Su1432 I-SCAN Detects More Polyps in Lynch Syndrome (HNPCC) Patients: A Prospective Controlled Randomized Back-to-Back Study

Abstract

I-SCAN Detects More Polyps in Lynch Syndrome (HNPCC) Patients: A Prospective Controlled Randomized Back-to-Back Study Raf Bisschops*, Sabine Tejpar, Hilde Willekens, Gert De Hertogh, Eric Van Cutsem Gastroenterology/Endoscopy, University Hospital UZ Leuven, Leuven, Belgium; Pathology, University Hospital UZ Leuven, Leuven, Belgium Background: Narrow-band imaging and chromo-endoscopy have been reported to detect more polyps in comparison to (high definition) white light endoscopy (HDWL) in hereditary non-polyposis colonic cancer (HNPCC) patients in a backto-back study. However, no randomisation for the order of imaging method was applied. I-scan with tone enhancement (TE) is a new form of digital chromoendoscopy. We aimed to assess the additional value of the i-scan TE system in polyp detection in HNPCC. Method: 49 HNPCC patients underwent a back-toback colonoscopy (Pentax EC3890Fi) with two imaging modalities and were randomized in 2 groups. Group 1 underwent HDWL first followed by i-scan, group 2 i-scan first followed by HDWL. For HDWL, standard settings and for i scan, the i-scan 2 preset (surface enhancement 4, TE c-modus) were used on a Pentax Hi-line processor. Patients with clinical diagnosis or proven gene abnormality for HNPCC were included in the study. Patients with known neoplasia or colectomy with 50cm remaining colon were excluded. Bowel preparation after PEG solution was assessed using the Bristol Bowel preparation scale (BBPS). Patients with a BBPS 6 were excluded. Total inspection time was calculated after subtracting the time needed for polypectomy. Lesion detection rate (total number of lesions for each method/total procedures) and the miss rate ( number of lesions/adenomas detected during second inspection/total number of lesions/adenomas in that group) were assessed. Results: 25 and 24 patients were included in group 1 and 2 respectively (mean age 45.3 1.69, 25 male). There was no difference in age or BBPS. The lesion detection rate was 0.73 019 for i-scan and 0.36 0.12 for HDWL (p 0.095). In group 1, 14 lesions were detected with HDWL first and 15 with subsequent i-scan. In group 2, 21 lesions were detected with i-scan first and 4 with subsequent HDWL. The miss rate for endoscopic lesions was 52% and 16 % respectively and was significantly different in favor of i-scan (p 0.01 95% CI 0.38 to 0.87). Similarly, 5 adenomas were detected with HDWL vs 7 with i-scan in group 1. In group 2, i-scan detected 13 of the 15 adenomas, resulting in a miss rate of 58% and 13% respectively (p 0.05 95% CI 0.24 to 0.96). The higher miss rate in group 1 was not due to a shorter inspection time. On the contrary, in general the second inspection time was significantly shorter than the first one (407 19 vs 503 24 sec, p 0.01) and inspection time during the second pass was not significantly different between group 1 and 2 (427 24 vs 384 32 sec resp p 0.27). Conclusion: In patients with HNPCC the miss rate for polyps is significantly reduced during colonoscopy performed with i-scan in comparison to HDWL, independently from inspection time. These findings add to the evidence that HNPCC may be a good indication for (virtual) chromoendoscopy.