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.

Independent and joint associations of general and abdominal obesity with the risk of conventional adenomas and serrated polyps: A large population-based study in East Asia

Evidence regarding associations of general and abdominal obesity with the risk of conventional adenomas (ADs) and serrated polyps (SPs) from Asian population is scarce. This study aimed to investigate the independent and joint associations of general obesity assessed by body mass index (BMI) and abdominal obesity assessed by waist circumference (WC) or waist-to-hip ratio (WHR) with the risk of ADs and SPs among 25 222 participants recruited by a population-based screening program. Compared to participants with normal BMI, those with a BMI ≥28 kg/m² had increased risk of ADs (odds ratio [OR] 1.52, 95% confidence interval [CI] 1.36-1.70) and SPs (OR 1.69, 95% CI 1.38-2.07). For participants with a WC ≥102 cm (≥88 cm for females), the risk of ADs (OR 1.37, 95% CI 1.25-1.51) and SPs (OR 1.81, 95% CI 1.52-2.16) was higher than that of the reference group. For participants with a WHR ≥0.95 (≥0.90 for females), the risk of ADs (OR 1.26, 95% CI 1.16-1.36) and SPs (OR 1.46, 95% CI 1.26-1.69) were higher than that of the reference group. Moreover, participants with both BMI ≥28 kg/m² and WC ≥102 cm (≥88 cm for females) had 61% and 119% higher risk of ADs (OR 1.61, 95% CI 1.39-1.85) and SPs (OR 2.19, 95% CI 1.70-2.82) compared to those with both normal BMI and WC. These findings indicate that both general and abdominal obesity are associated with SPs and ADs, presenting stronger association with SPs than ADs. Moreover, the association is more evident when both obesities exist. This article is protected by copyright. All rights reserved.

Sessile serrated lesion presenting as large pedunculated polyp in the rectum: A case report

RATIONALE

Sessile serrated lesions (SSLs) are serrated polyps (SP) with the typical serrated architecture of the crypt lining epithelium. SSL has an important clinical implication because they are recognized as precursor lesion of sporadic colorectal cancer (CRC) through "serrated pathway." SSLs usually appear flat to sessile, and are located in the right colon.

PATIENT CONCERNS

A 69-year-old man was referred to a tertiary medical center because of intermittent hematochezia for 2 years.

DIAGNOSIS

Colonoscopy revealed a large, pedunculated polyp in the rectum. The polyp surface was slightly reddish in color and the elongated stalk was covered with almost normal mucosa. Histopathological examination of the resected specimens revealed the typical features of SSL with low-grade dysplasia.

INTERVENTION

Endoscopic mucosal resection using a detachable snare was performed on the tumor for definite diagnosis and treatment.

OUTCOMES

There was no evidence of immediate or delayed bleeding after endoscopic mucosal resection, and the hemoglobin level normalized after a 1-year follow-up.

LESSONS

We report a rare case of a large pedunculated polyp with typical histological features of SSLs in the rectum. Endoscopists should always consider SSLs at any location even with unusual morphological findings.

Factors associated with lesion detection in colonoscopy among different indications

BACKGROUND AND OBJECTIVE

Different factors may influence colonoscopy performance measures. We aimed to analyze procedure- and endoscopist-related factors associated with detection of colorectal lesions and whether these factors have a similar influence in the context of different colonoscopy indications: positive fecal immunochemical test (+FIT) and post-polypectomy surveillance colonoscopies.

METHODS

This multicenter cross-sectional study included adults aged 40-80 years. Endoscopists (N = 96) who had performed ≥50 examinations were assessed for physician-related factors. Adenoma detection rate (ADR), adenomas per colonoscopy rate (APCR), advanced ADR, serrated polyp detection (SDR), and serrated polyps per colonoscopy rate (SPPCR) were calculated.

RESULTS

We included 12,932 procedures, with 4810 carried out after a positive FIT and 1967 for surveillance. Of the 96 endoscopists evaluated, 43.8% were women, and the mean age was 41.9 years. The ADR, advanced ADR, and SDR were 39.7%, 17.7%, and 12.8%, respectively. Adenoma detection rate was higher in colonoscopies after a +FIT (50.3%) with a more than doubled advanced ADR compared to non-FIT procedures (27.6% vs. 13.0%) and similar results in serrated lesions (14.7% vs. 13.5%). Among all the detection indicators analyzed, withdrawal time was the only factor independently related to improvement (p < 0.001). Regarding FIT-positive and surveillance procedures, for both indications, withdrawal time was also the only factor associated with a higher detection of adenomas and serrated polyps (p < 0.001). Endoscopist-related factors (i.e., weekly hours dedicated to endoscopy, annual colonoscopy volume and lifetime number of colonoscopies performed) had also impact on lesion detection (APCR, advanced ADR and SPPCR).

CONCLUSIONS

Withdrawal time was the factor most commonly associated with improved detection of colonic lesions globally and in endoscopies for + FIT and post-polypectomy surveillance. Physician-related factors may help to address strategies to support training and service provision. Our results can be used for establishing future benchmarking and quality improvement in different colonoscopy indications.

Healthy lifestyle and the risk of conventional adenomas and serrated polyps: Findings from a large colonoscopy screening population

Evidence on the link between healthy lifestyle and colorectal cancer (CRC) precursors is limited. Our study aimed to examine and compare the associations of healthy lifestyle with CRC precursors in adenoma (AD) -carcinoma and serrated pathways. A total of 24,480 participants including 6,309 ADs, 1,343 serrated polyps (SPs), and 16,828 polyp-free controls were included. A healthy lifestyle score (HLS) was constructed based on five lifestyle factors including cigarette smoking, alcohol drinking, physical activity, diet, and body weight, and categorized into least, slightly, moderately, and most healthy. Multivariable logistic regressions were used to estimate odds ratio (OR) and 95% confidence interval (CI). Inverse dose-response associations between the HLS and risk of ADs were observed (OR per 1 score increment for ADs: 0.82 [95% CI 0.79 - 0.84]; for SPs: 0.73 [95% CI 0.69 - 0.78]), and the association with SPs was more evident than with ADs (OR 0.90, 95% CI 0.85 - 0.96). Compared with participants with the least healthy lifestyle, those with the most healthy lifestyle had 47% lower risk of ADs (OR 0.53, 95% CI 0.47 - 0.59) and 70% lower risk of SPs (OR 0.30, 95% CI 0.23 - 0.39), respectively. These inverse associations were consistent across lesion stage and anatomic subsite and not modified by any stratification factors. The risk advancement periods for the most vs. the least healthy lifestyle were -9.49 years for ADs and -20.69 years for SPs. Our findings help confirm the preventive role of healthy lifestyle in colorectal carcinogenesis.

