Colon tumors and colonoscopy R. Singh, 1,2 M.J. Bourke, 3 M. Jayanna, 1 G. Nind 1 Adelaide, South Australia, and Sydney, NSW, Australia

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1 DDW HIGHLIGHTS Colon tumors and colonoscopy R. Singh, 1,2 M.J. Bourke, 3 M. Jayanna, 1 G. Nind 1 Adelaide, South Australia, and Sydney, NSW, Australia The 2012 Digestive Disease Week (DDW; May, San Diego, California, USA) received a record number of submissions on colonoscopy and colorectal cancer (CRC). Scientific presentations focused primarily on colonic polyps and can be broadly divided into polyp detection, characterization, and resection. Among the more interesting topics were the novel concept of polypectomy rate, newer-generation optical imaging technology, and advanced endoscopic resection techniques. DETECTION DISCLOSURE: The authors disclosed no financial relationships relevant to this publication. This report is published simultaneously in the journals Gastrointestinal Endoscopy and Endoscopy. Copyright 2012 by the American Society for Gastrointestinal Endoscopy and Georg Thieme Verlag KG /$ The American Society for Gastrointestinal Endoscopy requests that this document be cited as follows: Singh R, Bourke MJ, Jayanna M, et al. Colon tumors and colonoscopy. Gastrointest Endosc 2012;76: For screening colonoscopy, an adenoma detection rate (ADR) of 25% and 15% are recommended benchmarks in men and women, respectively. Although ADR is a robust quality indicator for colonoscopy, it is not available to the endoscopist at the time of the procedure. Calculation of the ADR requires a subsequent cumbersome correlation of endoscopy and pathology reports. Limited data suggest that polypectomy rate correlates well with ADR and has been proposed as a useful quality indicator of colonoscopy. In an interesting study, Gohel et al. 1 evaluated the polypectomy rate as a simple and reliable real-time tool to monitor quality during colonoscopy. A total of 7382 colonoscopy reports from 66 endoscopists (41 gastroenterologists, 15 colorectal surgeons, 7 general surgeons, and 3 other proceduralists) acquired during were reviewed. Up to 120 procedures per endoscopist were randomly selected. Colonoscopy findings, including quality of preparation, polyp size, location, morphology, and pathology, were retrieved. Patients with good or excellent bowel preparation were included, and exclusions were incomplete colonoscopy, fair or poor bowel preparation, prior colon resection, familial adenomatous polyposis, hereditary nonpolyposis colorectal cancer, and inflammatory bowel disease (IBD). ADR was defined as the percentage of colonoscopies with at least one adenoma detected and, similarly, the polypectomy rate was defined as the percentage of colonoscopies in which at least one polyp was removed. Paired t tests and linear regression analysis were used for statistical analysis. Colonoscopies of 3337 average-risk patients met the inclusion criteria. The mean age of patients was years, and 49.5% were men. The ADR and polypectomy rate in men were and , respectively. The ADR and polypectomy rate in women were and , respectively. There was good correlation between ADR and polypectomy rate in both men and women. The authors concluded that to obtain the benchmark ADR in men (25%) and women (15%), endoscopists needed polypectomy rates of 35% and 25%, respectively. This interesting concept, though practical, has a few drawbacks namely the polypectomy rate being a surrogate of another surrogate (ADR). It may also be subject to gaming, where endoscopists could potentially perform a suboptimal examination in the right colon and only resect rectosigmoid polyps in order to falsely produce a high polypectomy rate. However, incorporation of a segment-specific polypectomy rate (e.g. right colon vs. left colon) could overcome this limitation. These findings strengthen prior proposals that polypectomy rate might be useful as a quality indicator for colonoscopy. As polypectomy rate can be tracked by endoscopists during sequential colonoscopies, it may also serve as a real-time self-assessment tool and promote the quality and efficacy of colonoscopy. It is not