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The incidence of early-onset colorectal cnacer-ie, colorectal cancer diagnosed in patients under the age of 50 years- has been increasing around the world. This Series paper provides a comprehensive review on the topic of early-onset colorectal cancer, including examining the epidemiology of early-onset colorectal cancer around the world, clinical and pathological features, genetic and epigenetic landscapes, and emerging data on the clinical risk factors associated with this malignancy. Evidence-based approaches to prevention and early detection are also presented.

This document is a focused update to the 2017 colorectal cancer (CRC) screening recommendations from the U.S. Multi-Society Task Force on Colorectal Cancer, which represents the American College of Gastroenterology, the American Gastroenterological Association, and the American Society for Gastrointestinal Endoscopy. This update is restricted to addressing the age to start and stop CRC screening in average-risk individuals and the recommended screening modalities. Although there is no literature demonstrating that CRC screening in individuals under age 50 improves health outcomes such as CRC incidence or CRC-related mortality, sufficient data support the U.S. Multi-Society Task Force to suggest average-risk CRC screening begin at age 45. This recommendation is based on the increasing disease burden among individuals under age 50, emerging data that the prevalence of advanced colorectal neoplasia in individuals ages 45 to 49 approaches rates in individuals 50 to 59, and modeling studies that demonstrate the benefits of screening outweigh the potential harms and costs. For individuals ages 76 to 85, the decision to start or continue screening should be individualized and based on prior screening history, life expectancy, CRC risk, and personal preference. Screening is not recommended after age 85.

Lynch syndrome (LS) is the most common hereditary colorectal cancer (CRC) syndrome, yet is grossly under-recognized. Multiple professional societies recommend screening all CRCs for LS by performing tumor testing. The veterans affairs system has not adopted universal tumor testing as a national performance metric and leaves screening for LS to clinical care at individual sites. Describe adherence to LS screening in the VA system. Dual-center, retrospective review of all CRCs diagnosed between 2010 and 2016. Rates of tumor testing, personal and family history of cancer were extracted from the medical record. Univariate and multivariate regression analysis was performed to determine predictors of tumor-based screening for LS. A total of 421 cancers were reviewed. 15.1% of all cancers underwent either MSI and/or IHC for LS screening over the study period. There was improvement in LS screening from 3% of all CRCs in 2010 to 45% of all CRCs in 2016. 34% and 70% of patients did not have documentation of CRC in first- and second-degree relatives, respectively. Of the 73 patients who met one of the Revised Bethesda Criteria or had a PREMM1,2,6 score of ≥ 5, 34% and 56% underwent tumor testing, respectively. Younger age, non-Caucasian race, meeting Bethesda or PREMM1,2,6 criteria and right-sided tumor location were predictors of undergoing tumor testing. CRC tumor screening for LS is grossly inadequate when left to routine clinical care. Our results lend support to implementation of reflexive universal tumor testing within the VA system.

Advanced adenomas represent a subset of colorectal polyps that are known to confer an increased risk of colorectal neoplasia to the affected individual and their first-degree relatives (FDRs). Accordingly, professional guidelines suggest earlier and more intensive screening for FDRs of those with advanced adenomas similar to FDRs of those with colorectal cancer (CRC). Although the risk to family members is less clear among patients with advanced serrated polyps, they are often considered in the same category. Unfortunately, there is a growing concern that patients, endoscopists, and primary care providers are unaware of the familial risk associated with these polyps, leaving a wide gap in screening these high-risk individuals. Herein, we propose a standardized language around advanced colorectal polyps and present a detailed review of the literature on associated familial risk. We outline the challenges to implementing the current screening recommendations and suggest approaches to overcome these limitations, including a proposed new colonoscopy quality metric to capture communication of familial CRC risk. Improving screening in these high-risk groups has the potential to substantially reduce the burden of CRC.

