High prevalence of sessile serrated adenomas with BRAF mutations: a prospective study of patients undergoing colonoscopy

Advances in BRAF mutated colorectal cancer-could deoxycholic acid be the culprit?

BRAF mutated colorectal cancer (CRC) often demonstrates distinct molecular profiles characterized by a high methylator phenotype with two different microsatellite statuses (MSI and MSS) and corresponding methylation spectra. Prognostic disparities between these two different BRAF mutated CRC arise from divergent carcinogenic pathways, with BRAF-mutated MSS CRC exhibiting particularly unfavorable clinical outcomes. The underlying mechanism of these phenomena stems from epigenetic heterogeneity in methylation landscapes. Emerging evidences linking cholelithiasis and deoxycholic acid (DCA) to BRAF-mutated CRC pathogenesis warrant systematic investigation into their potential mechanistic relationships. Elucidating these connections could unravel novel pathogenetic pathways and inform targeted strategies for risk mitigation, molecular diagnostics, and therapeutic intervention of BRAF-mutated CRC.

The serrated pathway and colorectal cancer: what the gastroenterologist should know

INTRODUCTION

Serrated polyps can progress to colorectal cancer (CRC), through a pathway that is distinct from the conventional adenoma-carcinoma sequence. This pathway includes hyperplastic polyps (HPs), sessile serrated polyps (SSPs), and traditional serrated adenomas (TSAs).

AREAS COVERED

Our review includes the histology and pathological challenges, carcinogenesis, risk factors, detection, emerging technologies, resection, and surveillance.

EXPERT OPINION

Serrated polyp management presents many detection, diagnosis, resection, and surveillance challenges. Missed serrated polyps contribute to preventable CRCs. A new SSP detection rate benchmark will guide endoscopists with a goal when improving detection. Furthermore, new SSP-specific surveillance strategies may also aid in reducing CRC burden. Histologic differentiation remains a challenge, underscoring the need for standardized pathology practices and exploring novel ways to stratify risk independent of histology, given interobserver variation. Moreover, the clinical significance of proximal HPs requires further clarification. Which HPs < 1 cm require closer surveillance intervals? Molecular profiling may help identify markers that separate proximal low risk from high-risk HP. The best approach for resection of serrated polyps also needs to be clarified. There is also a lack of robust longitudinal outcome data to guide surveillance recommendations since current guidelines are based on low quality of evidence.

AI and Polyp Detection During Colonoscopy

Colorectal cancer (CRC) prevention depends on effective colonoscopy; yet variability in adenoma detection rates (ADRs) and missed lesions remain significant hurdles. Artificial intelligence-powered computer-aided detection (CADe) systems offer promising advancements in enhancing polyp detection. This review examines the role of CADe in improving ADR and reducing adenoma miss rates (AMRs) while addressing its broader clinical implications. CADe has demonstrated consistent improvements in ADRs and AMRs; largely by detecting diminutive polyps, but shows limited efficacy in identifying advanced adenomas or sessile serrated lesions. Challenges such as operator deskilling and the need for enhanced algorithms persist. Combining CADe with adjunctive techniques has shown potential for further optimizing performance. While CADe has standardized detection quality; its long-term impact on CRC incidence and mortality remains inconclusive. Future research should focus on refining CADe technology and assessing its effectiveness in reducing the global burden of CRC.

Endoscopic and Clinicopathological Features of a Colorectal Mucin-Rich Variant of Traditional Serrated Adenoma

INTRODUCTION

The mucin-rich variant of traditional serrated adenoma (MR-TSA), pathologically defined by the presence of goblet cells comprising over 50% of the lesion compared to the absorptive epithelial eosinophilic cytoplasm, was recently introduced as one morphological variants of traditional serrated adenoma (TSA). This study aimed to characterize the endoscopic and clinicopathological characteristics of MR-TSAs.

METHODS

Lesions pathologically diagnosed as TSAs at our hospital between 2011 and 2023 were reviewed. We analyzed the endoscopic and clinicopathological features of 49 MR-TSAs and 236 conventional TSAs (C-TSAs). Furthermore, immunohistochemical and genetic analyses were performed to ensure that there were no discrepancies with our previous study.

RESULTS

MR-TSAs, like C-TSAs, were often located in the sigmoid colon and rectum, with no significant difference in lesion size. Macroscopically, MR-TSAs frequently appeared as type 0-Is with a weak reddish color and had a mucous cap, less often exhibiting a pinecone-like or coral-shaped appearance compared to C-TSAs (p < 0.001). Magnifying endoscopy showed expanded crypt openings in 80% of MR-TSAs (p < 0.001). Both groups had similar IIIH and IVH pit patterns. Immunohistochemical analysis revealed that MUC5AC was expressed more frequently in MR-TSAs than in C-TSAs. Additionally, genetic analysis showed that MR-TSAs more frequently harbored the BRAF mutation than C-TSAs (p < 0.001), whereas MR-TSAs less frequently harbored the KRAS mutation than C-TSAs (p = 0.047).

CONCLUSION

MR-TSAs, frequently harboring the BRAF but not KRAS mutation, exhibited several distinct endoscopic findings, including a sessile morphology, lack of pinecone-like or coral-like appearance, weak reddish color, and mucous cap.

Calcium Intake and Risk of Colorectal Cancer in the NIH-AARP Diet and Health Study

Importance

Calcium intake is associated with a reduced risk of colorectal cancer (CRC), although it remains unclear whether this association varies by calcium source or tumor site. Moreover, there are disparities in calcium intake by race and ethnicity, but the impact of low calcium consumption on CRC risk in specific racial and ethnic populations is unclear.

Objective

To investigate the association between calcium intake and CRC risk, considering the source of calcium and tumor site and across racial and ethnic groups.

Design, Setting, and Participants

This cohort study analyzed data from the National Institutes of Health-AARP Diet and Health Study. Participants were aged 50 to 71 years at baseline (October 1995 to May 1996), had self-reported good health and neither extremely high nor low caloric or calcium intake, and were followed up until the date of their first primary cancer diagnosis, death, loss to follow-up, or end of follow-up (December 31, 2018). Data were analyzed from April 2022 to April 2024.

Exposure

Calcium intake was estimated from dietary sources (dairy and nondairy), supplements, and total intake.

Main Outcomes and Measures

The primary outcome was CRC incidence. Multivariable-adjusted Cox proportional hazards regression models estimated hazard ratios (HRs) and 95% CIs using the lowest sex-specific quintile of calcium intake as the reference.