known whether routinely inspecting and resecting adenomas on insertion improves the ADR. Sanaka et al. 2 evaluated the yield of adenoma detection by inspection during both insertion and withdrawal phases to see whether removal of polyps on the way in increases the yield. Patients undergoing screening or surveillance colonoscopy were randomized to undergo colonoscopy with inspection and removal of polyps performed during instrument withdrawal (control arm) or colonoscopy with inspection and removal of polyps performed during both instrument insertion and withdrawal (study arm). The primary outcome measure in both groups was the ADR. A total of 768 patients were randomized. After 151 exclusions, 617 were included in the analysis (328 in study arm and 289 in control arm). ADR (36% vs. 36.3%; P 0.93) Volume 76, No. 3 : 2012 GASTROINTESTINAL ENDOSCOPY 525

2 Colon tumors and colonoscopy Singh et al and polypectomy rate (57.3% and 55.7%; P 0.69) were similar in the study and control arms. The mean number of adenomas per patient was also similar ( in the study arm vs in the control arm; P 0.92). Mean insertion time was higher in the study group ( vs minutes; P 0.038). These results do not support a role for routine inspection during insertion. One of the main limitations of the study though was that the difference in the mean insertion time in the study and control arms was only 1 minute. Published data on the utility of the distal attachment cap to improve the yield of colonoscopy are conflicting. In an interesting and very methodological study, 3 the ADR in colonoscopies that were performed with and without a distal attachment cap was assessed. Utilizing MEDLINE and evidence-based medicine reviews (Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Review) randomized controlled clinical trials that compared the use of distal attachments with standard colonoscopy were identified by two independent reviewers. A total of 14 studies comprising 1629 patients met the inclusion criteria. The pooled ADR in patients who underwent colonoscopy with a cap was 46.6% (385/827) compared with 40.3% (323/802) without the cap. The heterogeneity between studies was low (I 2 8%). The mean number of adenomas detected per patient was marginally higher when a cap was used (mean difference 0.43; P 0.07; I 2 73%). The quality of evidence for both the ADR and mean number of adenomas detected was determined to be moderate. The use of a cap significantly increased the number of patients with at least one adenoma; however, the difference was in the detection of diminutive adenomas. The cap had no significant impact on the detection of adenomas in the right colon, on those 5 mm or larger, or on the mean number of advanced adenomas detected per patient. It was calculated that 17 colonoscopies with a cap would need to be performed in order to diagnose another patient with at least one adenoma. This additional yield must be balanced against the cost of using a disposable cap for each procedure and the increasing evidence that diminutive adenomas have an exceptionally low risk of harboring any cancer. Accurate and efficient surveillance in IBD remains problematic. In a multicenter randomized trial, Bisschops et al. 4 compared chromoendoscopy with narrow-band imaging (NBI) in patients with longstanding ulcerative colitis. In total, 52 patients were randomized to chromoendoscopy with 0.1% methylene blue and 41 to NBI. Both arms used an Olympus HQ 180 series colonoscope (Olympus, Tokyo, Japan). Only targeted biopsies of visible mucosal abnormalities were taken. Data were analyzed according to the number of patients who had suspected endoscopic lesions (per patient analysis) and also to the number of suspected endoscopic lesions (per lesion analysis). The median withdrawal time was significantly longer for chromoendoscopy (26 vs. 18 minutes; P 0.001). A total of 228 endoscopically raised lesions were detected in 68 patients (142 lesions in 39 patients with chromoendoscopy and 86 lesions in 29 patients with NBI). On histology, 35 were shown to be neoplastic (25 lesions in nine patients with chromoendoscopy and 10 lesions in seven patients with