Variation in Pathologist Classification of Colorectal Adenomas and Serrated Polyps

Sessile serrated lesion prevalence and factors associated with their detection: a post-hoc analysis of a multinational randomized controlled trial from Asia

BACKGROUND

Sessile serrated lesions (SSLs) are associated with an increased risk of colorectal cancer. Data on the prevalence of SSLs in Asia are limited. We performed this study to estimate the prevalence of SSLs in Asia and to explore endoscopic factors that are associated with SSL detection.

METHODS

This is a post-hoc analysis of a multicenter randomized controlled trial from four Asian countries/regions that compared adenoma detection rates using linked-color imaging (LCI) and white-light imaging. Colonoscopies were performed in an average-risk population for screening, diagnostic examination, or polyp surveillance. Patients with SSLs were compared against those without SSLs to evaluate for possible predictors of SSL detection using Firth's logistic regression.

RESULTS

2898 participants (mean age 64.5 years) were included in the analysis. The estimated prevalence of SSLs was 4.0% (95%CI 3.4%-4.8%), with no sex or age group differences. On multivariable analysis, use of LCI (adjusted odds ratio [aOR] 1.63, 95%CI 1.10-2.41), experienced endoscopists (aOR 1.94, 95%CI 1.25-3.00), use of transparent cap (aOR 1.75, 95%CI 1.09-2.81), and longer withdrawal time (aOR 1.06, 95%CI 1.03-1.10) were independently associated with SSL detection. Synchronous adenoma detection (aOR 1.89, 95%CI 1.20-2.99) was also predictive of SSL detection.

CONCLUSION

The prevalence of SSLs in Asia is 4.0%. Use of LCI or a transparent cap, greater endoscopist experience, and longer withdrawal time were all associated with increased SSL detection.

Prevalence, risk factors, and BRAF mutation of colorectal sessile serrated lesions among Vietnamese patients

BACKGROUND

Sessile serrated lesions (SSLs) are considered precancerous colorectal lesions that should be detected and removed to prevent colorectal cancer. Previous studies in Vietnam mainly investigated the adenoma pathway, with limited data on the serrated pathway.

AIM

To evaluate the prevalence, risk factors, and BRAF mutations of SSLs in the Vietnamese population.

METHODS

This is a cross-sectional study conducted on patients with lower gastrointestinal symptoms who underwent colonoscopy at a tertiary hospital in Vietnam. SSLs were diagnosed on histopathology according to the 2019 World Health Organization classification. BRAF mutation analysis was performed using the Sanger DNA sequencing method. The multivariate logistic regression model was used to determine SSL-associated factors.

RESULTS

There were 2489 patients, with a mean age of 52.1 ± 13.1 and a female-to-male ratio of 1:1.1. The prevalence of SSLs was 4.2% [95% confidence interval (CI): 3.5-5.1]. In the multivariate analysis, factors significantly associated with SSLs were age ≥ 40 [odds ratio (OR): 3.303; 95%CI: 1.607-6.790], male sex (OR: 2.032; 95%CI: 1.204-3.429), diabetes mellitus (OR: 2.721; 95%CI: 1.551-4.772), and hypertension (OR: 1.650, 95%CI: 1.045-2.605). The rate of BRAF mutations in SSLs was 35.5%.

CONCLUSION

The prevalence of SSLs was 4.2%. BRAF mutations were present in one-third of SSLs. Significant risk factors for SSLs included age ≥ 40, male sex, diabetes mellitus, and hypertension.

Colorectal adenomatous and serrated polyps in rural South Australia: who, why, what and where?

BACKGROUNDS

The adenoma-carcinoma and serrated pathways offer a window of opportunity for the removal of pre-malignant polyps and prevention of colorectal cancer (CRC) through the use of colonoscopy. The aim of this study was to investigate variation in polyp incidence in different age groups, gender and indications for undertaking colonoscopy. We also address histological types of polyps found and where in the bowel they are located.

METHODS

This study is based on the colonoscopy data collected prospectively over a one-year period in multiple South Australian rural centres, 24 general surgeons contributed to this study. All histopathology results were subsequently entered into the dataset.

RESULTS

A total of 3497 colonoscopies were performed, with a total of 2221 adenomatous and serrated polyps removed. Both serrated and adenomatous polyps were more common in the distal colon. Patients of male gender, aged 70 years and over and with an indication of polyp surveillance had higher adenoma and serrated polyp detection rates (ADR and SPDR). Patients aged 40-49 years old who underwent colonoscopy for positive faecal occult blood had an ADR and SPDR of 25.0% and 6.3%, respectively.

CONCLUSIONS

This study has shown variation in ADR and SPDR depending on age, gender and indication for colonoscopy. This variation will help further develop key performance indicators in colonoscopy. The high ADR and SPDR in patients aged 40-49 years old whom underwent colonoscopy for positive faecal occult blood may support lowering the age of commencement of CRC screening in Australia.

Artificial intelligence-based polyp size measurement in gastrointestinal endoscopy using the auxiliary waterjet as a reference

BACKGROUND

Measurement of colorectal polyp size during endoscopy is mainly performed visually. In this work, we propose a novel polyp size measurement system (Poseidon) based on artificial intelligence (AI) using the auxiliary waterjet as a measurement reference.