The gastrointestinal hamartomatous polyposis syndromes are rare, autosomal dominant disorders associated with an increased risk of benign and malignant intestinal and extraintestinal tumors. They include Peutz-Jeghers syndrome, juvenile polyposis syndrome, the PTEN hamartoma tumor syndrome (including Cowden's syndrome and Bannayan-Riley-Ruvalcaba syndrome), and hereditary mixed polyposis syndrome. Diagnoses are based on clinical criteria and, in some cases, confirmed by demonstrating the presence of a germline pathogenic variant. The best understood hamartomatous polyposis syndrome is Peutz-Jeghers syndrome, caused by germline pathogenic variants in the STK11 gene. The management is focused on prevention of bleeding and mechanical obstruction of the small bowel by polyps and surveillance of organs at increased risk for cancer. Juvenile polyposis syndrome is caused by a germline pathogenic variant in either the SMAD4 or BMPR1A genes, with differing clinical courses. Patients with SMAD4 pathogenic variants may have massive gastric polyposis, which can result in gastrointestinal bleeding and/or protein-losing gastropathy. Patients with SMAD4 mutations usually have the simultaneous occurrence of hereditary hemorrhagic telangiectasia (juvenile polyposis syndrome-hereditary hemorrhagic telangiectasia overlap syndrome) that can result in epistaxis, gastrointestinal bleeding from mucocutaneous telangiectasias, and arteriovenous malformations. Germline pathogenic variants in the PTEN gene cause overlapping clinical phenotypes (known as the PTEN hamartoma tumor syndromes), including Cowden's syndrome and related disorders that are associated with an increased risk of gastrointestinal and colonic polyposis, colon cancer, and other extraintestinal manifestations and cancers. Due to the relative rarity of the hamartomatous polyposis syndromes, recommendations for management are based on few studies. This U.S Multi-Society Task Force on Colorectal Cancer consensus statement summarizes the clinical features, assesses the current literature, and provides guidance for diagnosis, assessment, and management of patients with the hamartomatous polyposis syndromes, with a focus on endoscopic management.

The incidence of early onset colorectal cancer, or colorectal cancer (CRC) diagnosed before age 50, is increasing.

Background & Aims Incidence and mortality associated with early-age onset colorectal cancer (EAO-CRC) is increasing, prompting professional society recommendations to lower the screening age in average-risk individuals. The yield of screening individuals younger than 50 years is not known. Methods A systematic review of 3 databases from inception through July 2020 was performed in all languages that reported colonoscopy findings in average-risk individuals younger than 50 years. The primary outcomes were EAO colorectal neoplasia (CRN) and advanced colorectal neoplasia (aCRN) prevalence. Subgroup analyses were performed based on sex, geographic location, time period, and age, including comparison with those aged 50–59 years. Generalized linear mixed model with random intercept logistic regression and fixed subgroup effects were performed. Results Of 10,123 unique articles, 17 studies published between 2002 and 2020, including 51,811 average-risk individuals from 4 continents, were included. The pooled rate of EAO-CRN was 13.7% (95% confidence interval [CI], 0.112%–0.168%) and EAO-aCRN was 2.2% (95% CI, 0.016%–0.031%). Prevalence of CRC was 0.05% (95% CI, 0.00029%–0.0008%). Rates of EAO-CRN were higher in men compared with women (relative risk, 1.71%; 95% CI, 1.49%–1.98%), and highest in the United States (15.6%; 95% CI, 12.2%–19.7%) compared with Europe (14.9%; 95% CI, 6.9%–29.3%), East Asia (13.4%; 95% CI, 10.3%–17.2%), and the Middle East (9.8%; 95% CI, 7.8%–12.2%) (P = .04) The rate of EAO-CRN in age groups 45–49 years and 50–59 years was 17.8% (95% CI, 14.5%–21.6%) and 24.8% (95% CI, 19.5%–30.8%), respectively (P = .04). The rate of EAO-aCRN in age group 45–49 years was 3.6% (95% CI, 1.9%–6.7%) and 4.2% (95% CI, 3.2%–5.7%), respectively (P = .69). Conclusions The rate of aCRN in individuals aged 45–49 years was similar to the rate observed in individual aged 50–59 years, suggesting that expanding screening to this population could yield a similar impact on colorectal cancer risk reduction.

