Small Colonic Polyps Research Articles

Abstract 151: Modeling the rise of intratumoral heterogeneity in growing, static, and regressing human colorectal polyps

Abstract Benign adenomatous colon polyps are thought to be transformed into cancers through the stepwise accumulation of mutations. However, not all polyps progress. A significant number remain static in size, regress, or resolve completely. The mechanisms underlying these differential fates are unknown, and currently there are no biological characteristics that can reliably predict which polyps will grow or progress into invasive cancer. To determine the mutational landscape, targeted next generation sequencing was performed on a unique collection of small (6-9mm) colorectal polyps with known growth rates based on interval imaging with CT colonography. To determine spatial location of identified mutations within a polyp, micro-dissection was performed followed by quantitative PCR to validate low frequency mutations. The mutational landscape of small polyps is varied both within and among individual polyps. Polyps carried 0-3 pathogenic mutations with the most frequent being in APC (67%, 32/48), KRAS/NRAS (17%, 8/48), BRAF (17%, 8/48), FBXW7 (10%, 5/48), and TP53 (8%, 4/48). Additionally, 13% (6/48) contained driver mutations at varied mutant allele frequencies, indicating the presence of subclonal populations. In silico modeling of tumor growth was used to determine the likely size at which additional driver mutations arose in order to observe those varied frequencies. This model of colon tumor growth was adapted so that mutations occur with a given probability of 10−5, which may change the fitness positively or negatively, and the lineage from these mutant subpopulations was tracked during tumor growth. In silico polyps were sectioned and mutant allele frequency was recorded and compared to the frequencies observed from the targeted sequencing of human polyps. Contrary to the slow step-wise accumulation of mutations theory, these data indicate small colonic polyps can have multiple pathogenic mutations in crucial driver genes that arise early in a tumor's existence. Understanding the molecular pathway of tumorigenesis and clonal evolution in polyps that are at risk for progressing to invasive cancers will allow us to begin to better predict which polyps may be more likely to progress into adenocarcinomas and which patients are predisposed to developing advanced disease. Citation Format: Chelsie K. Sievers, Luli Zou, Perry J. Pickhardt, Kristina A. Matkowskyj, Dawn Albrecht, David H. Kim, Fouad J. Moawad, Brooks D. Cash, Mark Reichelderfer, Michael A. Newton, Richard B. Halberg. Modeling the rise of intratumoral heterogeneity in growing, static, and regressing human colorectal polyps. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 151.

Su1668 Endoscopic Prediction of Advanced Histology in Diminutive and Small Colon Polyps; A Trimodal Imaging Analysis on 6170 Polyps

Su1668 Endoscopic Prediction of Advanced Histology in Diminutive and Small Colon Polyps; A Trimodal Imaging Analysis on 6170 Polyps

Su1729 Does Size Really Matter? Risk Factors for Advanced Histological Features in Subcentimetric Adenomas

Diagnostic imaging by CT colonography and capsule endoscopy is used to detect colonic lesions. The management of patients whose largest polyp is less than 10 millimetres (mm) is uncertain. On the other hand, a “predict, resect and discard” strategy for diminutive (≤5 mm) colon polyps has been proposed to save costs of screening colonoscopy. Our aim is to evaluate the rate and the risk of advanced histology within small colonic polyps (< 10 mm).

Can optical diagnosis of small colon polyps be accurate? Comparing standard scope without narrow banding to high definition scope with narrow banding.

To study the accuracy of using high definition (HD) scope with narrow band imaging (NBI) vs standard white light colonoscope without NBI (ST), to predict the histology of the colon polyps, particularly those < 1 cm. A total of 147 African Americans patients who were referred to Howard University Hospital for screening or, diagnostic or follow up colonoscopy, during a 12-mo period in 2012 were prospectively recruited. Some patients had multiple polyps and total number of polyps was 179. Their colonoscopies were performed by 3 experienced endoscopists who determined the size and stated whether the polyps being removed were hyperplastic or adenomatous polyps using standard colonoscopes or high definition colonoscopes with NBI. The histopathologic diagnosis was reported by pathologists as part of routine care. Of participants in the study, 55 (37%) were male and median (interquartile range) of age was 56 (19-80). Demographic, clinical characteristics, past medical history of patients, and the data obtained by two instruments were not significantly different and two methods detected similar number of polyps. In ST scope 89% of polyps were < 1 cm vs 87% in HD scope (P = 0.7). The ST scope had a positive predictive value (PPV) and positive likelihood ratio (PLR) of 86% and 4.0 for adenoma compared to 74% and 2.6 for HD scope. There was a trend of higher sensitivity for HD scope (68%) compare to ST scope (53%) with almost the same specificity. The ST scope had a PPV and PLR of 38% and 1.8 for hyperplastic polyp (HPP) compared to 42% and 2.2 for HD scope. The sensitivity and specificity of two instruments for HPP diagnosis were similar. Our results indicated that HD scope was more sensitive in diagnosis of adenoma than ST scope. Clinical diagnosis of HPP with either scope is less accurate compared to adenoma. Colonoscopy diagnosis is not yet fully matched with pathologic diagnosis of colon polyp. However with the advancement of both imaging and training, it may be possible to increase the sensitivity and specificity of the scopes and hence save money for eliminating time and the cost of Immunohistochemistry/pathology.