NBI) including 1 adenocarcinoma, 2 high grade dysplasia, 2 dysplasia-associated lesions or masses, and 14 adenoma-like masses. The 193 non-neoplastic lesions revealed normal mucosa or inflammatory changes (63%), inflammatory pseudopolyps (9%), and hyperplastic polyps (28%). There was no significant difference in the detection rate of true neoplastic lesions in endoscopically suspicious raised lesions (per patient analysis: 23.1% for chromoendoscopy vs. 24.1% for NBI [P 0.919]; per lesion analysis: 17.9% for chromoendoscopy vs. 11.8% for NBI [P 0.225]). The authors concluded that chromoendoscopy and NBI performed equally for the detection of neoplastic lesions in patients with longstanding ulcerative colitis. Given the easier applicability of NBI and the longer withdrawal time for chromoendoscopy, NBI could possibly replace chromoendoscopy as a lesion-detection tool in IBD. However, the study may have been underpowered to detect a per lesion difference. A study of this scale (undertaken over a 4-year period) would be difficult to replicate. Lau et al. 5 examined the added benefit of NBI in a multicenter randomized study across the Asia Pacific region. Average-risk patients ( 50 years) undergoing screening colonoscopy were invited to participate. A new-generation high definition colonoscope (EXERA III; Olympus) was used and the ADR of the two modalities (white light endoscopy [WLE] and NBI) were compared. A total of 441 patients were randomized (219 NBI, 222 WLE). Examination using NBI took longer ( vs minutes; P 0.03). In the NBI group, 48.9% of patients had 1 polyp detected compared with 54.1% of the WLE group (P 0.28). The number of polyps per polyp carrier was 2.1 and 2.03, respectively (P 0.47). A total of 144 and 148 adenomas, respectively, were found. A total of 14 advanced neoplasms were found in each group (P 0.99). Hence, both modalities were comparable. The results from this study are not dissimilar to previously published studies on the additional yield of electronic chromoendoscopy to WLE. The investigators also looked at negative predictive value (NPV) of diagnosing adenomas ( 5 mm) in the rectosigmoid region using NBI and the modified Sano s classification and found an NPV of 91.3%, which is above the threshold of 90% recommended by the American Society for Gastrointestinal Endoscopy (ASGE) guidelines for preservation and incorporation of valuable endoscopic innovations (PIVI). There has been a return of interest lately in the utility of flexible sigmoidoscopy (FSG) as a screening tool to reduce the incidence and mortality from distal CRC. In an interesting multicenter study undertaken by Schoen et al., 6 patients with positive FSG were subjected to a further 526 GASTROINTESTINAL ENDOSCOPY Volume 76, No. 3 :

3 Singh et al Colon tumors and colonoscopy evaluation using colonoscopy. This large study was part of the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, which enrolled more than patients over a 9-year period. Of the patients in the FSG intervention arm, (28.5%) had a polyp or mass. Of these patients, 80.5% (17772/22083) subsequently underwent diagnostic intervention, of which 95.6% (16990/17772) were colonoscopies. A colonoscopy rate of 21.9% (16990/77445) was therefore achieved as a direct effect of FSG screening. The incidence of CRC was 11.9/ person years in the intervention arm compared with 15.2/10000 person years in the standard/ usual care arm (relative risk 0.79). There was a 26% reduction in mortality due to CRC (3.9/10000 person years in the usual care arm [341 deaths] vs. with 2.9/10000 person years in the intervention arm [252 deaths]). It appears that screening with FSG followed by colonoscopy in patients with a positive examination could result in a clinically important decrease in overall CRC incidence and mortality. Further information on the effect on this intervention strategy in the right colon is eagerly awaited. CHARACTERIZATION Numerous studies looked at the utility of characterizing polyps that are detected during colonoscopy. Kaltenbach et al. 7 assessed the capability of the EXERA III system in predicting polyp histology by combining confidence levels to a