Amid the COVID-19 pandemic, medical education organizations endorsed a virtual recruitment format, representing a stark change from traditional in-person interviews. We aimed to identify the attitudes and perceptions of Gastroenterology Fellowship Program Directors (PDs) and applicants regarding the virtual interview experience and the role of virtual interviews (VI) in the future. We designed separate surveys targeting PDs and applicants using the Qualtrics software. At the end of the interview season, we e-mailed both survey links to all PDs and requested that they forward the applicant survey to their interviewed candidates. Surveys were voluntary and anonymous. Descriptive statistics were used to analyze the data with results presented as percentages. A total of 29.7% of PDs completed the survey. Compared to traditional interviews, VI were viewed by 46.5% of PDs to be very suboptimal or suboptimal. Yet, 69.1% envisioned a role for VI in the future. A total of 14.2% of applicants completed the survey. Compared to traditional interviews, VI were viewed by 42.3% of applicants to be very suboptimal or suboptimal. However, 61.8% saw a future role for VI. While both applicants and PDs reported that establishing an interpersonal connection was a disadvantage with VI, applicants placed more emphasis on this need for connection (p = 0.001). Overall, PDs and applicants report mixed views with regard to VI but anticipate that it may continue to have a future role. VI may augment future recruitment cycles with care taken to not disadvantage applicants, who rely heavily on the interview process to create personal connections with programs.

Individuals whose families meet the Amsterdam II clinical criteria for hereditary non-polyposis colorectal cancer are recommended to be referred for genetic counseling and to have colonoscopic screening every 1-2 years. To assess the uptake and knowledge of guideline-based genetic counseling and colonoscopic screening in unaffected members of families who meet Amsterdam II criteria and their treating endoscopists.Participants in the Family Health Promotion Project who met the Amsterdam II criteria were surveyed regarding their knowledge of risk-appropriate guidelines for genetic counseling and colonoscopy screening. Endoscopy/pathology reports were obtained from patients screened during the study to determine the follow-up recommendations made by their endoscopists. Survey responses were compared using Fisher's Exact and the χ(2) test. Concordance in participant/provider-reported surveillance interval was assessed using the kappa statistic.Of the 165 participants, the majority (98%) agreed that genetics and family history are important predictors of CRC, and 63% had heard of genetic testing for CRC, although only 31% reported being advised to undergo genetic counseling by their doctor, and only 7% had undergone genetic testing. Only 26% of participants reported that they thought they should have colonoscopy every 1-2 years and 30% of endoscopists for these participants recommended 1-2-year follow-up colonoscopy. There was a 65% concordance (weighted kappa 0.42, 95% CI 0.24-0.61) between endoscopist recommendations and participant reports regarding screening intervals.A minority of individuals meeting Amsterdam II criteria in this series have had genetic testing and reported accurate knowledge of risk-appropriate screening, and only a small percentage of their endoscopists provided them with the appropriate screening recommendations. There was moderate concordance between endoscopist recommendations and participant knowledge suggesting that future educational interventions need to target both health-care providers and their patients.

Narrow-band imaging (NBI) allows real-time histologic classification of colorectal polyps. We investigated whether endoscopists without prior training in NBI can achieve the following thresholds recommended by the American Society for Gastrointestinal Endoscopy: for diminutive colorectal polyps characterized with high confidence, a ≥90% negative predictive value for adenomas in the rectosigmoid and a ≥90% agreement in surveillance intervals.Twenty-six endoscopists from 2 tertiary care centers underwent standardized training in NBI interpretation. Endoscopists made real-time predictions of diminutive colorectal polyp histology and surveillance interval predictions based on NBI. Their performance was evaluated by comparing predicted with actual findings from histologic analysis. Multilevel logistic regression was used to assess predictors of performance. Cumulative summation analysis was used to characterize learning curves.The endoscopists performed 1451 colonoscopies and made 3012 diminutive polyp predictions (74.3% high confidence) using NBI. They made 898 immediate post-procedure surveillance interval predictions. An additional 505 surveillance intervals were determined with histology input. The overall negative predictive value for high-confidence characterizations in the rectosigmoid was 94.7% (95% confidence interval: 92.6%-96.8%) and the surveillance interval agreement was 91.2% (95% confidence interval: 89.7%-92.7%). Overall, 97.0% of surveillance interval predictions would have brought patients back on time or early. High-confidence characterization was the strongest predictor of accuracy (odds ratio = 3.42; 95% confidence interval: 2.72-4.29; P.001). Performance improved over time, however, according to cumulative summation analysis, only 7 participants (26.9%) identified adenomas with sufficient sensitivity such that further auditing is not required.With standardized training, gastroenterologists without prior expertise in NBI were able to meet the negative predictive value and surveillance interval thresholds set forth by the American Society for Gastrointestinal Endoscopy. The majority of disagreement in surveillance interval brought patients back early. Performance improves with time, but most endoscopists will require ongoing auditing of performance. ClinicalTrials.gov ID NCT02441998.

