Serrated polyposis syndrome: a literature review

Serrated polyposis syndrome is considered the most prevalent colonic polyposis syndrome in the world. Its importance has been increasingly discussed due to the significant increase in the risk of developing colorectal cancer in its affected individuals, similarly to other well-known polyposis syndromes, such as familial adenomatous polyposis. Serrated lesions of the colon play a major role in this syndrome represented by hyperplastic polyps, serrated sessile lesions and traditional serrated adenomas. Among these lesions, the sessile serrated lesion stands out, considered the main precursor lesion of the serrated pathway of colon carcinogenesis. Diagnosis of serrated polyposis syndrome is given through colonoscopy examination. Diagnostic criteria are: 1) 5 or more serrated lesions proximal to the rectum, all >4mm in size, with at least two >9mm in size; or 2) 20 serrated lesions of any size located anywhere in the large intestine, with >4 lesions proximal to the rectum. The ideal treatment is removal of all relevant serrated lesions by colonoscopy. In case of failure of endoscopic therapy, surgery is indicated. This manuscript is based on two case reports and a literature review and aims to broaden the discussion about the subject. (AU)

Há diferenças endoscópicas e histopatológicas entre lesões serrilhadas superficiais nas suas fases iniciais? / Are there endoscopic and histopathological differences between superficial serrated lesions in their initial phases?

Introdução: Lesões serrilhadas são consideradas precursoras dos adenocarcinomas colorretais. Estudá-las em suas fases iniciais é importante ao pensar na prevenção do câncer, quando, então, são lesões hiperplásicas, ou sésseis serrilhadas Objetivo: Realizar revisão integrativa da literatura para comparar as características endoscópicas e histopatológicas nas fases iniciais da doença, com a intenção de auxiliar no entendimento do câncer colorretal. Métodos: Revisão integrativa da literatura baseada em material de análise existente nas plataformas digitais SciELO ­ Scientific Electronic Library Online, Google Scholar, Pubmed e Scopus. O início foi a busca com os seguintes descritores: "lesões sésseis serrilhadas, carcinoma colorretal, lesões superficiais", e seus equivalentes em inglês "serrated sessile lesions, colorectal carcinoma, superficial lesions" com busca AND ou OR, considerando o título e/ou resumo, e incluindo-se posteriormente somente aqueles com maior correlação para leitura dos textos completos. Resultados: Incluíram-se 39 artigos. Conclusão: A maioria das lesões serrilhadas superficialmente elevadas com mais de 5 mm e ressecadas por colonoscopias, são hiperplásicas. Elas ocorrem por todo o cólon e reto, enquanto as sésseis serrilhadas localizamse preferencialmente no cólon proximal. As hiperplásicas geralmente não apresentam displasias e as sésseis serrilhadas podem tê-las de forma intensa.

Introduction: Serrated lesions are considered precursors of colorectal adenocarcinomas. Studying them in their initial phases is important when thinking about cancer prevention, when they are hyperplastic lesions, or sessile serrated lesions. Objective: To carry out an integrative review of the literature to compare the endoscopic and histopathological characteristics in the initial phases of the disease, with the intention to help understand colorectal cancer. Methods: Integrative literature review based on existing analysis material on the digital platforms SciELO ­ Scientific Electronic Library Online, Google Scholar, Pubmed and Scopus. The beginning was the search with the following descriptors: "serrated sessile lesions, colorectal carcinoma, superficial lesions", with AND or OR search, considering the title and/or abstract , and subsequently including only those with the highest correlation for reading the full texts. Results: 39 articles were included. Conclusion: The majority of superficially elevated serrated lesions measuring more than 5 mm and resected by colonoscopies are hyperplastic. They occur throughout the colon and rectum, while the serrated sessiles are preferentially located in the proximal colon. Hyperplastic ones generally do not present dysplasias and sessile serrated ones can have them intensely.

