Sessile Serrated Adenomas Research Articles

ID: 3524880 COMPARISON OF RISK OF METACHRONOUS LESIONS BY PRESENCE OF A SESSILE SERRATED LESION AMONG INDIVIDUALS WITH ADENOMA ON INDEX COLONOSCOPY

Background & Aim: Surveillance guidelines suggest the interval of colonoscopy by stratifying the risk based on findings in index colonoscopy. However, the risk of metachronous lesions on the coexistence of adenoma and sessile serrated lesion (SSL) was rarely addressed. We aimed to evaluate the impact of the presence of synchronous SSL on the risk of metachronous lesions within a similar adenoma risk group.

Impact of the sessile serrated polyp pathway on predicted colorectal cancer outcomes in the CRC-AIM model.

10545 Background: Approximately 20–30% of colorectal cancers (CRC) arise from the serrated polyp pathway. The multitarget stool DNA (mt-sDNA) test has greater sensitivity to detect sessile serrated polyps (SSPs) than a leading fecal immunochemical test (FIT). However, most modeling analyses do not account for the contribution of the SSP pathway to risk of CRC. We used the CRC-AIM model to assess the impact of the SSP pathway on predicted CRC outcomes with mt-sDNA or FIT screening. Methods: A simulated cohort of average-risk US patients underwent triennial mt-sDNA or annual FIT screening from ages 50–75. The percentage of CRCs arising from the SSP pathway were modeled at 0% (base case), 20%, and 30%, with stool screening adherence based on theoretical (100%) or previously reported (mt-sDNA 71%; FIT 43%) rates. Published SSP sensitivities for mt-sDNA and FIT were used. All other model inputs were identical to CISNET models. Sensitivity analyses used screening adherence rates of 40–70%. Key outcomes were life-years gained (LYG), CRC incidence and CRC mortality per 1000 patients. Results: Including SSPs in the model demonstrated a greater loss of LYG with FIT than mt-sDNA (Table). At 100% adherence, compared with base case, modeling 20% or 30% SSP pathway CRCs resulted in a decrease of 9–15 LYG with FIT and 2–4 LYG with mt-sDNA, a decrease in CRC incidence reduction of 3.9–6.1% with FIT and 0.7–1.1% with mt-sDNA, and a decrease in CRC mortality reduction of 2.6–4.0% with FIT and 0.4–0.8% with mt-sDNA. Using previously reported adherence, compared with base case, modeling 20% or 30% SSP pathway CRCs resulted in a decrease of 13–20 LYG with FIT and 2–5 LYG with mt-sDNA, a decrease in CRC incidence reduction of 4.4–6.9% with FIT and 0.6–1.1% with mt-sDNA, and a decrease in CRC mortality reduction of 3.5–5.4% with FIT and 0.4–0.9% with mt-sDNA. Assuming reported adherence and 30% SSP pathway CRCs, mt-sDNA had 48 more LYG, 14.6% greater CRC incidence reduction, and 12.4% greater CRC mortality reduction than FIT. Assuming 30% SSP pathway CRCs, outcomes favored mt-sDNA vs FIT even after modeling equivalent adherence rates ranging from 40–70%. Conclusions: After incorporating the SSP pathway into the model, outcomes with mt-sDNA neared those of FIT at 100% screening adherence rates and surpassed FIT at more realistic reported screening adherence rates.[Table: see text]

DNA mismatch repair protein immunohistochemistry - an illustrated guide.

DNA mismatch repair (MMR) is an essential physiological process for correcting mutations occurring during DNA replication. Deficient MMR (dMMR) leads to increased tumour mutational burden, with a heightened risk of neoplasia. Demonstration of dMMR via the immunohistochemical assessment of MMR proteins is useful when screening for inherited cancer syndromes (especially Lynch syndrome) and for the prediction of clinical cancer response to conventional chemotherapy and novel immunotherapies. Identification of dMMR may also be helpful in other situations e.g. when considering a diagnosis of conventional dysplasia in sessile serrated lesions of the large intestine. This article provides a practical illustrated guide to DNA MMR interpretation, using a series of clinical examples.