The Accreditation Council for Graduate Medical Education (ACGME) emphasizes the importance of medical trainees meeting specific performance benchmarks and demonstrating readiness for unsupervised practice. The aim of this study was to examine the readiness of Gastroenterology (GI) fellowship programs for competency-based evaluation in endoscopic procedural training.ACGME-accredited GI program directors (PDs) and GI trainees nationwide completed an online survey of domains relevant to endoscopy training and competency assessment. Participants were queried about current methods and perceived quality of endoscopy training and assessment of competence. Participants were also queried about factors deemed important in endoscopy competence assessment. Five-point Likert items were analyzed as continuous variables by an independent t-test and χ(2)-test was used for comparison of proportions.Survey response rate was 64% (94/148) for PDs and 47% (546/1,167) for trainees. Twenty-three percent of surveyed PDs reported that they do not have a formal endoscopy curriculum. PDs placed less importance (1—very important to 5—very unimportant) on endoscopy volume (1.57 vs. 1.18, P0.001), adenoma detection rate (2.00 vs. 1.53, P0.001), and withdrawal times (1.96 vs. 1.68, P=0.009) in determining endoscopy competence compared with trainees. A majority of PDs report that competence is assessed by procedure volume (85%) and teaching attending evaluations (96%). Only a minority of programs use skills assessment tools (30%) or specific quality metrics (28%). Specific competencies are mostly assessed by individual teaching attending feedback as opposed to official documentation or feedback from a PD. PDs rate the overall quality of their endoscopy training and assessment of competence as better than overall ratings by trainees.Although the majority of PDs and trainees nationwide believe that measuring specific metrics is important in determining endoscopy competence, most programs still rely on procedure volume and subjective attending evaluations to determine overall competence. As medical training transitions from an apprenticeship model to competency-based education, there is a need for improved endoscopy curricula which are better suited to demonstrate readiness for unsupervised practice.

The management of complex colorectal polyps varies in practice. Accurate descriptions of the endoscopic appearance by using a standardized classification system (Paris classification) and size for complex colon polyps may guide subsequent providers regarding curative endoscopic resection vs. need for surgery. The accuracy of this assessment is not well defined. Furthermore, the factors associated with decisions for endoscopic vs. surgical management are unclear. To characterize the accuracy of physician assessment of polyp morphology, size, and suspicion for malignancy among physician subspecialists performing colonoscopy and colon surgery. In addition, we aimed to assess the influence of these polyp characteristics as well as physician type and patient demographics on recommendations for endoscopic vs. surgical resection of complex colorectal polyps.An online video-based survey was sent to gastroenterologists (GIs) and gastrointestinal surgeons affiliated with six tertiary academic centers. The survey consisted of high-definition video clips (30-60 s) of six complex colorectal polyps (one malignant) and clinical histories. Respondents were blinded to histology. Respondents were queried regarding polyp characteristics, suspicion for malignancy, and recommendations for resection.The survey response rate was 154/317 (49%). Seventy-eight percent of respondents were attending physicians (91 GIs and 29 surgeons) and 22% were GI trainees. Sixteen percent of respondents self-identified as specialists in complex polypectomy. Accurate estimation of polyp size was poor (28.4%) with moderate interobserver agreement (k=0.52). Accuracy for Paris classification was 47.5%, also with moderate interobserver agreement (k=0.48). Specialists in complex polypectomy were most accurate, whereas surgeons were the least accurate in assigning Paris classification (66.0 vs. 28.7%, P0.0001). Specialists in complex polypectomy were most likely to correctly identify the malignant lesion compared with other physicians (87.5 vs. 56.2%, P=0.008). Surgical removal of colon adenomas was recommended least frequently by specialists in complex polypectomy (3.1%) compared with nonspecialists in complex polypectomy (13.3%); surgeons were most likely to recommend surgical resection (17.2%, P=0.009). There were no differences in recommendations for endoscopic vs. surgical resection observed on the basis of years in practice, polyp morphology (polypoid vs. nonpolypoid), polyp location (right vs. left colon), or patient ASA class.In this large survey of GIs and surgeons, physician specialty was strongly associated with accurate polyp characterization and a recommendation for endoscopic resection of complex polyps. Surgeons were most likely to recommend surgical resection of complex nonmalignant colorectal polyps compared with specialists in complex polypectomy who were the least likely. Therefore, collaboration with specialists in complex polypectomy may be helpful in determining the appropriate management of complex colon polyps. Further teaching is needed among all specialists to improve accurate communication and ensure optimal management of these lesions.

