Narrow-band imaging observation of colorectal lesions using NICE classification to avoid discarding significant lesions

AIM: To assess the risk of failing to detect diminutive and small colorectal cancers with the "resect and discard" policy.METHODS: Patients who received colonoscopy and polypectomy were recruited in the retrospective study. Probable histology of the polyps was predicted by six colonoscopists by the use of NICE classification. The incidence of diminutive and small colorectal cancersand their endoscopic features were assessed. RESULTS: In total, we found 681 cases of diminutive(1-5 mm) lesions in 402 patients and 197 cases of small(6-9 mm) lesions in 151 patients. Based on pathology of the diminutive and small polyps, 105 and 18 were non-neoplastic polyps, 557 and 154 were low-grade adenomas, 18 and 24 were high-grade adenomas or intramucosal/submucosal(SM) scanty invasive carcinomas, 1 and 1 were SM deeply invasive carcinoma, respectively. The endoscopic features of invasive cancer were classified as NICE type 3 endoscopically.CONCLUSION: The risk of failing to detect diminutive and small colorectal invasive cancer with the "resect and discard" strategy might be avoided through the use of narrow-band imaging observation with the NICE classification scheme and magnifying endoscopy.

Prospective real-time evaluation of diagnostic performance using endocytoscopy in differentiating neoplasia from nonneoplasia for colorectal diminutive polyps(≤ 5 mm)

AIM To clarify the diagnostic performance of endocytoscopy for differentiation between neoplastic and nonneoplastic colorectal diminutive polyps.METHODS Patients who underwent endocytoscopy between October and December 2016 at Sano Hospital were prospectively recruited. When diminutive polyps(≤5 mm) were detected, the lesions were evaluated by endocytoscopy after being stained with 0.05% crystal violet and 1% methylene blue. The diminutivepolyps were classified into five categories(EC 1 a, 1 b, 2, 3 a, and 3 b). Endoscopists were asked to take a biopsy from any lesion diagnosed as EC1 b(indicator of hyperplastic polyp) or EC2(indicator of adenoma). We have assessed the diagnostic performance of endocytoscopy for EC2 and EC1 b lesions by comparison with the histopathology of the biopsy specimen. RESULTS A total of 39 patients with 63 diminutive polyps were analyzed. All polyps were evaluated by endocytoscopy. The mean polyp size was 3.3 ± 0.9 mm. Among the 63 diminutive polyps, 60 were flat and 3 were pedunculated. The mean time required for EC observation, including the time for staining with crystal violet and methylene blue, was 3.0 ± 1.9 min. Histopathologic evaluation showed that 13 polyps were hyperplastic and 50 were adenomas. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of EC2 for adenoma compared with EC1 b for hyperplastic polyp were 98.0%, 92.3%, 96.8%, 98.0% and 92.3%, respectively. There were only two cases of disagreement between the endoscopic diagnosis made by endocytoscopy and the corresponding histopathological diagnosis.CONCLUSION Endocytoscopy showed a high diagnostic performance for differentiating between neoplastic and non-neoplastic colorectal diminutive polyps, and therefore has the potential to be used for "real-time histopathology".

Post-colonoscopy colorectal cancer rate in the era of highdefinition colonoscopy

AIM To investigate the post-colonoscopy colorectal cancer(PCCRC) rate for high-definition(HD) colonoscopy compared with that for standard-definition colonoscopy reported previously.METHODS Using medical records at Sano Hospital(SH) and Dokkyo Medical University Koshigaya Hospital(DMUKH), we retrospectively obtained data on consecutive patients diagnosed as having CRC between January 2010 andDecember 2015. The definition of PCCRC was diagnosis of CRC between 7 and 36 mo after initial high-definition colonoscopy that had detected no cancer, and patients were divided into a PCCRC group and a non-PCCRC group. The primary outcome was the rate of PCCRC for HD colonoscopy. The secondary outcomes were factors associated with PCCRC and possible reason for occurrence of early and advanced PCCRC.RESULTS Among 892 CRC patients, 11 were diagnosed as having PCCRC and 881 had non-PCCRC. The PCCRC rate was 1.7%(8/471) at SH and 0.7%(3/421) at DMUKH. In comparison with the non-PCCRC group, the PCCRC group had a significantly higher preponderance of smaller tumors(39 mm vs 19 mm, P = 0.002), a shallower invasion depth(T1 rate, 25.4% vs 63.6%, P = 0.01), a non-polypoid macroscopic appearance(39.0% vs 85.7%, P = 0.02) and an earlier stage(59.7% vs 90.9%, P = 0.03). Possible reasons for PCCRC were "missed or new" in 9 patients(82%), "incomplete resection" in 1(9%), and "inadequate examination'" in 1(9%). Among 9 "missed or new" PCCRC, the leading cause was non-polypoid shape for early PCCRC and blinded location for advanced PCCRC.CONCLUSION The PCCRC rate for HD colonoscopy was 0.7%-1.7%, being lower than that for standard-definition colonoscopy(1.8%-9.0%) reported previously employing the same methodology.