Comprehensive analyses of microRNA and mRNA expression in colorectal serrated lesions and colorectal cancer with a microsatellite instability phenotype

MicroRNA (miRNA) expression is dysregulated in human tumors, thereby contributing to tumorigenesis through altered expression of mRNA. Thus, identification of the relationships between miRNAs and mRNAs is important for evaluating the molecular mechanisms of tumors. In addition, elucidation of the molecular features of serrated lesions is essential in colorectal tumorigenesis. Here, we examined the relationships of miRNA and mRNA expressed in serrated lesions, including 26 sessile serrated lesions (SSLs), 12 traditional serrated adenomas (TSAs), and 11 colorectal cancers (CRCs) with a microsatellite instability (MSI) phenotype using crypt isolation. We divided the samples into the first and second cohorts for validation. Array-based expression analyses were used to evaluate miRNAs and mRNAs with opposite expression patterns in isolated tumor glands. In addition, we validated the relationships of miRNA/mRNA pairs in the second cohort using real-time polymerase chain reaction. We found that the expression of miRNA-5787 was correlated with reciprocal expression of two mRNAs, that is, SRRM2 and POLR2J3, in SSL samples. In TSA samples, two pairs of miRNAs/mRNAs showing opposite expression patterns, that is, miRNA-182-5p/ETF1 and miRNA-200b-3p/MYB, were identified. Ultimately, three pairs of miRNAs/mRNAs with opposite expression patterns, including miRNA-222-3p/SLC26A3, miRNA-6753-3p/FABP1, and miRNA-222-3p/OLFM4, were retained in CRC with an MSI phenotype. Finally, we performed transfection with an miR-222-3p mimic to confirm the expression of SLC26A3 and OLFM4; the results showed that ectopic expression of miR-222-3p moderately suppressed OLFM4 and downregulated SLC26A3 to some extent. Overall, our results provided basic insights into the evaluation of colorectal tumorigenesis of serrated lesions and CRC with an MSI phenotype.

NTRK oncogenic fusions are exclusively associated with the serrated neoplasia pathway in the colorectum and begin to occur in sessile serrated lesions

Neurotrophic tropomyosin receptor kinase (NTRK) gene fusions are emerging tissue-agnostic drug targets in malignancies including colorectal carcinomas (CRCs), but their detailed landscape in the context of various colorectal carcinogenesis pathways remains to be investigated. In this study, pan-tropomyosin receptor kinase (TRK) protein expression was assessed by immunohistochemistry (IHC) in retrospectively collected colorectal epithelial tumor tissues, including 441 CRCs [133 microsatellite instability-high (MSI-high) and 308 microsatellite stable (MSS)] and 595 premalignant colorectal lesions (330 serrated lesions and 265 conventional adenomas). TRK-positive cases were then subjected to next-generation sequencing and/or fluorescence in situ hybridization to confirm NTRK rearrangements. TRK IHC positivity was not observed in any of the MSS CRCs, conventional adenomas, traditional serrated adenomas, or hyperplastic polyps, whereas TRK positivity was observed in 11 of 58 (19%) MLH1-methylated MSI-high CRCs, 4 of 23 (17%) sessile serrated lesions with dysplasia (SSLDs), and 5 of 132 (4%) sessile serrated lesions (SSLs). The 11 TRK-positive MSI-high CRCs commonly harbored CpG island methylator phenotype-high (CIMP-high), MLH1 methylation, BRAF/KRAS wild-type, and NTRK1 or NTRK3 fusion (TPM3-NTRK1, TPR-NTRK1, LMNA-NTRK1, SFPQ-NTRK1, ETV6-NTRK3, or EML4-NTRK3). Both NTRK1 or NTRK3 rearrangement and BRAF/KRAS wild-type were detected in all nine TRK-positive SSL(D)s, seven of which demonstrated MSS and/or CIMP-low. TRK expression was selectively observed in distorted serrated crypts within SSLs and was occasionally localized at the base of serrated crypts. NTRK fusions were detected only in SSLs of patients aged ≥50 years, whereas BRAF mutation was found in younger age-onset SSLs. In conclusion, NTRK-rearranged colorectal tumors develop exclusively through the serrated neoplasia pathway and can be initiated from non-dysplastic SSLs without BRAF/KRAS mutations prior to full occurrence of MSI-high/CIMP-high. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Ulcerative Colitis With Concomitant Serrated Polyposis Syndrome: A Case Report and Literature Review

Serrated polyposis syndrome (SPS) is a pre-cancerous condition associated with increased risk of developing colorectal cancer (CRC). Its role in inflammatory bowel disease (IBD)-associated CRC remains unknown. Despite the growing understanding and recognition of SPS, there is limited literature about its impact on the colon in individuals with IBD. Herein, we report a case of a 45-year-old female who was diagnosed with ulcerative colitis (UC) and SPS. We also reviewed the literature surrounding this association and highlighted the intricacies in managing this unique patient population. At present, there are no screening guidelines for CRC in SPS patients with IBD. However, given the potential synergistic risk for CRC, a close surveillance approach may be utilized. Tracking lifetime cumulative features of SPS and endoscopic clearance of adenomas and serrated polyps are the mainstays of management.

