CompletedInterventional

Multicentre randomised trial of 'once only' flexible sigmoidoscopy screening for prevention of bowel cancer morbidity and mortality

Bowel cancer is the fourth most common cancer in the UK. It often begins as small, harmless growths called polyps that can slowly become cancerous over many years. Removing polyps early can stop cancer from developing. This major UK trial looked at whether a single quick camera test of the lower bowel, called a flexible sigmoidoscopy or 'bowel scope', can protect people in the long run. Men and women aged 55 to 64 joined through their local GP surgeries. Half were invited for the one-off bowel scope test to find and remove polyps, while the other half received standard care. Researchers have followed participants for up to 30 years to find out how long the protection lasts and whether this simple test reduces bowel cancer cases and saves lives across the NHS.

At a glance

Status

Completed

Sponsor

Medical Research Council (MRC) (UK)

Enrolment target

170,000

Start

01 Jul 1995

Estimated completion

28 Feb 2014

Colorectal cancer

What is this study about?

Bowel cancer is one of the most common cancers diagnosed across the UK. Most bowel cancers develop very slowly from tiny growths on the lining of the bowel, known as polyps. While most polyps never cause harm, some can turn into cancer over time if left untreated. Catching and removing them early is one of the best ways to stop bowel cancer before it even starts.

This study, known as the UK Flexible Sigmoidoscopy Screening Trial, focuses on a simple hospital test called a flexible sigmoidoscopy (or 'bowel scope'). During this test, a specialist doctor or nurse gently inserts a thin, bendy tube with a light and camera into the lower bowel. This allows them to check the bowel wall and remove any small growths painlessly during the same appointment.

The main aim of the trial is to see if having just one bowel scope test around the age of 60 gives lasting protection against bowel cancer. The researchers want to know how many cancer cases and deaths can be prevented, how long that protection lasts, and the best age to offer the test.

By following thousands of participants over several decades, this study provides vital information that helps shape national NHS bowel cancer screening programmes and improve cancer prevention for everyone.

Key takeaways

The study tests whether a single bowel camera check around age 60 prevents bowel cancer.
Removing small growths called polyps during the test can stop cancer before it starts.
Participants were followed for up to 30 years to check how long the protection lasts.
Taking part helped provide key evidence used to shape modern NHS cancer screening.
Final analysis of the long-term study data is expected by March 2027.

Who may be eligible?

This trial recruited men and women aged between 55 and 64 who were registered with participating GP surgeries across England, Wales, and Scotland during the recruitment window.

People could not join if they had already had bowel cancer or had a strong family history of the disease, defined as two or more close relatives diagnosed with bowel cancer. People who had recently had an examination of their bowel, such as a colonoscopy or sigmoidoscopy, were also not eligible.

Additionally, the study was not suitable for anyone with a severe medical condition, a life expectancy of under five years, or anyone who was unable to give fully informed consent.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Aged between 55 and 64 at the time of recruitment
Registered with a participating GP surgery in England, Wales, or Scotland
No personal history of bowel cancer
No strong family history of bowel cancer (fewer than two close relatives affected)
No recent bowel camera tests (such as a colonoscopy or sigmoidoscopy)
Able to give informed consent and in generally stable health

Answer every question to see your result.

What does participation involve?

Participants were split by chance into two groups. One group was invited for a one-off flexible sigmoidoscopy examination at a local hospital endoscopy clinic. The other group received standard NHS care, which did not include routine screening at the time. The camera test takes about 10 to 15 minutes, and any small polyps found were safely removed during the procedure. There was no need for regular medication or ongoing hospital visits after the test. Instead, researchers follow up on participants' health records over several decades—up to 2024, with final results reported by 2027—to see if the screened group had fewer bowel cancer cases over their lifetimes.

Potential risks and benefits

The main benefit of taking part was the chance to have early bowel growths detected and safely removed, which can stop bowel cancer from developing. For those in the usual care group, their regular NHS healthcare was unchanged. Possible risks included brief discomfort, mild tummy cramps, or very rare complications like slight bleeding or a small tear in the bowel lining from the camera. Some people also felt brief anxiety waiting for test results. Taking part in clinical trials is always completely voluntary, and participants have the right to withdraw at any time without their regular medical care being affected.

Locations (1)

Imperial College London
Approximate
London, England

Common questions

What is a flexible sigmoidoscopy?

It is a short test where a healthcare professional uses a thin, flexible tube with a camera to look at the lower part of your bowel and check for small growths.

Does having a bowel scope test hurt?

Most people find it slightly uncomfortable or feel mild period-like cramps, but it is generally quick and does not usually require a general anaesthetic.

Why was the test only done once?

The researchers wanted to discover whether a single screening around age 60 could offer enough long-term protection against bowel cancer for the rest of a person's life.

Can people still join this trial today?

No, recruitment took place between 1994 and 1999. The trial is now in its long-term follow-up and analysis phase, which runs until 2027.

How does this study help current NHS bowel screening?

The results help doctors understand how well bowel scope tests prevent cancer over decades, helping the NHS decide which screening methods work best.

How to find out more

Amanda Cross

amanda.cross@imperial.ac.uk - Official trial record

Always speak to your GP or specialist before deciding to take part in a study.