validated NBI International Colorectal Endoscopic (NICE) classification. They compared the accuracy and confidence of NBI diagnosis of diminutive polyps by five colonoscopists, using two randomly assigned colonoscopes: a pre-commercially available CF- HQ190 colonoscope (Olympus) vs. a conventional high definition colonoscope (CF-H180; Olympus). For each polyp, the endoscopists stated the diagnosis (neoplastic vs. non-neoplastic) and assigned a confidence level to their diagnosis (high vs. low), then removed and submitted the polyp for histopathology. Initial endoscopic polyp diagnoses and surveillance recommendations were compared with the final histopathological diagnosis and surveillance recommendations. A total of 748 polyps in 311 patients in well-balanced study arms were assessed. The polyps were predominantly 5 mm (74.3%), neoplastic (65.6%), and right-sided (51.2%). Endoscopists were twice as likely to make a high-confidence diagnosis in diminutive polyps using the CF-HQ190 colonoscope (84.6%) than when using the CF-H180 colonoscope (71.5%) (odds ratio: 2.0; 95% confidence interval ; P ). These high-confidence diagnoses had 96% and 89% NPV with CF-HQ190 and CF-H180, respectively. The mean diagnostic time per polyp was seconds using either model. The authors found 95% agreement in the surveillance interval periods made using CF-HQ190, and 93% using CF-H180, compared with those made based on pathology results. They concluded that the findings of the newer-generation colonoscope do meet the recommended ASGE PIVI guideline for using endoscopic diagnosis in clinical practice. The benefits are most likely largely derived from the dual focus magnification function. This novel study adds to the growing data that diminutive rectosigmoid polyps can be assessed endoscopically and that the resect and discard policy can be applied safely. It remains to be seen, however, where the sessile serrated adenoma/polyp (SSA) fits into the NICE classification. The investigators did clarify that most of the sessile diminutive-to-medium-sized polyps detected in the right colon were graded with low confidence and removal and histological evaluation was recommended. Is it possible to reliably predict SSAs using endoscopic criteria? This question was addressed by a multicenter study spearheaded by the Academic Medical Centre in Amsterdam. 8 Endoscopic features of SSAs were assessed in a systematic manner. During an exploratory meeting, two expert endoscopists and one expert pathologist developed a standardized consensus of eight potential SSA features (cloud-like surface, irregular shape, indistinct borders, dark spots inside crypts, absence of tiny microvessels on the surface, Kudo s type I or II, normal vascular pattern intensity, and size). Subsequently, high resolution white light endoscopy (HRE) and NBI images of 150 polyps (SSAs, hyperplastic polyps, and adenomas) were divided into a learning set (60 polyps) and validation set (90 polyps). In the learning set, HRE and NBI images were combined and displayed to two expert endoscopists who were blinded to histopathology. In the validation set, 90 HRE images were followed by 90 corresponding NBI images and displayed to five expert endoscopists. Features found to be significantly associated with SSAs in the learning set were scored in the validation set, in which a feature was defined as present when at least three experts scored it as positive. All tissue specimens were examined by one pathologist. Images were derived from a prospectively collected database that included data from 49 patients with serrated polyposis syndrome who were undergoing surveillance. HRE and NBI images of 150 polyps (50 SSAs, 50 hyperplastic polyps, and 50 adenomas) were selected based on their quality. After assessment of both the learning and the validation set, three features were found to be independent predictors of SSA histology by multivariate analysis: cloud-like surface, irregular shape, and dark spots inside the crypts. These three features were used to develop a predictive algorithm, in which the image of a polyp was defined as SSA when two or all features were present. Using this algorithm, the accuracies of HRE and NBI for differentiation of SSAs were 80% and 90%, respectively (P 0.02). This is very promising and one wonders if confidence levels were utilized, whether accuracies demonstrated with NBI could have been even higher. Can some of these new classifications be learnt and how applicable are they in the community? Rastogi et al. 9 Volume 76, No. 3 : 2012 GASTROINTESTINAL ENDOSCOPY 527