Sessile serrated adenomas detection rate among the surgeons and the gastroenterologists: A retrospective analysis

Background: Sessile serrated adenomas (SSAs) are flat or sessile benign lesions occasionally covered by a mucous cap and invariably lead to colorectal cancer. The adenoma detection rate (ADR) is recognized as an important quality measure for colonoscopy. Objective: The objective of the study was to evaluate and compare the ADR during colonoscopy among surgeons and gastroenterologists. Materials and Methods: In this retrospective analysis, all colonoscopies performed during July 2018–July 2019 at Caboolture Hospital, Queensland, Australia were included in the study. After considering the inclusion and exclusion criteria, the rate of sessile polyp detection among the gastroenterologist versus surgeons was investigated by calculating a correlation coefficient weighted by factors such as experience, colonoscopy intubation time, and removal of scopes. Results: A total of 3425 colonoscopies performed by 7 surgeons and 4 gastroenterologists were assessed. Among them, 58.7% colonoscopies were performed by the surgeons, while gastroenterologists performed 41.3% colonoscopies. The median age of patients was 56.5 years (25–88 years), more common in male than female (58.9% and 41.1%, respectively, p<0.0001). The average withdrawal time among the surgeons and gastroenterologist was 8.05 and 8.54 min, respectively (p=0.02). Mean cecal intubation rate among the surgeons and gastroenterologist was 94.7% and 97.4%, respectively. Most patients had adequate bowel preparations; however, poor bowel preparation was observed among 6.15% gastroenterology patients and 5.6% in surgical patients. Conclusion: Based on the longer withdrawal time and improved skillset, sessile serrated polyp detection rate during colonoscopy was higher among the gastroenterologist as compared to the surgeons.

Quality Control in the Slovenian National Colorectal Cancer Screening Program

Objectives: The objective of the study was to assess the impact of an internal quality indicator (QI) audit on the quality level of colonoscopies in the National Colorectal Cancer Screening Program (NCCSP). Design: Sixty-eight colonoscopists from 29 endoscopic centres participated in the NCCSP from April 2009 to January 2015. Controlled QIs were the percentage of total colonoscopies, adenoma detection rate (ADR), mean adenoma per procedure (MAP), mean adenoma per positive procedure (MAP+), right-sided ADR, sessile serrated lesion (SSL) detection rate, and patient responses to post-procedural questionnaires. A group of 3 expert endoscopists from the NCCSP Council performed 91 inspections and provided education. Results: A total of 891.364 (58.2%) Slovenian citizens participated in the first 3 screening rounds of the NCCSP. Among 46.552 (6%) positive individuals, 42.866 (92.1%) underwent first colonoscopies. Total colonoscopies were performed in 98% of endoscopies (p = 0.459 between cycles), mean ADR was 51.8% (p = 0.872 between cycles), mean percentage of adenoma in the right colon was 37.5% (p = 0.227 between cycles), mean MAP was 1.1 (p = 0.981 between cycles), mean MAP+ was 2.0 (p = 0.824 between cycles), and mean SSL detection rate was 3% (p < 0.001). We observed great difference in QIs between endoscopists and a significant increase in MAP, ADR in the right colon, and SSL per endoscopist during the 6-year period. Due to quality underperformance, 3 endoscopic centres (10.3%) and 13 endoscopists (19.1%) were excluded from the program. Conclusions: The success of the NCCSP is related to the quality of colonoscopies performed. To ensure the proper quality level, regular audit and permanent education are needed.

Self-reported Metabolic Risk Factor Associations with Adenomatous, Sessile Serrated, and Synchronous Adenomatous and Sessile Serrated Polyps.