The Influence of Snare Size on the Utility and Safety of Cold Snare Polypectomy for the Removal of Colonic Polyps in Japanese Patients.

BackgroundCold snare polypectomy (CSP) has been recently reported to be useful for the removal of small colonic polyps. However, the relationship between the histologically complete resection rate and snare size used during CSP has not been reported. Our aim was to assess the utility of CSP.MethodsWe analyzed the histologically complete resection rates and the frequency of complications for 175 colon polyps removed by CSP. Moreover, we examined the histologically complete resection rate associated with different snare sizes used during CSP.ResultsThere was no significant difference in the histologically complete resection rate between endoscopic mucosal resection (EMR) (60.9%) and CSP (53.1%). There were also no significant differences in the frequency of complications including perforation and postoperative bleeding between EMR (perforation: none; postoperative bleeding: two patients) and CSP (perforation: none; postoperative bleeding: none). Histological examination revealed that the complete resection rate of CSP using a short snare (61.6%) was significantly higher than that of CSP using a long snare (44.9%; P < 0.05). There were no significant differences in the frequency of complications between CSP using the short snare and that using the long snare.ConclusionsCSP is a safe, useful method for the removal of colonic polyps. CSP using the short snare improved the histologically complete resection rates compared to the long snare. Future studies to further assess the utility of CSP are required.

Abstract 4799: Variation in mutational landscape among small colonic polyps with differential growth rates

Abstract Background: Benign adenomatous colonic polyps are transformed into cancers through the stepwise accumulation of mutations. However, not all polyps will progress. A significant number remain static in size, regress, or resolve completely. The mechanisms underlying these differential fates are unknown, and currently there are no biological characteristics that can reliably predict which polyps will grow or progress into invasive cancer. A multiancestral origin contributes to tumor heterogeneity and might provide additional growth promoting signals via increased genetic diversity. Methods: Utilizing a unique cohort of patients with small (&amp;lt;9mm) colorectal polyps in which growth was followed over a mean of 2.3 years by CT colonography, we performed next generation sequencing followed by micro-dissection and quantitative PCR to determine tumor origin. Results: The mutational landscape of small polyps is highly heterogeneous. Polyps carried 0 - 5 pathogenic mutations, with the most commonly altered gene being APC, which is considered the gatekeeper of the intestine. Interestingly, the percentage of cells harboring mutations in APC within a single polyp ranged from 2.0% to 70.6% with an average of 22.1%. In contrast, the frequency of a common APC single nucleotide polymorphism was 0% for non-carriers (n = 3), 55.9% for heterozygotes (n = 6), and 97.9% for homozygotes (n = 10). In the presence of an APC mutation, the average frequency of a second pathogenic mutation within a sample was 6.2% (n = 10). Conclusions: These data indicate that early intratumoral heterogeneity arising as a consequence of multiancestral origin affects tumor formation and growth. By determining the relative fitness advantage of heterogeneous polyps, we can begin to better predict which polyps may be more likely to progress into adenocarcinomas and which patients are predisposed to developing advanced disease. Citation Format: Chelsie K. Sievers, Perry J. Pickhardt, Kristina Matkowskyj, Dawn Albrecht, Luli Zou, David Kim, Meghan Lubner, Mark Reichelderfer, Richard Halberg. Variation in mutational landscape among small colonic polyps with differential growth rates. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4799. doi:10.1158/1538-7445.AM2015-4799

PTH-011 Defining the optimal i-scan settings for small colonic polyp characterisation – results from a large prospective series: Abstract PTH-011 Table 1