Long-Term Incidence of Advanced Colorectal Neoplasia in Patients with Serrated Polyposis Syndrome: Experience in a Single Academic Centre

Simple Summary

Serrated polyposis syndrome is characterized by the development of large and/or multiple serrated polyps throughout the colorectum and is associated with an increased risk of colorectal cancer (CRC). Even though CRC incidence is low under adequate endoscopic follow-up, a substantial risk of advanced neoplasia (AN) has been described. Nevertheless, very few studies have focused on long-term surveillance. The main aim of this study was to evaluate the incidence of AN in a single-centre cohort followed over 10 years. Within endoscopic surveillance we did not find any CRC and we observed that five-year cumulative incidences of AN were much lower than in other studies. However, a significant reduction of these incidences during follow-up was not proven. Individuals at higher risk of AN were those who fulfilled both 2010 WHO criteria I and III. Our results suggest that at least patients at lower risk might benefit from the extension of surveillance intervals.

Abstract

Serrated polyposis syndrome (SPS) implies a slightly elevated risk of colorectal cancer (CRC) during endoscopic follow-up, but its natural course is still not well known. The main objective of this study was to describe the long-term risk of developing advanced neoplasia (AN) in these patients. Until October 2020, individuals who fulfilled 2010 WHO criteria I and/or III for SPS were retrospectively recruited. We selected those under endoscopic surveillance after resection of all lesions >3 mm in a high-quality colonoscopy. We excluded patients with total colectomy at diagnosis and those with any interval between colonoscopies >3.5 years. We defined AN as advanced serrated polyp (≥10 mm and/or with dysplasia), advanced adenoma, or CRC. In 109 patients, 342 colonoscopies were performed (median = 3, median interval = 1.8 years) during a median follow-up after colonic clearance of 5.0 years. Five-year cumulative incidences of AN were 21.6% globally, and 5.6%, 10.8%, and 50.8% in patients who fulfilled criterion I, III, and both, respectively (p < 0.001). No CRC was diagnosed and only 1 (0.9%) patient underwent surgery. In conclusion, cumulative incidences of AN could be lower than previously described, at least in patients who fulfil the 2010 WHO criterion III alone. Therefore, low-risk individuals might benefit from less stringent surveillance.

The spectrum of serrated colorectal lesions-new entities and unanswered questions

Hyperplastic polyps (HPs) of the colon and rectum were historically thought not to be associated with an increased risk of development of colorectal cancer (CRC). The recognition of variants of serrated colorectal lesions that possessed relatively subtle but significant morphological differences from those of HPs and that could be associated with epithelial dysplasia and CRC led to the characterisation of sessile serrated lesions (SSLs) and traditional serrated adenomas (TSAs). These links were supported by the identification of genetic alterations that are commonly found in HPs, SSLs, TSAs, and CRC, e.g. BRAF and KRAS mutations. The 'serrated pathway' to CRC may progress faster than the traditional 'adenoma-carcinoma sequence', underlining the importance of identifying these lesions. The diagnostic histological criteria for SSLs have since been more clearly defined, in parallel with a drive to increase the recognition of these lesions at endoscopy. The existence of lesions showing overlapping morphological and molecular features with those of HPs, SSLs and TSAs has most recently been highlighted-including mucin-rich TSA, serrated tubulovillous adenoma, and those showing mixed histological features, e.g. comprising differing combinations of HP, SSL, and TSA. Morphological and molecular studies of this range of lesions are providing insights into the relationships of serrated colorectal lesions with each other and with CRC. This article provides an overview of the current understanding of serrated colorectal lesions, including a discussion of those with overlapping and mixed features.

Different TERT Expression between Colorectal Adenoma and Serrated Polyp

Background and Objectives: Telomere regulation have an association with colorectal cancer. Previous studies demonstrated its implication in colorectal carcinogenesis. This study aimed to identify the role of telomerase reverse transcriptase (TERT) in colorectal carcinogenesis and determine TERT expression and their associated genes in precancerous lesions. Materials and Methods: TERT expression in 93 colorectal precursor lesions was analyzed. This included 61 tubular adenomas (TAs) and 32 serrated polyps (SPs). Furthermore, KRAS and BRAF gene mutations and microsatellite instability were analyzed. Statistical tests were performed to analyze the relationship between variables. Results: TERT expression in TAs, when compared with those observed in paired adjacent nontumor tissues, was 0.92 ± 0.78. TERT expression levels were significantly lower in SPs (0.38 ± 0.14, p < 0.001). KRAS and BRAF mutations were mutually exclusive in TAs and SPs (p < 0.001). TERT expression tended to be associated with KRAS mutations (46.7% vs. 22.0%, p = 0.098) and low-grade tumors (35.0% vs. 16.0%, p = 0.096), but this difference was insignificant. Conclusions: TERT expression has a pivotal role in progression to TAs in colorectal tissue. Considering the association between TERT expression and KRAS mutation, therapeutic drugs targeting this pathway can be developed for cancer prevention.

Simple proxies for detection of clinically significant serrated polyps and data for their benchmarks

BACKGROUND AND AIMS

Serrated polyp detection rate (SDR) is a potential quality indicator for preventing colorectal cancer associated with the serrated pathway. Using clinically significant SDR (CSSDR) has been suggested based on clinically significant serrated polyp's ability to be colorectal cancer precursors. Correlations between CSSDR and simpler SDRs, other than proximal SDR, have not yet been studied. We aimed to investigate which simpler SDR indicator is most relevant to CSSDR or adenoma detection rate (ADR) and provide benchmark data.

METHODS

We analyzed 26 627 colonoscopies performed by 30 endoscopists. Clinically significant serrated polyps were defined as any sessile serrated adenoma/polyp or traditional serrated adenoma, hyperplastic polyps ≥ 5 mm in the proximal colon, or hyperplastic polyps ≥ 10 mm anywhere in the colon. Correlation of CSSDR and ADR with other simple SDRs, SDR-pathology (sessile serrated adenoma/polyp or traditional serrated adenoma), SDR-size (≥ 10 mm), and SDR-location (proximal location) was analyzed using Pearson's correlation test and Steiger's z-test.

