Dye chromoENDOscopy versus virtual chromoendoscopy for assessment of the ileo-anal pouch in patients with familial adenomatous POLyposis: a randomized controlled trial

Familial adenomatous polyposis (FAP) is an inherited gastrointestinal disorder
in which patients develop extensive polyps in the colon that, if left
untreated, lead to colon cancer. As a preventive measure, patients are
endoscopically monitored and the colon is typically removed before the age of
25. This operation can be performed with the possibility of either rectum
preservation via ileorectal/ileosigmoidal anastomisis or a pouch procedure.
However, polyps can still form in the pouch, remaining rectum, and upper
gastrointestinal tract after the operation.

Various modalities are utilized to surveil these patients, including
high-definition endoscopy, virtual chromoendoscopy, and dye chromoendoscopy.
While both virtual and dye chromoendoscopy have been proven effective in
detecting polyps, guidelines currently lack recommendations regarding the
preference for a particular modality, and some centers utilize both modalities.

This study aims to examine the difference in adenoma detection through the use
of these modalities. Adenomas can develop in the pouch, with the incidence of
cancer in the pouch being described as 1-2%. Optimizing endoscopic surveillance
techniques in FAP patients is crucial to 1) prevent the development of cancer
and 2) avoid the need for a pouch excision.

The primary outcome of this study is the detection of clinical relevant
adenomas (>= 5mm) in the ileal pouch.

This study is designed as an international multi-center randomized controlled
trial with an estimated duration of 2 years. Patients will undergo their
scheduled regular surveillance pouchoscopy, performed by endoscopists with
experience with FAP. Prior to the endoscopy, patients will be randomly assigned
to undergo pouchoscopy with dye-based chromoendoscopy or with NBI/BLI (virtuel
chromoendoscopy). After diagnostic assessment, adenomas with an indication for
endoscopic intervention will be removed.

Both interventions are standard care for detecting adenomas.

1. Virtual chromoendoscopy
2. Dye chromoendoscopy

Both interventions are standard care, and pouchoscopies are not scheduled more
frequently than previously agreed upon for the surveillance of FAP patients.

The standard risks of pouch endoscopy will be considered similar to the risks
of colonoscopy:

Gastrointestinal risks:
- Perforation occurs in 4 per 10,000 endoscopies
- Bleeding at biopsy or polypectomy site. A major haemorrhage occurs in 8 per
10,000

Non-gastrointestinal risks
- Sedation-related change in breathing, heart rate and blood pressure
- Pulmonary, cardiovascular, and cerebrovascular complications are rare and are
associated with an older age and increasing comorbidity