4 Colon tumors and colonoscopy Singh et al looked at the impact of a computer-based teaching module on characterization of diminutive colon polyps using NBI by nonexperts from academia and community practice. A 20-minute audiovisual (Power Point) teaching module was developed demonstrating previously described criteria to differentiate adenomas from hyperplastic polyps using NBI. A total of 80 short video clips of 5-mm polyps with NBI without magnification were randomly allocated to pre- and post-test sets in a blinded fashion using a computer-generated random sequence stratified by polyp histology. Each set consisted of 40 videos (26 adenomas and 14 hyperplastic). Three groups of reviewers were recruited experts in NBI (Group A), nonexperts in academia (Group B), and nonexperts in community practice (Group C). All participants (five in each group) reviewed pre-test videos and reported their diagnosis and confidence level high ( 90%) or low ( 90%). They then viewed the teaching module followed by the post-test videos. The sensitivity, specificity, and accuracy were calculated by comparing predicted and actual histology for each group, both for pre- and post-tests. Fisher s exact test was used for statistical analysis. For nonexperts (Groups B and C), the accuracy improved significantly in post-test compared with the pre-test (81% vs. 64%; P 0.001). Accuracy of nonexperts was significantly lower than that of experts (Group A) in both pre-test (64% vs. 87%; P 0.001) and post-test evaluations (81% vs. 93%; P 0.001). In all three groups, accuracy was significantly higher when participants had high confidence in their diagnosis. Nonexperts made a greater proportion of high-confidence diagnoses following the teaching module (Group B: 69% vs. 49% [P 0.001]; Group C: 72% vs. 49% [P 0.001]). In a novel video-based assessment, practicing academic and community gastroenterologists can achieve significant improvements in both accuracy for polyp histology characterization and proportion of high-confidence diagnoses following a brief computer-based training module. However, PIVI thresholds were still not met in the nonexpert group. Further clinical experience and perhaps a longer training period may be required to surmount the final part of the learning curve before widespread implementation can be contemplated. RESECTION The Australian Colonic Endoscopic (ACE) resection study published last year assessed predictors of technical success and invasive disease in a multicenter cohort of large colonic lesions 20 mm. This follow-up study evaluated the long term recurrence after wide-field endoscopic mucosal resection (WF-EMR). 10 The optimal surveillance schedule following WF-EMR is unknown. Follow-up colonoscopy was performed in most patients at 4 months and 12 months with photo-documentation and biopsy of the scar. Of the 940 patients enrolled to date (May 2012), WF-EMR was attempted in 903 and was successful in 818 (91%). Of these 818, 604 (74%) have had follow-up colonoscopy at 4 months. A total of 513 (85%) had no recurrence. Of these, 193 have undergone 12- month colonoscopy, of whom only 1 (0.5%) had a late recurrence. This was a 30-mm-sized tubulovillous adenoma of the rectum. A total of 91 (15%) had early recurrence at 4 months, which was unifocal and diminutive in most cases and was treated endoscopically. Of these, 43 have undergone 12-month colonoscopy, of whom only 3 (7%) had persisting recurrence at 12 months. All three lesions were in the rectum or left colon, measured mm in size, and were tubulovillous adenomas with high grade dysplasia. The recurrence was successfully treated endoscopically in two of the three cases, but one required surgery for persisting recurrence in an inaccessible area. The authors