. There are lots of others — but nobody’s been able to test for them all.” The right time to test 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. In retrospect, Professor Cooper said, the answer is obvious.

“We hit on the idea of simply turning the biopsy through 90 degrees, and taking a series of slices across it. That way, you can get thousands of slices.”

In the online version of British Journal of Cancer, Dr Sameer Jhavar and colleagues including Professor Cooper explain how to do it. Each biopsy is cut into cubes which are then reorientated to expose a cross-section, and arranged in a chequerboard pattern called a tissue microarray.

The first use of the technique will be in research. The Institute has collected many biopsy samples over the years, from tumours that were lethal, and from apparently identical tumours that turned out to be harmless. The team will take 60 such samples, half of each type, make a microarray out of them, and 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 tigers from the pussycats. That is expected to take two years.

Then the key markers will be used to characterise newly taken biopsies from new patients, using the same microarrays. That should enable men to be told, with far greater certainty than at present, whether they are harbouring a dangerous tumour or one that is unlikely to do much harm.

“It should be just as quick as a normal diagnosis but it will tell us a lot more,” Professor Cooper said. “It’s really exciting. When we’ve presented the idea at conferences, people’s mouths drop open.”

COMMONEST CANCER AMONG MEN IN BRITAIN

Prostate cancer is the commonest cancer among men in Britain. More than 30,000 have it diagnosed every year, and almost 10,000 men die from it