Application of narrow-band imaging without magnifying in diagnosis of colorectal lesions by NICE classification / 上海交通大学学报（医学版）

Objective: To evaluate narrow-band imaging (NBI) without magnifying in the diagnosis of colorectal lesions by NBI International Colorectal Endoscopic Criteria (NICE classification), and analyze the safety and practicability of "do-not-resect" and "resect and discard" policies in clinical practice. Methods: The patients undergoing screening or surveillance colonoscopy, who were found colorectal lesions in the examination, from May to December in 2017 were enrolled. All the patients were examined by NBI without magnifying by any of the designated two physicians. NICE classification was used to diagnose colorectal lesions, and the diagnostic confidence of each lesion was recorded. The results of endoscopy were compared with those of pathology, and the accuracy rate and the confidence rate of diagnosis were calculated. The sensitivity, specificity, positive predictive value and negative predictive value of the diagnostic method for differentiating superficial tumors from non-tumors were also calculated. Finally, the feasibility, safety and cost savings of using "do-not-resect" and "resect and discard" policies in clinic were analyzed. Results: A total of 764 lesions were detected in the 636 enrolled patients. The overall accuracy of NICE classification was 84.95% and the diagnostic confidence rate was 81.68%. The sensitivity, specificity, positive predictive value and negative predictive value for differentiating tumors from non-tumors were 91.77%, 67.68%, 88.69%, and 74.86%, respectively. The diagnostic accuracy of diminutive colorectal lesions (≤5 mm) with high confidence was 94.98%, and the negative predictive value of diminutive rectosigmoid lesions (≤5 mm) with high confidence was 96.25%. They achieved the criteria of "resect and discard" and "do-not-resect" policies. If "do-not-resect" and "resect and discard" policies had been executed in clinical practice, ¥165 490 could have been saved and the omission diagnostic rates of "do-not-resect" and "resect and discard" policies would have been 3.75% and 0, respectively, in this study. Conclusion: It is feasible to use NBI without magnifying in differentiating tumors from non-tumors. The diminutive colorectal lesions and rectosigmoid lesions with high diagnostic confidence may achieve the criteria of "resect and discard" and "do-not-resect" policies, respectively.

Optical diagnosis of small colorectal polyps during colonoscopy: when to resect and discard?

Colonoscopy with polypectomy has been shown to be effective in reducing incidence and mortality from colorectal cancer (CRC). The increase in use of colonoscopy in national bowel cancer screening programmes combined with improved technology has resulted in a large increase in detection of polyps. Most polyps detected at screening colonoscopy are small (<10 mm) or diminutive (<6 mm) and, in particular the latter, have a very small chance of containing advanced features or cancer. The main reason for resecting small adenomas and sending them to histopathology serves to inform on the future surveillance intervals. Being able to diagnose adenomas in vivo would allow for them to be resected and discarded, saving the costs associated with histopathology. Diagnosing distal hyperplastic polyps in vivo would allow for these to be left in situ reducing the risks associated with polypectomy. There are now a number of new technologies that could potentially make optical diagnosis a reality. Resect and discard policy is an attractive concept for patients, gastroenterologists and health service providers and would present an enticing change to current clinical practice.

A prospective dual-center proof-of-principle study evaluating the incremental benefit of narrow-band imaging with a fixed zoom function in real-time prediction of polyp histology. Can we resect and discard?

BACKGROUND: Advancements in endoscopic technology have increased the ability to distinguish neoplastic polyps during colonoscopy. If a minimum accuracy can be achieved, then a resect-and-discard model can be implemented, although studies to date have demonstrated limited success, especially in the assessment of serrated polyps. OBJECTIVE: To perform a proof-of-principle study assessing the accuracy of narrow-band imaging with near focus in predicting polyp histology including serrated polyps and to determine whether the minimum requirements can be achieved for a resect-and-discard policy. DESIGN: Dual-center, prospective case series. SETTING: Two tertiary-care referral endoscopic centers in Australia. PATIENTS: Two hundred consecutive patients undergoing colonoscopy for routine indications were recruited. INTERVENTIONS: Any polyps identified were assessed by using standard white light followed by narrow-band imaging with near focus for Kudo pit patterns and modified Sano capillary patterns. Based on this assessment and the macroscopic appearance, the polyp histology was predicted and subsequently compared with histopathology results. MAIN OUTCOME MEASUREMENTS: Correlation in postpolypectomy surveillance intervals between endoscopic and pathologic assessments as well as negative predictive value for rectosigmoid hyperplastic polyps. RESULTS: There was a 96% agreement for surveillance intervals between endoscopic assessment and histology by using the American Society for Gastrointestinal Endoscopy guidelines. There was a 96% negative predictive value in assessing rectosigmoid hyperplastic polyps. LIMITATIONS: Because this was a proof-of-principle study, there was no control arm, and there were small numbers, especially in assessing subgroups. The results have limited generalizability with the training requirements for polyp recognition, with confidence to be determined. CONCLUSION: Narrow-band imaging with near focus can predict polyp histology (including serrated polyps) accurately in the hands of trained endoscopists. Further studies with larger numbers are required to further validate this practice.

