Around 1 in 5 people diagnosed with cancer in the UK take part in a clinical trial.
A trial comparing 2 different ways of doing a colonoscopy to screen for bowel cancer (CONSCOP)
This trial looked at a way of doing a colonoscopy that involves spraying a blue dye throughout the large bowel. This is called contrast enhanced colonoscopy or chromocolonoscopy.
Everyone that took part had already given a poo (stool) sample as part of the NHS Bowel Cancer Screening Programme in Wales.
The bowel cancer screening programme aims to detect bowel cancer when it is at an early stage and treatment is more likely to work. It can also reduce the risk of bowel cancer developing in the first place by finding and removing small growths called polyps. If polyps aren’t removed, they may develop into cancer.
Cancer Research UK supported this trial.
More about this trial
This study started in 2014 and researchers looked at these results in 2018.
At the time this study was done, the NHS Bowel Cancer Screening Programme in Wales used a test called faecal occult blood (FOB) test to look for hidden traces of blood in poo samples. Hidden traces of blood can be a sign of bowel cancer.
You have a test called colonoscopy if the FOB test shows blood in your poo. A doctor or specialist nurse uses a small camera on the end of a thin, flexible tube to look inside your bowel. If they see polyps during the colonoscopy, they can remove them.
But some people develop bowel cancer despite having a colonoscopy as part of the screening programme. These cancers are usually in the upper part of the large bowel, on the right hand side. They are sometimes caused by a type of polyp called serrated polyp. Serrated polyps are often flat and difficult to see during a colonoscopy.
Doctors wanted to see if spraying a blue dye throughout the upper part of the large bowel helps to find more serrated polyps. This is called a contrast enhanced colonoscopy or chromocolonoscopy.
The main aim of this trial was to find out whether a contrast enhanced colonoscopy is safe and can be used in the screening programme. If successful, then doctors want to do a larger trial to see if the contrast enhanced colonoscopy finds more people with serrated polyps that are close to become cancer.
Summary of results
- 381 people joined the contrast enhanced colonoscopy group
- 360 people joined the normal colonoscopy (standard test) group
Number of polyps found
- 903 polyps found in the contrast enhanced colonoscopy group
- 570 polyps found in the standard colonoscopy group
- 45 out of the 381 people (almost 12%) who joined the contrast enhanced colonoscopy group had serrated polyps
- 23 out of the 360 people (about 6%) who joined the standard colonoscopy group had serrated polyps
- 5 people had bleeding from the bowel
- 1 person had anxiety and a very fast breathing (hyperventilation)
- around 37 minutes to do a contrast enhanced colonoscopy
- around 31 minutes to do a standard colonoscopy
How to join a clinical trial
Dr Sunil Dolwani
Cancer Research UK
Health and Care Research Wales
Wales Cancer Trials Unit (WCTU)