concluded that early recurrence occurred in 15% of colonic WF-EMR cases, but was of little long term clinical significance as this could be successfully treated endoscopically in a single session in 91% of cases and requiring no more than two sessions in 97% of cases. The apparent clinical significance of low recurrence rates conferred by alternative techniques such as ESD may be overstated in the context of the increased complexity, costs, and risks associated with ESD compared with EMR. Late recurrence was rare in this study, occurring in 1% of cases where the interval colonoscopy was normal. Surveillance cannot be abandoned after 4 months, but a normal 4-month colonoscopy is reassuring. These results have implications for the timing of surveillance colonoscopy following EMR of large sessile lesions. In a related single-center study, Holt et al. 11 also assessed mucosal defects after WF-EMR in a systematic manner to look for potential features that could predict delayed bleeding, need for admission or perforation. A total of 342 consecutive patients referred for WF-EMR of large ( 20 mm) flat colonic polyps were enrolled over a 24- month period up to November Comprehensive demographic, procedural, and post-procedural data were collected. Multiple features in the colonic defect were assessed. Median polyp size was 30 mm (range mm) and 62% were in the right colon. A bland defect was seen in 34%, vessels in 41%, fibrosis in 23%, and deep resection in 9%. A total of 12 patients (5.8%) had postprocedural bleeding. Herniated vessels and increased number of vessels were significantly associated with intraprocedural bleeding. No features within the defect, including the presence, size, and number of vessels, were significantly associated with post-emr bleeding. Thus prophylactic coagulation of visible vessels to prevent delayed bleeding may not reduce bleeding risk. However, the presence of vessels and increasing number and size of vessels, exposed muscle, and muscularis propria resection (mirror target sign) were all significantly associated with the need for post-procedural admission. No defect feature predicted re-admission following discharge home. In summary, significant stig- 528 GASTROINTESTINAL ENDOSCOPY Volume 76, No. 3 :

5 Singh et al Colon tumors and colonoscopy mata within the defect predicted immediate outcomes such as bleeding and need for admission but did not seem to influence post-discharge outcomes. Characterization and interpretation of the post-emr defect is an evolving field of knowledge that requires ongoing study. It may prove useful in predicting outcomes and enhancing safety. Endoscopic resection of large early colorectal neoplasms are generally performed using the ESD technique in expert centers in Japan. This large prospective multicenter study undertaken by the Japanese Society for Cancer of the Colon and Rectum looked at outcomes and risk factors of colorectal ESDs for superficial colorectal neoplasia (CRN) in lesions larger than 20 mm in 15 specialized institutions. 12 Characteristics of the lesions and technical outcomes of ESD for CRN were collected and analyzed. Multivariate logistic regression analysis identified independent risk factors for technical difficulty of ESD, which was defined as procedural failure, procedural duration 2 hours or perforation. A total of 816 CRNs in 808 patients (mean age 67 years; 465 males; median tumor size 35 mm) underwent ESD. A total of 101 ESDs (12%) were performed in less-experienced institutions ( 30 cases) and 285 (35%) were performed by less-experienced endoscopists ( 11 years). In total, 520 (64%) of the lesions were located in the colon and 296 (36%) in the rectum. The lesions included 459 (56%) granular laterally spreading tumors (LSTs), 281 (34%) nongranular LSTs, 58 (7%) protruded lesions, and 5 recurrent lesions after previous endoscopic resection. Lifting by submucosal injection was poor in 208 cases (25%). En bloc resection was abandoned in 45 cases, with the procedure totally discontinued in 1 case and piecemeal resection performed in the other 44. The median procedure duration was 78 minutes (interquartile range minutes) and the operation