Determining the adenoma detection rate and adenomas per colonoscopy by photography alone: proof-of-concept study.

BACKGROUND AND STUDY AIMS: The adenoma detection rate (ADR) and adenomas detected per colonoscopy (APC) are measures of the quality of mucosal inspection during colonoscopy. In a resect and discard policy, pathologic assessment for calculation of ADR and APC would not be available. The aim of this study was to determine whether ADR and APC calculation based on photography alone is adequate compared with the pathology-based gold standard. PATIENTS AND METHODS: A prospective, observational, proof-of-concept study was performed in an academic endoscopy unit. High definition photographs of consecutive polyps were taken, and pathology was estimated by the colonoscopist. Among 121 consecutive patients aged ≥ 50 years who underwent colonoscopy, 268 polyps were removed from 97 patients. Photographs of consecutive polyps were reviewed by a second endoscopist. RESULTS: The resect and discard policy applied to lesions that were ≤ 5 mm in size. When only photographs of lesions that were ultimately proven to be adenomas were included, the reviewer assessed ADR and APC to be lower than that determined by pathology (absolute reductions of 6.6 % and 0.17, and relative reductions of 12.6 % and 13.1 % in ADR and APC, respectively). When all photographs were included for calculation of ADR and APC, the reviewer determined the ADR to be 3.3 % lower (absolute reduction) and the APC to be the same as the rates determined by pathology. CONCLUSIONS: In a simulated resect and discard strategy, a high-level detector can document adequate ADR and APC by photography alone.

Electronic chromoendoscopy.

Electronic chromoendoscopy technologies provide image enhancement and may improve the diagnosis of mucosal lesions. Although strides have been made in standardization of image characterization, especially with NBI, further image-to-pathology correlation and validation are required. There is promise for the development of a resect and discard policy for diminutive adenomas by using electronic chromoendoscopy; however, before this can be adopted, further community-based studies are needed. Further validated training tools for NBI, FICE, and i-SCAN will also be required for the use of these techniques to become widespread.

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 cancers and 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-d 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.

Endoscopic features and management of diminutive colorectal submucosal invasive carcinoma.

BACKGROUND AND AIM: The vast majority of diminutive (∼5 mm) colorectal tumors consist of a very low prevalence of advanced neoplasia, and a predict-resect-and-discard policy has been proposed recently in Western countries. The histology of some diminutive colorectal tumors reveals carcinoma, not adenoma, although the frequency is relatively low. Clarifying the endoscopic features of diminutive submucosal invasive colorectal carcinoma (CRC) during colonoscopy is important for managing diminutive lesions. METHODS: A total of 111 cases of submucosal invasive CRC ≤ 10 mm were analyzed. The incidence of submucosal invasion in early CRC per gross type, size, location, pit pattern diagnosis, and rate of lymph node (LN) metastasis was evaluated. RESULTS: In diminutive tumors, the overall submucosal invasion rate in early CRC was 9.6%; however, depressed tumors had a significantly higher frequency of submucosal invasion than protruded or flat elevated tumors. There were no significant differences in the distribution of submucosal invasive CRC between the diminutive tumors and those that were 6-10 mm. The pit pattern diagnosis of diminutive submucosal invasive CRC was type VI pit pattern in all cases. Each case of submucosal invasive CRC was completely resected by en bloc endoscopic resection, and there were no cases of LN metastasis. CONCLUSION: Diminutive tumors with depression have a high frequency of submucosal invasive CRC and an initial indication for endoscopic resection.

Current status and future perspectives of endoscopic diagnosis and treatment of diminutive colorectal polyps.

