Gene indentification could bring bowel cancer screening
Adam Creswell, The Australian
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Researchers have identified for the first time a gene that triggers bowel cancer, a move that could bring closer a genetic screening test for the disease.
The gene, carried by about half the population, appears to increase the risk of developing bowel cancer by 20per cent.
Bowel cancer is the second most commonly diagnosed cancer in Australia, accounting for about 13,000 new cases a year.
So far, faulty genes have only been implicated in about 5 per cent of all cancers, and 5 per cent of bowel cancers.
In the case of bowel cancers, the genetic defects so far associated with the disease are all thought to be associated with faulty cellular repair mechanisms, meaning that the body loses the ability to kill off cells that start to divide abnormally.
Bowel cancer is also the second most common cause of cancer death in Australia, accounting for 4372 deaths in 2003, or 11.5 per cent of the total fatalities. It is notoriously hard to pick up for a number of reasons, including the difficulty of picking up warning signs - such as blood in the faeces - and patients' reluctance to see their doctors.
This year the federal Government began rolling out a screening program, costing $43 million over three years, whereby older Australians send in a faecal sample for testing.
If blood that could indicate a cancer is detected in the sample, the patient may be called in for further examinations.
The latest findings, published in international journal Nature Genetics, suggest a faulty gene found on chromosome 8 may trigger bowel cancer, and account for 10per cent of all cases of the disease.
Ian Olver, head of Cancer Council Australia, said the implications of the discovery were "several-fold", including the fact that people carrying the gene were 20 per cent more likely to develop bowel cancer.
"Now that we have a gene associated with a bigger percentage of bowel cancer cases, we are closer to developing a screening test for bowel cancer," Professor Olver said.
Although the new gene was only responsible for 10 per cent of cases by itself, by adding various other genes associated with an increased risk for the disease researchers could build up "a genetic profile for people likely to develop bowel cancer", Professor Olver said.
"It really is a step forward - we have done a lot better at discovering the genes responsible for breast cancer.
"Bowel cancer was lagging behind and this has taken it a major step forward."
Up to about 30 per cent of bowel cancers are thought to have a hereditary element, suggesting that even with the new discovery there is much scientists have yet to discover about which genes are involved and how bowel cancers start.
The bowel cancer gene identified in the new research is found on the same chromosome as genes already linked to prostate cancer, the most commonly diagnosed cancer in Australia, at 13,526 new cases in 2003.
Breast cancer comes third, causing 11,889 new cases in 2003, followed by melanoma, which caused 9524.
AAP
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