METHODS

Visual estimation, biopsy forceps-based estimation, and Poseidon were compared using a computed tomography colonography-based silicone model with 28 polyps of defined sizes. Four experienced gastroenterologists estimated polyp sizes visually and with biopsy forceps. Furthermore, the gastroenterologists recorded images of each polyp with the waterjet in proximity for the application of Poseidon. Additionally, Poseidon's measurements of 29 colorectal polyps during routine clinical practice were compared with visual estimates.

RESULTS

In the silicone model, visual estimation had the largest median percentage error of 25.1 % (95 %CI 19.1 %-30.4 %), followed by biopsy forceps-based estimation: median 20.0 % (95 %CI 14.4 %-25.6 %). Poseidon gave a significantly lower median percentage error of 7.4 % (95 %CI 5.0 %-9.4 %) compared with other methods. During routine colonoscopies, Poseidon presented a significantly lower median percentage error (7.7 %, 95 %CI 6.1 %-9.3 %) than visual estimation (22.1 %, 95 %CI 15.1 %-26.9 %).

CONCLUSION

In this work, we present a novel AI-based method for measuring colorectal polyp size with significantly higher accuracy than other common sizing methods.

Updates in narrow-band imaging for colorectal polyps: Narrow-band imaging generations, detection, diagnosis, and artificial intelligence

Narrow-band imaging (NBI) is an optical digital enhancement method that allows the observation of vascular and surface structures of colorectal lesions. Its usefulness in the detection and diagnosis of colorectal polyps has been demonstrated in several clinical trials and the diagnostic algorithms have been simplified after the establishment of endoscopic classifications such as the Japan NBI Expert Team classification. However, there were issues including lack of brightness in the earlier models, poor visibility under insufficient bowel preparation, and the incompatibility of magnifying endoscopes in certain endoscopic platforms, which had impeded NBI from becoming standardized globally. Nonetheless, NBI continued its evolution and the newest endoscopic platform launched in 2020 offers significantly brighter and detailed images. Enhanced visualization is expected to improve the detection of polyps while universal compatibility across all scopes including magnifying endoscopy will promote the global standardization of magnifying diagnosis. Therefore, knowledge related to magnifying colonoscopy will become essential as magnification becomes standardly equipped in future models, although the advent of computer-aided diagnosis and detection may greatly assist endoscopists to ensure quality of practice. Given that most endoscopic departments will be using both old and new models, it is important to understand how each generation of endoscopic platforms differ from each other. We reviewed the advances in the endoscopic platforms, artificial intelligence, and evidence related to NBI essential for the next generation of endoscopic practice.

Clip Closure Does Not Reduce Risk of Bleeding After Resection of Large Serrated Polyps: Results From a Randomized Trial

BACKGROUND & AIMS

Serrated polyps are important colorectal cancer precursors and are most commonly located in the proximal colon, where post-polypectomy bleeding rates are higher. There is limited clinical trial evidence to guide best practices for resection of large serrated polyps (LSPs).

METHODS

In a multicenter trial, patients with large (≥20 mm) non-pedunculated polyps undergoing endoscopic mucosal resection (EMR) were randomized to clipping of the resection base or no clipping. This analysis is stratified by histologic subtype of study polyp(s), categorized as serrated [sessile serrated lesions (SSLs) or hyperplastic polyps (HPs)] or adenomatous, comparing clip vs control groups. The primary outcome was severe post-procedure bleeding within 30 days of colonoscopy.

RESULTS

A total of 179 participants with 199 LSPs (191 SSLs and 8 HPs) and 730 participants with 771 adenomatous polyps were included in the study. Overall, 5 patients with LSPs (2.8%) experienced post-procedure bleeding compared with 42 (5.8%) of those with adenomas. There was no difference in post-procedure bleeding rates between patients in the clip vs control group among those with LSPs (2.3% vs 3.3%, respectively, difference 1.0%; P = NS). However, among those with adenomatous polyps, clipping was associated with a lower risk of post-procedure bleeding (3.9% vs 7.6%, difference 3.7%; P = .03) and overall serious adverse events (5.5% vs 10.6%, difference 5.1%; P = .01).

CONCLUSION

The post-procedure bleeding risk for LSPs removed via EMR is low, and there is no discernable benefit of prophylactic clipping of the resection base in this group. This study indicates that the benefit of endoscopic clipping following EMR may be specific for >2 cm adenomatous polyps located in the proximal colon.

CLINICALTRIALS

gov, Number: NCT01936948.

Predictors of Incident Serrated Polyps: Results from a Large Multicenter Clinical Trial

BACKGROUND

Serrated polyps (SP) are important colorectal cancer precursors, yet their epidemiology is incompletely understood. We measured risk factors for incident sessile-serrated lesions (SSL) and microvesicular (MVHP) and goblet-cell rich (GCHP) hyperplastic polyp subtypes.

METHODS

We conducted a cohort study of patients undergoing colonoscopic surveillance nested within a chemoprevention trial. Outcomes of interest were ≥1 SPs, including SSLs, MVHPs, and GCHPs specifically. Multivariable generalized estimating equation models were used to estimate adjusted risk ratios (RR) and 95% confidence intervals (CI) for different polyp types.