Studies have found a positive association between metabolic risk factors, such as obesity and diabetes, and adenomatous polyps (AP). However, fewer studies have assessed the association between sessile serrated polyps (SSP) or synchronous diagnosis of APs and SSPs (synch polyps). Study participants (N = 1,370; ages 40-85) undergoing screening colonoscopy were enrolled between August 2016 and February 2020. Self-reported metabolic risk factors, including diabetes, hypertension, hyperlipidemia, and overweight/obesity, were evaluated for associations with new diagnoses of APs, SSPs, and synch polyps at the present colonoscopy. Average participant age was 60.73 ± 8.63 (SD) years; 56.7% were female and 90.9% white. In an assessment of individual metabolic risk factors, adjusted for age, sex, race, and smoking status, increased body mass index (BMI; overweight or obese vs. normal BMI of <25 kg/m2) was associated with an increased odds for new onset of colon APs (P trend < 0.001) as was a diagnosis of diabetes [adjusted conditional OR (aCOR) = 1.59 (1.10-2.29)]. No associations were seen between the metabolic risk factors and onset of SSPs. Being obese or hypertensive each increased the odds of new onset of synch polyps with aCOR values of 2.09 (1.01-4.32) and 1.79 (1.06-3.02), respectively. Self-reported risk factors may help assess polyp type risk. Because SSPs and synch polyps are rare, larger studies are needed to improve our understanding of the contribution of these factors to polyp risk. These data lead us to hypothesize that differences in observed metabolic risk factors between polyp types reflect select metabolic impact on pathways to colorectal cancer. PREVENTION RELEVANCE: Self-reported medical history provides valuable insight into polyp risk, potentially enabling the use of larger retrospective studies of colonoscopy populations to assess knowledge gaps. More aggressive colonoscopy screening, critical to colorectal cancer prevention, may be considered in populations of individuals with metabolic risk factors and modifiable lifestyle risk factors.

Clinical Features and Predictors of Dysplasia in Proximal Sessile Serrated Lesions.

Background/AimsProximal colorectal cancers (CRCs) account for up to half of CRCs. Sessile serrated lesions (SSLs) are precursors to CRC. Proximal location and presence of dysplasia in SSLs predict higher risks of progression to cancer. The prevalence of dysplasia in proximal SSLs (pSSLs) and clinical characteristics of dysplastic pSSLs are not well studied. MethodsEndoscopically resected colonic polyps at our center between January 2016 and December 2017 were screened for pSSLs. Data of patients with at least one pSSL were retrieved and clinicopathological features of pSSLs were analysed. pSSLs with and without dysplasia were compared for associations. ResultsNinety pSSLs were identified, 45 of which had dysplasia giving a prevalence of 50.0%. Older age (65.9 years vs. 60.1 years, p=0.034) was associated with the presence of dysplasia. Twelve pSSLs were 10 mm or larger. After adjusting for age, pSSLs ≥10 mm had an adjusted odds ratio of 5.98 (95% confidence interval, 1.21–29.6) of having dysplasia compared with smaller pSSLs. ConclusionsIn our cohort of pSSLs, the prevalence of dysplasia is high at 50.0% and is associated with lesion size ≥10 mm. Endoscopic resection for all proximal serrated lesions should be en bloc to facilitate accurate histopathological examination for dysplasia as its presence warrants shorter surveillance intervals.

Circumferential submucosal incision prior to endoscopic mucosal resection versus conventional endoscopic mucosal resection for colorectal lesions with endoscopic features of sessile serrated lesions.

Sessile serrated lesions (SSLs) are more prone to incomplete resection than conventional adenomas. This study evaluated whether circumferential submucosal incision prior to endoscopic mucosal resection (CSI-EMR) can increase the rate of complete and en bloc resections of colorectal lesions with endoscopic features of SSL. Retrospective analyses and propensity score matching were performed for the resection of colorectal lesions ≥ 10mm with endoscopic features of SSL. After 1:1 ratio matching, 127 lesions in the CSI-EMR group and 127 in the EMR group were selected for analysis. The median size of the lesions was 15mm (IQR 12-16) in both groups. There was no significant difference in either the complete resection rate or en bloc resection rate between CSI-EMR and EMR groups (96.9% vs. 92.9%, P = 0.155; 92.1% vs. 89.0%, P = 0.391). By contrast, the R0 resection rate was significantly higher in the CSI-EMR group than in the EMR group (89.8% vs. 59.8%, P < 0.001). The median procedure time was significantly longer in the CSI-EMR group than in the EMR group (6.28min vs. 2.55min, P < 0.001), whereas there was no significant difference between the two groups in the incidence of adverse events or recurrence rate. Multivariate analysis showed that CSI-EMR was the only factor significantly associated with R0 resection (P < 0.001). For colorectal lesions with endoscopic features of SSL, CSI-EMR does not increase the complete or en bloc resection rate, but does increase the R0 resection rate. The procedure time is longer for CSI-EMR than EMR. The association of CSI-EMR with R0 resection and non-recurrence should be further evaluated.

