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Tuesday, 24 October, 2000, 22:53 GMT 23:53 UK
Bowel cancer test 'could save thousands'
microscope
A simple lab test is more acceptable for screening
A new test for bowel cancer holds out hope for saving thousands of lives, scientists believe.

The DNA test, developed at the Mayo Clinic in the US, is 91% accurate for detecting cancer of the colon.

The stool sample test can pick up DNA shed from the surface of tumours at an early stage, as well as detecting precancerous polyps.

In the UK 34,000 new cases of bowel cancer - the second most common of all cancers - are diagnosed every year.

US doctors, writing in the journal Gastroenterology, believe that in about two years the test will be widely available for screening, taking over from existing methods.

Major clinical trials of the DNA test are due to begin in January, and Mayo Clinic gastroenterologist Dr David Ahlquist believes it has the potential to replace the existing faecal blood test.

The difficulty with a screening programme for colorectal cancer is that you have to ask people without symptoms to undergo a rather unpleasant procedure

Kate Law, Cancer Research Campaign

Measuring blood in stool samples does not reveal early stage cancers or precancerous growths and may also simply be an indication of a minor problem such as piles.

"A major problem with the faecal blood test is that as many as 5 to 10% of the screened individuals have a false positive or incorrect reading," he said.

"This means that one in every 10 to 20 people screened has to unnecessarily undergo a colonoscopy, a costly and invasive medical procedure to further evaluate the colon."

Colonoscopy

In the UK three pilot studies are underway to evaluate the potential for colonoscopy to screen people at risk of bowel cancer.

But the Cancer Research Campaign's head of clinical programmes, Kate Law said a simple laboratory test would be much more acceptable than a procedure that requires passing a camera probe into the bowel.

The success of screening programmes depends to a great extent on how acceptable they are to the general public, she pointed out.

"The difficulty with a screening programme for colorectal cancer is that you have to ask people without symptoms to undergo a rather unpleasant procedure and you also have to have specially trained staff and a reliable system to deal with the cancers you do find," she said.


"A major problem with the faecal blood test is that as many as 5 to 10% of the screened individuals have a false positive

Dr David Ahlquist, Mayo Clinic
"So it would be ideal if you simply had a lab test that allowed you to do the same thing."

The US study involved scientists from Exact Laboratories analysing stool specimens from 61 patients.

The test picked up 91% of the colorectal cancers and 73% of the polyps with no incorrect readings of normal colons.

The test is simple, requiring no special preparation and the stool sample can be provided at home.

Dr Law is wary about the one in ten cancers the test did not pick up, though she believes it would be further refined before becoming widely used.

"The thing is if this is easy for people to do then we are still going to pick up a lot more cancers than by a method which people are not keen to turn up for," she added.

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See also:

08 Dec 99 | Health
Blood test for colorectal cancer
23 Aug 00 | Health
Scientists 'stop' cancer tumours
04 Apr 00 | Health
Naked bottoms in cancer campaign
19 Nov 99 | Medical notes
Bowel cancer
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