RESULTS

The CSSDR was 1.7% to 13.2% (mean = 6.1%). The correlation coefficient of CSSDR/SDR-size was 0.91 (P < 0.01), which was higher than that of CSSDR/SDR-location (0.64, P < 0.01) (0.91 vs 0.61, P < 0.01). The correlation coefficient of ADR/CSSDR and ADR/SDR-location was 0.41 (P < 0.01) and 0.81 (P < 0.01), respectively. For ADR ≥ 25%, endoscopists' median screening CSSDR was 5.4%, while SDR-location and SDR-size were 10.9% and 2.2%, respectively.

CONCLUSION

Large SDR could be a simple proxy for CSSDR, in addition to proximal SDR. Large SDR and proximal SDR benchmarks of 2.2% and 10.9% may guide adequate serrated polyp detection with uniform definitions and simpler calculations.

Comparison of different virtual chromoendoscopy classification systems for the characterization of colorectal lesions

Background and Aim

Commonly used classifications for colorectal lesions (CLs) include the Narrow Band Imaging (NBI) International Colorectal Endoscopic (NICE) and Japan NBI Expert Team (JNET) classifications. However, both lack a sessile serrated adenoma/polyp (SSA/P) category. This has been addressed by the modified Sano's (MS) and Workgroup serrAted polypS and Polyposis (WASP) classifications. This study aims to compare the accuracy of wNICE and wJNET (WASP added to both) with the stand‐alone MS classification.

Methods

Patients undergoing colonoscopy at an Australian tertiary hospital who had at least one CL detected were prospectively enrolled. In the exploratory phase, CLs were characterized in real time with NBI and magnification using all classifications. In the validation phase, CLs were assessed with both NBI and Blue Laser Imaging (BLI) by four external endoscopists in Japan. The primary outcome was the comparison of wJNET and MS. Secondary outcomes included comparisons among all classifications and the calculation of interrater reliability.

Results

A total of 483 CLs were evaluated in real time in the exploratory phase, and four sets of 30 CL images (80 on NBI and 40 on BLI) were scored in the validation phase. For high‐confidence diagnoses, MS accuracy was superior to wJNET in both the exploratory (86% vs 79%, P < 0.05) and validation (85% vs 69%, P < 0.05) phases. The interrater reliability was substantial for all classifications (κ = 0.74, 0.69, and 0.63 for wNICE, wJNET, and MS, respectively).

Conclusions

MS classification achieved the highest accuracy in both the exploratory and validation phases. MS can differentiate serrated and adenomatous polyps as a stand‐alone classification.

Detection rates for adenomas, serrated polyps and clinically relevant serrated polyps can be easily estimated by individually calculated detection rate ratios

Background and aims: Adenoma detection rate (ADR) is a key quality indicator for colonoscopy; however, it is cumbersome to obtain. We investigated if detection rates (DRs) for adenomas, serrated polyps (SPs) and clinically relevant SP (crSPDR) can be accurately estimated by individualized DR ratios (DRRs) in a multicenter primary colonoscopy screening cohort of average-risk individuals.Methods: DRRs were calculated by dividing DRs for a certain polyp entity by polyp detection rate (PDR) for each endoscopist individually on the basis of his/her first 50 (DRR₅₀) and 100 (DRR₁₀₀) consecutive colonoscopies. DRs were estimated for each endoscopist by multiplying his/her DRR for a certain polyp entity with his/her PDR of subsequent colonoscopies in groups of 50 (DRR₅₀) and 100 (DRR₁₀₀) consecutive colonoscopies. Estimated and actual DRs were compared.Results: Estimated DRs showed a strong correlation with actual DRs for adenomas (r = 0.86 and 0.87; each p < .001), SPs (r = 0.85 and 0.91; each p < .001) and crSPs (r = 0.82 and 0.86; each p < .001) using DRRs derived from first 50 and 100 consecutive colonoscopies. Corresponding root mean square error (RMSE) between individual estimated and actual DRs using DRR₅₀ and DRR₁₀₀ was 5.3(±4.6)% and 4.5(±4.8)% for adenomas, 5.2(±4.1)% and 3.9(±2.8)% for SP, 3.1(±3.1)% and 2.8(±2.5)% for crSP, respectively. RMSE was not significantly different between DRR₅₀ and DRR₁₀₀ for ADR (p = .445), SPDR (p = .178) and crSP (p = .544).Conclusions: DR for all relevant polyp entities can be accurately estimated by using individual DRRs. This approach may enable endoscopists to easily track their performance measures in daily routine.

Body fatness over the life course and risk of serrated polyps and conventional adenomas

Serrated polyps (SPs) and conventional adenomas represent 2 distinct groups of colorectal premalignancy. The influence of early life adiposity on risk of these precursors remains unclear. Within the Nurses' Health Study, the Nurses' Health Study 2, and the Health Professionals Follow-up Study, we assessed body fatness during childhood using 9-level somatotype and obtained weight and body mass index (BMI) in adulthood. We used multivariable-adjusted logistic regression to examine the association of SPs and conventional adenomas with body fatness in early childhood (age 5), late childhood (age 10), early adulthood (age 18/21) and middle adulthood (baseline) and weight change during early-to-middle adulthood. During 18-20 years of follow-up, we documented 8,697 SPs and 10,219 conventional adenomas in 132,514 women; 2,403 SPs and 4,495 conventional adenomas in 29,207 men. We found a modest positive association of adiposity in early and late childhood with risk of SPs and conventional adenomas, with odds ratios ranging from 1.12 to 1.18 for comparison of extreme somatotypes groups. The associations were attenuated after adjusting for adulthood BMI but remained significant for conventional adenomas. No association with early life body fatness was found in men. Adulthood body fatness and weight change during early-to-middle adulthood showed positive relationships with SPs and conventional adenomas in both women and men, with stronger associations observed for SPs (p_{heterogeneity}  < 0.0001). Our findings indicated a potential role in development of colorectal cancer precursors of childhood body fatness in women, and early-to-middle adulthood weight gain and attained adiposity in both sexes.