Results

Among 471 396 participants who were cancer-free at baseline, mean (SD) baseline age was 62.0 (5.4) years and 59.5% were male. During 7 339 055 person-years of follow-up (median, 18.4 years [IQR, 9.2-22.5 years]), 10 618 first primary CRC cases were identified. Mean (SD) total calcium intake for the lowest quintile (Q1) was 401 mg/d (104 mg/d) for females and 407 mg/d (95 mg/d) for males and for the highest quintile (Q5) was 2056 mg/d (412 mg/d) for females and 1773 mg/d (444 mg/d) for males. Dairy, nondairy, and supplemental sources contributed a mean (SD) of 42.1% (43.5%), 34.2% (24.5%), and 23.7% (38.3%) of total calcium intake, respectively. Higher total calcium intake (Q5 vs Q1) was associated with a lower risk of CRC (hazard ratio [HR], 0.71; 95% CI, 0.65-0.78; P < .001 for trend), with consistent results across calcium sources and tumor sites. Among non-Hispanic Black participants, the mean (SD) calcium intake was 382 mg/d (108 mg/d) for Q1 and 1916 mg/d (466 mg/d) for Q5, with no association of total calcium intake with CRC risk (Q5 vs Q1: HR, 0.60; 95% CI, 0.32-1.13; P = .12 for trend); there was no evidence of effect measure differences by race and ethnicity.

Conclusions and Relevance

In this cohort study, higher calcium intake was consistently associated with reduced CRC risk across tumor sites and sources of calcium. Increasing calcium intake, especially among groups with lower consumption, may be associated with reductions in avoidable differences in CRC risk.

Optimizing colorectal cancer segmentation with MobileViT-UNet and multi-criteria decision analysis

Colorectal cancer represents a significant health challenge as one of the deadliest forms of malignancy. Manual examination methods are subjective, leading to inconsistent interpretations among different examiners and compromising reliability. Additionally, process is time-consuming and labor-intensive, necessitating the development of computer-aided diagnostic systems. This study investigates the segmentation of colorectal cancer regions of normal tissue, polyps, high-grade intraepithelial neoplasia, low-grade intraepithelial neoplasia, adenocarcinoma, and serrated Adenoma, using proposed segmentation models: VGG16-UNet, ResNet50-UNet, MobileNet-UNet, and MobileViT-UNet. This is the first study to integrate MobileViT as a UNet encoder. Each model was trained with two distinct loss functions, binary cross-entropy and dice loss, and evaluated using metrics including Dice ratio, Jaccard index, precision, and recall. The MobileViT-UNet+Dice loss emerged as the leading model in colorectal histopathology segmentation, consistently achieving high scores across all evaluation metrics. Specifically, it achieved a Dice ratio of 0.944 ± 0.030 and a Jaccard index of 0.897 ± 0.049, with precision at 0.955 ± 0.046 and Recall at 0.939 ± 0.038 across all classes. To further obtain the best performing model, we employed multi-criteria decision analysis (MCDA) using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). This analysis revealed that the MobileViT-UNet+Dice model achieved the highest TOPSIS scores of 1, thereby attaining the highest ranking among all models. Our comparative analysis includes benchmarking with existing works, the results highlight that our best-performing model (MobileViT-UNet+Dice) significantly outperforms existing models, showcasing its potential to enhance the accuracy and efficiency of colorectal cancer segmentation.

BRAF-mutant mismatch repair deficient invasive colon cancer regressing to sessile serrated lesion

A 69-year-old female was presented with a history of sigmoid colon cancer, uterine cancer, and intrahepatic carcinomas. After computed tomography revealed a disseminated nodule located in the peritoneum, colonoscopy demonstrated a rather flat-to-slightly elevated lesion with a depressed area located in the ascending colon. The flat component showed color similar to its surrounding area, and the depressed area showed redness and an expanded appearance. We obtained a biopsy specimen from the depressed area, and microscopic examination revealed well-differentiated adenocarcinoma, which was immunohistochemically positive for BRAF V600E-mutated and PMS2 proteins, and showed loss of MSH2 and MSH6 protein expressions. These findings suggested the lesion to have transformed from a sessile serrated lesion (SSL) to mismatch repair (MMR) deficient colon cancer. The patient underwent surgical removal of the nodule, which interpreted as metastasis of intrahepatic cholangiocarcinoma histopathologically. After postoperative chemotherapy, the follow-up colonoscopy revealed only the flat portion of the lesion without depressed area. Consequently, we performed an endoscopic resection, and microscopic examination confirmed the existence of BRAF V600E-mutated protein-positive and MMR protein-retained SSL without residual carcinoma. This is the first report of BRAF-mutant and MMR-deficient colon cancer, in association with SSL, showing regression.

Usefulness of magnifying endoscopy for diagnosis of sessile serrated lesion with dysplasia or carcinoma: Large retrospective study

Background and study aims Sessile serrated lesions (SSLs) are precursor lesions in the serrated neoplasia pathway that lead to invasive carcinoma from dysplasia arising from SSLs. This study aimed to elucidate the clinicopathological and endoscopic features of SSLs with and without dysplasia or carcinoma. Patients and methods We reviewed the clinicopathological and endoscopic data from all colorectal lesions pathologically diagnosed as SSLs at Juntendo University Hospital, Tokyo, Japan, between 2011 and 2022. In addition to conventional endoscopic findings, we retrospectively evaluated magnifying endoscopic findings with narrow-band imaging (NBI) or blue laser imaging (BLI) using the Japan NBI Expert Team system and analyzed pit patterns using magnified chromoendoscopic images. Results Of the 2,132 SSLs, 92.5%, 4.7%, 1.8%, and 0.9% had no dysplasia, low-grade dysplasia, high-grade dysplasia, and submucosal invasive carcinoma, respectively. Older age, the proximal colon, and larger lesions were more frequently associated with SSLs with dysplasia or carcinoma. However, 41.3% of the SSLs with dysplasia or carcinoma were ≤ 10 mm in size. Endoscopic findings, such as (semi)pedunculated morphology, double elevation, central depression, and reddishness, were frequently found in SSLs with dysplasia or carcinoma. Furthermore, magnifying endoscopy using NBI or BLI and magnifying chromoendoscopy showed high sensitivity, specificity, and accuracy for diagnosing dysplasia or carcinoma within SSLs. Conclusions SSLs with and without dysplasia or carcinoma exhibit distinct clinicopathological and endoscopic features. In an SSL series, conventional endoscopic characteristics in addition to use of magnifying endoscopy may be useful for accurately diagnosing advanced histology within an SSL.

Clinical and endoscopic characteristics of colorectal sessile serrated lesions with or without dysplasia/carcinoma: A systematic review and meta-analysis

OBJECTIVE

We aimed to compare the clinical and endoscopic characteristics of sessile serrated lesions (SSLs) with dysplasia/carcinoma (SSLD/Cs) and SSLs without dysplasia in this systematic review and meta-analysis.

METHODS

MEDLINE, EMBASE, and Cochrane Library databases and Clinicaltrials.gov were searched for relevant studies published up to August 28, 2023. The primary outcome was lesion size in SSLD/Cs and SSLs without dysplasia. The secondary outcomes included risk of dysplasia/carcinoma, morphology (classified based on the Paris classification), and lesion features such as mucus cap and nodules/protrusions in the two groups.