RESULTS

Among 2,102 participants, a total of 1,615 SPs (including 212 SSLs) were found among 758 participants during follow-up. Prior history of SPs was strongly associated with subsequent occurrence of SPs. There was no apparent association between age, sex, or education and risk of SPs. Black participants were at lower risk of SSLs and MVHPs, but higher risk of GCHPs compared with white participants [RR, 0.40; 95% CI, 0.16-0.99); RR, 0.63 (95% CI, 0.42-0.96); and RR, 1.83 (95% CI, 1.23-2.72) respectively]. Alcohol and smoking exposure were also associated with SPs, including hyperplastic polyp subtypes in particular.

CONCLUSIONS

In this prospective study, the risk of SP subtypes differed by race, alcohol, and smoking status, and prior history of SPs. Risk factor associations for SPs differ from risk factors for conventional adenomas, supporting the concept of etiologic heterogeneity of colorectal cancer.

IMPACT

These findings allow for better risk stratification of patients undergoing colorectal cancer screening and could inform screening test selection.

Quality Indicators for the Detection and Removal of Colorectal Polyps and Interventions to Improve Them

Modifiable risk factors for postcolonoscopy colorectal cancer include suboptimal lesion detection (missed neoplasms) and inadequate lesion removal (incomplete polypectomy) during colonoscopy. Competent detection and removal of colorectal polyps are thus fundamental to ensuring adequate colonoscopy quality. Several well-researched quality metrics for polyp detection have been implemented into clinical practice, chief among these the adenoma detection rate. Less data are available on quality indicators for polyp removal, which currently include complete resection rates and skills assessment tools. This review summarizes the available literature on quality indicators for the detection and removal of colorectal polyps, as well as interventions to improve them.

Accuracy in optical diagnosis for polyps between 5 and 15 mm and its implications on surveillance. A prospective, multicenter study. (POPS study)

BACKGROUND AND AIMS

Polyps histology and diameter up to 1 cm determine whether a patient needs a colonoscopy after 3 years or less, or far ahead. Endoscopists' and pathologists' size estimations can be imprecise. Our aim was to assess endoscopist ability to correctly recommend surveillance colonoscopies for patients with polyps around the 10 mm threshold, based on its endoscopic sizing and optical diagnosis by NBI.

METHODS

NBI-assisted diagnosis and endoscopist estimation of polyp size were compared with reference standard, considering this as the post resection polyp measurements by the nurse assistant and the pathologic results, in a prospective, multicenter, real life study, that recruited adults undergoing colonoscopy in five hospitals. By comparing the endoscopic and pathologist size estimation, with polyps' measurement after resection, and optical and histological diagnoses in patients with polyps between 5 and 15 mm, sensitivity was assessed at the patient level by means of two characteristics: the presence of adenoma, and the surveillance interval. Surveillance intervals were established by the endoscopist, based on optical diagnosis, and by another gastroenterologist, grounded on the pathologic report. Determinants of accuracy were explored at the polyp level.

RESULTS

532 polyps were resected in 451 patients. Size estimation was more precise for the endoscopist. Endoscopist sensitivity for the presence of adenoma or carcinoma was 98.7%. Considering the presence of high-grade dysplasia or cancer, sensitivity was 82.6% for the endoscopic optical diagnosis. Sensitivity for a correct 3-year surveillance interval was 91.5%, specificity 82.3%, with a PPV of 93.2% and NPV of 78.5% for the endoscopist. 6.51% of patients would have had their follow-up colonoscopy delayed, whereas 22 (4.8%) would have it been performed earlier, had endoscopist recommendations been followed.

CONCLUSION

Our study observes that NBI optical diagnosis can be recommended in routine practice to establish surveillance intervals for polyps between 5 and 15 mm.

CLINICAL TRIALS REGISTRATION NUMBER

NCT04232176.

Impact of comprehensive optical diagnosis training using Workgroup serrAted polypS and Polyposis classification on detection of adenoma and sessile serrated lesion

OBJECTIVES

Many interventions have been attempted to improve adenoma detection rate (ADR) and sessile serrated lesion detection rate (SDR), and one of these interventions is educational training to recognize polyp characteristics. This study aimed to investigate the change in polyp detection rates of endoscopists before and after comprehensive training through the Gangnam-Real Time Optical Diagnosis (Gangnam-READI) program.

METHODS

Fifteen gastroenterologists participated in a 1-year comprehensive training program that consisted of ex vivo and in vivo training that encompasses knowledge and skills in endoscopic characterization of colonic polyps using the Workgroup serrAted polypS and Polyposis (WASP) classification. We evaluated the impact of the training program by comparing the overall and individual ADR and SDR 6 months before and after the training.

RESULTS

Overall, 18,280 polyps (9337 adenomas and 855 sessile serrated lesion) were collected. The optical diagnosis training had no significant impact on the difference in ADR after training compared to before training (47.7% vs. 46.5%, P = 0.608). A tendency for a decrease in ADR variance was noted among the endoscopists after training (74.9 vs. 32.7, P = 0.121). The overall pre-training period SDR was 4.5% and showed a statistically significant increase to 5.6%, 8.0%, and 7.1% in the first and second half of the training period, and post-training period, respectively (P = 0.003). The optical diagnosis training did not decrease variance in SDR (8.9 vs. 8.8, P = 0.985).

CONCLUSION

Comprehensive optical diagnosis training with WASP classification has a significant impact on increasing the overall SDR of expert endoscopists.

Disparate age and sex distribution of sessile serrated lesions and conventional adenomas in an outpatient colonoscopy population-implications for colorectal cancer screening?