Colonoscopic screening and surveillance have been very effective tools in the fight against colorectal cancer (CRC). Colonoscopy is more than a cancer screening test; it also can prevent CRC by detecting and removing precancerous lesions. Despite this potential, there has been increasing concern about CRCs that occur after a previous colonoscopy and before the next screening/surveillance examination (interval CRCs). The etiology of interval CRC is thought to be caused mostly by missed or incompletely resected lesions on index colonoscopy with some contribution of rapidly progressive new lesions. If this is true, many interval cancers should be preventable by improving colonoscopy technique. There are a variety of strategies to decrease interval CRC rates including use of a split-dosed bowel preparation, optimizing withdrawal technique, ensuring complete polypectomy, and careful pathologic examination of the tissue removed. Furthermore, there should be an increased emphasis on how endoscopists are trained to cultivate high-quality technique throughout their careers. It is important to inform patients that even high-quality colonoscopy is not perfectly sensitive for the detection of advanced neoplasia. Improving colonoscopy quality can decrease interval CRC rates and further decrease CRC incidence and mortality.

Colonoscopy is central to one of the great success stories of the war on cancer. Although colorectal cancer (CRC) is still the second leading cause of cancer death in the United States, both the incidence and mortality has been declining by 2–3% per year for the last 15 years. This decline has been largely attributed to increasing rates of CRC screening. Although guidelines list other screening options (stool tests/imaging/flexible sigmoidoscopy) colonoscopy has become the dominant CRC screening test in the US while fecal testing has declined slowly, and flexible sigmoidoscopy has declined markedly over the last decade [1]. Colonoscopy is widely viewed in the US as the single best test for both detection and removal of pre-cancerous lesions. The efficacy of colonoscopic polypectomy was initially highlighted by the National Polyp Study (NPS), which estimated a 76–90% reduction in incidence of colorectal cancer after polyp removal [2]. Subsequent studies [3], which often have not shown as robust a CRC risk reduction as the NPS, have highlighted the importance of the quality of colonoscopy as a critical element in its efficacy. There is compelling evidence that colonoscopy quality is highly variable [4] and guidelines for a high-quality colonoscopy have been published [5], but in the end, quality needs to be assessed by whether a test accomplishes its primary goal. In the case of colonoscopy, directly measuring whether a colonoscopy has prevented a CRC is not feasible in the short term. Instead, more measurable surrogates of quality such as cecal intubation rates, withdrawal times, and particularly adenoma detection rates (ADR) have been used as quality measures. Kaminski et al. found that ADR appeared to be an acceptable surrogate for real colonoscopy quality as it was an independent predictor of the risk of interval colorectal cancer [6]. Numerous studies have demonstrated marked (twofold to sixfold) variability in ADRs among endoscopists working in the same endoscopy unit [4]. Although some of this variability might be due to patient factors such as age, gender, or adequacy of bowel preparation, individual endoscopists appear to be the single most predictive factor in adenoma detection [7], implying that the efficacy of colonoscopy is highly dependent on the individual skill of the endoscopist. To compound matters, Brenner [8] and Lakoff [9] presented data from Germany and Canada that showed that while colonoscopy does decrease the rate of distal CRCs by approximately 67–79%, it was not at all protective for proximal colon cancers, suggesting that there is a substantial need for improvement in colonoscopy quality by all endoscopists. The variability in colonoscopy quality among providers and the dubious utility of colonoscopy in preventing rightsided colon cancers have called into question the overall efficacy of colonoscopy as it is used today and would seem to be a clear mandate for endoscopists and professional organizations to critically examine colonoscopist performance and address areas in need of improvement. Is it possible to identify provider characteristics that are predictive of quality procedures? If so, can we incorporate these findings into endoscopic training, continuing medical education and ultimately ongoing quality assurance programs? Any such efforts are dependent, in part, on an understanding of the relationships between endoscopist characteristics and quality outcomes and there is growing literature examining one aspect of this relationship—the S. G. Patel D. J. Ahnen (&) Department of Medicine, Division of Gastroenterology, Denver VA Medical Center and University of Colorado School of Medicine, Denver, CO, USA e-mail: dennis.ahnen@ucdenver.edu