Morphological characteristics, classifications and difficulties in the use of diagnostic criteria for serrated lesions of the large intestine

Abstract: Introduction Colorectal carcinoma (CRC) is the most common gastrointestinal neoplasm in the world, accounting for 15% of cancer-related deaths. This condition is related to different molecular pathways, among them the recently described serrated pathway, whose characteristic entities, serrated lesions, have undergone important changes in their names and diagnostic criteria in the past thirty years. The multiplicity of denominations and criteria over the last years may be responsible for the low interobserver concordance (IOC) described in the literature. Objectives: The present study aims to describe the evolution in classification of serrated lesions, based on the last three publications of theWorld Health Organization (WHO) and the reproducibility of these criteria by pathologists, based on the evaluation of the IOC. Methods: A search was conducted in the PubMed, ResearchGate and Portal Capes databases, with the following terms: sessile serrated lesion; serrated lesions; serrated adenoma; interobserver concordance; andreproducibility.Articlespublished since 1990were researched. Results and Discussion: The classification of serrated lesions in the past thirty years showed different denominations and diagnostic criteria. The reproducibility and IOC of these criteria in the literature, based on the kappa coefficient, varied in most studies, from very poor to moderate. Conclusions: Interobserver concordance and the reproducibility of microscopic criteria may represent a limitation for the diagnosis andappropriatemanagementof these lesions. It is necessary to investigate diagnostic tools to improve the performance of the pathologist's evaluation, for better concordance, and, consequently, adequate diagnosis and treatment. (AU)

Clinicopathological features of the colorectal serrated adenoma and analysis on influencing factors of malignancy / 中华胃肠外科杂志

Objective: Serrated adenoma is recognized as a precancerous lesion of colorectal cancer, and the serrated pathway is considered as an important pathway that can independently develop into colorectal cancer. However, little is known about the related risk factors of carcinogenesis of serrated adenoma. The purpose of this study was to analyze the distribution characteristics and potential malignant factors of serrated adenoma in the colon and rectum. Methods: A retrospective case-control study was conducted to collect the clinical data of patients with serrated adenoma who underwent colonoscopy and were pathologically diagnosed in the Cancer Hospital of Chinese Academy of Medical Sciences from April 2017 to July 2019, and exclude patients with two or more pathological types of lesions. The clinical characteristics of serrated adenoma were summarized, and univariate and logistic multivariate regression analysis was conducted to explore the influencing factors for serrated adenoma to develop malignant transformation. Results: Among 28 730 patients undergoing colonoscopy, 311 (1.08%) were found with 372 serrated adenomas, among which 22 (5.9%) were sessile serrated adenomas/polyps, 84 (22.6%) were traditional serrated adenomas, and 266 (71.5%) were unclassified serrated adenomas according to WHO classification. The pathological results showed that 106 (28.5%) lesions were non-dysplasia, 228 (61.3%) lesions were low grade intraepithelial neoplasia, and 38 (10.2%) lesions were high grade intraepithelial neoplasia or cancer. There were 204 (54.8%) lesions with long-axis diameter <10 mm and 168 (45.2%) lesions with length long-axis ≥ 10 mm. 238 (64.0%) lesions were found in the left side colon and rectum and 134 (36.0%) lesions in the right side colon. Gross classification under endoscopy: 16 flat type lesions (4.3%), 174 sessile lesions (46.8%), 117 semi-pedunculated lesions (31.5%), 59 pedunculated lesions (15.9%). Narrow-band imaging international colorectal endoscopic (NICE) classification: 85 (22.8%) type I lesions, 280 (75.3%) type II lesions, 4 (1.1%) type III lesions. Univariate analysis showed that lesion size, lesion location, lesion site and different WHO classifications were associated with malignant transformation of colorectal serrated adenoma (all P<0.05). For the serrated adenomas with different NICE classifications, there were statistically significant differences in the distribution of malignant lesions among groups (P=0.001). Multivariate analysis showed that the long-axis diameter of the lesion ≥10 mm (OR=6.699, 95% CI: 2.843-15.786) and the lesion locating in the left side colorectum (OR=2.657, 95% CI: 1.042-6.775) were independent risk factors for malignant transformation. Conclusions: Serrated adenomas mainly locate in the left side colon and rectum, and are prone to malignant transformation when the lesions are ≥10 mm in long-axis diameter or left-sided.

