Genes 'that triple bowel cancer risk' are found

The breakthrough will hasten the search to find new ways of treating - and even preventing - the illness, which claims more than 16,000 lives a year in the UK.

The two sections of flawed DNA, which were found by British researchers, are thought to be common and linked to around 15 per cent of bowel cancers - the equivalent of 5,400 cases a year in Britain.

If carried with a bowel cancer gene identified earlier this year, the two stretches of DNA could double or even treble the risk of bowel cancer, according to Cancer Research UK, which funded the study.

Usually, men have a one in 20 chance of developing the disease in their lifetime, while for women, the risk is one in 18.

The disease is the second-biggest cancer killer after lung cancer and is most common in the over 60s.

The two rogue stretches, which have not been given names, were found after researchers scrutinised the DNA of 15,000 people. These were mainly Britons, and more than half had bowel cancer.

The sequences are part of a larger section of DNA which four years ago was found to be behind Hereditary Mixed Polyposis Syndrome.

This is a rare condition that increases the risk of bowel cancer and is usually only found in Ashkenazi Jews. The latest research did not find any genes directly responsible for the syndrome.

But it did find the two sections of flawed DNA that increase bowel cancer risk in the general population.

Professor Ian Tomlinson, of Cancer Research UK's London Research Institute and joint lead researcher on the study, said:

"Increasing our understanding of genes like this may make it possible for scientists to eventually develop ways of stopping many people at increased risk of bowel cancer from developing the disease altogether."

Professor Richard Houlston, of the Institute of Cancer Research at the University of London, and the study's co-leader, said: "This is an exciting development.

"By pinpointing more genes which increase an individual's risk of bowel cancer, we ultimately hope to improve diagnosis and treatment of this cancer."

The researchers added that the increased risk is still too small for genetic testing to be useful.

But it may be possible to design a test for a combination of genes as more genetic flaws are found.

Dr Lesley Walker, Cancer Research UK's director of cancer information, said:

"Cancer Research UK is launching a series of studies, including searches for genes that influence lung and ovarian cancer risk."

The research, published in the journal Nature Genetics, is the latest to make use of advances in genetic technology to identify genes behind common conditions.

Other recent breakthroughs include the identification of a genetic flaw that doubles the risk of heart attacks and another gene that increases the risk of obesity by more than 70 per cent.