time in 240 cases (29%) was longer than 2 hours. Perforation occurred in 17 cases (2%). Two cases (0.2%) underwent emergent surgery due to perforation and intraoperative bleeding. The histopathological examination disclosed 264 adenomas (32%) and 549 carcinomas (67%) according to Japanese criteria. A total of 663 lesions (81%) were intramucosal cancers, 88 (11%) deemed slightly invasive submucosal cancers (invasion 1000 microns), and 62 (7%) deeply invasive submucosal cancers (invasion 1000 microns). Larger lesions ( 40 mm), lesions attempted by less-experienced endoscopists ( 11 years) or in lessexperienced institutions, lesions with poor lifting, and deeply invaded submucosal cancers were the independent risk factors for technical difficulty of ESD for CRN. This study does raise some important questions. Close to one-third of the procedures extended beyond 2 hours, confirming the technical difficulty of ESD in the colon even among those who have world-leading experience in gastric ESD. Lifting was poor in a quarter of the lesions. En bloc resection though was possible in close to 95% of the cases, although more significantly 7% of the lesions were deeply invasive submucosal cancers that required further surgical intervention. A further 11% were deemed to be slightly invasive submucosal lesions. In most Western institutions, patients who are fit to undergo a surgical intervention may have been advised to do so given the inherent risks of lymph node metastases in this subgroup of patients. REFERENCES 1. Gohel T, Lankaala P, Podugu A, et al. Polypectomy rate (PR) a simple reliable tool that endoscopists can use to monitor quality during colonoscopy. Gastrointest Endosc 2012;75(4 Suppl):AB Sanaka MR, Parsi MA, Burke CA, et al. Comparison of adenoma detection by inspection during both insertion and withdrawal phases versus only withdrawal phase of colonoscopy: a randomized controlled trial. Gastrointest Endosc 2012;75(4 Suppl):AB Yague AS, Kaltenbach T, Anglemyer A, et al. To CAP or not to CAP during screening colonoscopy: a meta-analysis. Gastrointest Endosc 2012;75(4 Suppl):AB Bisschops R, Bessissow T, Baert FJ, et al. Chromoendoscopy versus narrow band imaging in ulcerative colitis: a prospective randomized controlled trial. Gastrointest Endosc 2012;75(4 Suppl):AB Lau JY, Teo EK, Rerknimitr R, et al. An interim analysis of an Asia-Pacific multicenter randomized study comparing colonoscopy using a new high definition system in either white light or narrow band imaging in the detection of adenomas in subjects undergoing screening. Gastrointest Endosc 2012;75(4 Suppl):AB Schoen RE, Pinsky P, Weissfeld J, et al. Effect of flexible sigmoidoscopy screening on incidence and mortality from colorectal cancer in the PLCO Screening Trail. Gastroenterology 2012;142(5 Suppl 1):S Kaltenbach T, Rastogi A, Rouse RV, et al. The valid colonoscopy study results of a multicenter prospective randomized controlled trial on real time colorectal polyp diagnosis using narrow band imaging (NBI). Gastrointest Endosc 2012;75(4 Suppl):AB Hazewinkel Y, Lopez-Ceron M, Rastogi A, et al. Validation of endoscopic features of sessile serrated adenomas by international experts using high resolution endoscopy and narrow band imaging. Gastrointest Endosc 2012;75(4 Suppl):AB Rastogi A, Rao DS, Gupta N, et al. Impact of a computer based teaching module on characterization of diminutive colon polyps using narrow band imaging (NBI) by non-experts in academics and community practice a video based study. Gastrointest Endosc 2012;75(4 Suppl): AB Moss A, Williams SJ, Hourigan LF, et al. Long term recurrence following wide field endoscopic mucosal resection (WF-EMR) for advanced colonic mucosal neoplasia results of the Australian Colonic EMR (ACE) multicenter prospective study of 940 patients. Gastrointest Endosc 2012;75(4 Suppl):AB Holt BA, Bassan MS, Trivedi S, et al. Interrogation of the mucosal defect after advanced endoscopic resection: predicting post-procedural outcomes. Gastrointest Endosc 2012;75(4 Suppl):AB Takeuchi Y, Saito Y, Iishi H, et al. Outcomes of colorectal endoscopic submucosal dissection and risk factors for technical difficulty: a prospective multi-center study on endoscopic treatment of large early colorectal neoplasms. Gastrointest Endosc 2012;75(4 Suppl):AB ADDITIONAL REFERENCES Detection Patel NC, Islam S, Wu Q, et al. Measurement of polypectomy rate using administration claims data with validation against the adenoma detection rate (ADR). Gastrointest Endosc 2012;75(4 Suppl):AB163. Borg FT, Brouwer EJ, Arbouw M, et al. 