RESULTS

Thirteen studies with 14 381 patients were included. The proportion of SSLD/Cs ≥10 mm was significantly higher than that of SSLs without dysplasia (odds ratio [OR] 3.82, 95% confidence interval [CI] 1.21-12.02, p = 0.02). There was no significant difference in the risk of dysplasia/carcinoma between the proximal (OR 0.80, 95% CI 0.57-1.14) and distal colon (OR 1.25, 95% CI 0.88-1.77, p = 0.21). The 0-Ip (OR 2.47, 95% CI 1.50-4.09) and 0-IIa + Is (OR 10.38, 95% CI 3.08-34.98) morphologies were more prevalent among SSLD/Cs, whereas the 0-IIa morphology (OR 0.38, 95% CI 0.22-0.65) was more prevalent among SSLs without dysplasia (all p < 0.001). Furthermore, mucus cap (OR 0.61, 95% CI 0.42-0.89, p = 0.01) was more common among SSLs without dysplasia, whereas nodules/protrusions (OR 7.80, 95% CI 3.07-19.85, p < 0.001) were more common in SSLD/Cs.

CONCLUSION

SSLs >10 mm, 0-Ip or 0-IIa + Is morphologies, and those with nodules/protrusions are significantly associated with dysplasia/carcinoma.

Computer-aided colorectal cancer diagnosis: AI-driven image segmentation and classification

Colorectal cancer is an enormous health concern since it is among the most lethal types of malignancy. The manual examination has its limitations, including subjectivity and data overload. To overcome these challenges, computer-aided diagnostic systems focusing on image segmentation and abnormality classification have been developed. This study presents a two-stage approach for the automatic detection of five types of colorectal abnormalities in addition to a control group: polyp, low-grade intraepithelial neoplasia, high-grade intraepithelial neoplasia, serrated adenoma, adenocarcinoma. In the first stage, UNet3+ was used for image segmentation to locate the anomalies, while in the second stage, the Cross-Attention Multi-Scale Vision Transformer deep learning model was used to predict the type of anomaly after highlighting the anomaly on the raw images. In anomaly segmentation, UNet3+ achieved values of 0.9872, 0.9422, 0.9832, and 0.9560 for Dice Coefficient, Jaccard Index, Sensitivity, Specificity respectively. In anomaly detection, the Cross-Attention Multi-Scale Vision Transformer model attained a classification performance of 0.9340, 0.9037, 0.9446, 0.8723, 0.9102, 0.9849 for accuracy, F1 score, precision, recall, Matthews correlation coefficient, and specificity, respectively. The proposed approach proves its capacity to alleviate the overwhelm of pathologists and enhance the accuracy of colorectal cancer diagnosis by achieving high performance in both the identification of anomalies and the segmentation of regions.

Sporadic Polyps of the Colorectum

Colorectal polyps are common, and their diagnosis and classification represent a major component of gastrointestinal pathology practice. The majority of colorectal polyps represent precursors of either the chromosomal instability or serrated neoplasia pathways to colorectal carcinoma. Accurate reporting of these polyps has major implications for surveillance and thus for cancer prevention. In this review, we discuss the key histologic features of the major colorectal polyps with a particular emphasis on diagnostic pitfalls and areas of contention.

Analysis of Predictors and Risk Factors of Postpolypectomy Syndrome

BACKGROUND AND AIMS

Postpolypectomy syndrome (PPS) is a relevant adverse event that can appear after polypectomy. Several publications mention postpolypectomy syndrome using different criteria to define it. The aim of this study is to detect potential risk factors and predictors for developing PPS and to define the main criteria of PPS.

METHODS

In this retrospective monocentric study, 475 out of 966 patients who underwent colonoscopy with polypectomy from October 2015 to June 2020 were included. The main criterion of PPS is defined as the development of postinterventional abdominal pain lasting more than six hours.

RESULTS

A total of 9.7% of the patients developed PPS, which was defined as local abdominal pain around the polypectomy area after six hours. A total of 8.6% of the study population had abdominal pain within six hours postintervention. A total of 3.7% had an isolated triad of fever, leukocytosis, and increased CRP in the absence of abdominal pain. Increased CRP combined with an elevated temperature over 37.5 °C seems to be a positive predictor for developing PPS. Four independent risk factors could be detected: serrated polyp morphology, polypoid configurated adenomas, polyp localization in the cecum, and the absence of intraepithelial neoplasia.

CONCLUSIONS

Four independent risk factors for developing PPS were detected. The combination of increased CRP levels with elevated temperature seems to be a predictor for this pathology. As expected, the increasing use of cold snare polypectomies will reduce the incidence of this syndrome. Key summary: Our monocentric study on 966 patients detected four independent risk factors for developing PPS: pedunculated polyp, resected polyps in the cecum, absence of IEN, and serrated polyp morphology. The combination of increased CRP levels with elevated temperature seems to be a predictor for this pathology.

Hierarchical contribution of individual lifestyle factors and their interactions on adenomatous and serrated polyp risk

BACKGROUND

Individual colorectal polyp risk factors are well characterized; however, insights into their pathway-specific interactions are scarce. We aimed to identify the impact of individual risk factors and their joint effects on adenomatous (AP) and serrated polyp (SP) risk.

METHODS

We collected information on 363 lifestyle and metabolic parameters from 1597 colonoscopy participants, resulting in over 521,000 data points. We used multivariate statistics and machine-learning approaches to assess associations of single variables and their interactions with AP and SP risk.

RESULTS

Individual factors and their interactions showed common and polyp subtype-specific effects. Abdominal obesity, high body mass index (BMI), metabolic syndrome, and red meat consumption globally increased polyp risk. Age, gender, and western diet associated with AP risk, while smoking was associated with SP risk. CRC family history was associated with advanced adenomas and diabetes with sessile serrated lesions. Regarding lifestyle factor interactions, no lifestyle or dietary adjustments mitigated the adverse smoking effect on SP risk, whereas its negative effect was exacerbated by alcohol in the conventional pathway. The adverse effect of red meat on SP risk was not ameliorated by any factor, but was further exacerbated by western diet along the conventional pathway. No modification of any factor reduced the negative impact of metabolic syndrome on AP risk, whereas increased fatless fish or meat substitutes' intake mitigated its effect on SP risk.

CONCLUSIONS

Individual risk factors and their interactions for polyp formation along the adenomatous and serrated pathways are strongly heterogeneous. Our findings may facilitate tailored lifestyle recommendations and contribute to a better understanding of how risk factor combinations impact colorectal carcinogenesis.

Sessile serrated lesions with dysplasia: is it possible to nip them in the bud?