Location and Size are Useful Features in Diagnosing Sessile Serrated Adenoma/Polyp

@#Introduction: According to the predefined 2010 World Health Organisation criteria, serrated colonic polyps (SCP) are pathologically classified into hyperplastic polyp (HP), sessile serrated adenoma/polyp (SSA/P) with or without cytological dysplasia and traditional serrated adenoma (TSA). Sessile serrated adenoma/polyp is acknowledged as a precursor of colorectal carcinoma through the serrated neoplastic pathway. Hyperplastic polyps display similar histological features to SSA/P, in comparison to other types of SCP. It is noteworthy to discriminate between HP and SSA/P, since only the latter has a malignant potential. Method: A total of 198 cases of SCP were identified and the slides were reexamined and reclassified accordingly. Analysis on the proportion of SSA/P among SCP and underdiagnosed cases of SSA/P was performed. The association between SSA/P and non-SSA/P with demographic data and colonoscopic findings were also studied. Results: From the 198 cases of SCP, 164, 29 and five cases were reclassified as HP, SSA/P and TSA respectively. Sixteen cases of SSA/P were underdiagnosed as HP. From among 29 cases of SSA/P, the majority were ≥ 65 years old (17; 58.6%), male (21; 72.4 %) and Chinese (17; 58.6%). Most of the SSA/P (16; 55.2 %) were located in the right colon and measured ≥ 10mm (9; 31%) in size. Location (p=0.004) and size (p=0.013) of the colonoscopic findings were significantly associated with SSA/P. Conclusion: Underdiagnosed cases of SSA/P among HP were identified most likely because of the resemblance of their histological features. The location and size of SCP may suggest the probability of SSA/P.

Detection of proximal serrated polyps:a single-center retrospective analysis / 中华消化内镜杂志

Objective To investigate the prevalence and endoscopic detection rate of proximal serrated polyps and to screen the risk factors. Methods The data of 9010 colonoscopies performed by 22 endoscopists between September 2016 and September 2017 were reviewed. The adenoma detection rate (ADR) and proximal serrated polyp detection rate (PSDR) were calculated, and the correlation between ADR and PSDR was estimated by Pearson correlation coefficients. Multivariate logistic regression was used to analyze PSDR among endoscopists. Results For all subjects, the mean ADR was 30. 07％ ( ranged from 20. 00％ to 40. 78％) and mean PSDR was 4. 70％ ( ranged from 1. 52％ to 9. 28％) . PSDR of males was 1. 38 times of that of females ( OR=1. 38, 95％CI:1. 13-1. 69, P<0. 01) . For 3560 cases ( 39. 51％) of 50 years and older subjects, the mean ADR was 45. 01％ ( 28. 99％-57. 78％) and mean PSDR was 6. 08％(2. 07％-10. 56％). PSDR was moderately correlated with ADR (r=0. 48, P=0. 02). PSDR of males was 1. 36 times of that of females (OR=1. 36, 95％CI: 1. 04-1. 80, P=0. 03). Endoscopist was a significant risk factor for detection of proximal serrated polyps ( P<0. 01) . Compared with endoscopist with the highest PSDR, odds ratio of other endoscopists ranged from 0. 16 (95％CI:0. 06-0. 40, P<0. 01) to 0. 83 (95％CI:0. 53-1. 32, P=0. 44) . Conclusion Proximal serrated polyps are more common in males, who are over 50 years old. The PSDR is highly variable and dependent on endoscopists. It is possible that a certain proportion of proximal serrated polyps are missed during colonoscopy.