Adenoma and Serrated Lesion Detection by Colonoscopy Indication: The ADR-ESS (ADR Extended to all Screening/Surveillance) Score

The adenoma detection rate at screening (ADR) predicts interval colorectal cancer. Monitoring other lesion detection rates and colonoscopy indications has been proposed. We developed a comprehensive, automated colonoscopy audit program based on standardized clinical documentation, explored detection rates across indications, and developed the Adenoma Detection Rate - Extended to all Screening / Surveillance (ADR-ESS) score. In a prospective cohort study, we calculated overall and advanced adenoma and sessile serrated lesion (SSL) detection rates among 15,253 colonoscopies by 35 endoscopists from 4 endoscopy units across all colonoscopy indications. We explored correlations between detection rates, and the precision and stability of ADR-ESS versus ADR. The overall "screening, first" ADR was 36.3% (95% confidence interval [CI], 34.5%-38.1%). The adenoma detection rate was lower for "screening, not first" (relative rate [RR], 0.80; 95% CI, 0.74-0.87) and "family history" (RR, 0.84; 95% CI, 0.74-0.96), and higher for "surveillance" (RR, 1.22; 95% CI, 1.15-1.31) and "follow-up, FIT" (RR, 1.21; 95% CI, 1.07-1.37). For "screening, first," the detection rates for advanced adenoma, SSL, and advanced SSL were 6.7% (95% CI, 5.7%-7.7%), 7.2% (95% CI, 6.2%-8.2%), and 2.6% (95% CI, 2.0%-3.2%), respectively. Adenoma and SSL detection were correlated (r= 0.44; P= .008). ADR-ESS had substantially narrower confidence intervals and less period-to-period variability than ADR, and was not improved by weighting for indication volume and correction for detection by indication. Comprehensive, automated colonoscopy audit based on standardized clinical documentation is feasible. Adenoma detection is a fair but imperfect proxy for SSL detection. ADR-ESS increases the precision of adenoma detection assessments and emphasizes quality across colonoscopy indications.

Guidance for setting easy-to-adopt competence criteria for optical diagnosis of diminutive colorectal polyps: a simulation approach

One reason the optical diagnosis strategy for diminutive colorectal polyps has not yet been implemented is that the current competence criteria (Preservation and Incorporation of Valuable Endoscopic Innovation [PIVI] initiative) are difficult to use in daily practice. To provide guidance for setting alternative easy-to-adopt competence criteria, we determined the lowest proportion of diminutive polyps that should have a correct optical diagnosis to meet the PIVI. For this simulation study, we used datasets from 2 prospectively collected cohorts of patients who underwent colonoscopy in either a primary colonoscopy or fecal immunochemical test (FIT) screening setting. In the simulation approach, virtual endoscopists or computer-aided diagnosis systems performed optical diagnosis of diminutive polyps with a fixed diagnostic performance level (strategy) on all individuals in the cohort who had≥1 diminutive polyp. Strategies were defined by systematically varying the proportion of correct optical diagnoses for each polyp subtype (ie, adenomas, hyperplastic polyps, sessile serrated lesions). For each strategy, we determined whether PIVI-1 (≥90% agreement with U.S. or European Society for Gastrointestinal Endoscopy [ESGE] surveillance guidelines) and PIVI-2 (≥90% negative predictive value [NPV] for neoplastic lesions in the rectosigmoid) were met using Monte Carlo sampling with 1000 repetitions, with histology as reference. The level of overall diagnostic accuracy to achieve the PIVI differed significantly depending on the clinical setting and guidelines used. In the colonoscopy screening setting, all diagnostic strategies in which 92% of all diminutive polyps (regardless of histology) were diagnosed correctly led to 90% or more agreement with U.S. surveillance intervals (ie, PIVI-1). For all diagnostic strategies in which≥89% of all diminutive polyps were correctly diagnosed, at least 90% NPV was achieved (ie, PIVI-2). For the FIT screening setting, values were respectively≥77% and≥94%. When using ESGE guidelines, PIVI-1 was in both settings already met when 40% of all diminutive polyps were diagnosed correctly. In contrast to the fixed PIVI criteria, our simulation study shows that different thresholds for the proportion of correctly diagnosed diminutive polyps lead to different clinical consequences depending on guidelines and clinical setting. However, this target proportion of diminutive colorectal polyps correctly diagnosed with optical diagnosis represents easier-to-adopt competence criteria.