The serrated neoplasia pathway constitutes an "alternative route" to colorectal cancer (CRC), and sessile serrated lesions with dysplasia (SSLDs) are an intermediate step between sessile serrated lesions (SSLs) and invasive CRC in this pathway. While SSLs show indolent growth before becoming dysplastic (> 10-15 years), SSLDs are considered to rapidly progress to either immunogenic microsatellite instable-high (MSI-H) CRC (presumably 75% of cases) or mesenchymal microsatellite stable (MSS) CRC. Their flat shapes and the relatively short window of this intermediate state make it difficult to detect and diagnose SSLDs; thus, these lesions are potent precursors of post-colonoscopy/interval cancers. Confusing terminology and the lack of longitudinal observation data of serrated polyps have hampered the accumulation of knowledge about SSLDs; however, a growing body of evidence has started to clarify their characteristics and biology. Together with recent efforts to incorporate terminology, histological studies of SSLDs have identified distinct dysplastic patterns and revealed alterations in the tumor microenvironment (TME). Molecular studies at the single-cell level have identified distinct gene alterations in both the epithelium and the TME. Mouse serrated tumor models have demonstrated the importance of TME in disease progression. Advances in colonoscopy provide clues to distinguish pre-malignant from non-malignant-SSLs. Recent progress in all aspects of the field has enhanced our understanding of the biology of SSLDs. The aim of this review article was to assess the current knowledge of SSLDs and highlight their clinical implications.

Adherence to the World Cancer Research Fund/American Institute for Cancer Research cancer prevention recommendations throughout the life course and risk of colorectal cancer precursors

BACKGROUND

Despite the increasing incidence in colorectal cancer (CRC) among the young population, the involvement of modifiable early-life exposures is understudied.

METHODS

We prospectively investigated the association of lifestyle score, which measures adherence to the 2018 World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) cancer prevention recommendations, in adolescence and adulthood with risk of CRC precursors in 34,509 women enrolled in the Nurses' Health Study II. Participants reported adolescent diet in 1998 and subsequently underwent at least one lower gastrointestinal endoscopy between 1999 and 2015. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using multivariable logistic regression for clustered data.

RESULTS

During follow-up (1998-2015), 3036 women had at least one adenoma, and 2660 had at least one serrated lesion. In multivariable analysis, per unit increase in adolescent WCRF/AICR lifestyle score was not associated with risk of total adenoma or serrated lesions, in contrast to adult WCRF/AICR lifestyle score (OR = 0.92, 95% CI: 0.87-0.97, Ptrend = 0.002 for total adenoma; and OR = 0.86, 95% CI: 0.81-0.92, Ptrend < 0.001 for total serrated lesions).

CONCLUSION

Adherence to the 2018 WCRF/AICR recommendations during adulthood but not during adolescence was associated with a lower risk of CRC precursors.

Risk of Metachronous Neoplasia with High-Risk Adenoma and Synchronous Sessile Serrated Adenoma: A Systematic Review and Meta-Analysis

Background: Sessile serrated adenomas are important precursors to colorectal cancers and account for 30% of colorectal cancers. The United States Multi-Society Task Force recommends that patients with sessile serrated adenomas undergo surveillance similar to tubular adenomas. However, the risk of metachronous neoplasia when the high-risk adenoma co-exists with sessile serrated adenomas is poorly defined. Objective: To examine the risk of metachronous neoplasia in the presence of high-risk adenoma and synchronous sessile serrated adenomas compared with isolated high-risk adenoma. Data sources: PubMed, Embase, Scopus, Cochrane Library. Study selection: A literature search for studies evaluating the risk of metachronous neoplasia in patients with high-risk adenoma alone and those with synchronous high-risk adenoma and sessile serrated adenomas during surveillance colonoscopy was conducted on online databases. Main outcome measures: The primary outcome of interest was the presence of metachronous neoplasia. Results: Of the 1164 records reviewed, six (four retrospective and two prospective) studies met inclusion criteria with 2490 patients (1607 males, mean age 59.98 ± 3.23 years). Average follow-up was 47.5 ± 12.5 months. There were 2068 patients with high-risk adenoma on index colonoscopy and 422 patients with high-risk adenoma and synchronous sessile serrated adenomas. Pooled estimates showed a significantly elevated risk for metachronous neoplasia in patients with high-risk adenoma and synchronous sessile serrated adenomas (pooled odds ratio 2.21; 95% confidence intervals 1.65-2.96; p < 0.01). There was low heterogeneity (I2 = 11%) among the studies. Sensitivity analysis of the prospective studies alone also showed elevated risk of metachronous neoplasm (pooled odds ratio 2.56; 95%, confidence intervals 1.05-6.23; p = 0.04). Limitations: Inclusion of a small number of retrospective studies. Conclusions: The presence of high-risk adenomas and synchronous sessile serrated adenomas is associated with an increased risk of metachronous neoplasia. Therefore, shorter surveillance intervals may be considered in patients with high-risk adenoma and synchronous sessile serrated adenomas compared to those with high-risk adenoma alone.

Targeting BRD3 eradicates nuclear TYRO3-induced colorectal cancer metastasis

Metastasis is the main cause of death in many cancers including colorectal cancer (CRC); however, the underlying mechanisms responsible for metastatic progression remain largely unknown. We found that nuclear TYRO3 receptor tyrosine kinase is a strong predictor of poor overall survival in patients with CRC. The metastasis-promoting function of nuclear TYRO3 requires its kinase activity and matrix metalloproteinase-2 (MMP-2)-mediated cleavage but is independent of ligand binding. Using proteomic analysis, we identified bromodomain-containing protein 3 (BRD3), an acetyl-lysine reading epigenetic regulator, as one of nuclear TYRO3's substrates. Chromatin immunoprecipitation-sequencing data reveal that TYRO3-phosphorylated BRD3 regulates genes involved in anti-apoptosis and epithelial-mesenchymal transition. Inhibition of MMP-2 or BRD3 activity by selective inhibitors abrogates nuclear TYRO3-induced drug resistance and metastasis in organoid culture and in orthotopic mouse models. These data demonstrate that MMP-2/TYRO3/BRD3 axis promotes the metastasis of CRC, and blocking this signaling cascade is a promising approach to ameliorate CRC malignancy.

Fourier transformation based texture analysis for differentiating between hyperplastic polyps and sessile serrated adenomas

Colorectal cancer (CRC) is the third most common type of cancer. One major pathway involved in the development of CRC is the serrated pathway. Colorectal polyps can be divided in benign, like small hyperplastic polyps and premalignant polyps, like the sessile serrated adenomas (SSA) that has a significant potential of malignant transformation. The morphological similarity between these types of polyp, not-infrequently raises diagnostic difficulties. This study aimed to morphologically differentiate between hyperplastic polyps (HP) and SSAs by using automated computerized texture analysis of Fourier transformed histological images. Thirty images of HP and 58 images of SSA were analyzed by computerized texture analysis. A fast Fourier transformation was applied to the images. The Fourier frequency plots were further transformed into gray level co-occurrence matrices and four textural variables were extracted: entropy, correlation, contrast, and homogeneity. Our study is the first to combine this type of analysis for automated classification of colonic neoplasia. The results were analyzed using statistical and neural network (NNET) classification models. The predictive values of these classifiers were compared. The statistical regression algorithm presented a sensitivity of 95% to detect the SSA and a specificity of 80% to detect the HP. The NNET analysis was superior to the statistical analysis displaying a classification accuracy of 100%. The results of this study have confirmed the hypothesis that Fourier based texture image analysis is helpful in differentiating between HP and SSA. RESEARCH HIGHLIGHTS: Colorectal polyps can be divided in benign, like hyperplastic polyps (HP) and premalignant, like the sessile serrated adenomas (SSA). There is a high morphologic similarity between these two types of polyp that not-infrequently raises diagnostic difficulties. The results of our morphometric analysis that were used to build a neural network based model of prediction of the polyp types, have a great clinical importance of identifying SSA polyps which have significant potential of malignant progression as compared to HP.