CpG Island Methylation in Sessile Serrated Adenoma/Polyp of the Colorectum: Implications for Differential Diagnosis of Molecularly High-Risk Lesions among Non-dysplastic Sessile Serrated Adenomas/Polyps

BACKGROUND: Although colorectal sessile serrated adenomas/polyps (SSA/Ps) with morphologic dysplasia are regarded as definite high-risk premalignant lesions, no reliable grading or risk-stratifying system exists for non-dysplastic SSA/Ps. The accumulation of CpG island methylation is a molecular hallmark of progression of SSA/Ps. Thus, we decided to classify non-dysplastic SSA/Ps into risk subgroups based on the extent of CpG island methylation. METHODS: The CpG island methylator phenotype (CIMP) status of 132 non-dysplastic SSA/Ps was determined using eight CIMP-specific promoter markers. SSA/Ps with CIMP-high and/or MLH1 promoter methylation were regarded as a high-risk subgroup. RESULTS: Based on the CIMP analysis results, methylation frequency of each CIMP marker suggested a sequential pattern of CpG island methylation during progression of SSA/P, indicating MLH1 as a late-methylated marker. Among the 132 non-dysplastic SSA/Ps, 34 (26%) were determined to be high-risk lesions (33 CIMP-high and 8 MLH1-methylated cases; seven cases overlapped). All 34 high-risk SSA/Ps were located exclusively in the proximal colon (100%, p = .001) and were significantly associated with older age (≥ 50 years, 100%; p = .003) and a larger histologically measured lesion size (> 5 mm, 100%; p = .004). In addition, the high-risk SSA/Ps were characterized by a relatively higher number of typical base-dilated serrated crypts. CONCLUSIONS: Both CIMP-high and MLH1 methylation are late-step molecular events during progression of SSA/Ps and rarely occur in SSA/Ps of young patients. Comprehensive consideration of age (≥ 50), location (proximal colon), and histologic size (> 5 mm) may be important for the prediction of high-risk lesions among non-dysplastic SSA/Ps.

Expressions of HOXA11 andβ-catenin in colorectal serrated lesion tissues and their significances / 肿瘤研究与临床

Objective To investigate the expressions of HOXA11 and β-catenin proteins in colorectal serrated lesions and their roles in carcinogenesis. Methods A total of 252 cases of colorectal biopsy specimens in Shanxi Dayi Hospital from January 2012 to December 2016 were analyzed retrospectively, including 97 serrated lesions, 46 common adenomas, 109 adenocarcinomas, and 24 normal colorectal mucosa tissues were selected as controls. The expressions of HOXA11 and β-catenin proteins were detected by immunohistochemical EnVision method. Methylation of HOXA11 gene was detected by specific methylation polymerase chain reaction (MSP) in 25 paraffin-embedded adenocarcinoma tissues. Results In 97 serrated lesions, 29 (29.9％) occurred in the left colon;in 46 common adenomas, 27 (58.7％) occurred in the left colon;in 109 adenocarcinomas, 76 (69.7％) occured in the left colon. The difference of the occurrence location among three groups was statistically significant (χ2 = 34.75, P< 0.01). The heterotopic expression rate ofβ-catenin protein in serrated lesions, common adenomas and adenocarcinomas was significantly higher than that in normal mucosae [96.9％ (94/97), 82.6％ (38/46), 86.2％ (94/109) vs. 0 (0/24), P < 0.01]. The heterotopic expression of β-catenin protein was found in serrated lesions and the co-expression of cytoplasm and nucleus was found in common adenomas and adenocarcinomas. The normal expression rate of HOXA11 protein in serrated lesions, common adenomas and adenocarcinomas was lower than that in normal mucosae [33.0％ (32/97), 67.4％ (31/46), 48.6％ (53/109) vs. 100.0％ (24/24), all P< 0.05]. The methylation rate of HOXA11 gene was 84.0％ (21/25). Conclusion The ectopic expression of β-catenin in colorectal serrated lesions suggests that it is associated with serrated lesions, and the low expression of HOXA11 may be an early event in the carcinogenesis of serrated lesions.