How to Manage the Large Nonpedunculated Colorectal Polyp

How to Manage the Large Nonpedunculated Colorectal Polyp

Endoscopic diagnosis for colorectal sessile serrated lesions.

BACKGROUNDHyperplastic polyps are considered non-neoplastic, whereas sessile serrated lesions (SSLs) are precursors of cancer via the ‘‘serrated neoplastic pathway’’. The clinical features of SSLs are tumor size (> 5 mm), location in the proximal colon, coverage with abundant mucus called the ‘‘mucus cap’’, indistinct borders, and a cloud-like surface. The features in magnifying narrow-band imaging are varicose microvascular vessels and expanded crypt openings. However, accurate diagnosis is often difficult.AIMTo develop a diagnostic score system for SSLs.METHODSWe retrospectively reviewed consecutive patients who underwent endoscopic resection during colonoscopy at the Toyoshima endoscopy clinic. We collected data on serrated polyps diagnosed by endoscopic or pathological examination. The significant factors for the diagnosis of SSLs were assessed using logistic regression analysis. Each item that was significant in multivariate analysis was assigned 1 point, with the sum of these points defined as the endoscopic SSL diagnosis score. The optimal cut-off value of the endoscopic SSL diagnosis score was determined by receiver-operating characteristic curve analysis.RESULTSAmong 1288 polyps that were endoscopically removed, we analyzed 232 diagnosed as serrated polyps by endoscopic or pathological examination. In the univariate analysis, the location (proximal colon), size (> 5 mm), mucus cap, indistinct borders, cloud-like surface, and varicose microvascular vessels were significantly associated with the diagnosis of SSLs. In the multivariate analysis, size (> 5 mm; P = 0.033), mucus cap (P = 0.005), and indistinct borders (P = 0.033) were independently associated with the diagnosis of SSLs. Size > 5 mm, mucus cap, and indistinct borders were assigned 1 point each and the sum of these points was defined as the endoscopic SSL diagnosis score. The receiver-operating characteristic curve analysis showed an optimal cut-off score of 3, which predicted pathological SSLs with 75% sensitivity, 80% specificity, and 78.4% accuracy. The pathological SSL rate for an endoscopic SSL diagnosis score of 3 was significantly higher than that for an endoscopic SSL diagnosis score of 0, 1, or 2 (P < 0.001).CONCLUSIONSize > 5 mm, mucus cap, and indistinct borders were significant endoscopic features for the diagnosis of SSLs. Serrated polyps with these three features should be removed during colonoscopy.

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.

Targeted next-generation sequencing supports serrated epithelial change as an early precursor to inflammatory bowel disease–associated colorectal neoplasia