Introduction Characterisation of small colonic polyps has been identified as a key goal for advanced imaging modalities by the ASGE and ESGE. Pentax i-Scan is an endoscopic digital contrast technology shown to be an accurate tool for characterising small colonic polyps in-vivo. I-Scan combines features which accentuate dark-light borders (surface and contrast enhancement, SE/CE) and suppression of red light whist enhancing blue/green light (tone enhancement, TE). The optimal settings for use of i-Scan in the colon have yet to be determined. Method High quality digital images of 100 small colonic polyps were recorded as part of a prospective study (NCT 01761279). Images of each polyp were recorded in 3 i-Scan modes: i-Scan 1 (SE/CE), i-Scan 2 (TE) and i-Scan 3 (SE/CE/TE). Randomised images were viewed by 2 blinded endoscopists who rated visibility of diagnostic features and predicted polyp histology (neoplastic vs non-neoplastic). Results The proportion of adenomas rated as having visible pericryptal vessels were 59%, 81% and 82% for i-Scan 1, 2 and 3 respectively. The differences between i-Scan 1 and 2 (P = 0.001) and i-Scan 1 and 3 (P The difference in proportion of adenomas with no visible surface pattern between i-Scan 1 and 2 was statistically significant (26% vs 8%, P = 0.001), as was the difference between i-Scan 1 and 3 (26% vs 9%, P = 0.003). There was no significant difference between i-Scan 2 and 3 (8% vs 9%, P = 1.00). Mean sensitivity for adenomatous histology between the two endoscopists was 69% for polyps viewed with i-Scan 1. Compared to i-Scan 1 assessments sensitivity was significantly higher with i-Scan 2 (86%, P = 0.006 for comparison), and with i-Scan 3 (87%, P = 0.003 for comparison). There was no significant difference in sensitivity between i-Scan 2 and i-Scan 3 assessments (86% vs 87%, P = 1.000). No significant differences in specificity were found between the 3 i-Scan modes (i-Scan 1 vs i-Scan 2 P = 0.828, i-Scan 1 vs i-Scan 3 P = 1.000, i-Scan 1 vs i-Scan 3 P = 1.000). Overall accuracy increased from 79% with i-Scan 1 to 86.5% with i-Scan 2 and 87.5% with i-Scan 3. There was no significant difference in overall accuracy between i-Scan 1 and i-Scan 2 (P = 0.063) or i-Scan 2 and i-Scan 3 (P = 0.882). However there was a significant difference between i-Scan 1 and i-Scan 3 assessments (P = 0.032). Conclusion Tone enhancement appears to be the most effective component of the i-Scan system for accurate small colonic polyp characterisation, with no additional benefit from the addition of surface/contrast enhancement. Disclosure of interest None Declared.

PWE-002 How accurately are we tattooing colonic lesions prior to laparoscopic surgery? an institutional report

<h3>Introduction</h3> Small colonic cancers or polyps can be difficult to identify during laparoscopic surgery, hence the need to tattoo lesions when seen during endoscopic examination. The Joint Advisory Group on GI endoscopy (JAG) have minimal guidance on tattooing. The aim here was to assess the accuracy and frequency of tattooing within our trust with regards to local tattooing policy within our endoscopy unit. <h3>Method</h3> Data was retrospectively analysed over a 12 month period between January 2013 – January 2014 in patients undergoing a laparoscopic resection for a colonic lesion. Areas examined looked at frequency of tattooing, site and documentation. <h3>Results</h3> 43 patients underwent surgery during this time period. 80% of these were tattooed at the time of endoscopic investigation. Of these only 46% were tattooed according to the unit’s tattooing protocol. 25% of these had no clear documentation as to the method of tattooing. At the time of surgery, in 10% the tattoo was not deemed visible. The conversion rate was not higher in the group that were not tattooed according to local policy in comparison to the group that were (p = 0.8). <h3>Conclusion</h3> Huge variability exists in the tattooing methods of the endoscopists within our unit, which quite often does not adhere to local policy. This could potentially result in failure to identify lesions during surgery or resection of an incorrect segment altogether. <h3>Disclosure of interest</h3> None Declared.