During colonoscopy, small and diminutive colorectal polyps are commonly encountered. It is estimated that at least one adenomatous polyp is detected in almost half of all patients undergoing screening colonoscopy. In contrast, the 'predict, resect, and discard' strategy for diminutive and small colorectal polyps is a current topic especially in Western countries. 'Is this an acceptable policy in Japan?' Herein, we report the results of a questionnaire survey with regard to the management of diminutive colorectal polyps, including the thoughts of Japanese endoscopists regarding the 'predict, resect, and discard' strategy. At the moment, we propose that this strategy should be used by skilled endoscopists only.

New paradigms for colonoscopic management of diminutive colorectal polyps: predict, resect, and discard or do not resect?

The possibility to predict in vivo the histology of colorectal polyps by advanced endoscopic imaging has resulted in the implementation of a more conservative management for diminutive lesions detected at colonoscopy. In detail, a predict-and-do-not-resect strategy has been proposed for diminutive lesions located in the rectosigmoid tract, whilst a predict-resect-and-discard policy has been advocated for nonrectosigmoid diminutive polyps. Recently, the American Society for Gastrointestinal Endoscopy set required thresholds to be met, before allowing the adoption of these policies in the clinical field. The ability of current endoscopic imaging in reaching these thresholds would depend on a complex interaction among the accuracy of advanced endoscopic imaging in differentiating between adenomatous and hyperplastic lesions, the prevalence of (advanced) neoplasia within diminutive lesions, and the type of surveillance intervals recommended. Aim of this review is to summarize the data supporting the application of both a predict-and-do-not-resect and a predict-resect-and-discard policies, also addressing the potential pitfalls associated with these strategies.

New Paradigms for Colonoscopic Management of Diminutive Colorectal Polyps: Predict, Resect, and Discard or Do Not Resect?

The possibility to predict in vivo the histology of colorectal polyps by advanced endoscopic imaging has resulted in the implementation of a more conservative management for diminutive lesions detected at colonoscopy. In detail, a predict-and-do-not-resect strategy has been proposed for diminutive lesions located in the rectosigmoid tract, whilst a predict-resect-and-discard policy has been advocated for nonrectosigmoid diminutive polyps. Recently, the American Society for Gastrointestinal Endoscopy set required thresholds to be met, before allowing the adoption of these policies in the clinical field. The ability of current endoscopic imaging in reaching these thresholds would depend on a complex interaction among the accuracy of advanced endoscopic imaging in differentiating between adenomatous and hyperplastic lesions, the prevalence of (advanced) neoplasia within diminutive lesions, and the type of surveillance intervals recommended. Aim of this review is to summarize the data supporting the application of both a predict-and-do-not-resect and a predict-resect-and-discard policies, also addressing the potential pitfalls associated with these strategies.

A resect and discard strategy would improve cost-effectiveness of colorectal cancer screening.

BACKGROUND & AIMS: A "resect and discard" policy has been proposed for diminutive polyps detected by screening colonoscopy, because hyperplastic and adenomatous polyps can be distinguished, in vivo, by using narrow-band imaging (NBI). We modeled the cost-effectiveness of this policy. METHODS: Markov modeling was used to compare the cost-effectiveness of universal pathology evaluations with a resect and discard policy for colonoscopy screening. In a resect and discard approach, diminutive lesions (≤5 mm), classified by endoscopy with high confidence, were not analyzed by a pathologist. Base case assumptions of an 84% rate of high-confidence classification, with a sensitivity and specificity for adenomas of 94% and 89%, respectively, were used. Census data were used to project outputs of the model onto the US population, assuming 23% as the current rate of adherence to a colonoscopy screening. RESULTS: With universal referral of resected polyps to pathology, colonoscopy screening costs an estimated $3222/person, with a gain of 51 days/person. Endoscopic polypectomy accounted for $179/person, of which $46/person was related to pathology examination. Adoption of a resect and discard policy for eligible diminutive polyps resulted in a savings of $25/person, without any meaningful effect on screening efficacy. Projected onto the US population, this approach would result in an undiscounted annual savings of $33 million. In the sensitivity analysis, the rate of high-confidence diagnosis and the accuracy for endoscopic polyp determination were the most meaningful variables. CONCLUSIONS: In a simulation model, a resect and discard strategy for diminutive polyps detected by screening colonoscopy resulted in a substantial economic benefit without an impact on efficacy.