Patterns of polyp histology: predictors of peril in the mucosa

BACKGROUND

Precursor colonic polyps of varied subtypes correlate with the known neoplastic pathways. When patients present with synchronous pre-malignant polyps of multiple histologies, multiple genetic mechanisms are likely to be active, potentially resulting in a more unstable, tumourigenic mucosa.

METHODS

We hypothesized that patients with a combination of sessile serrated adenomas/polyps (SSA/Ps), hyperplastic (HP) polyps and adenomas would be at highest risk of developing dysplasia/cancer compared to SSA/Ps alone, due to the synergistic effect of multiple active carcinogenic pathways. A prospective colonoscopy database was examined for patients with a history of SSA/P. Patients were placed into four groups based on patterns of polyp histology as follows: (i) only SSA/Ps; (ii) SSA/P + HP; (iii) SSA/Ps + adenomas; and (iv) SSA/Ps + HP + adenomas. These groups were compared in terms of the numbers, size, location and histology of polyps and personal or family history of colorectal cancer.

RESULTS

A total of 374 patients were included. The average age was 70 years (range 21-88), and 43% were male. There was a trend towards the most aggressive neoplastic pattern in group 4, associated with a tendency to larger SSA/Ps, more villous architecture in the adenomas and more high-grade dysplasia in both types of polyps. It was also associated with multiplicity of both SSA/Ps and adenomas. No SSA/Ps existing in the absence of adenomas had cytological dysplasia.

CONCLUSION

The combination of SSA/Ps, HP and adenomas in the colorectal epithelium seems to be a marker for aggressive carcinogenesis and suggests that accurate and effective surveillance is important to manage this risk.

Pathways of Colorectal Carcinogenesis

Colorectal cancer is a heterogeneous disease that develops via stepwise accumulation of well-characterized genetic and epigenetic alterations. We review the genetic changes associated with the development of precancerous colorectal adenomas and their progression to tumors, as well as the effects of defective DNA repair, chromosome instability, microsatellite instability, and alterations in the serrated pathway and DNA methylation. We provide insights into the different molecular subgroups of colorectal tumors that develop via each of these different mechanisms and their associations with patient outcomes.

Traditional serrated adenoma: an overview of pathology and emphasis on molecular pathogenesis

Objective

To provide an overview of the pathology and molecular pathogenesis of traditional serrated adenomas (TSA).

Design

Describe the morphology and molecules that play a role in their pathogenesis.

Results

These exuberant polypoid lesions are typified by tall cells with deeply eosinophilic cytoplasm, elongated nuclei bearing delicate chromatin, ectopic crypt foci, deep clefting of the lining mucosa and an overall resemblance to small bowel mucosa.

Broadly, TSAs arise via three mechanisms. They may be BRAF mutated and CpG island methylator phenotype (CIMP)-high: right sided, mediated through a microvesicular hyperplastic polyp or a sessile serrated adenoma, may also have RNF43 mutations and result in microsatellite stable (MSS) colorectal cancers (CRC). The second pathway that is mutually exclusive of the first is mediated through KRAS mutation with CIMP-low TSAs. These are left-sided TSAs, are not associated with another serrated polyp and result in MSS CRC. These TSAs also have RSPO3, RNF43 and p53 mutations together with aberrant nuclear localisation of β-catenin. Third, there is a smaller group of TSAs that are BRAF and KRAS wild type and arise by as yet unknown molecular events. All TSAs show retention of mismatch repair proteins.

Conclusion

These are characteristic unusual polyps with a complex molecular landscape.

The Molecular Hallmarks of the Serrated Pathway in Colorectal Cancer. Cancers (Basel). 2019;11. [PMID: 31330830 PMCID: PMC6678087 DOI: 10.3390/cancers11071017]

Colorectal cancer (CRC) is a leading cause of cancer death worldwide. It includes different subtypes that differ in their clinical and prognostic features. In the past decade, in addition to the conventional adenoma-carcinoma model, an alternative multistep mechanism of carcinogenesis, namely the “serrated pathway”, has been described. Approximately, 15 to 30% of all CRCs arise from neoplastic serrated polyps, a heterogeneous group of lesions that are histologically classified into three morphologic categories: hyperplastic polyps, sessile serrated adenomas/polyps, and the traditional serrated adenomas/polyps. Serrated polyps are characterized by genetic (BRAF or KRAS mutations) and epigenetic (CpG island methylator phenotype (CIMP)) alterations that cooperate to initiate and drive malignant transformation from normal colon mucosa to polyps, and then to CRC. The high heterogeneity of the serrated lesions renders their diagnostic and pathological interpretation difficult. Hence, novel genetic and epigenetic biomarkers are required for better classification and management of CRCs. To date, several molecular alterations have been associated with the serrated polyp-CRC sequence. In addition, the gut microbiota is emerging as a contributor to/modulator of the serrated pathway. This review summarizes the state of the art of the genetic, epigenetic and microbiota signatures associated with serrated CRCs, together with their clinical implications.

Colonic Perineurioma's Malignant Proximity to Serrated Colonic Polyps

A colonic perineurioma is often considered a benign cousin to a colonic polyp. However, in the submucosal type of perineurioma, it is important to rule out the malignant gastrointestinal stromal tumor (GIST). Alternatively, in the BRAF-positive serrated types of perineuriomas, surveillance is equivalent to intervals designated to serrated polyps due to a similar malignant potential. These versions serve as reminders that colonic perineuriomas are not to be disregarded.

A morphological and molecular study of proposed early forms of traditional serrated adenoma

AIMS

Traditional serrated adenoma (TSA) is the least common subtype of serrated colorectal polyp. Large protuberant lesions are easily recognised; however, the origins of TSAs are not known, and early forms have not been described. Some large TSAs present with a flat 'shoulder' component surrounding the central protuberant component. We hypothesised that small polyps with the same histology as these shoulder regions may represent early TSAs. Thus the primary aim of the study is to describe the histology of these presumptive early TSAs.