714 The Efficacy and Safety of Cold snare Polypectomy

Small colonic polyps are commonly encountered at colonoscopy and are usually removed due to the risk of progression to colorectal cancer. Cold snare polypectomy is used to remove these lesions without diathermy. In essence, the polyp is transected by a snare, along with a rim of surrounding normal mucosa. This theoretically allows complete polyp removal without the potential complications of electrocautery, particularly delayed bleeding and perforation. However, the adequacy of cold snare polypectomy (in terms of completeness of resection) has not been studied in a real world setting. This study prospectively examined the efficacy and safety of this technique.

Small and diminutive colorectal polyps: risk of malignancy

The prevalence of advanced histological features in diminutive (≤5 mm) and small (6-9 mm) colon polyps is low, and they are considered to have low potential for malignant transformation. Performing a polypectomy increases the costs associated with a colonoscopy as well as the risk of complications. Newer diagnostic techniques have prompted the approach of ‘predict, resect and discard’ for diminutive and small polyps, a strategy whereby real time diagnosis of polyps would serve as a substitute for histopathological diagnosis to reduce costs.

Quality indicators common to all GI endoscopic procedures.

Quality of care is the degree to which health services for individuals and populations increase the likelihood of desired health outcomes and are consistent with current professional knowledge (1). The American Society for Gastrointestinal Endoscopy (ASGE), the American College of Gastroenterology (ACG), and the American Gastroenterological Association (AGA) have continually promoted the ideal that all patients have access to high-quality GI endoscopy services. A high-quality endoscopy is an examination in which patients receive an indicated procedure, correct and relevant diagnoses are recognized or excluded, any therapy provided is appropriate, and all steps that minimize risk have been taken.

The comparative study of acetyl-11-keto-beta-boswellic acid (AKBA) and aspirin in the prevention of intestinal adenomatous polyposis in APCMin/+ mice

Acetyl-11-keto-beta-BA (AKBA), a component of the gum resin of Boswellia serrata, has been recognized as a promising agent for the prevention of intestinal tumorigenesis. Aspirin, a non-steroidal anti-inflammatory drug (NSAID), has also been considered to have the activity against intestinal tumorigenesis. However, the prevention of colonic cancer is insufficient and no definitive recommendation has been made for clinic use. Herein, we compared the efficacy of AKBA with that of aspirin in an adenomatous polyposis coli intestinal neoplasia consecutive weeks. Mice were sacrificed by anesthetizing. The whole intestine was removed from each mouse. The number, size and histopathology of intestinal adenomatous polyps were examined under microscopy. The adenomatous polyps were removed for further analysis by the assays of western blotting and immunohistochemical staining. AKBA significantly prevented the formation of intestinal adenomatous polyps without toxicity to mice. Statistical analysis indicated that AKBA's activity both in the prevention of small intestinal and colonic polyps was more potently than aspirin. Histopathologic examination revealed that AKBA's effect, that is the reduction of polyp size and degree of dysplasia, was more prominent in larger sized polyps, especially those originating in colon. These effects of AKBA were associated with its role in the induction of apoptosis in carcinomas. The assays of western blotting and immunohistochemistry staining indicated that the efficacy of AKBA might arise from its activity in the modulation of the Wnt/β-catenin pathway and NF-κB/COX-2 pathway in adenomatous polyps. Conclusion, AKBA by oral application prevented intestinal tumorigenesis more potential than aspirin.

High-definition vs. standard-definition endoscopy with indigo carmine for the invivo diagnosis of colonic polyps.

There is growing evidence that indigo carmine chromoendoscopy is effective for the invivo diagnosis of colonic polyps. However, the impact of colonoscope resolution on diagnostic accuracy has not been investigated. We aimed to compare the effectiveness of invivo diagnosis of small colonic polyps using indigo carmine dye spray with standard-definition and high-definition colonoscopes. Procedures were performed using Fujinon colonoscopes and EPX 4400 processor. Fujinon standard-definition (SD) and high-definition (HD) colonoscopes were used, with the endoscopist blinded to colonoscope definition. Polyps <10 mm were assessed using 0.2% indigo carmine dye spray, with the predicted diagnosis recorded. In each case the kind of colonoscope (SD or HD) was recorded. Polyps were removed and sent for histological analysis, with the pathologist blinded to the diagnosis made by the endoscopist. The predicted diagnosis was compared with the true histology to calculate the accuracy, sensitivity and specificity of invivo assessment using either SD or HD scopes. In total 237 polyps <10 mm in size were examined. There was no statistically significant difference for any of the measured parameters between SD and HD assessments, with an accuracy, sensitivity and specificity of 89%, 91% and 87% with SD colonoscopes and 92%, 96% and 84% with HD colonoscopes. The accuracy of invivo assessment of small colonic polyps with indigo carmine dye spray is excellent with standard-definition colonoscopes and is not improved with high-definition colonoscopes.

