Endoscopic surveillance using narrow-band imaging in patients with hyperplastic polyposis syndrome (HPS): A multicentre cohort study

Hyperplastic polyposis syndrome (HPS) is characterized by the presence of
multiple colorectal serrated polyps and co-existent conventional adenomas and
is associated with an increased colorectal cancer (CRC) risk. Considering the
presumed increased risk of malignant progression of polyps in HPS, detection
and removal of polyps seems necessary to prevent CRC development in these
patients. In HPS however, serrated polyps, which are the overall majority, are
generally small in size, flat in shape and unremarkable in colour. These
features are associated with polyp miss-rates of up to 26% using standard
colonoscopy. Narrow-band imaging (NBI) may improve the detection and
differentiation of these polyps. In a recent randomized cross-over study from
our group, comparing NBI with standard white-light endoscopy (HRE) for the
detection of polyps in HPS, we demonstrated that NBI had a significantly lower
polyp miss-rate than HRE (10% versus 36%; OR 0.21; p<0.001) in HPS 1. However
this pilot study was performed by a single endoscopist in one academic centre.
To confirm these findings, a subsequent multi-centre study involving more
patients and multiple endoscopists is required.

To prospectively compare NBI with HRE for the detection and differentiation of
polyps in HPS in a large multicentre HPS cohort (n~125).

All HPS patients will be invited to undergo tandem colonoscopy with HRE and NBI
for their first prospective screening round or their annual prospective
surveillance colonoscopy. All individuals will be prepared with 4 litre Poly
Ethylene Glycol solution (Kleanprep) or 2 liters PEG (Moviprep) with an
additional 2 liters of fluids. All procedures will be performed under conscious
sedation with midazolam and/or fentanyl, according to current clinical
practice. Cecal intubation is confirmed by identification of the appendiceal
orifice and ileocecal valve.
Subsequently, each colonic segment (ascending, transverse, descending and recto
sigmoid colon) will be inspected twice; by both HRE and NBI. The order of the
two techniques will be determined by the randomization procedure. During the
withdrawal phase, each segment of the colon will be meticulously inspected for
the presence of lesions of 3mm in size and larger. When lesions are found they
will be classified according to the shape (Paris classification).49 In
addition, the size (estimated by an opened biopsy forceps which measures 8 mm),
localization (part of colon and distance from the anus), predicted histology of
each lesion and VPI with NBI and with HRE will be recorded. Subsequently,
digital still images of the lesion with both imaging modes (HRE and NBI) will
be taken. Immediately after these images are taken, the lesion will be removed.
After having inspected a segment with the first imaging modality and removal of
all detected lesions by the first technique, the endoscope is advanced again to
the beginning of the colonic segment and the other mode will be used for the
second inspection of the same segment. If new lesions are found, the above
mentioned polyp characteristics will be recorded before removal of the lesions.
A maximum time of approximately 1.5 hours will be used for the endoscopic
procedure; otherwise examination times become too long and the procedure
becomes too inconvenient for the patient. One investigator or research nurse
will be present during the procedure to collect procedure data using a case
record form.

The endoscopic procedure in this study is comparable to the standard procedure
for regular patient care except that each segment of the colon will be
inspected twice, which may lead to increasing the procedural time with about 15
minutes. Increasing the procedural time does not increase the risk of
complications. The risk of a diagnostic colonoscopy is minimal (< 1%)