Bowel cancer screening saves lives, but it is far better at catching cancers on the left side of the colon than on the right, where tumours are harder to spot and more deadly. This trial tests whether spraying a blue dye during a colonoscopy—a technique called chromocolonoscopy—helps doctors find the flat, subtle lesions on the right side that often turn into cancer. The researchers will recruit 2,652 people from 20 screening centres across England, Wales, and Scotland, randomly assigning them to either standard high-definition white light colonoscopy or the dye-enhanced version. They will then compare how many significant lesions each method detects, and track patients for three years to see which approach leads to fewer cancers and deaths. If chromocolonoscopy proves superior, adopting it across UK screening programmes could cut bowel cancer incidence by an estimated 1%, saving the NHS in England roughly £10 million per year. The study also aims to personalise surveillance intervals, potentially reducing unnecessary follow-up colonoscopies and saving an additional £640,000 annually.
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Research question Does chromocolonoscopy lead to an increased proximal significant serrated lesion detection rate compared to standard (high definition white light) colonoscopy in participants of the UK bowel screening programmes who had a positive FIT and are eligible for colonoscopy? Background Screening has been shown to reduce colorectal cancer (CRC) incidence and mortality. This benefit is substantial in the reduction of distal CRCs, but modest for proximal colon cancers. Proximal CRCs have worse survival outcomes and often develop from serrated lesions that are more difficult to detect at colonoscopy. Some evidence suggests that detection of significant serrated polyps may be improved with chromocolonoscopy (colonoscopy using blue dye). There is also evidence to suggest that the current guidelines for allocating patients to different surveillance frequencies may be causing unnecessary colonoscopies. Aims and objectives Primary aim: Establish whether or not chromocolonoscopy should be used instead of standard HD white light for index colonoscopies within the UK bowel cancer screening programmes. We will compare significant proximal serrated lesion detection rates (and other lesion detection rates) for chromocolonoscopy and standard colonoscopy, assess the impact of FIT thresholds, and evaluate the longer-term economic impact of chromocolonoscopy within the screening setting, and model cancer detection and death rates for the two arms. Secondary aim: To understand the impact of demographic and lifestyle facts on polyp incidence and development in order to make recommendations about beneficial demographic and lifestyle factor changes and personalising and stratifying surveillance frequency. We will assess the association between demographic and lifestyle factors. We will also assess the association between demographic, lifestyle factors, polyps detected at index and polyps detected at surveillance colonoscopies. Methods We will conduct a multicentre, open-label, individually randomised controlled trial of standard versus chromocolonoscopy. We will recruit 2652 patients from 20 centres in England, Wales and Scotland and follow them up through routinely collected data systems. We will collect all proximal polyps removed at the index procedures for central review to ensure accurate assessment of the primary endpoint. Timelines for delivery. In stage 1 we aim to open the first site to recruitment in 6 months, recruit over 2 years, collect data on index colonoscopies and associated repeats and analyse the primary endpoint by the end of year 4. In stage 2 we aim to finish the follow up of all patients up to 3 years post index colonoscopy then analyse and report the secondary endpoints before the end of year 6. Anticipated impact and dissemination If successful we anticipate that chromocolonoscopy will be adopted into routine use in the UK screening programmes resulting in a reduction in the incidence of bowel cancer (reducing cancer incidence by 1% could save the NHS in England £10million per year). It could also prevent the need for unnecessarily frequent surveillance colonoscopies by personalising recommendations (reducing the number of surveillance colonoscopies at 1 year from 13% to 10% would save the NHS in England ~£640,000 per year) and increase awareness of factors that are associated with significant polyp development. Dissemination will be through academic papers, guidelines, charities, and public health bodies.
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