High-definition endoscopy with i-Scan for evaluation of small colon polyps: the HiSCOPE study

Traditional white-light endoscopy cannot reliably distinguish between small (<10 mm) adenomatous and hyperplastic colon polyps. High-definition white-light (HDWL) endoscopy and i-Scan may improve in vivo characterization of small colon polyps. To compare HDWL endoscopy and HDWL plus i-Scan for the assessment of small colon polyps and to measure performance against the American Society for Gastrointestinal Endoscopy (ASGE) thresholds for assessment of diminutive colon polyps. Prospective cohort study. Single academic hospital. Patients undergoing bowel cancer screening colonoscopy. In vivo assessment of all polyps <10 mm by using HDWL and i-Scan image enhancement. The primary outcome measure was overall diagnostic accuracy of in vivo assessment of colon polyps <10 mm. Secondary outcome measures were sensitivity and specificity for adenomatous histology, negative predictive value for adenomatous histology of diminutive rectosigmoid polyps, and accuracy of prediction of polyp surveillance intervals. A total of 209 polyps in 84 patients were included. There were no significant differences between HDWL endoscopy and i-Scan in characterization of polyps <10 mm (accuracy 93.3% vs 94.7%; P = 1.00; sensitivity 95.5% vs 97.0%; P = .50; specificity 89.3% vs 90.7%; P = 1.00). The negative predictive value for adenomatous histology of diminutive rectosigmoid polyps was 100% with both HDWL endoscopy and i-Scan. U.K. and U.S. polyp surveillance intervals were predicted with 95.2% accuracy with HDWL endoscopy and 97.2% accuracy with i-Scan. Single-center study. HDWL endoscopy may be as accurate as HDWL with i-Scan image enhancement for the in vivo characterization of small colon polyps. Both modalities fulfil the ASGE performance thresholds for the assessment of diminutive colon polyps. ( NCT01761279.).

Clinicopathological features of colorectal polyps: evaluation of the ‘predict, resect and discard’ strategies

'Predict, resect and discard' strategies for diminutive and small colonic polyps are considered to be cost effective for treating colorectal cancers. The aim of this study was to determine, retrospectively, the histological features of colonic polyps resected by endoscopic procedures or surgery using an updated database. We retrospectively analysed the clinicopathological features of colorectal polyps, less than 20 mm in size, which were removed by endoscopy from January 2009 to November 2011 at the National Cancer Center Hospital (NCCH) in Tokyo, Japan. Less than 1% of diminutive polyps (≤ 5 mm) were classified as mucosal high-grade neoplasia (Category 4), and no submucosal invasion by carcinoma (Category 5) lesions were noted. However, 3% of small polyps (6-9 mm) were classified as Category 5; of these, 6% were submucosal deep invasive cancers. Morphologically, depressed components were observed more frequently in carcinomas than in adenomas in both small and large polyps (10-20 mm). In light of the 'predict, resect and discard' strategies for small polyps, we should pay attention to the possible clinical malignancy of small and large polyps. We recommend that these strategies should be applied selectively and that they should be informed by accurate endoscopic evaluations.

OC-045 High Definition White Light Endoscopy and I-Scan for small Colonic Polyp Evaluation : Results of the Hiscope Study: Abstract OC-045 Table 1