Clinical outcomes of surveillance colonoscopy for patients with sessile serrated adenoma

BACKGROUND/AIMS: Sessile serrated adenomas (SSAs) are known to be precursors of colorectal cancer (CRC). The proper interval of follow-up colonoscopy for SSAs is still being debated. We sought to determine the proper interval of colonoscopy surveillance in patients diagnosed with SSAs in South Korea. METHODS: We retrospectively reviewed the medical records of patients diagnosed with SSAs who received 1 or more follow-up colonoscopies. The information reviewed included patient baseline characteristics, SSA characteristics, and colonoscopy information. RESULTS: From January 2007 to December 2011, 152 SSAs and 8 synchronous adenocarcinomas were identified in 138 patients. The mean age of the patients was 62.2 years and 60.1% patients were men. SSAs were located in the right colon (i.e., from the cecum to the hepatic flexure) in 68.4% patients. At the first follow-up, 27 SSAs were identified in 138 patients (right colon, 66.7%). At the second follow-up, 6 SSAs were identified in 65 patients (right colon, 66.7%). At the 3rd and 4th follow-up, 21 and 11 patients underwent colonoscopy, respectively, and no SSAs were detected. The total mean follow-up duration was 33.9 months. The mean size of SSAs was 8.1±5.0 mm. SSAs were most commonly found in the right colon (126/185, 68.1%). During annual follow-up colonoscopy surveillance, no cancer was detected. CONCLUSIONS: Annual colonoscopy surveillance is not necessary for identifying new CRCs in all patients diagnosed with SSAs. In addition, the right colon should be examined more carefully because SSAs occur more frequently in the right colon during initial and follow-up colonoscopies.

Serrated neoplasia pathway as an alternative route of colorectal cancer carcinogenesis

In the past two decades, besides conventional adenoma pathway, a subset of colonic lesions, including hyperplastic polyps, sessile serrated adenoma/polyps, and traditional serrated adenomas have been suggested as precancerous lesions via the alternative serrated neoplasia pathway. Major molecular alterations of sessile serrated neoplasia include BRAF mutation, high CpG island methylator phenotype, and escape of cellular senescence and progression via methylation of tumor suppressor genes or mismatch repair genes. With increasing information of the morphologic and molecular features of serrated lesions, one major challenge is how to reflect this knowledge in clinical practice, such as pathologic and endoscopic diagnosis, and guidelines for treatment and surveillance.

Endoscopic Features of Mucous Cap Polyps: A Way to Predict Serrated Polyps

BACKGROUND/AIMS: The aims of the study were to identify whether a mucous-cap predicts the presence of serrated polyps, and to determine whether additional endoscopic findings predict the presence of a sessile serrated adenomas/polyp (SSA/P). METHODS: We analyzed 147 mucous-capped polyps with corresponding histology, during 2011–2014. Eight endoscopic features (presence of borders, elevation, rim of debris, location in the colon, size ≥10 mm, varicose vessels, nodularity, and alteration in mucosal folds) of mucous-capped polyps were examined to see if they can predict SSA/Ps. RESULTS: A total of 86% (n=126) of mucous-capped polyps were from the right sided serrated pathway (right-sided hyperplastic [n=83], SSA/Ps [n=43], traditional serrated adenoma [n=1]), 10% (n=15) were left-sided hyperplastic polyps, and 3% (n=5) were from the adenoma-carcinoma sequence. The presence of a mucous cap combined with varicose vessels was the only significant predictor for SSA/Ps. The other seven characteristics were not found to be statistically significant for SSA/Ps, although location in the colon and the presence of nodularity trended towards significance. CONCLUSIONS: Our study suggests that mucous-capped polyps have high predictability for being a part of the serrated pathway. Gastroenterologists should be alert for a mucous-capped polyp with varicose veins, as these lesions have a higher risk of SSA/P.

Progress in Research on Serrated Polyps / 胃肠病学

Colorectal cancer is a common malignant tumor of digestive tract,and its carcinogenesis pathway includes adenoma pathway (50％-70％),de novo pathway (3％-5％) and serrated polyps pathway (30％-50％).Although a lot of studies on serrated polyps have been published,there is still no consensus understanding on carcinogenesis,endoscopic features and therapeutic strategies of serrated polyps.This article reviewed the endoscopic features,molecular pathological features,and therapeutic strategies of serrated polyps.