Background: Insufficient inhibition of gastric acid during Helicobacter pylori treatment and bacterial resistance to antibiotics frequently results in failure to eradicate infection. Twicedaily dosing (b.i.d.) of a proton pump inhibitor (PPI) using standard eradication therapy has shown difficulty in maintaining high gastric pH values for 24 h in patients. However, four-times-daily dosing (q.i.d.) achieves these goals, irrespective of CYP2C19 genotype status, and might therefore be an optimal regimen for use in eradicating H. pylori infection. The fluoroquinolone sitafloxacin (STFX) was recently reported to have a lower minimum inhibitory concentration for H. pylori compared with levofloxacin and has become clinically available as a third-line treatment and for patients with penicillin allergy. An STFX-based eradication regimen with maintenance of acid inhibition might therefore have a high success rate. We investigated the efficacy of this treatment and maintenance of acid inhibition by PPI q.i.d. treatment. Methods: In 136 H. pylori-positive Japanese patients (for first-line treatment: n=40, second-line: n=30, third-line: n=66), the efficacy of the following treatment regimen was investigated: a PPI (rabeprazole 10 mg, q.i.d.), metronidazole (250 mg, b.i.d.), and STFX (100 mg, b.i.d.) for 1 week, irrespective of CYP2C19 genotype status and numbers of previous eradication therapy. At four to eight weeks after treatment, patients underwent the [13C]-urea breath test to assess successful eradication. Results: First-resistance to antimicrobial agents was 51.4% for clarithromycin, 56.7% for metronidazole and 30.0% for levofloxacin. The intention-to-treat eradication rate in the tailored group was 93.4% (95%CI: 87.8%-96.9%, 127/136). Although the eradication rate in patients treated as first-line therapy (100%, 95%CI: 92.8%-100%, 40/40) was higher than that in those treated as second-line (93.3%, 95%CI: 77.9%-99.2%, 28/30) and third-line therapy (89.4%, 95%CI: 87.8%-96.9%, 59/66), no significant differences were shown among numbers of previous eradication therapy (p = 0.08). The eradication rates were similar among all three CYP2C19 genotype groups (extensive metabolizer, 91.7% [66/73]; intermediate metabolizer, 96.1% [49/51]; poor metabolizer, 91.7% [11/12]), exceeding 90% for all genotypes. Conclusions: A sitafloxacinbased H. pylori eradication regimen based on maintaining acid secretion (rabeprazole 10 mg, q.i.d.) achieved an eradication rate of more than 90%, irrespective of eradication history and CYP2C19 genotype. In addition, as this regimen reduces the cost of CYP2C19 genotyping and culture tests, it might be more cost-effective than CYP2C19 genotype-based treatments.

Little is known about how teaching gastroenterology trainees polyp patterns by using narrow band imaging (NBI) affects their ability to characterize the histology of diminutive colorectal polyps. We developed and tested a tool to teach trainees to characterize the histology of diminutive polyps by using NBI.Twelve gastroenterology trainees with varying levels of colonoscopy experience watched a teaching tool that described the NBI criteria to distinguish polyp histology. The trainees then watched 80 videos of NBI examination of diminutive polyps, recording their predictions of polyp histology and their degree of confidence. After each video, an expert provided feedback about actual polyp histology and the NBI criteria that supported each diagnosis. Twelve weeks later, without training or feedback during the interval, the trainees watched the same videos and predicted histologies of the polyps. Performance was evaluated by comparing predicted classification with actual histologic findings. Cumulative sum analysis was used to determine the learning curve for each trainee.Trainees made significant improvements in accuracy and the proportion of high-confidence predictions as they progressed through video blocks during the first session (P.001). With active feedback, all trainees predicted polyp histologies with90% accuracy, with a negative predictive value90% for adenomatous histology. A median of 49 videos was required to achieve competency. For diagnoses made with high confidence, trainee performance exceeded 90% during the first and second sessions. Interobserver agreement was substantial (session 1, κ = 0.71; session 2, κ = 0.70).We developed a computer-based tool, combined with short videos and active feedback, to train gastroenterologists to identify polyp histology by using NBI. After training, gastroenterology trainees characterized the histology of diminutive polyps with ≥ 90% accuracy.