<h3>Introduction</h3> Standard definition white light endoscopy is inadequate for in-vivo characterisation of small colonic polyps. The ASGE has identified prediction of polyp surveillance intervals and negative predictive value for adenomatous histology of diminutive recto-sigmoid polyps as key targets for new technologies. High definition white light endoscopy is now available but there is little data on it’s use. <h3>Methods</h3> We aimed to examine the in-vivo characterisation accuracy of high definition white light endoscopy (HDWL) plus a novel electronic imaging modality – i-Scan (Pentax, Japan). Patients undergoing colonoscopy through the UK Bowel Cancer Screening Programme were prospectively recruited. All colonoscopies were performed by a single expert endoscopist with extensive experience in in-vivo diagnosis. Procedures were performed with Pentax EC-3890Li 1.2 Megapixel HD+ colonoscopes and EPKi processor. An initial classification &amp; validation exercise was carried out to determine the optimum i-Scan settings for in-vivo diagnosis, and to develop a novel in-vivo diagnosis assessment tool. All polyps &lt; 10mm in size were assessed sequentially with HDWL and i-Scan. Optical magnification was not used. Predicted histology (non-neoplastic, adenoma, cancer) was recorded for both modalities and compared to the final histopathological diagnosis as reported by an expert gastrointestinal pathologist. Predictions were rated as high or low confidence assessments. Results were analysed for sensitivity and specificity for neoplasia, overall accuracy, and negative predictive value for rectosigmoid polyps ≤5 mm as recommended by the ASGE PIVI statement. <h3>Results</h3> 84 patients were recruited, in whom 209 polyps &lt; 10 mm were included. Mean polyp diameter was 4.3mm, median 4mm. 134 polyps were neoplastic and 75 non-neoplastic. There were no significant differences in sensitivity (95.5% vs 97.0%) and specificity (89.3% vs 90.7%) for neoplasia and overall diagnostic accuracy (93.3% vs 94.7%) between HDWL and i-Scan. Negative predictive value for adenomatous histology of rectosigmoid polyps ≤5 mm was 100% with both modalities. Polyp surveillance intervals using in-vivo assessment of diminutive polyps were correct in 95% and 97% of patients with HDWL and i-Scan respectively. <h3>Conclusion</h3> Excellent in vivo diagnostic accuracy, in excess of 90% can be achieved with HDWL alone. No significant gains in accuracy over HDWL were noted with i-Scan when used with a 1.2Megapixel HD colonoscope Both HDWL and i-Scan fulfil the ASGE criteria for ‘resect and discard’ and ‘do not resect’ strategies for diminutive polyps <h3>Disclosure of Interest</h3> None Declared

PTH-015 Prospective Comparison of Fice and I-Scan for In-Vivo Characterisation of Small Colonic Polyps

IntroductionIn-vivo characterisation of small colonic polyps has been reported using several technologies but with few prospective comparisons between them. We aimed to compare the accuracy of Flexible Spectral Imaging Colour...

Tu1468 Magnifying the Endoscopic Characteristics of Colorectal Lesions With Narrow Band Imaging System

who each evaluated at least 25 colorectal polyps by HD i-scan participated. All small colorectal polyps were examined using HD white-light followed by HD i-scan, then classified into adenomatous or non-adenomatous with a high-or low level of confidence, and subsequently removed and sent for histopathologic examination. Distal colon was defined as rectosigmoid whereas proximal colon was defined as proximal to the rectosigmoid. Sensitivity, specificity, positive, negative predictive value and accuracy with corresponding 95% confidence intervals for prediction of histopathology were calculated. The agreement between surveillance recommendations that would follow optical diagnosis for small colorectal polyps combined with histopathology assessment of the remaining polyps versus histopathology assessment alone was calculated. Results: A total of 309 small colorectal polyps from 93 patients were examined. Of them, 295 (95.5%) were predicted with high-confidence and hence, included in the final analyses. Of these, 110 (37.3%) were located in the distal colon of which 33 (30%) were adenomatous and 77 (70%) non-adenomatous. Diagnostic performances of the endoscopists are depicted in the Table. The negative predictive value for adenoma histology of all small colonic polyps was 87% and increased to 97% for small distal polyps only. In addition, the agreement between surveillance recommendations by formal histopathology versus HD iscan analysis of all small colonic polyps was 81% and increased to 94% for small distal polyps only (Table). Of note, the 6% disagreement reflects patients receiving surveillance earlier than recommended by histopathology alone. Conclusion: Our data indicate that optical diagnosis of small rectosigmoid polyps using HD i-scan is already feasible in the routine practice, with a negative predictive value of 97% and 94% agreement of surveillance recommendations. However, prediction of histology in proximal polyps is only moderate, emphasizing the need for continuous training.

Tu1497 Comparison of Jumbo Biopsy Forceps and Standard Biopsy Forceps in the Treatment of Small Colon Polyps

Tu1497 Comparison of Jumbo Biopsy Forceps and Standard Biopsy Forceps in the Treatment of Small Colon Polyps

Tu1405 The Learning Curve for in-Vivo Characterisation of Small Colonic Polyps: Number Needed to Train (NNT) Is 200 Polyps

Tu1405 The Learning Curve for in-Vivo Characterisation of Small Colonic Polyps: Number Needed to Train (NNT) Is 200 Polyps