Endoscopic and pathological features of advanced colorectal serrated adenoma / 中华消化内镜杂志

Objective To analyze the clinical and pathological features of advanced colorectal serrated adenoma(ACSA). Methods The endoscopic and pathological features of 156 cases of ACSA and 121 cases of non-ACSA diagnosed in General Hospital, Tianjin Medical University from January 2010 to March 2016 were retrospectively analyzed and compared.Results ACSA and non-ACSA cases accounted for 56.3%(156/277)and 43.7%(121/277)of all patients with colorectal serrated lesions,respectively. The mean age of ACSA patients was 57.79±13.65 years and 89(57.1%)of these patients were male. There was no significant difference in age and gender between ACSA and non-ACSA patients. A total of 161 ACSA lesions were diagnosed,including 71 sessile serrated adenoma/polyps and 90 traditional serrated adenomas. Among the 161 ACSA lesions,there were 29(18.0%)lesions whose diameter≥10 mm, and 84(52.2%) lesions located in the proximal colon, which were more than non-ACSA(84/161 VS 49/134,P=0.007). ACSA was classified under endoscopy into pedunculated type(20/161),sub-pedunculated type(35/161), sessile type(24/161),flat type(79/161)and laterally spreading tumor(3/161), and the distribution of lesion type was significantly different from non-ACSA(P<0.001). One hundred and sixty(99.4%)ACSA lesions were diagnosed as dysplasia, including 158 low degree dysplasia and 2 high degree dysplasia.Moreover,16 ACSA patients were accompanied with synchronous advanced colorectal neoplasia(sACN), and large serrated polyps(diameter≥10 mm)might have a strong association with sACN(OR=4.35, 95%CI:1.467-12.894, P<0.05). Conclusion ACSA is more common in proximal colon and sub-pedunculated type,sessile type and flat type. ACSA diameter≥10 mm is significantly associated with sACN.

Diagnostic value of white light endoscopy and narrow band imaging for colorectal sessile serrated adenoma and hyperplastic polyp / 中华消化内镜杂志

Objective To differentiate colorectal sessile serrated adenoma(SSA)and large hyperplastic polyp(HP)with white light endoscopy and narrow band imaging. Methods Retrospective analysis was performed on the clinical data of 953 patients who underwent endoscopic screening for colorectal cancer at digestive endoscopy center of Peking Union Medical College Hospital from January 2015 to December 2015.Endoscopic features were compared with white light endoscopy and narrow band imaging between SSA and large HP in location, size, Paris classification, surface mucus, NICE classification and varicose microvascular vessel(VMV). Results A total of 28(2.9%)SSAs and 25(2.6%)HPs of diameter not less than 0.5 cm were detected in the total of 953 patients.Statistically significant difference was found in right hemi-colon, diameter not less than 1.0 cm and VMV in two groups(P<0.05). The sensitivities of the above three markers for SSA were 89.3%, 67.9% and 46.4% respectively. The specificities were 64.0%,76.0% and 84.0% respectively. Diagnostic accuracies were 77.4%,71.7% and 64.2% respectively. And the sensitivity, specificity and accuracy of three markers combined(at least two markers)were 75.0%, 88.0% and 81.1%, respectively. Conclusion SSA and large HP could be differentiated with a systemic consideration of lesion location, size, and surface of microvessels by using white light endoscopy and image-enhanced technique.

Clinical and pathological features of upper gastrointestinal serrated lesions / 中华消化内镜杂志