METHODS AND RESULTS

We collected 70 small (<10 mm) polyps that may represent early TSAs on the basis of typical TSA cytology covering the luminal surface. We also identified 12 large TSAs with a shoulder component resembling these small polyps. The study polyp patients had a mean age of 58 years, and 54% were female; the polyps had a mean diameter of 4.1 mm and were predominantly distal (71%). Morphologically, slit-like serrations were present in 81%, ectopic crypt formations were present in 67%, and a villous component was present in 47%. These histological features were similar to those of the 12 shoulder lesions. Immunohistochemical stains showed an absence of β-catenin nuclear expression in 96% of the small polyps, retained expression of MLH1 in 100%, and Ki67 positivity restricted to the crypt bases and ectopic crypt formations. BRAF and KRAS mutations were identified in 47% and 31% of the polyps, respectively. BRAF-mutated polyps were more likely than KRAS-mutated polyps to arise in a precursor polyp (82% versus 18%, P < 0.001), and were more likely to have slit-like serrations (100% versus 73%, P = 0.003).

CONCLUSIONS

These morphological, immunohistochemical and molecular findings are similar to what has been reported in large TSAs, and support the hypothesis that these polyps represent early forms of TSA.

Colorectal cancer: genetic abnormalities, tumor progression, tumor heterogeneity, clonal evolution and tumor-initiating cells

Colon cancer is the third most common cancer worldwide. Most colorectal cancer occurrences are sporadic, not related to genetic predisposition or family history; however, 20-30% of patients with colorectal cancer have a family history of colorectal cancer and 5% of these tumors arise in the setting of a Mendelian inheritance syndrome. In many patients, the development of a colorectal cancer is preceded by a benign neoplastic lesion: either an adenomatous polyp or a serrated polyp. Studies carried out in the last years have characterized the main molecular alterations occurring in colorectal cancers, showing that the tumor of each patient displays from two to eight driver mutations. The ensemble of molecular studies, including gene expression studies, has led to two proposed classifications of colorectal cancers, with the identification of four/five non-overlapping groups. The homeostasis of the rapidly renewing intestinal epithelium is ensured by few stem cells present at the level of the base of intestinal crypts. Various experimental evidence suggests that colorectal cancers may derive from the malignant transformation of intestinal stem cells or of intestinal cells that acquire stem cell properties following malignant transformation. Colon cancer stem cells seem to be involved in tumor chemoresistance, radioresistance and relapse.

Providing data for serrated polyp detection rate benchmarks: an analysis of the New Hampshire Colonoscopy Registry

BACKGROUND AND AIMS

Similar to achieving adenoma detection rate (ADR) benchmarks to prevent colorectal cancer (CRC), achieving adequate serrated polyp detection rates (SDRs) may be essential to the prevention of CRC associated with the serrated pathway. Previous studies have been based on data from high-volume endoscopists at single academic centers. Based on a hypothesis that ADR is correlated with SDR, we stratified a large, diverse group of endoscopists (n = 77 practicing at 28 centers) into high performers and low performers, based on ADR, to provide data for corresponding target SDR benchmarks.

METHODS

By using colonoscopies in adults aged ≥50 years (4/09-12/14), we stratified endoscopists by high and low ADRs (<15%, 15%-<25%, 25%-<35%, ≥35%) to determine corresponding SDRs by using 2 SDR measures, for screening and surveillance colonoscopies separately: (1) Clinically significant SDR (CSSDR), meaning colonoscopies with any sessile serrated adenoma/polyp (SSA/P), traditional serrated adenoma (TSA), or hyperplastic polyp (HP) >1 cm anywhere in the colon or HP >5 mm in the proximal colon only divided by the total number of screening and surveillance colonoscopies, respectively. (2) Proximal SDR (PSDR) meaning colonoscopies with any serrated polyp (SSA/P, HP, TSA) of any size proximal to the sigmoid colon divided by the total number of screening and surveillance colonoscopies, respectively.

RESULTS

A total of 45,996 (29,960 screening) colonoscopies by 77 endoscopists (28 facilities) were included. Moderately strong positive correlation coefficients were observed for screening ADR/CSSDR (P = .69) and ADR/PSDR (P = .79) and a strong positive correlation (P = .82) for CSSDR/PSDR (P < .0001 for all) was observed. For ADR ≥25%, endoscopists' median (interquartile range) screening CSSDR was 6.8% (4.3%-8.6%) and PSDR was 10.8% (8.6%-16.1%).

CONCLUSIONS

Derived from ADR, the primary colonoscopy quality indicator, our results suggest potential SDR benchmarks (CSSDR = 7% and PSDR = 11%) that may guide adequate serrated polyp detection. Because CSSDR and PSDR are strongly correlated, endoscopists could use the simpler PSDR calculation to assess quality.

Hyper-Methylated Loci Persisting from Sessile Serrated Polyps to Serrated Cancers. Int J Mol Sci. 2017;18:pii: E535. [PMID: 28257124 PMCID: PMC5372551 DOI: 10.3390/ijms18030535]

Although serrated polyps were historically considered to pose little risk, it is now understood that progression down the serrated pathway could account for as many as 15%-35% of colorectal cancers. The sessile serrated adenoma/polyp (SSA/P) is the most prevalent pre-invasive serrated lesion. Our objective was to identify the CpG loci that are persistently hyper-methylated during serrated carcinogenesis, from the early SSA/P lesion through the later cancer phases of neoplasia development. We queried the loci hyper-methylated in serrated cancers within our rightsided SSA/Ps from the New Hampshire Colonoscopy Registry, using the Illumina Infinium Human Methylation 450 k panel to comprehensively assess the DNA methylation status. We identified CpG loci and regions consistently hyper-methylated throughout the serrated carcinogenesis spectrum, in both our SSA/P specimens and in serrated cancers. Hyper-methylated CpG loci included the known the tumor suppressor gene RET (p = 5.72 x 10-10), as well as loci in differentially methylated regions for GSG1L, MIR4493, NTNG1, MCIDAS, ZNF568, and RERG. The hyper-methylated loci that we identified help characterize the biology of SSA/P development, and could be useful as therapeutic targets, or for future identification of patients who may benefit from shorter surveillance intervals.