Epidemiology of overall and early-onset serrated polyps versus conventional adenomas in a colonoscopy screening cohort

Serrated polyps (SPs) are precursors to one-third of colorectal cancers (CRCs), with histological subtypes: hyperplastic polyps (HPs), sessile serrated lesions (SSLs) and traditional serrated adenomas (TSAs). The incidence of early-onset CRC before the age of 50 is increasing, with limited understanding of SPs in younger cohorts. Using a large colonoscopy-based cohort, we characterized epidemiologic profiles of SP subtypes, compared to conventional adenomas, with secondary analysis on early-onset polyps. Ninety-four thousand four hundred and twenty-seven patients underwent screening colonoscopies between 2010 and 2018. Demographic, endoscopic and histopathologic characteristics of each polyp subtype were described. High-risk polyps included SSLs ≥10 mm/with dysplasia and conventional adenomas ≥10 mm/with tubulovillous/villous histology/high-grade dysplasia. We examined polyp prevalence with age and compared early- (age < 50) and late-onset polyps (age ≥ 50). Eighteen thousand one hundred and twenty-five patients had SPs (4357 SSLs, 15 415 HPs, 120 TSAs) and 26 699 had conventional adenomas. High-risk SSLs were enriched in the ascending colon (44.1% vs 2.6-35.8% for other locations; P < .003). Early- and late-onset SPs had similar subsite distribution. Early-onset conventional adenomas were more enriched in the distal colon/rectum (51.8% vs 43.4%, P < .001). Multiple conventional adenomas were more represented in late-onset groups (40.8% vs 33.8%, P < .001), with no difference in SSLs. The prevalence of conventional adenomas/high-risk conventional adenomas increased continuously with age, whereas the prevalence of SSLs/high-risk SSLs was stable from age 40 years onwards. A higher proportion of women were diagnosed with early-onset than late-onset SSLs (62.9% vs 57.6%, P = .03). Conventional adenomas, SSLs, early- and late-onset polyps have distinct epidemiology. The findings have implications for improved colonoscopy screening and surveillance and understanding the etiologic heterogeneity of CRC.

Accuracy and Inter-observer Agreement Among Endoscopists for Visual Identification of Colorectal Polyps Using Endoscopy Images

BACKGROUND

It is essential to accurately distinguish small benign hyperplastic colon polyps (HP) from sessile serrated lesions (SSL) or adenomatous polyps (TA) based on endoscopic appearances. Our objective was to determine the accuracy and inter-observer agreements for the endoscopic diagnosis of small polyps.

METHODS

High-quality endoscopic images of 30 small HPs, SSLs, and TAs were used randomly to create two-timed PowerPoint slide sets-one with and another one without information on polyp size and location. Seven endoscopists viewed the slides on two separate occasions 90 days apart, identified the polyp type, and graded their confidence level. Overall and polyp-specific accuracies were assessed for the group and individual endoscopists. Chi-square tests and Kappa (κ) statistics were used to compare differences as appropriate.

RESULTS

When polyp size and location were provided, overall accuracy was 67.1% for TAs, 50.0% for SSLs, and 41.4% for HPs; the corresponding accuracies were 60%, 44.3%, and 34.3% when polyp size and location were withheld (p < .001). Inter-observer agreement was moderate for TAs (κ = 0.50) and fair for SSLs (κ = 0.26) and HPs (κ = 0.29); the corresponding inter-observer agreements were 0.44, 0.31, and 0.17 with polyp size and location withheld. Accuracy was not affected by knowledge of polyp size, location, or confidence level. Endoscopists with ≥ 10 years (vs. < 10 years) of colonoscopy experience had marginally higher (56% vs. 40%, p = 0.05) accuracy for SSL diagnosis.

CONCLUSIONS

The ability to distinguish between small TAs, SSLs, and HPs on their endoscopic appearance is poor regardless of the endoscopists' knowledge of polyp size and location.

Effect of computer-aided colonoscopy on adenoma miss rates and polyp detection: A systematic review and meta-analysis

BACKGROUND AND AIM

Multiple computer-aided techniques utilizing artificial intelligence (AI) have been created to improve the detection of polyps during colonoscopy and thereby reduce the incidence of colorectal cancer. While adenoma detection rates (ADR) and polyp detection rates (PDR) are important colonoscopy quality indicators, adenoma miss rates (AMR) may better quantify missed lesions, which can ultimately lead to interval colorectal cancer. The purpose of this systematic review and meta-analysis was to determine the efficacy of computer-aided colonoscopy (CAC) with respect to AMR, ADR, and PDR in randomized controlled trials.

METHODS

A comprehensive, systematic literature search was performed across multiple databases in September of 2022 to identify randomized, controlled trials that compared CAC with traditional colonoscopy. Primary outcomes were AMR, ADR, and PDR.

RESULTS

Fourteen studies totaling 10 928 patients were included in the final analysis. There was a 65% reduction in the adenoma miss rate with CAC (OR, 0.35; 95% CI, 0.25-0.49, P < 0.001, I²  = 50%). There was a 78% reduction in the sessile serrated lesion miss rate with CAC (OR, 0.22; 95% CI, 0.08-0.65, P < 0.01, I²  = 0%). There was a 52% increase in ADR in the CAC group compared with the control group (OR, 1.52; 95% CI, 1.39-1.67, P = 0.04, I²  = 47%). There was 93% increase in the number of adenomas > 10 mm detected per colonoscopy with CAC (OR 1.93; 95% CI, 1.18-3.16, P < 0.01, I²  = 0%).

CONCLUSIONS

The results of the present study demonstrate the promise of CAC in improving AMR, ADR, PDR across a spectrum of size and morphological lesion characteristics.

EBHI-Seg: A novel enteroscope biopsy histopathological hematoxylin and eosin image dataset for image segmentation tasks

Background and purpose

Colorectal cancer is a common fatal malignancy, the fourth most common cancer in men, and the third most common cancer in women worldwide. Timely detection of cancer in its early stages is essential for treating the disease. Currently, there is a lack of datasets for histopathological image segmentation of colorectal cancer, which often hampers the assessment accuracy when computer technology is used to aid in diagnosis.

Methods

This present study provided a new publicly available Enteroscope Biopsy Histopathological Hematoxylin and Eosin Image Dataset for Image Segmentation Tasks (EBHI-Seg). To demonstrate the validity and extensiveness of EBHI-Seg, the experimental results for EBHI-Seg are evaluated using classical machine learning methods and deep learning methods.