Serrated epithelial change (SEC) manifests in patients with long-standing inflammatory bowel disease (IBD) and is characterized by disorganized crypt architecture, irregular serrations, and goblet cell-rich epithelium. The serrated nature of SEC is reminiscent of serrated colorectal polyps, which frequently harbor KRAS/BRAF mutations. SEC is, however, not only histologically distinct from sporadic serrated polyps but also associated with colorectal neoplasia. Whether SEC is a precursor to IBD-associated neoplasia remains unclear. To further define the relationship of SEC with serrated colorectal polyps and IBD-associated neoplasia, we performed targeted next-generation sequencing on colorectal specimens to include the following: SEC without dysplasia/neoplasia (n=10), SEC with separate foci of associated dysplasia/adenocarcinoma from the same patients (n=17), and uninvolved mucosa (n=10) from 14 patients. In addition, we molecularly profiled sessile serrated lesion (SSL)-like or serrated lesion, not otherwise specified (SL-NOS), specimens, from 11 patients who also had IBD. This control cohort included SSL-like/SL-NOS without dysplasia/neoplasia (n=11), SSL-like/SL-NOS with associated low-grade dysplasia (n=2), and uninvolved mucosa (n=8). By next-generation sequencing, the most frequently mutated gene in SEC without neoplasia and associated dysplasia/adenocarcinoma from separate foci in the same patients was TP53. Recurrent TP53 mutations were present in 50% of SEC specimens without dysplasia/neoplasia. In addition, alterations in TP53 were detected at a prevalence of 71% in low-grade dysplasia, 83% in high-grade dysplasia, and 100% in adenocarcinoma. Paired sequencing of SEC and associated neoplasia revealed identical TP53 missense mutations for 3 patients. In contrast, 91% of SSL-like/SL-NOS specimens without dysplasia/neoplasia harbored KRAS/BRAF mutations, which were conserved in associated low-grade dysplasia. No genomic alterations were found in uninvolved mucosa from either patients with SEC or patients with SSL-like/SL-NOS. Based on our findings, we conclude SEC is distinct from SSL-like serrated colorectal lesions in patients with IBD and an early precursor to IBD-associated neoplasia that warrants colonoscopic surveillance.

Serrated Lesion Detection in a Population-based Colon Screening Program.

Serrated lesions give rise to 15% to 30% of all colorectal cancers, driven predominantly by the sessile serrated polyp (SSP). Fecal immunochemical test (FIT), has low sensitivity for SSPs. SSP detection rate (SSPDR) is influenced by performance of both endoscopists and pathologists, as diagnosis can be subtle both on endoscopy and histology. To evaluate the SSPDR in a population-based screening program, and the influence of subspecialty trained pathologists on provincial reporting practices. The colon screening program database was used to identify all FIT-positive patients that received colonoscopy between January 2014 and June 2017. Patient demographics, colonoscopy quality indicators, pathologic diagnoses, and FIT values were collected. This study received IRB approval. A total of 74,605 colonoscopies were included and 26.6% had at least 1 serrated polyp removed. The SSPDR was 7.0%, with 59% of the SSPs detected having a concurrent conventional adenoma. The mean FIT value for colonoscopies with only serrated lesions was less than that for colonoscopies with a conventional adenoma or colorectal cancer (P<0.0001). Centers with a gastrointestinal subspecialty pathologist diagnosed proportionally more SSPs (P<0.0001), and right-sided SSPs than centers without subspecialists. Serrated lesions often occur in conjunction with conventional adenomas and are associated with lower FIT values. Knowledge of the characteristics of SSPs is essential for pathologists to ensure accurate diagnosis of SSPs.

Molecular profiling of appendiceal serrated lesions, polyps and mucinous neoplasms: a single-centre experience

PurposeNon-neuroendocrine neoplasms of the appendix are a phenotypically heterogeneous group of lesions; a comprehensive molecular characterization of these tumors is still lacking.MethodsA total of 52 samples taken from 49 patients was evaluated: 18 sessile serrated lesions (SSL; 3 with dysplasia), 2 high-grade tubular adenomas, 1 tubulo-villous adenoma,1 hyperplastic polyp, 18 low-grade appendiceal mucinous neoplasms (LAMN), 3 high-grade appendiceal mucinous neoplasms (HAMN) and 9 mucinous adenocarcinomas. Hotspot mutational profiling of the RNF43, SMAD4, KRAS, NRAS, BRAF and PIK3CA genes was performed. Expression of p53, MLH1, PMS2, MSH2, and MSH6 was evaluated by immunohistochemistry.ResultsKRAS was the most frequently mutated gene (53.9% of cases), followed by RNF43 (15.4%), and BRAF (13.5%). In particular: KRAS was mutated in 44.4% of adenocarcinomas, 66.7% of HAMNs, 61.1% of LAMNs, 53.3% of SSL without dysplasia and in 66.7% of SSL with dysplasia; RNF43 was mutated in 33.3% of adenocarcinomas, 66.7% of HAMNs, 11.1% of LAMNs and in 6.7% of SSL without dysplasia; BRAF was mutated in 11.1% of adenocarcinomas, 26.7% of SSL without dysplasia and in 5.6% of LAMNs. Only a case of high-grade tubular adenoma showed mismatch repair deficiency, while immunohistochemical expression of p53 was altered in 21.1% of cases.ConclusionsThe histological phenotypic similarities between appendicular mucinous lesions and serrated colon lesions do not reflect a similar genetic landscape. Mismatch repair deficiency is a rare event during appendiceal mucinous carcinogenesis.