The clinical impact of serrated colorectal polyps

Serrated polyps (SPs) of the colorectum pose a novel challenge to practicing gastroenterologists. Previously thought benign and unimportant, there is now compelling evidence that SPs are responsible for a significant percentage of incident colorectal cancer worldwide. In contrast to conventional adenomas, which tend to be slow growing and polypoid, SPs have unique features that undermine current screening and surveillance practices. For example, sessile serrated polyps (SSPs) are flat, predominately right-sided, and thought to have the potential for rapid growth. Moreover, SSPs are subject to wide variations in endoscopic detection and pathologic interpretation. Unfortunately, little is known about the natural history of SPs, and current guidelines are based largely on expert opinion. In this review, we outline the current taxonomy, epidemiology, and management of SPs with an emphasis on the clinical and public health impact of these lesions.

Adenoma Detection Rates for Screening Colonoscopies in Smokers and Obese Adults: Data From the New Hampshire Colonoscopy Registry

GOAL

To examine screening adenoma detection rates (ADR) and serrated detection rates (SDR) among smokers and obese adults in the New Hampshire Colonoscopy Registry.

BACKGROUND

ADR, a quality measure for screening colonoscopies, is associated with protection from interval colorectal cancer. Currently, only sex-specific ADR benchmarks are reported. However, obesity and smoking ≥20 pack-years are strong predictors for colorectal neoplasia, as highlighted by the 2009 American College of Gastroenterology CRC Screening Guidelines. Data comparing ADR in smokers and obese adults to those without these risks are limited.

STUDY

We calculated ADR, SDR, and 95% confidence intervals for screening colonoscopies in participants ≥50 years. Sex-specific and sex-age-specific rates were compared by smoking exposure (never vs. <20 vs. ≥20 pack-years) and body mass index (<30 vs. ≥30).

RESULTS

A total of 21,539 screening colonoscopies were performed by 77 endoscopists at 20 facilities (April 2009 to September 2013). The difference in ADR between nonsmokers and smokers with ≥20 pack-years was 8.8% (P<0.0001) and between obesity groups 5.0% (P<0.0001). Significant sex-specific and sex-age-specific increases in ADR and SDR were found among smokers and obese participants.

CONCLUSIONS

ADR and SDR for smokers and obese adults were significantly higher than their counterparts without those risks. Endoscopists should consider the prevalence of these risks within their screening population when comparing their rates to established benchmarks. Calculating sex-specific or sex-age-specific ADR and SDR based on smoking and obesity may provide optimal protection for populations with a particularly high prevalence of smokers and obese adults.

The molecular characteristics of colonic neoplasms in serrated polyposis: a systematic review and meta-analysis

Serrated polyposis is a rare disorder characterised by the presence of multiple serrated polyps in the large intestine, and an increased personal and familial risk of colorectal cancer. Knowledge of the molecular characteristics of colonic lesions which develop in this syndrome is fragmented, making it difficult to understand the underlying genetic basis of this condition. We conducted a systematic review and meta-analysis of all studies which evaluated the molecular characteristics of colorectal neoplasms found in individuals with serrated polyposis. We identified 4561 potentially relevant studies, but due to a lack of consensus in the reporting of findings, only fourteen studies were able to be included in the meta-analysis. BRAF mutation was found in 73% (95% CI 65-80%) of serrated polyps, 0% (95% CI 0-3%) of conventional adenomas and 49% (95%CI 33-64%) of colorectal cancers. In contrast, KRAS mutation was present in 8% (95% CI 5-11%) of serrated polyps, 3% (95% CI 0-13%) of conventional adenomas and 6% (95% CI 0-13%) of colorectal cancers. Absence of MLH1 immunostaining was found in 3% (95% CI 0-10%) of serrated polyps and 53% (95% CI 36-71%) of colorectal cancers. Overall, microsatellite instability was found in 40% (95% CI 18-64%) of colorectal cancers arising in the setting of serrated polyposis. Our results indicate that diverse molecular pathways are likely to contribute to the increased predisposition for colorectal cancer in individuals with serrated polyposis. We also propose a set of minimum standards for the reporting of future research in serrated polyposis as this is a rare syndrome and collation of research findings from different centres will be essential to identify the molecular mechanisms involved in the pathogenesis of this condition.

The endoscopist's guide to serrated polyposis

AIM

Serrated polyposis is a condition of the colon characterized by multiple serrated polyps. This review aims to provide a practical guide to the day-to-day management of serrated polyposis, including diagnosis, endoscopic identification of serrated polyps, surveillance, the role of endoscopic and surgical management and the screening of family members.

METHOD

The literature was searched using PubMed and MEDLINE databases for the terms "serrated polyp", "serrated polyposis" and "hyperplastic polyposis". English-language abstracts were read and the full article was retrieved if relevant to the review. Expert opinion from the authors was also sought.

RESULTS

Advances in our knowledge of the molecular pathways involved in serrated polyposis and an improved clinical picture of the disease from retrospective studies have led to better understanding of its pathogenesis and natural history. However, there are still areas not answered by the literature, and hence empirical management or expert opinion has to be followed.

CONCLUSION

Improvements in our understanding of serrated polyposis, together with improvements in endoscopic equipment and technique, have enabled the endoscopist to be at the forefront of managing this condition from diagnosis to endoscopic surveillance and control of the polyps.