Objective To analyze the clinical and pathological features of upper gastrointestinal serrated lesions.Methods A total of 21 patients with upper gastrointestinal serrated lesions in Tianjin Medical University General Hospital between January 2011 and December 2015 were retrospective analyzed.Data of the patients including demographics, clinical and pathological features were collected.Among the 21 patients, 18 patients, who underwent colonoscopy simultaneously or within six months, were selected as the study group, each patient was compared to 4 randomly selected controls without serrated lesions, who also underwent colonoscopy within the same time period.Differences of colorectal neoplasia detection were analyzed between the cases and controls.Results The mean age of 21 patients was 55.3±17.2 years, and 11 cases were male.Involving the locations of serrated lesions, 17 cases were found in the stomach (including 3 in the cardia, 9 in the corpus, and 5 in the antrum), and followed by 3 in the duodenum and 1 in lower esophagus.The mucosa pathological morphology showed that 6 cases were serrated hyperplasia, 8 cases were hyperplastic polyps, 6 cases were serrated adenomas with low grade dysplasia and 1 case was in the duodenum intramucosal carcinoma.Seven (38.9%) colorectal adenomas were found in the study group, including 3 (16.7%) non-advanced colorectal adenomas and 4 (22.2%) advanced colorectal adenomas.Eight (11.1%) colorectal adenomas were found in the control group, including 5 (6.9%) non-advanced colorectal adenomas and 3 (4.2%) advanced colorectal adenomas.The rate of colorectal adenoma detection in the study group was significantly higher than that in the control group (38.9% VS 11.1%, P=0.010, OR=5.091, 95%CI:1.534-16.890).Conclusion Upper gastrointestinal serrated lesions can be found in various mucosal lesions with different pathological morphologies.Moreover colonoscopy is likely to be recommended to detect concurrent colorectal adenoma for these patients.

Morphological features of colorectal sessile serrated adenoma/polyp under white light endoscopy and narrow band imaging / 中国内镜杂志

Objective To investigate the morphological features of colorectal sessile serrated adenoma/polyp (SSA/P) by white light endoscopy (WLE) and narrow band imaging (NBI). Methods A retrospective analysis was made on the morphological characteristics of SSA/P from January 2014 to March 2017, and compared with HP. Results There were 50 cases of SSA/P from 41 patients and 50 cases of HP from 43 patients. SSA/P located in the right colon was more than HP, but the difference was no statistical significance (16 cases vs 14 cases,P > 0.05). SSA/P have 11 cases of Type Is, 21 cases of Type IIa, 16 cases of Type IIb, 2 cases of Type LST, HP have 17 cases of Type Is, 25 cases of Type IIa, 8 cases of Type IIb, there was no significant difference (P > 0.05); SSA/P has more mucus than HP (37 cases vs 11 cases, P < 0.05). In NBI: The proportion of SSA/P with a red mucus cap, indistinctive borders, irregular shape, black dots inside the crypts, Cloud-like surface, Type II-O pit pattern and varicose microvascular vessels were higher than that of HP (P < 0.05). In the differential prediction of SSA/P and HP: Black dots inside the crypts (OR

Comparisons of Gut Microbiota Among Healthy Control, Patients With Conventional Adenoma, Sessile Serrated Adenoma, and Colorectal Cancer

BACKGROUND: Studies on gut microbiota regarding colorectal carcinogenesis, including sessile serrated adenoma (SSA), have been scarce. The aim of this study is to investigate the role of mucosa-associated gut microbiota in the colorectal carcinogenesis. METHODS: We collected biopsy samples of normal rectal mucosa during colonoscopy from healthy control and patients with conventional adenoma, SSA, and colorectal cancer (CRC), respectively (n = 6). Pyrosequencing for 16S rRNA gene of bacteria was performed to compare gut microbiota. RESULTS: The most abundant phylum in total samples was Proteobacteria (55.6%), followed by Firmicutes (27.4%) and Bacteroidetes (11.6%). There was no significant difference in relative abundance of the phylum level among the four groups. Fusobacterium nucleatum, known to be frequently detected during colorectal carcinogenesis, was found in only one sample of patient with SSA. The rarefaction curves showed that the diversity of mucosal communities of patients with CRC is the lowest among the four groups and the diversity of mucosal communities of patients with SSA is higher than that of healthy control. Among the four groups, Shannon's and Simpson's index for diversity was the lowest and the highest in the patients with CRC, respectively; it did not reach statistical significance. The proportion of genus Pseudomonas was very high in the samples of patients with stage II–IV CRC compared with those with stage I CRC (59.3% vs. 0.3%, P = 0.064). CONCLUSIONS: Our study suggests no significant role of mucosa-associated gut microbiota in the colorectal carcinogenesis. Further study for many samples or using fecal material could be helpful.

