Panchromoendoscopy for the Surveillance of Serrated Polyposis Syndrome, a Multicenter, Prospective and Randomized Trial.

Serrated polyposis syndrome (SPS) is the most common colorectal polyposis syndrome and is characterized by the combination of large and/or numerous serrated lesions (SLs) throughout the colorectum. SLs are classified into sessile serrated polyps (SSP) with or without dysplasia, hyperplastic polyps (HP) and traditional serrated adenomas (TSA). In 2010 the World Health Organization (WHO) defined this syndrome by any one of the following conditions: criterion I, at least 5 SLs proximal to the sigmoid colon with 2 or more of these being >10mm in size; criterion II, any SLs proximal to the sigmoid colon in a first-degree relative with SPS; criterion III, more than 20 SLs of any size distributed throughout the colon. It has been demonstrated that 11.8-28.5% of patients with SPS present with colorectal cancer (CRC) at diagnosis. Tandem colonoscopy studies have demonstrated that a significant number of lesions are missed during conventional colonoscopy. This finding is even more evident when focusing SLs where a 31% miss rate has been reported. SLs are often overlooked due to their typical appearance: flat morphology, similar colour to the surrounding mucosa, subtle and indistinctive borders. Chromoendoscopy (dye spraying onto the surface of the colon) enhances the detection of subtle and flat polyps in the colon. Until the date no studies have assessed the use of dye-based chromoendoscopy in SPS patients.

The aim of this trial was to evaluate the usefulness of panchromoendoscopy with indigo carmine for the detection of polyps in the colon in patients with SPS. Secondary aims were to estimate the SLs and adenoma miss rates in these patients.

Patients were randomized in a 1:1 distribution to one of the two arms of the study by a list of random numbers distributed by the coordinator center. After randomization, patients were submitted to tandem colonoscopies by the same endoscopist:

• In group A (HR-WLE) the first inspection was on high-resolution white-light endoscopy from the cecum/ileo-colonic anastomosis to the rectum, followed by a second inspection also on HR-WLE.
• In group B (HR-CE) the first inspection was on HR-WLE from the cecum/ileo-colonic anastomosis to the rectum, followed by a second inspection with panchromoendoscopy. For this, the lumen was sprayed in a segmental fashion using 0.4% indigo carmine delivered via a specially designed dye spray catheter (Olympus PW-5V1) or via the accessory channel with a 50cc syringe filled with indigo carmine and air. After allowing a few seconds for the dye to settle onto the mucosal surface, excess pools of indigo carmine were suctioned and the mucosa was then scrutinised.

Time to withdrawal from the cecum was measured using a stopwatch excluding time needed for polypectomy and biopsies.

Lesions detected during each inspection were described and then removed. Size (measured in comparison with an open biopsy forceps), morphology (using the Paris classification), location and polypectomy technique were recorded before removal. Histology was used as gold standard.