PURPOSE

Colorectal cancer (CRC) is increasingly diagnosed in individuals aged < 50 years, resulting in advocacy of screening from age 45 years. Despite existing knowledge associating CRC with conventional adenomas, the significance of sessile serrated lesions (SSLs) on the burden of CRC is less detailed. We aimed to provide contemporary estimates for SSL prevalence and examine patient and procedure factors associated with SSL detection.

METHODS

Retrospective observational study examining associations between SSL and conventional adenoma detection, polyp histopathology, patient, and procedure characteristics in an outpatient colonoscopy unit over 12 months.

RESULTS

From 2097 colonoscopies, SSL detection was 13.8% overall and 12.5% in patients < 50 years. SSLs were mostly proximal in location (64%), and SSL detection was significantly higher in females compared with males (16.2% vs. 11.7%, p = 0.003), particularly in those < 50 years (16.8% vs. 8.6%, p < 0.001). In multivariable analysis, SSL detection was associated with female sex (adjusted odds ratio [aOR] 1.48, 95% confidence interval [CI] 1.15-1.91), synchronous conventional adenoma detection (aOR 1.36, 95% CI 1.04-1.78) and BMI ≥ 25 kg/m² (aOR 1.34, 95% CI 1.02-1.77). Conventional adenoma detection was 33.6% and associated with age ≥ 50 years (aOR 3.57, 95% CI 2.84-4.47) and synchronous SSL detection (aOR 1.36, 95% CI 1.03-1.79).

CONCLUSIONS

We observed age and sex disparities in polyp types and prevalence in this outpatient colonoscopy population. SSLs were most prevalent in females aged < 50 years, suggesting a potential increased susceptibility of young females to SSLs and CRC. Our findings may have implications for the design of CRC screening programs.

The prevalence of sessile serrated lesion in the colorectum and its relationship to synchronous colorectal advanced neoplasia: a systemic review and meta-analysis

BACKGROUND

The aim of this systemic review and meta-analysis was to evaluate the prevalence of sessile serrated lesion (SSL) and its relationship to synchronous colorectal advanced neoplasia.

MATERIALS AND METHODS

Comprehensive, computerized research was performed on PubMed and published from 1 January 2010 to 6 July 2018 which searched relevant articles without any language limitations. Clinical trials were included in the narrative systemic review if they matched the following inclusion criteria: (1) published as a case-controlled study, cohort study or cross-sectional study; (2) defined objectively for diagnosis of SSL within the studies; (3) addressed the prevalence and characteristics of SSL. Within these trials, if they met additional criteria involving the reported outcome of risk regarding advanced neoplasia in relation to SSL, they were enrolled into meta-analysis.

RESULTS

Forty-one trials were enrolled for the systematic review, with a total of eight analyzed for the meta-analysis. The prevalence of all SSL ranged from 0.038 to 20.23% and the prevalence by pooled analysis was 2.7%. In a subgroup analysis, the overall prevalence of SSL during the periods of 2010-2014 and 2015-2018 was shown to be 2.7 and 2.8%, respectively. We calculated the pooled data on the cancer risk of SSL and the risk of synchronous advanced neoplasia in patients with SSL made available from the eight trials, which resulted in a pooled odds ratio of 3.53 (95% confidence interval 2.39-5.20, I2 = 4%, P = 0.40).

CONCLUSION

In this systemic review, SSL was found to be associated with an increased risk of synchronous advanced neoplasia in the colorectum.

A Polyp Worth Removing: A Paradigm for Measuring Colonoscopy Quality and Performance of Novel Technologies for Polyp Detection

Leaving no significant polyp behind while avoiding risks due to unnecessary resections is a commonsense strategy to safely and effectively prevent colorectal cancer (CRC) with colonoscopy. It also alludes to polyps worth removing and, therefore, worth finding. The majority of "worthy" precancerous polyps are adenomas, which for over 2 decades, have received the most attention in performance research and metrics. Consequently, the detection rate of adenomas is currently the only validated, outcome-based measure of colonoscopy demonstrated to correlate with reduced risk of postcolonoscopy CRC. However, a third or more of postcolonoscopy CRCs originate from sessile serrated polyps (SSPs), which are notoriously difficult to find, diagnose and completely resect. Among serrated polyps, the agreement among pathologists differentiating SSPs from non-neoplastic hyperplastic polyps is moderate at best. This lack of ground truth precludes SSPs from consideration in primary metrics of colonoscopy quality or performance of novel polyp detection technologies. By instead leveraging the distinct endoscopic and clinical features of serrated polyps, including those considered important due to proximal location and larger size, clinically significant serrated polyps represent serrated polyps worth removing, enriched with subtle precancerous SSPs. With the explosion of technologies to assist polyp detection, now is the time to broaden benchmarks to include clinically significant serrated polypss alongside adenomas, a measure that is relevant both for assessing the performance of endoscopists, and for assessing new polyp detection technologies.

AGA Clinical Practice Update on Strategies to Improve Quality of Screening and Surveillance Colonoscopy: Expert Review

The purpose of this American Gastroenterological Association Institute Clinical Practice Update was to review the available evidence and provide best practice advice regarding strategies to improve the quality of screening and surveillance colonoscopy. This review is framed around 15 best practice advice statements regarding colonoscopy quality that were agreed upon by the authors, based on a review of the available evidence and published guidelines. This is not a formal systematic review and thus no formal rating of the quality of evidence or strength of recommendation has been carried out.