A120 NO EVIDENCE OF A FRIDAY EFFECT ON COLONOSCOPY QUALITY OUTCOMES

Abstract Background Colonoscopy quality may be influenced by operator fatigue. Prior studies have shown lower adenoma detection rates for procedures performed at the end of the day. However, it is unknown if colonoscopy quality is impaired at the end of the work week. Aims We investigated whether colonoscopy quality-related metrics differ at the end of the work week using the South West Ontario Colonoscopy Cohort. Methods Between April 2017 to February 2018, 45,510 consecutive colonoscopies from 20 academic and community hospitals in our health region were captured to form the cohort. In Canada, outpatient endoscopies are generally performed between Monday to Friday, taking Friday, or the last business day, as the last day of the work week compared to the rest of the work week. When a statutory holiday occurred on a Friday, Thursday was designated the last day of the work week. The primary outcome was adenoma detection rate (ADR), and secondary outcomes were sessile serrated polyp detection rate (ssPDR), polyp detection rate (PDR), and failed cecal intubation. Outcomes were presented as unadjusted and adjusted risk ratios derived from modified Poisson regression and adjusting for physician-level clustering, and characteristics of the patient (age, sex, severity), procedure (hospital setting, trainee presence, indication, sedation, bowel preparation quality) and physician (experience and specialty). Results During the observation period, 9,132 colonoscopies were performed on the last day of the work week compared to 36,378 procedures during the rest of the work week. No significant difference was observed for ADR (26.4% vs. 26.6%, p=0.75), ssPDR (4.5% vs. 5.0%, p=0.12), PDR (44.1% vs. 43.1%, p=0.081), or failed cecal intubation (2.8% vs. 2.9%, p=0.51) for colonoscopies performed on the last day of the work week compared to the rest of the week, respectively. After adjusting for potential confounders, there were no significant differences in the ADR (RR 1.01, 95% CI [0.88, 1.15], p=0.94), ssPDR (RR 0.90, 95% CI [0.70, 1.14], p=0.38), PDR (RR 1.00, 95% CI [0.92, 1.09], p=0.94), or failed cecal intubation (RR 0.92, 95% CI [0.72, 1.18], p=0.51) for colonoscopies performed on the last day of the work week compared to the rest of week, respectively. Conclusions Colonoscopy quality metrics, including ADR, ssPDR, PDR, and failed cecal intubation are not significantly different at the end of the week. Funding Agencies None

ACG Clinical Guidelines: Colorectal Cancer Screening 2021.

Colorectal cancer (CRC) is the third most common cancer in men and women in the United States. CRC screening efforts are directed toward removal of adenomas and sessile serrated lesions and detection of early-stage CRC. The purpose of this article is to update the 2009 American College of Gastroenterology CRC screening guidelines. The guideline is framed around several key questions. We conducted a comprehensive literature search to include studies through October 2020. The inclusion criteria were studies of any design with men and women age 40 years and older. Detailed recommendations for CRC screening in average-risk individuals and those with a family history of CRC are discussed. We also provide recommendations on the role of aspirin for chemoprevention, quality indicators for colonoscopy, approaches to organized CRC screening and improving adherence to CRC screening. CRC screening must be optimized to allow effective and sustained reduction of CRC incidence and mortality. This can be accomplished by achieving high rates of adherence, quality monitoring and improvement, following evidence-based guidelines, and removing barriers through the spectrum of care from noninvasive screening tests to screening and diagnostic colonoscopy. The development of cost-effective, highly accurate, noninvasive modalities associated with improved overall adherence to the screening process is also a desirable goal.