Results

The experimental results showed that deep learning methods had a better image segmentation performance when utilizing EBHI-Seg. The maximum accuracy of the Dice evaluation metric for the classical machine learning method is 0.948, while the Dice evaluation metric for the deep learning method is 0.965.

Conclusion

This publicly available dataset contained 4,456 images of six types of tumor differentiation stages and the corresponding ground truth images. The dataset can provide researchers with new segmentation algorithms for medical diagnosis of colorectal cancer, which can be used in the clinical setting to help doctors and patients. EBHI-Seg is publicly available at: https://figshare.com/articles/dataset/EBHI-SEG/21540159/1.

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.

Comparison of adenoma detection rate and proximal serrated polyp detection rate and their effect on post-colonoscopy colorectal cancer mortality in screening patients

BACKGROUND

Patients with serrated polyps are at increased risk for post-colonoscopy colorectal cancer (PCCRC); however, evidence for a dedicated serrated polyp detection rate is lacking. The aim of this study was to investigate the association of the proximal serrated polyp detection rate (PSDR) and adenoma detection rate (ADR) with PCCRC death.

METHODS

This was a retrospective analysis within the Austrian quality assurance program for screening colonoscopy. Spearman's rank coefficient was calculated for the assessment of association between ADR and PSDR. Whether ADR or PSDR were associated with colorectal cancer mortality was assessed by Cox proportional hazards model.

RESULTS

229 /729 screening colonoscopies performed by 308 endoscopists were analyzed. The ADR (hazard ratio [HR] per 1 percentage point increase 0.98, 95 %CI 0.96-0.99) as well as the PSDR (HR per 1 percentage point increase 0.97, 95 %CI 0.94-0.99) were significantly associated with PCCRC death. The correlation coefficient of the ADR and PSDR calculated at every colonoscopy was 0.70 (95 %CI 0.70-0.71), and the corresponding PSDR value for an ADR performance standard of 25 % was 11.1 %. At the end of the study period, 86 endoscopists (27.9 %) reached an ADR of > 25 % and a PSDR of > 11.1 %.

CONCLUSIONS

The ADR as well as the PSDR were associated with PCCRC death. Striving for a high PSDR in addition to a high ADR might reduce the risk for PCCRC mortality in patients undergoing screening colonoscopy.

Pure somatic pathogenic variation profiles for patients with serrated polyposis syndrome: a case series

OBJECTIVE

The serrated pathway is a distinct genetic/epigenetic mechanism of the adenoma-carcinoma sequence in colorectal carcinogenesis. Although many groups have reported the genetic-phenotypic correlation of serrated lesions (SLs), previous studies regarding the serrated pathway were conducted on patients with SLs that have different germline and environmental genetic backgrounds. We aimed to compare pure somatic genetic profiles among SLs within identical patient with SPS.

RESULTS

We analyzed SLs from one patient with SPS (Case #1) and compared DNA variant profiles using targeted DNA multigene panels via NGS among the patient's hyperplastic polyp (HP), three sessile serrated lesions (SSLs), and one traditional serrated adenoma (TSA), and separately analyzed three SSLs and one tubular adenoma (TA) within another patient with SPS (Case #2). In two patients, known pathogenic variant of BRAF (c.1799 T > A, p.Val600Glu) was observed in one TSA and one SSL in Case #1, and in three SSLs within Case #2. The pure somatic pathogenic variant BRAF (c.1799 T > A, p.Val600Glu) among SLs with identical germline genetic background supports its importance as a strong contributor for SLs.

Sessile serrated lesions: Clinicopathological characteristics, endoscopic diagnosis, and management

The 2019 World Health Organization (WHO) Classification of Tumours of the Digestive System (5th edition) introduced the term "sessile serrated lesion" (SSL) to replace the term "sessile serrated adenoma/polyp" (SSA/P). SSLs are early precursor lesions in the serrated neoplasia pathway that result in colorectal carcinomas with BRAF mutations, methylation for DNA repair genes, a CpG island methylator phenotype, and high levels of microsatellite instability. Some of these lesions can rapidly become dysplastic or invasive carcinomas that exhibit high lymphatic invasion and lymph node metastasis potential. The 2019 WHO classification noted that dysplasia arising in an SSL most likely is an advanced polyp, regardless of the morphologic grade of the dysplasia. Detecting SSLs with or without dysplasia is critical; however, detection of SSLs is challenging, and their identification by endoscopists and pathologists is inconsistent. Furthermore, indications for their endoscopic treatment have not been established. Moreover, SSLs are considered to contribute to the development of post-colonoscopy colorectal cancers. Herein, the clinicopathological and endoscopic characteristics of SSLs, including features determined using white light and image-enhanced endoscopy, therapeutic indications, therapeutic methods, and surveillance are reviewed based on the literature. This information may lead to more intensive research to improve detection, diagnosis, and rates of complete resection of these lesions and reduce post-colonoscopy colorectal cancer rates.

Braf mutation induces rapid neoplastic transformation in the aged and aberrantly methylated intestinal epithelium

OBJECTIVE

Sessile serrated lesions (SSLs) are common across the age spectrum, but the BRAF mutant cancers arising occur predominantly in the elderly. Aberrant DNA methylation is uncommon in SSL from young patients. Here, we interrogate the role of ageing and DNA methylation in SSL initiation and progression.

DESIGN

We used an inducible model of Braf mutation to direct recombination of the oncogenic Braf V637E allele to the murine intestine. BRAF mutation was activated after periods of ageing, and tissue was assessed for histological, DNA methylation and gene expression changes thereafter. We also investigated DNA methylation alterations in human SSLs.

RESULTS

Inducing Braf mutation in aged mice was associated with a 10-fold relative risk of serrated lesions compared with young mice. There were extensive differences in age-associated DNA methylation between animals induced at 9 months versus wean, with relatively little differential Braf-specific methylation. DNA methylation at WNT pathway genes scales with age and Braf mutation accelerated age-associated DNA methylation. In human SSLs, increased epigenetic age was associated with high-risk serrated colorectal neoplasia.

CONCLUSIONS

SSLs arising in the aged intestine are at a significantly higher risk of spontaneous neoplastic progression. These findings provide support for a new conceptual model for serrated colorectal carcinogenesis, whereby risk of Braf-induced neoplastic transformation is dependent on age and may be related to age-associated molecular alterations that accumulate in the ageing intestine, including DNA methylation. This may have implications for surveillance and chemopreventive strategies targeting the epigenome.

Activating KRAS and GNAS mutations in heterotopic submucosal glands of the stomach

BACKGROUND

The heterotopic submucosal gland (HSG) is a common incidental finding in gastrectomy specimens. The majority of HSGs are small incidental lesions, which are also known as gastritis cystica profunda. However, larger lesions may appear as an inverted growth of well-organized mucosa referred to as gastric inverted polyps.

METHODS

To determine whether genetic alterations are involved in HSG development, we analyzed 63 gastric HSG lesions using targeted next-generation sequencing and immunohistochemistry.