Sessile serrated lesion detection rates during average risk screening colonoscopy: A systematic review and meta-analysis of the published literature

Background and study aims  Sessile serrated lesion (SSL) detection rate has been variably reported and unlike adenoma detection rate (ADR) is not currently a quality indicator for screening colonoscopy. Composite detection rates of SSL in patients undergoing average risk screening colonoscopy are not available. Methods  Electronic database search (Medline, Embase and Cochrane) was conducted for studies reporting detection rates of serrated polyps (SSL, Hyperplastic polyp, traditional serrated adenoma) among average risk subjects undergoing screening colonoscopy. Primary outcomes were pooled SDR (SSL detection rate) and proximal serrated polyp detection rate (PSPDR). Pooled proportion rates were calculated with 95 %CI with assessment of heterogeneity (I ² ). Publication bias, regression test and 95 %prediction interval were calculated. Results  A total of 280,370 screening colonoscopies among average risk subjects that were eligible with 48.9 % males and an average age of 58.7 years (± 3.2). The pooled SDR was available from 16 studies: 2.5 % (1.8 %-3.4 %) with significant heterogeneity (I ²  = 98.66 %) and the 95 % prediction interval ranging from 0.6 % to 9.89 %. When analysis was restricted to large (n > 1000) and prospective studies (n = 4), SDR was 2 % (1.1 %-3.3 %). Pooled PSPDR was 10 % (8.5 %-11.8 %; 12 studies). There was evidence of publication bias ( P  < 0.01). Conclusion  Definitions of SSL have been varying over years and there exists significant heterogeneity in prevalence reporting of serrated polyps during screening colonoscopy. Prevalence rate of 2 % for SSL and 10 % for proximal serrated polyps could serve as targets while robust high-quality data is awaited to find a future benchmark showing reduction in colorectal cancer arising from serrated pathway.

Evolving Role and Future Directions of Natural Language Processing in Gastroenterology

In line with the current trajectory of healthcare reform, significant emphasis has been placed on improving the utilization of data collected during a clinical encounter. Although the structured fields of electronic health records have provided a convenient foundation on which to begin such efforts, it was well understood that a substantial portion of relevant information is confined in the free-text narratives documenting care. Unfortunately, extracting meaningful information from such narratives is a non-trivial task, traditionally requiring significant manual effort. Today, computational approaches from a field known as Natural Language Processing (NLP) are poised to make a transformational impact in the analysis and utilization of these documents across healthcare practice and research, particularly in procedure-heavy sub-disciplines such as gastroenterology (GI). As such, this manuscript provides a clinically focused review of NLP systems in GI practice. It begins with a detailed synopsis around the state of NLP techniques, presenting state-of-the-art methods and typical use cases in both clinical settings and across other domains. Next, it will present a robust literature review around current applications of NLP within four prominent areas of gastroenterology including endoscopy, inflammatory bowel disease, pancreaticobiliary, and liver diseases. Finally, it concludes with a discussion of open problems and future opportunities of this technology in the field of gastroenterology and health care as a whole.

Effect of successive endoscopic procedures in polyp and adenoma detection rates: Too early is not always too good

BACKGROUND AND AIMS: There is conflicting evidence regarding the impact of hypothetical cumulative fatigue after performing too many endoscopic procedures on both polyp and adenoma detection rates (PDR, and ADR, respectively). The aim of this study is to evaluate the effect of successive endoscopic procedures on PDR and ADR.

METHODS

A retrospective cross-sectional study was undertaken among consecutive patients on whom colonoscopy and/or esophagogastroduodenoscopy were performed between January 2012 and August 2014. Data regarding polyp and adenoma detection, cecal intubation, and bowel cleansing quality as well as demographical data of subjects were extracted. Endoscopic procedures were classified according to the time slots of the procedures throughout the endoscopy session in three groups: from the 1st to 4th endoscopy study (round 1), from the 5th to the 8th study (round 2), above the 9th study (round 3). We compared PDR and ADR among rounds.

RESULTS

Overall, 3388 patients were enrolled. Median age was 50 years (range 18-95) and 52.39% were female. There was a significant difference in terms of PDR among rounds (36.83%, 41.24%, and 43.38%, respectively, p = 0.007) and a non-significant numerical difference when ADR was compared (23.2%, 25.71%, and 26.78%, p = 0.07). On multivariate analysis, ADR was significantly associated with age (odds ratio [OR] 1.02 [1.01-1.03]), and male sex (OR 1.64 [1.38-1.94]).

CONCLUSION

Theoretical endoscopist's fatigue due to cumulative performance of endoscopies does not diminish colonoscopy quality. Both PDR and ADR seem to improve after endoscopist's cumulative rounds of performed endoscopies. This could be due to a "warm-up" effect.

Molecular Biomarkers of Sessile Serrated Adenoma/Polyps

OBJECTIVES:

Sessile serrated adenoma/polyps (SSA/Ps) contribute up to 30% of all colon cancers. There is considerable histological overlap between SSA/Ps and hyperplastic polyps. Inadequate consensus exists among pathologists, and no molecular biomarkers exist to differentiate these lesions with high accuracy. Lack of reliable diagnosis adversely affects clinical care. We previously defined a novel 7-gene panel by RNA sequencing that differentiates SSA/Ps from hyperplastic polyps. Here, we use the 7-gene panel as a molecular approach to differentiate SSA/Ps and HPs with higher sensitivity and specificity in a large sample set from a tertiary health care center.

