Bowel cancer rates could be reduced by up to 80 per cent in people with a moderate family history of the disease by screening with colonoscopy, according to new research published in the British Medical Journal.

But the research shows that most people, even those who have two or three relatives with the disease, do not need to be screened before the age of 45 or need to be screened very frequently.

The new research from Cancer Research UK could help prevent thousands of cases of bowel cancer and guide doctors in how best to use precious screening resources.

As many as a third of the 34,000 bowel cancer cases diagnosed in the UK each year occur in someone with a family history of the disease. A small proportion of these people have a fault in a specific gene which leads to a condition called hereditary nonpolyposis Colorectal cancer (HNPCC) but the majority of cases have no known genetic fault.

HNPCC families are currently screened with colonoscopy every two years from the age of 25 and the new research supports this practice, estimating that screening reduces cancer deaths in this group by up to 70 per cent.

But until now, there has been no strong evidence on how to deal with the remaining majority of people with a family history of bowel cancer. The new study shows an 80 per cent decrease of tumours by screening this group.

Screening with colonoscopy means that pre-cancerous growths can be detected and removed before they progress to cancer.

Study author, Professor Peter Sasieni of Cancer Research UK explains: “We now know that screening with colonoscopy prevents the majority of bowel cancers in people with a family history. The study also shows that screening isn’t necessary before the age of 45 and, even then, it only needs to be performed every five years or so.

“This is good news for people with a family history because it means they can dramatically reduce their risk of cancer by going for occasional screening.

“It’s also good news for hospitals because, in most cases, this will mean less intensive screening and less of a drain on resources.”

The research took place at Cancer Research UK’s family cancer clinic at St Mark’s Hospital, Middlesex. The study involved over 1,600 people with at least one close relative diagnosed with bowel cancer. Study participants were screened regularly and monitored for up to 16 years. The number of cancers found was compared to the number of cancers expected in a similar, unscreened population.

A national bowel screening programme will be phased in across England over three years, starting in April 2006. Men and women aged between 60-69 years old will be screened every two years*.

Professor John Toy, Cancer Research UK’s Medical Director, says: “With the introduction of a national screening programme for bowel cancer due to begin next year, we anticipate a major increase in the number of people referred for colonoscopy.

“This research is important because it shows how most cancers can be prevented in people with a family history. It also indicates how resources can best be used and help to minimise unnecessary colonoscopies for people.”