Randomised controlled trial of contrast-enhanced colonoscopy in the reduction of right-sided bowel cancer

Background and study aims
The UK Bowel Cancer Screening Programme has reduced the risk of death from bowel cancer by 15%. People testing positive on a bowel cancer screening stool test are offered colonoscopy (bowel camera examination) through the UK Bowel Cancer Screening Programme. About half of those have cancers or polyps (small abnormal growths that might lead to cancer in the future) found on colonoscopy. There is some evidence to suggest that these cancers could be caused by a certain type of flat polyp called a serrated polyp which can be difficult to detect during standard colonoscopy. Small studies have suggested that these polyps and may grow into cancer faster than the usual polyps and up to 1 in 5 bowel cancers may actually have developed from these subtle serrated polyps. Moreover, deaths from cancer of the upper bowel are not reducing.
This study will investigate if spraying a blue dye in the upper large bowel helps the doctor to detect more flat polyps during the colonoscopy. At the moment it is not known if spraying the dye in the upper large bowel is the best way to improve detection so participants who are due to have a screening colonoscopy will be randomly assigned into two groups; one to have a standard colonoscopy and the other to have a colonoscopy using the dye spray. This will allow a comparison of what happens between the two groups. The aim is to find out through this study if this method works in practice and improves the detection and removal of more serrated polyps within the screening programme.
Who can participate?
All participants in the UK bowel screening programmes (Wales, England, Scotland) who test positive on the FIT test (bowel cancer screening stool test) and are eligible for an index screening colonoscopy. Participants will only be ineligible for the study if they have received previous resectional colorectal surgery (as this would influence both study methods and outcomes depending on the length of residual colon in the individual), and/or have a known allergy to food colouring agent (as the Indigo Carmine dye is a safe food colouring agent but extremely rarely there may be individuals with a specific allergic response to this in the past).
What does the study involve?
Participants are randomly allocated into two groups; one to have a standard colonoscopy and the other to have a colonoscopy using the dye spray. They are followed up through routinely collected data systems/