METHODS:

Reverse transcription quantitative polymerase chain reaction of the 7-gene panel was performed on 223 formalin-fixed, paraffin-embedded serrated polyp and normal colon samples. We compare the sensitivity and specificity of the 7-gene panel with the BRAF and KRAS mutation incidence in differentiating SSA/Ps and HPs. We also evaluate the clinical data of patients with SSA/Ps showing high and low expression of the gene panel.

RESULTS:

The 7-gene RNA expression panel differentiates SSA/Ps and HPs with 89.2% sensitivity and 88.4% specificity. The gene panel outperforms BRAF mutation in identification of SSA/Ps. Clinical data suggest that expression of the 7-gene panel correlates with the development of SSA/Ps in the future.

DISCUSSION:

This study describes a novel 7-gene panel that identifies SSA/Ps with improved accuracy. Our data show that RNA markers of SSA/Ps advance the distinction of serrated lesions and contribute to the study of the serrated pathway to colon cancer.

Prevalence and Clinical Features of Sessile Serrated Polyps: A Systematic Review

BACKGROUND & AIMS

Sessile serrated polyps (SSPs) could account for a substantial proportion of colorectal cancers. We aimed to increase clarity on SSP prevalence and clinical features.

METHODS

We performed a systematic review of MEDLINE, Web of Science, Embase, and Cochrane databases for original studies published in English since 2000. We included studies of different populations (United States general or similar), interventions (colonoscopy, autopsy), comparisons (world regions, alternative polyp definitions, adenoma), outcomes (prevalence, clinical features), and study designs (cross-sectional). Random-effects regression was used for meta-analysis where possible.

RESULTS

We identified 74 relevant colonoscopy studies. SSP prevalence varied by world region, from 2.6% in Asia (95% confidence interval [CI], 0-5.9) to 10.5% in Australia (95% CI, 2.8-18.2). Prevalence values did not differ significantly between the United States and Europe (P = .51); the pooled prevalence was 4.6% (95% CI, 3.4-5.8), and SSPs accounted for 9.4% of polyps with malignant potential (95% CI, 6.6-12.3). The mean prevalence was higher when assessed through high-performance examinations (9.1%; 95% CI, 4.0-14.2; P = .04) and with an alternative definition of clinically relevant serrated polyps (12.3%; 95% CI, 9.3-15.4; P < .001). Increases in prevalence with age were not statistically significant, and prevalence did not differ significantly by sex. Compared with adenomas, a higher proportion of SSPs were solitary (69.0%; 95% CI, 45.9-92.1; P = .08), with diameters of 10 mm or more (19.3%; 95% CI, 12.4-26.2; P = .13) and were proximal (71.5%; 95% CI, 63.5-79.5; P = .008). The mean ages for detection of SSP without dysplasia, with any or low-grade dysplasia, and with high-grade dysplasia were 60.8 years, 65.6 years, and 70.2 years, respectively. The range for proportions of SSPs with dysplasia was 3.7%-42.9% across studies, possibly reflecting different study populations.

CONCLUSIONS

In a systematic review, we found that SSPs are relatively uncommon compared with adenoma. More research is needed on appropriate diagnostic criteria, variations in detection, and long-term risk.

Surveying ADR Knowledge and Practices Among US Gastroenterologists

BACKGROUND

The adenoma detection rate (ADR) is of primary importance to the quality of screening colonoscopy. An online survey was conducted to assess knowledge and practices on ADR.

METHODS

Paid questionnaire distributed by email. Eligible respondents were board certified gastroenterologists who perform >80 colonoscopies per month with 3 to 35 years practice after fellowship.

RESULTS

There were 250 respondents. In total, 39% were unaware that ADR applies only to screening colonoscopies and 76% incorrectly answered that ADR includes sessile-serrated polyps/adenomas. A total of 51% of respondents incorrectly believe the threshold is set at 25% because 25% is a national ADR average. Many also believe the threshold depends on the patient population (current evidence suggests adjusting ADR for factors other than age and sex is unnecessary). 75% ranked ADR as highly important. 80% reported tracking ADR. A busy practice was the most common reason for not tracking ADR. Caps, chromoendoscopy, and good bowel preparation were viewed as valuable for improving ADR (this is true except for caps). High-definition colonoscopes and education were considered less valuable, despite evidence indicating that both are associated with improved ADR. In total, 57% reported not sharing ADR information with their patients, and 59% reported that no patients in the last 6 months asked for their ADR.

CONCLUSIONS

The importance of ADR as a quality measure is well understood, but there are misconceptions among gastroenterologists regarding the definition and measurement of ADR, and which methods are proven to increase ADR. Patients are having very little impact on ADR measurement.

