Doctors have developed a simple way to improve identification of people at high risk of bowel and colon cancer.

It is based on the principle that patients know best what symptoms they have, but may be too embarrassed to talk openly about them to doctors.

Colorectal cancer is the second most common cause of death from cancer in the UK, with 30,000 new cases and 19,000 deaths every year.

It has the potential to detect more cancers

Dr David Cade

A new study by US researchers has concluded that one way to tackle the disease would be to introduce screening for all adults over 50.

The new assessment system, details of which are published on The Lancet online, has been developed by a team of UK researchers from Leighton Hospital, Crewe.

They believe it could help to predict colorectal cancers more reliably than current NHS guidelines which can often over or under-estimate the real risk to patients.

Questionnaire

First, patients complete a questionnaire giving details of their symptoms and how long they have had them.

Colon cancer symptoms

Bleeding from the rectum Diarrhoea Constipation lasting more than a few weeks Pain or a lump in the abdomen Unexplained tiredness

The answers are then analysed by a computer which generates a risk score based on ranking symptoms in order of importance.

Those with the highest level of risk can be prioritised for further tests and treatments.

In total, 2,268 patients who had been referred by their GP to a specialist with symptoms such as rectal bleeding, and increased bowel movements were studied. Ninety-five were subsequently diagnosed with cancer.

The system accurately detected 99% of cancers, including 13% of cancer patients who would have been categorised as low risk under the current guidelines.

However, overall 10% fewer patients were rated as being at high risk.

Researcher Dr David Cade said: "It has the potential to detect more cancers.

"We put the emphasis back on the patients so they share responsibility for their health care."

Professor Robert Steele, an advisor to the charity Colon Cancer Concern, told BBC News Online any measure which would improve the predicted value of symptoms is to be welcomed.

However, he said: "It must be stressed that early cancers are asymptomatic and often by the time colorectal cancer produces symptoms the disease is advanced locally."

Screening study

In a separate study, the US Preventive Services Task Force has recommended widespread screening for adults aged over 50.

The researchers recommended two screening methods:

• Flexible Sigmoidoscopy: the visual examination of the inside of the rectum and sigmoid colon, using a lighted, flexible tube
• Faecal occult blood test: a chemical analysis designed to detect the presence of blood in a stool sample

The UK currently has no national approach to colon cancer screening.

Research published earlier this year suggested a single bowel examination at around the age of 60 could potentially cut deaths from the disease by 40%.

Faecal Occult Blood pilots are running in Coventry and Warwickshire and in Grampian, Tayside and Fife. According to the National Cancer Plan, the pilots will be complete in 2002.

The US research appears in the journal Annals of Internal Medicine.