CpG Island Methylator Phenotype-High Colorectal Cancers and Their Prognostic Implications and Relationships with the Serrated Neoplasia Pathway

The concept of a CpG island methylator phenotype (CIMP) was first introduced by Toyota and Issa to describe a subset of colorectal cancers (CRCs) with concurrent hypermethylation of multiple CpG island loci. The concept of CIMP as a molecular carcinogenesis mechanism was consolidated by the identification of the serrated neoplasia pathway, in which CIMP participates in the initiation and progression of serrated adenomas. Distinct clinicopathological and molecular features of CIMP-high (CIMP-H) CRCs have been characterized, including proximal colon location, older age of onset, female preponderance, and frequent associations of high-level microsatellite instability and BRAF mutations. CIMP-H CRCs arise in sessile or traditional serrated adenomas and thus tend to display the morphological characteristics of serrated adenomas, including epithelial serration, vesicular nuclei, and abundant cytoplasm. Both the frequent association of CIMP and poor prognosis and different responses of CRCs to adjuvant therapy depending on CIMP status indicate clinical implications. In this review, we present an overview of the literature documenting the relevant findings of CIMP-H CRCs and their relationships with the serrated neoplasia pathway.

Sessile Serrated Adenomas: How to Detect, Characterize and Resect

Serrated polyps are important contributors to the burden of colorectal cancers (CRC). These lesions were once considered to have no malignant potential, but currently up to 30% of all CRC are recognized to arise from the serrated neoplasia pathway. The primary premalignant lesions are sessile serrated adenomas/polyps (SSA/Ps), although traditional serrated adenomas are relatively uncommon. Compared to conventional adenomas, SSA/Ps are morphologically subtle with indistinct borders, may be difficult to detect endoscopically, are more prevalent than previously thought, are associated with synchronous and metachronous advanced neoplasia, and have a higher risk of incomplete resection. Although many lesions remain “dormant,” progressive disease is associated with the development of dysplasia and more rapid progression to CRC. As a result, SSA/Ps are strongly implicated in the development of interval cancers. These factors represent unique challenges that require a meticulous approach to their management. In this review, we summarize the contemporary literature on the characterization, detection and resection of SSA/Ps.

Clinical characteristics of patients with serrated polyposis syndrome in Korea: comparison with Western patients

BACKGROUND/AIMS: Serrated polyposis syndrome (SPS) has been shown to increase the risk of colorectal cancer (CRC). However, little is known about the characteristics of Asian patients with SPS. This study aimed to identify the clinicopathological features and risk of CRC in Korean patients with SPS as well as the differences between Korean and Western patients based on a literature review. METHODS: This retrospective study included 30 patients with SPS as defined by World Health Organization classification treated at Samsung Medical Center, Korea, between March 1999 and May 2011. RESULTS: Twenty patients (67%) were male. The median patient age at diagnosis was 56 years (range, 39–76 years). A total of 702 polyps were identified during a median follow-up of 43 months (range, 0–149 months). Serrated polyps were noted more frequently in the distal colon (298/702, 55%). However, large serrated polyps and serrated adenomas were mainly distributed throughout the proximal colon (75% vs. 25% and 81% vs. 19%, respectively); 73.3% had synchronous adenomatous polyps. The incidence of CRC was 10% (3/30 patients), but no interval CRC was detected. A total of 87% of the patients underwent esophagogastroduodenoscopy and 19.2% had significant lesions. CONCLUSIONS: The phenotype of SPS in Korean patients is different from that of Western patients. In Korean patients, SPS is more common in men, there were fewer total numbers of serrated adenoma/polyps, and the incidence of CRC was lower than that in Western patients. Korean patients tend to more frequently have abnormal gastric lesions. However, the prevalence of synchronous adenomatous polyps is high in both Western and Korean patients.