RESULTS

Histologically, HSG lesions consistently had areas of pyloric gland differentiation with variable extent of foveolar differentiation. Although the background mucosa showed intestinal metaplasia in most cases (98%), intestinal-type epithelium was seen in only one HSG lesion (2%). Sequencing analysis identified activating KRAS, BRAF, CTNNB1, and GNAS mutations in 34 (54%), 1 (2%), 1 (2%), and 7 (11%) lesions, respectively. HSG lesions harboring a KRAS mutation were more likely to present extensive foveolar differentiation (P = 0.013) and absence of parietal cells (P = 0.0081). Five HSG lesions had a dysplastic component, and concordant genetic alterations were detected between the non-dysplastic and dysplastic areas of two lesions that were successfully analyzed. Immunohistochemical staining demonstrated diffuse expression of mutant KRAS protein in lesions with the most common genetic alteration, KRAS G12D.

CONCLUSIONS

Our study demonstrated that a major proportion of HSGs were proliferative lesions associated with oncogenic mutations, with more than half of lesions harboring activating KRAS mutations.

Serrated Colorectal Lesions: An Up-to-Date Review from Histological Pattern to Molecular Pathogenesis

Until 2010, colorectal serrated lesions were generally considered as harmless lesions and reported as hyperplastic polyps (HPs) by pathologists and gastroenterologists. However, recent evidence showed that they may bear the potential to develop into colorectal carcinoma (CRC). Therefore, the World Health Organization (WHO) classification has identified four categories of serrated lesions: hyperplastic polyps (HPs), sessile serrated lesions (SSLs), traditional serrated adenoma (TSAs) and unclassified serrated adenomas. SSLs with dysplasia and TSAs are the most common precursors of CRC. CRCs arising from serrated lesions originate via two different molecular pathways, namely sporadic microsatellite instability (MSI) and the CpG island methylator phenotype (CIMP), the latter being considered as the major mechanism that drives the serrated pathway towards CRC. Unlike CRCs arising through the adenoma-carcinoma pathway, APC-inactivating mutations are rarely shown in the serrated neoplasia pathway.

Cause, Epidemiology, and Histology of Polyps and Pathways to Colorectal Cancer

Colorectal cancer is the second leading cause of cancer-associated mortality, with a lifetime risk of approximately 4% to 5%. Colorectal cancer develops from the sequential acquisition of defined genetic mutations in the colonic epithelium. Tumorigenesis from normal tissue to cancer occurs largely through 3 pathways: the chromosomal instability pathway, the microsatellite instability pathway, and the sessile serrated pathway. Colorectal cancer incidence and mortality have decreased by approximately 35% since the beginning of screening programs in the 1990s, although other factors such as use of aspirin for coronary disease prevention and decreased smoking rates may also be important. In this review, we discuss the etiology, epidemiology, and histology of colorectal polyps and cancer.

Molecular Biologic and Epidemiologic Insights for Preventability of Colorectal Cancer

The etiology of colorectal cancer (CRC) has been informed from both a molecular biology perspective, which concerns the study of the nature, timing, and consequences of mutations in driver genes, and epidemiology, which focuses on identifying risk factors for cancer. For the most part, these fields have developed independently, and it is thus important to consider them in a more integrated manner. The molecular mutational perspective has stressed the importance of mutations due to replication of adult stem cells, and the molecular fingerprint of most CRCs does not suggest the importance of direct carcinogens. Epidemiology has identified numerous modifiable risk factors that account for most CRCs, most of which are not direct mutagens. The distribution of CRCs across the large bowel is not uniform, which is possibly caused by regional differences in the microbiota. Some risk factors are likely to act through or interact with the microbiota. The mutational perspective informs when risk factors may begin to operate in life and when they may cease to operate. Evidence from the mutational model and epidemiology supports that CRC risk factors begin early in life and may contribute to the risk of early-onset CRC. Later in carcinogenesis, there may be a "point of no return" when sufficient mutations have accumulated, and some risk factors do not affect cancer risk. This period may be at least 5-15 years for some risk factors. A more precise knowledge of timing of risk factor to cancer is required to inform preventive efforts.

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

BACKGROUND AND AIMS

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.

METHODS

Retrospective analyses and propensity score matching were performed for the resection of colorectal lesions ≥ 10 mm with endoscopic features of SSL.

RESULTS

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 15 mm (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 (6.28 min vs. 2.55 min, 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).

CONCLUSIONS

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.

Development of a Large Colonoscopy-Based Longitudinal Cohort for Integrated Research of Colorectal Cancer: Partners Colonoscopy Cohort

BACKGROUND AND AIMS

Conventional adenomas (CAs) and serrated polyps (SPs) are precursors to colorectal cancer (CRC). Understanding metachronous cancer risk is poor due to lack of accurate large-volume datasets. We outline the use of natural language processing (NLP) in forming the Partners Colonoscopy Cohort, an integrated longitudinal cohort of patients undergoing colonoscopies.

METHODS

We identified endoscopy quality data from endoscopy reports for colonoscopies performed from 2007 to 2018 in a large integrated healthcare system, Mass General Brigham). Through modification of an established NLP pipeline, we extracted histopathological data (polyp location, histology and dysplasia) from corresponding pathology reports. Pathology and endoscopy data were merged by polyp location using a four-stage algorithm. NLP and merging procedures were validated by manual review of 500 pathology reports.

RESULTS

305,656 colonoscopies in 213,924 patients were identified. After merging, 76,137 patients had matched polyp data for 334,750 polyps. CAs and SPs were present in 86,707 (28.5%) and 55,373 (18.2%) colonoscopies. Among patients with polyps at index screening colonoscopy, 14,931 (33.4%) had follow-up colonoscopy (median 46.4, interquartile range 33.8-62.4 months); 91 (0.2%) and 1127 (2.5%) patients developed metachronous CRC and high-risk polyps (polyps ≥ 10 mm or CAs having high-grade dysplasia/villous/tublovillous histology or SPs with dysplasia). Genetic data were available for 23,787 (31.7%) patients with polyps from the Partners Biobank. The validation study showed a positive predictive value of 100% for polyp histology and locations.

CONCLUSION

We created the Partners Colonoscopy Cohort providing essential infrastructure for future studies to better understand the natural history of CRC and improve screening and post-polypectomy strategies.

Current Approaches in Managing Colonic Serrated Polyps and Serrated Polyposis

For decades, conventional adenomas were the only known precursor lesions of colorectal cancer (CRC). Accordingly, education and research regarding CRC prevention were mainly focused on adenomas. The groundbreaking discovery that serrated polyps (SPs) also have the potential to develop into CRCs, and seem to account for a considerable proportion of sporadic CRCs, has led to a paradigm shift in the prevention, diagnosis, and treatment of CRC. Studies in recent years have led to our current understanding of SPs and associated CRC, but a lot of work is still to be done to further improve knowledge about this serrated neoplasia pathway and the clinical management of SPs and serrated polyposis syndrome (SPS). In this review, we reflect on the current understanding of SPs with respect to terminology, detection, resection, and surveillance and reflect on the management of SPS.