Terminology, Molecular Features, Epidemiology, and Management of Serrated Colorectal Neoplasia

In addition to the adenoma to carcinoma sequence, colorectal carcinogenesis can occur via the serrated pathway. Studies have focused on clarification of categories and molecular features of serrated polyps, as well as endoscopic detection and risk assessment. Guidelines from the World Health Organization propose assigning serrated polyps to categories of hyperplastic polyps, traditional serrated adenomas, and sessile serrated lesions (SSLs). Traditional serrated adenomas and SSLs are precursors to colorectal cancer. The serrated pathway is characterized by mutations in RAS and RAF, disruptions to the Wnt signaling pathway, and widespread methylation of CpG islands. Epidemiology studies of serrated polyps have been hampered by inconsistencies in terminology and reporting, but the prevalence of serrated class polyps is 20%-40% in average-risk individuals; most serrated polyps detected are hyperplastic. SSLs, the most common premalignant serrated subtype, and are found in up to 15% of average-risk patients by high-detecting endoscopists. Variations in rate of endoscopic detection of serrated polyps indicate the need for careful examination, with adequate bowel preparation and sufficient withdrawal times. Risk factors for SSLs include white race, family history of colorectal cancer, smoking, and alcohol intake. Patients with serrated polyps, particularly SSLs and traditional serrated adenomas, have an increased risk of synchronous and metachronous advanced neoplasia. Surveillance guidelines vary among countries, but SSLs and proximal hyperplastic polyps require special attention in assignment of surveillance interval-especially in light of concerns regarding incomplete detection and resection.

Association Between Endoscopist Personality and Rate of Adenoma Detection

BACKGROUND & AIMS

There is significant variation among endoscopists in their adenoma detection rates (ADRs). We explored associations between ADR and characteristics of endoscopists, including personality traits and financial incentives.

METHODS

We collected electronic health record data from October 2013 through September 2015 and calculated ADRs for physicians from 4 health systems. ADRs were risk-adjusted for differences in patient populations. Physicians were surveyed to assess financial motivations, knowledge and perceptions about colonoscopy quality, and personality traits. Of 140 physicians sent the survey, 117 responded.

RESULTS

The median risk-adjusted ADR for all surveyed physicians was 29.3% (interquartile range, 24.1%-35.5%). We found no significant association between ADR and financial incentives, malpractice concerns, or physicians' perceptions of ADR as a quality metric. ADR was associated with the degree of self-reported compulsiveness relative to peers: among endoscopists who described themselves as much more compulsive, the ADR was 33.1%; among those who described themselves as somewhat more compulsive, the ADR was 32.9%; among those who described themselves as about the same as others, the ADR was 26.4%; and among those who described themselves as somewhat less compulsive, the ADR was 27.3%) (P = .0019). ADR was also associated with perceived thoroughness (much more thorough than peers, ADR = 31.5%; somewhat more, 31.9%; same/somewhat less, 27.1%; P = .0173). Physicians who reported feeling rushed, having difficulty pacing themselves, or having difficulty in accomplishing goals had higher ADRs. A secondary analysis found the same associations between personality and adenomas per colonoscopy.

CONCLUSIONS

We found no significant association between ADR and financial incentives, malpractice concerns, or perceptions of ADR as a quality metric. However, ADRs were higher among physicians who described themselves as more compulsive or thorough, and among those who reported feeling rushed or having difficulty accomplishing goals.

Magnitude, Risk Factors, and Factors Associated With Adenoma Miss Rate of Tandem Colonoscopy: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

We performed a systematic review and meta-analysis to comprehensively estimate adenoma miss rate (AMR) and advanced AMR (AAMR) and explore associated factors.

METHODS

We searched the PubMed, Web of Science, and Ovid EMBASE databases for studies published through April 2018 on tandem colonoscopies, with AMR and AAMR as the primary outcomes. We performed meta-regression analyses to identify risk factors and factors associated with outcome. Primary outcomes were AMR and AAMR and secondary outcomes were AMR and AAMR for different locations, sizes, pathologies, morphologies, and populations.

RESULTS

In a meta-analysis of 43 publications and more than 15,000 tandem colonoscopies, we calculated miss rates of 26% for adenomas (95% confidence interval [CI] 23%-30%), 9% for advanced adenomas (95% CI 4%-16%), and 27% for serrated polyps (95% CI 16%-40%). Miss rates were high for proximal advanced adenomas (14%; 95% CI 5%-26%), serrated polyps (27%; 95% CI 16%-40%), flat adenomas (34%; 95% CI 24%-45%), and in patients at high risk for colorectal cancer (33%; 95% CI 26%-41%). Miss rates could be decreased by adequate bowel preparation and auxiliary techniques (P = .06; P = .04, and P = .01, respectively). The adenoma detection rate (ADR), adenomas per index colonoscopy, and adenomas per positive index colonoscopy (APPC) were independently associated with AMR (P = .02, P = .01, and P = .008, respectively), whereas APPC was the only factor independently associated with AAMR (P = .006). An APPC value greater than 1.8 was more effective in monitoring AMR (31% vs 15% for AMR P < .0001) than an ADR value of at least 34% (27% vs 17% for AMR; P = .008). The AAMR of colonoscopies with an APPC value below 1.7 was 35%, vs 2% for colonoscopies with an APPC value of at least 1.7 (P = .0005).

CONCLUSIONS

In a systematic review and meta-analysis, we found that adenomas and advanced adenomas are missed (based on AMR and AAMR) more frequently than previously believed. In addition to ADR, APPC deserves consideration as a complementary indicator of colonoscopy quality, if it is validated in additional studies.

