Background: Capillary patterns (CP) observed by magnifying Narrow Band Imaging (NBI) are useful for differentiating non-adenomatous from adenomatous colorectal polyps. However, there are few studies concerning the effectiveness of magnifying NBI for determining the depth of invasion in early colorectal neoplasms. We aimed to determine whether CP type IIIA/IIIB identified by magnifying NBI is effective for estimating the depth of invasion in early colorectal neoplasms. Methods: A series of 127 consecutive patients with 130 colorectal lesions were evaluated from October 2005 to October 2007 at the National Cancer Center Hospital East, Chiba, Japan. Lesions were classified as CP type IIIA or type IIIB according to the NBI CP classification. Lesions were histopathologically evaluated. Inter and intraobserver variabilities were assessed by three colonoscopists experienced in NBI. Results: There were 15 adenomas, 66 intramucosal cancers (pM) and 49 submucosal cancers (pSM): 16 pSM superficial (pSM1) and 33 pSM deep cancers (pSM2-3). Among lesions diagnosed as CP IIIA 86 out of 91 (94.5%) were adenomas, pM-ca, or pSM1; among lesions diagnosed as CP IIIB 28 out of 39 (72%) were pSM2-3. Sensitivity, specificity and diagnostic accuracy of the CP type III for differentiating pM-ca or pSM1 (<1000 μm) from pSM2-3 (≥1000 μm) were 84.8%, 88.7 % and 87.7%, respectively. Interobserver variability: κ = 0.68, 0.67, 0.72. Intraobserver agreement: κ = 0.79, 0.76, 0.75 Conclusion: Identification of CP type IIIA/IIIB by magnifying NBI is useful for estimating the depth of invasion of early colorectal neoplasms.

Background and study aims: Because of technical difficulty, colorectal endoscopic submucosal dissection (CR-ESD) is not widely performed. We aimed to determine risk factors for such technical difficulty as defined by long procedure duration (≥ 150 min), perforation, and piecemeal resection. Patients and methods: Patients with consecutive colorectal tumors treated with ESD between April 2006 and December 2010 were enrolled in a prospective cohort study. For prediction of technical difficulty, three types of factor were investigated: tumor location, tumor type, and colonoscopy-related. Cases were subsequently categorized into earlier and later periods (April 2006 – August 2008, 123 lesions; September 2008 – December 2010, 124 lesions). Variables were analyzed using multiple logistic regression, with subgroup analyses for each period. Results: 247 lesions were analyzed. Flexure location was an independent risk factor for technical difficulty as measured by longer procedure duration (odds ratio [OR] 4.1, 95 % confidence interval [95 %CI] 1.1 – 14.9), piecemeal resection (4.7, 1.1 – 17.2), or perforation (8.8, 1.1 – 56.8). Tumor with scarring or locally recurrent was a risk factor for longer procedure duration (4.7, 1.7 – 13.7), and for piecemeal resection (7.8, 2.4 – 25.0). Tumor of size ≥ 50 mm or spreading across ≥ 2 folds was the strongest independent risk factor for longer duration (6.3, 2.8 – 15.4), and was an independent risk factor for longer duration in both time periods (earlier, 3.3, 1.1 – 10.4; later, 27.4, 7.4 – 138.0). Flexure location was an independent risk factor for perforation (13.9, 1.5 – 129.1) and for piecemeal resection (5.1, 0.9 – 25.2) in the earlier but not the later period. Conclusions: Factors predicting technical difficulty of CR-ESDs were clarified. Their importance was influenced by the increasing experience of the endoscopist.