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6 Colon tumors and colonoscopy Singh et al domized placebo-controlled clinical trial. Gastrointest Endosc 2012;75(4 Suppl):AB168. Bisschops R, Tejpar S, Willekens H, et al. I-SCAN detects more polyps in Lynch Syndrome (HNPCC) patients: a prospective controlled randomized backto-back study. Gastrointest Endosc 2012;75(4 Suppl):AB330. Dzeletovic I, Pasha SF, Crowell MD, et al. Comparison of single-balloon versus double-balloon assisted colonoscopy for colon examination after previous incomplete colonoscopy using a standard colonoscope. Gastrointest Endosc 2012;75(4 Suppl):AB332. Uddin FS, Iqbal R, Harford W, et al. Prone vs. standard, left lateral decubitus position colonoscopy for obese patients: a randomised prospective study. Gastrointest Endosc 2012;75(4 Suppl):AB155. Daker C, Brier T, Besherdas K. Is colonoscopy required post CT scan confirming diverticultis? Gastrointest Endosc 2012;75(4 Suppl):AB404. Gupta S, Balasubramanian BA, Lash RH, et al. Polyps with advanced neoplasia are smaller in right versus left colon: a possible explanation as to why colonoscopy inconsistently protects against right-sided cancer. Gastroenterology 2012;142(5 Suppl 1):S-141. Coe SG, Wallace MB. Gender trends in detection: Should the guidelines for ADR change? Gastrointest Endosc 2012;75(4 Suppl):AB Characterization André B, Vercauteren TK, Buchner A, et al. Image-based semantic learning software for automatic detection of discriminative criteria used for probe-based confocal laser endomicroscopy (pcle) diagnosis of colorectal polyps. Gastrointest Endosc 2012;75(4 Suppl):AB329. Coe SG, Almansa C, Crook J, et al. Accuracy of in-vivo colorectal polyp discrimination using dual focus high definition narrow band imaging colonoscopy: a randomized controlled trial; preliminary results. Gastrointest Endosc 2012;75(4 Suppl):AB Singh R, Tam W, Jayanna M, et al. Preliminary feasibility study using a novel narrow band imaging system with dual focus magnification capability in differentiating colorectal polyps. Gastrointest Endosc 2012;75(4 Suppl): AB327. Ladabaum U, Fioritto A, Paik J, et al. A standardized learning module improves the accuracy of ex-vivo endoscopic diagnosis of polyp histology with narrow band imaging (NBI) by community based endoscopists. Gastrointest Endosc 2012;75(4 Suppl):AB152. Pohl H, Bensen SP, Berk BS, et al. Real time diminutive polyp diagnosis accurately determines colonoscopy surveillance interval in clinical practice. Gastrointest Endosc 2012;75(4 Suppl):AB151. Resection Ikematsu H, Yoda Y, Saito Y, et al. A large scale multi-center study of longterm outcomes after resection for submucosal invasive colorectal cancer (colon vs. rectum). Gastrointest Endosc 2012;75(4 Suppl):AB178. Sasajima K, Chinzei R, Oshima T, et al. Endoscopic submucosal dissection for early colorectal neoplasm: detailed analysis and strategy against fibrosis. Gastrointest Endosc 2012;75(4 Suppl):AB417. Cha JM, Lee J II, Joo KR, et al. Clinicopathological risk factors for early carcinoma in colorectal neoplasias according to Japanese and Western criteria. Gastrointest Endosc 2012;75(4 Suppl):AB423. Received June 27, Accepted June 27, Current affiliations: Lyell McEwin Hospital (1), University of Adelaide (2), Adelaide, South Australia, Australia, Westmead Hospital (3), Sydney, New South Wales, Australia. Reprint requests: R. Singh, MBBS, MRCP, MPhil, FRACP, AM, FRCP, Lyell McEwin Hospital, Adelaide, South Australia, Australia. Moving To ensure continued service please notify us of a change of address at least 6 weeks before your move. Phone Subscription Services at (outside the U.S. call ), fax your information to , or elspcs@elsevier.com. 530 GASTROINTESTINAL ENDOSCOPY Volume 76, No. 3 :