Confounders in Adenoma Detection at Initial Screening Colonoscopy: A Factor in the Assessment of Racial Disparities as a Risk for Colon Cancer

Background and Aims

The incidence and mortality of colorectal cancer is persistently highest in Black/African-Americans in the United States. While access to care, barriers to screening, and poverty might explain these findings, there is increased interest in examining biological factors that impact the colonic environment. Our group is examining biologic factors that contribute to disparities in development of adenomas prospectively. In preparation for this and to characterize a potential patient population, we conducted a retrospective review of initial screening colonoscopies in a cohort of patients.

Methods

A retrospective review was performed on initial average risk screening colonoscopies on patients (age 45-75 years) during 2012 at three institutions. Descriptive statistics and multivariable logistic regression models were used to examine the relationship between potential risk factors and the detection of adenomas.

Results

Of the 2225 initial screening colonoscopies 1495 (67.2%) were performed on Black/African-Americans and 566 (25.4%) on Caucasians. Multivariable logistic regression revealed that older age, male sex, current smoking and teaching gastroenterologists were associated with higher detection of adenomas and these were less prevalent among Black/African-Americas except for age. Neither race, ethnicity, BMI, diabetes mellitus, HIV nor insurance were associated with adenoma detection.

Conclusion

In this sample, there was no association between race and adenoma detection. While this may be due to a lower prevalence of risk factors for adenomas in this sample, our findings were confounded by a lower detection rate by consultant gastroenterologists at one institution. The study allowed us to rectify the problem and characterize patients for future trials.

The proto CpG island methylator phenotype of sessile serrated adenomas/polyps

Sessile serrated adenomas/polyps (SSA/Ps) are the putative precursors of the ~20% of colon cancers with the CpG island methylator phenotype (CIMP). To investigate the epigenetic phenotype of these precancers, we prospectively collected fresh-tissue samples of 17 SSA/Ps and 15 conventional adenomas (cADNs), each with a matched sample of normal mucosa. Their DNA was subjected to bisulfite next-generation sequencing to assess methylation levels at ~2.7 million CpGs located predominantly in gene regulatory regions and spanning 80.5Mb; RNA was sequenced to define the samples' transcriptomes. Compared with normal mucosa, SSA/Ps and cADNs exhibited markedly remodeled methylomes. In cADNs, hypomethylated regions were far more numerous (18,417 vs 4288 in SSA/Ps) and rarely affected CpG islands/shores. SSA/Ps seemed to have escaped this wave of demethylation. Cytosine hypermethylation in SSA/Ps was more pervasive (hypermethylated regions: 22,147 vs 15,965 in cADNs; hypermethylated genes: 4938 vs 3443 in cADNs) and more extensive (region for region), and it occurred mainly within CpG islands and shores. Given its resemblance to the CIMP typical of SSA/Ps' putative descendant colon cancers, we refer to the SSA/P methylation phenotype as proto-CIMP. Verification studies of six hypermethylated regions in an independent series of precancers demonstrated DNA methylation markers' high potential for predicting the diagnosis of SSA/Ps and cADNs. Surprisingly, proto-CIMP in SSA/Ps was associated with upregulated gene expression; downregulation was more common in cADNs. In conclusion, the epigenetic landscape of SSA/Ps differs markedly from that of cADNs. These differences are a potentially rich source of novel tissue-based and noninvasive biomarkers.

Number of Adenomas Removed and Colorectal Cancers Prevented in Randomized Trials of Flexible Sigmoidoscopy Screening

BACKGROUND & AIMS

Screening for colorectal cancer (CRC) with sigmoidoscopy reduces CRC incidence by detecting and removing adenomas. The number needed to screen is a measure of screening efficiency, but is not directly associated with adenoma removal. We propose the following 2 new metrics for quantifying the relationship between adenoma removal and CRC prevented: number of adenomas needed to remove (NNR) and adenoma dwell time avoided (DTA).

METHODS

We collected data from 4 randomized trials of sigmoidoscopy screening (1 in the United States and 3 in Europe) to assess NNR and DTA. For each trial, NNR was computed as the number of adenomas removed from subjects in the intervention group, divided by the number of CRCs prevented. DTA was computed similarly but taking into account the timing of adenoma removal. Combined results across trials were assessed using standard meta-analytic techniques.

RESULTS

The estimated NNR for the PLCO (Prostate, Lung, Colorectal and Ovarian) trial was 74 (95% confidence interval [CI], 56-110), for the NORCCAP (Norwegian Colorectal Cancer Prevention) trial was 71 (95% CI, 44-174), for the SCORE (Screening for Colon Rectum) trial was 27 (95% CI, 14-135), and for the UKFSST (UK Flexible Sigmoidoscopy Screening Trial) was 36 (95% CI, 28-52). The combined estimate (meta-analysis) of NNR was 52 (95% CI, 36-93) assuming heterogeneity (P for heterogeneity = .014). DTA estimates among trials ranged from 278 to 730 years, with a combined estimate of 500 (95% CI, 344-833) years assuming heterogeneity (P for heterogeneity = .035), or 2 CRC cases prevented per 1000 adenoma dwell years avoided. The combined estimates of NNR and DTA restricted to advanced adenomas were 13 (95% CI, 9-22) and 122 (95% CI, 90-190) years, respectively.

CONCLUSIONS

We collected data from 4 randomized trials of sigmoidoscopy screening for CRC to develop metrics of endoscopic efficiency, NNR and DTA, which are directly linked to adenoma detection and removal. They can be used to compare screening among endoscopic modalities and to more precisely measure adenoma to carcinoma transition rates.