Rate of detection of serrated lesions at colonoscopy in an average-risk population: a meta-analysis of 129,001 individuals.

Background and study aims Serrated lesions are precursors of approximately one-third of colorectal cancers (CRCs). Information on their detection rate was lacking as an important reference for CRC screening. This study was a systematic review and meta-analysis to determine the overall detection rate for serrated lesions and their subtypes in average-risk populations undergoing CRC screening with colonoscopy. Patient and methods MEDLINE and Embase were searched to identify population-based studies that reported the detection rate for serrated lesions. Studies on average-risk populations using colonoscopy as a screening tool were included. Metaprop was applied to model within-study variability by binomial distribution, and Freeman-Tukey Double Arcsine Transformation was adopted to stabilise the variances. The detection rate was presented in proportions using random-effects models. Results In total, 17 studies involving 129,001 average-risk individuals were included. The overall detection rates for serrated lesions (19.0 %, 95 % CI = 15.3 %–23.0 %), sessile serrated polyps (2.5 %, 95 % CI = 1.5 %–3.8 %), and traditional serrated adenomas (0.3 %, 95 % CI = 0.1 %–0.8 %) were estimated. Subgroup analysis indicated a higher detection rate for serrated lesions among males (22.0 %) than females (14.0 %), and Caucasians (25.9 %) than Asians (14.6 %). The detection rate for sessile serrated polyps was also higher among Caucasians (2.9 %) than Asians (0.7 %). Conclusions This study determined the overall detection rate for serrated lesions and their different subtypes. The pooled detection rate estimates can be used as a reference for establishing CRC screening programs. Future studies may evaluate the independent factors associated with the presence of serrated lesions during colonoscopy to enhance their rate of detection.

Cold snare polypectomy for large sessile serrated lesions is safe but follow‐up is needed: a single‐centre retrospective study

Background and AimCold snare polypectomy (CSP) is growing in popularity due to its safety and convenience. Its indication is benign tumours such as adenoma and sessile serrated lesions (SSLs) <10 mm in size. CSP for SSLs ≥10 mm in size has not been well examined. In this study, we aimed the feasibility of this treatment regarding therapeutic results and local recurrence.MethodsThis was a single‐centre retrospective cohort study. We reviewed SSLs with or without dysplasia of 10–20 mm that were resected by CSP from 2014 to 2020. All tumours were diagnosed endoscopically as SSLs without dysplasia before CSP with the help of magnifying narrow band imaging or blue laser imaging. We analysed the lesion characteristics, en bloc resection, histopathological diagnosis, adverse events and local recurrence. We analysed risk factors for recurrence, comparing recurrent lesions to non‐recurrent lesions. We also compared risk factors for lesions 10–14 mm in size to those for lesions 15–20 mm in size.ResultsWe analysed 160 lesions in 100 patients (M age ± SD = 67.7 ± 10.1 years). The polyp size (M ± SD) was 11.8 ± 2.8 mm, and the en bloc resection rate was 60.0% (96 cases). The rates of massive perioperative haemorrhage, postoperative haemorrhage and perforation were 1.3%, 0% and 0%, respectively. Regarding histopathological diagnosis, two (1.2%) cases showed SSLs with high‐grade dysplasia. The recurrence rate in 101 lesions with a median follow‐up period of 18 months (interquartile range 12–24 months) was 5.0%. There were no significant risk factors such as tumour size, location, morphology and so on in terms of recurrence. All recurrent cases could be resected by repeat CSP. The recurrence rates of lesions 10–14 mm in size and 15–20 mm in size were 4.7% and 6.3%, respectively (p = 0.713).ConclusionCSP of SSLs ≥10 mm in size according to magnifying endoscopic diagnosis was safe and promising, but the rate of recurrence was slightly high, meaning that close follow‐up is required.