MicroRNA-31 expression in relation to BRAF mutation, CpG island methylation and colorectal continuum in serrated lesions

The CpG island methylator phenotype (CIMP) is a distinct form of epigenomic instability. Many CIMP-high colorectal cancers (CRCs) with BRAF mutation are considered to arise from serrated pathway. We recently reported that microRNA-31 (miR-31) is associated with BRAF mutation in colorectal tumors. Emerging new approaches have revealed gradual changes in BRAF mutation and CIMP-high throughout the colorectum in CRCs. Here, we attempted to identify a possible association between miR-31 and epigenetic features in serrated pathway, and hypothesized that miR-31 supports the "colorectal continuum" concept. We evaluated miR-31 expression, BRAF mutation and epigenetic features including CIMP status in 381 serrated lesions and 222 non-serrated adenomas and examined associations between them and tumor location (rectum; sigmoid, descending, transverse and ascending colon and cecum). A significant association was observed between high miR-31 expression and CIMP-high status in serrated lesions with BRAF mutation (p = 0.0001). In contrast, miR-31 was slightly but insignificantly associated with CIMP status in the cases with wild-type BRAF. miR-31 expression in sessile serrated adenomas (SSAs) with cytological dysplasia was higher than that in SSAs, whereas, no significant difference was observed between traditional serrated adenomas (TSAs) and TSAs with high-grade dysplasia. The frequency of miR-31, BRAF mutation CIMP-high and MLH1 methylation increased gradually from the rectum to cecum in serrated lesions. In conclusion, miR-31 expression was associated with CIMP-high status in serrated lesions with BRAF mutation. Our data also suggested that miR-31 plays an important role in SSA evolution and may be a molecule supporting the colorectal continuum.

Hyperplastic polyps identified during screening endoscopy: reevaluated by histological examinations and genetic alterations

BACKGROUND/PURPOSE

Screening colonoscopy is one of the most effective methods to detect and prevent colorectal cancer by removing neoplastic polyps. The recent discovery of serrated polyps with neoplastic potential has reclassified these polyps into hyperplastic polyps (HPs), sessile serrated adenoma (SSA), and traditional serrated adenoma (TSA) on the basis of macroscopic morphology and microscopic histology. In this study, we aimed to revisit HPs identified during screening endoscopy by histological reevaluation and genetic alterations.

METHODS

A total of 253 HPs found by screening endoscopy were rechecked by two pathologists, and mutual agreement on the diagnosis of polyps was subjected for further statistical analysis. Direct sequencing for gene mutation at BRAF V600E and KRAS G12D was performed.

RESULTS

Among the 253 HPs analyzed, 175 were classified as serrated polyps, while 78 were reclassified into other diagnosis. The concordance among pathologists in diagnosing these serrated polyps was substantial (κ = 0.6672). About 11.5% of the reviewed HPs turned out to be with neoplastic potential, including 7 SSAs, 5 TSAs, as well as 17 conventional adenomas. Results of subgroup analyses revealed that polyps >10 mm were more likely to be found in proximal colon (p = 0.0006) and tended to harbor neoplastic components. We found that two SSAs and one TSA had BRAF mutation, while one TSA had KRAS mutation. The mean size of these mutated adenomas (9.0 mm) was larger than those with wild-type genes (4.9 mm).

CONCLUSION

Serrated polyps with neoplastic potential were prone to be overlooked as hyperplastic and innocent ones during screening colonoscopy. Therefore, both endoscopists and pathologists should pay attention to understand the importance of recognizing serrated adenomas, especially for those polyps >10 mm, or those that are located in the proximal colon.

Extensive DNA methylation in normal colorectal mucosa in hyperplastic polyposis

BACKGROUND

Hyperplastic polyposis of the colorectum is a precancerous condition that has been linked with DNA methylation. The polyps in this condition have been distinguished from typical small hyperplastic polyps and renamed sessile serrated adenomas. Sessile serrated adenomas also occur sporadically and appear to be indistinguishable from their counterparts in hyperplastic polyposis.

AIMS AND METHODS

The existence of distinguishing molecular features was explored in a series of serrated polyps and matched normal mucosa from patients with and without hyperplastic polyposis by assessing mutation of BRAF, DNA methylation in 14 markers (MINTs 1, 2 and 31, p16, MGMT, MLH1, RASSF1, RASSF2, NORE1 (RASSF5), RKIP, MST1, DAPK, FAS, and CHFR), and immunoexpression of MLH1.

RESULTS

There was more extensive methylation in sessile serrated adenomas from subjects with hyperplastic polyposis (p<0.0001). A more clearcut difference in patients with hyperplastic polyposis was the finding of extensive DNA methylation in normal mucosa from the proximal colon.

CONCLUSIONS

A genetic predisposition may underlie at least some forms of hyperplastic polyposis in which the earliest manifestation may be hypermethylation of multiple gene promoters in normal colorectal mucosa. Additionally, some of the heterogeneity within hyperplastic polyposis may be explained by different propensities for MLH1 inactivation within polyps.

No major tumorigenic role for beta-catenin in serrated as opposed to conventional colorectal adenomas

Intracellular redistribution of beta-catenin through mutation of the adenomatous polyposis coli (APC) gene has been proposed as an early tumorigenic event in most colorectal tumours. In serrated adenoma (SA), a newly recognised subtype of colorectal adenoma, APC mutations are uncommon, and the contribution of beta-catenin to tumorigenesis remains unclear. We compared intracellular localisation of beta-catenin and presence of mutations in exon 3 of beta-catenin between 45 SAs, with 71 conventional adenomas (CADs), and eight carcinomas invading the submucosa (SCAs). Widespread or focal nuclear beta-catenin expression was demonstrated in 7% of SAs (three out of 45), 61% of CADs (43 out of 71), and 88% of SCAs (seven out of eight). Cytoplasmic immunostaining for beta-catenin was demonstrated in 16% of SAs (seven out of 45), 77% of CADs (55 out of 71), and 88% of SCAs (seven out of eight). No mutation in exon 3 of beta-catenin was found in SAs or SCAs, while 7% of CADs (five out of 71) had beta-catenin mutations. No nuclear or cytoplasmic expression of beta-catenin was observed in the hyperplastic or conventionally adenomatous epithelium of mixed-type SAs. These findings suggest that beta-catenin mutation is unlikely to contribute to the tumorigenesis in SA, and that intracellular localisation of beta-catenin may not be associated with an early event of the tumour progression in most SAs.