Total Vitamin D Intake and Risks of Early-Onset Colorectal Cancer and Precursors

BACKGROUND & AIMS

Vitamin D has been implicated in colorectal cancer (CRC) pathogenesis, but it remains unknown whether total vitamin D intake is associated with early-onset CRC and precursors diagnosed before age 50.

METHODS

We prospectively examined the association between total vitamin D intake and risks of early-onset CRC and precursors among women enrolled in the Nurses' Health Study II. Multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for early-onset CRC were estimated with Cox proportional hazards model. Multivariable-adjusted odds ratios (ORs) and 95% CIs for early-onset conventional adenoma and serrated polyp were estimated with logistic regression model.

RESULTS

We documented 111 incident cases of early-onset CRC during 1,250,560 person-years of follow-up (1991 to 2015). Higher total vitamin D intake was significantly associated with a reduced risk of early-onset CRC (HR for ≥450 IU/day vs <300 IU/day, 0.49; 95% CI, 0.26-0.93; P for trend = .01). The HR per 400 IU/day increase was 0.46 (95% CI, 0.26-0.83). The inverse association was significant and appeared more evident for dietary sources of vitamin D (HR per 400 IU/day increase, 0.34; 95% CI, 0.15-0.79) than supplemental vitamin D (HR per 400 IU/day increase, 0.77; 95% CI, 0.37-1.62). For CRC precursors, the ORs per 400 IU/day increase were 0.76 (95% CI, 0.65-0.88) for conventional adenoma (n = 1,439) and 0.85 (95% CI, 0.75-0.97) for serrated polyp (n = 1,878).

CONCLUSIONS

In a cohort of younger women, higher total vitamin D intake was associated with decreased risks of early-onset CRC and precursors.

Usefulness of the Japan narrow-band imaging expert team classification system for the diagnosis of sessile serrated lesion with dysplasia/carcinoma

BACKGROUND

Sessile serrated lesion (SSL) is a colorectal polyp that has malignant potential. However, the dysplastic components within an SSL can be difficult to diagnose with conventional endoscopy, because most SSLs with dysplasia/carcinoma have subtle mucosal features. Many studies have indicated that narrow-band imaging (NBI) observations of colorectal polyps are very useful, accurate predictors of histology. We aimed to verify the usefulness of the Japan NBI Expert Team (JNET) classification system for the diagnosis of SSLs with dysplasia/carcinoma.

METHODS

We examined 709 endoscopically or surgically resected lesions that were pathologically diagnosed as SSL, including 647 with no dysplasia, 37 with low-grade dysplasia, 15 with high-grade dysplasia, and 10 with submucosal invasive carcinoma. We retrospectively evaluated their clinicopathologic characteristics and conventional endoscopic and magnifying NBI endoscopic findings using the JNET system.

RESULTS

Cases in all groups were more frequently located in the proximal colon. Submucosal invasive carcinomas were significantly larger than no dysplasia and low-grade dysplasia lesions. Almost all studied lesions (96.3%) were covered with a mucus cap. Five hundred and eighty (81.8%) lesions exhibited dark spots inside the crypts, which are NBI findings' characteristic of SSL. As for the JNET classification of magnifying NBI endoscopic findings, all 709 lesions showed Type 1. Six hundred and eighteen (95.5%) SSLs with no dysplasia lesions exhibited Type 1 only, whereas 52 (83.9%) SSLs with dysplasia/carcinoma had a combination of Type 1 and Type 2A, 2B, or 3, corresponding to SSL and dysplasia/carcinoma, respectively. The JNET classification had high sensitivity (83.9%), specificity (95.5%), and overall diagnostic accuracy (94.5%) for diagnosing SSLs with dysplasia/carcinoma.

CONCLUSIONS

Use of magnifying NBI endoscopy with the JNET classification might be useful for diagnosing SSLs with dysplasia/carcinoma. This increased awareness may also improve the recognition of SSLs with dysplasia/carcinoma.

The prognostic and predictive impact of BRAF mutations in deficient mismatch repair/microsatellite instability-high colorectal cancer: systematic review/meta-analysis

Aims: The authors present a systematic review/meta-analysis of the impact of BRAF mutations on prognosis and immune checkpoint inhibitor (ICI) response in deficient mismatch repair/microsatellite instability-high colorectal cancer. Methods: Hazard ratios for overall survival and odds ratios for objective response rate to ICIs were calculated in BRAF-mutated versus BRAF wild-type patients. Results: After screening, nine and three studies, respectively, were included for analysis of prognosis (analysis A) and ICI response (analysis B). Analysis A showed worse overall survival in BRAF-mutated compared with BRAF wild-type stage I-IV patients (hazard ratio: 1.57; 95% CI: 1.23-1.99), and analysis B showed no difference in objective response rate (odds ratio: 1.04; 95% CI: 0.48-2.25). Conclusion: BRAF mutations are associated with worse overall survival but not differential response to ICIs in deficient mismatch repair/microsatellite instability-high colorectal cancer.

Cancer Genomic Profiling in Colorectal Cancer: Current Challenges in Subtyping Colorectal Cancers Based on Somatic and Germline Variants

Colorectal cancer (CRC) is a heterogeneous disease caused by the accumulation of multistep genetic alterations under the influence of genomic instability. Different backgrounds of genomic instability, such as chromosomal instability, microsatellite instability, hypermutated-single nucleotide variants, and genome stable-induced transformation in the colonic epithelium, can result in adenomas, adenocarcinomas, and metastatic tumors. Characterization of molecular subtypes and establishment of treatment policies based on each subtype will lead to better treatment outcomes and an improved selection of molecularly targeted agents. In Japan, cancer precision medicine has been introduced in the National Health Insurance program through the addition of the cancer genomic profiling (CGP) examination. It has also become possible to access a large amount of genomic information, including information on pathogenic somatic and germline variants, incomparable to conventional diagnostic tests. This information enables us to apply research data to clinical decision-making, benefiting patients and their healthy family members. In this article, we discuss the important molecules and signaling pathways presumed to be the driver genes of CRC progression and the signal transduction system in which they are involved. Molecular subtypes of CRC based on CGP examinations and gene expression profiles have been established in The Cancer Genome Atlas Network with the advent of next-generation sequencing technology. We will also discuss the recommended management of secondary/germline findings, pathogenic germline variants, and presumed germline pathogenic variants obtained from CGP examination and review the current challenges to better understand these data in a new era of cancer genomic medicine.

Beyond Colonoscopy: Exploring New Cell Surface Biomarkers for Detection of Early, Heterogenous Colorectal Lesions

Colorectal cancer (CRC) is the third leading cause of cancer-related deaths among both men and women in the United States. Early detection and surgical removal of high-risk lesions in the colon can prevent disease from developing and spreading. Despite implementation of programs aimed at early detection, screening colonoscopies fail to detect a fraction of potentially aggressive colorectal lesions because of their location or nonobvious morphology. Optical colonoscopies, while highly effective, rely on direct visualization to detect changes on the surface mucosa that are consistent with dysplasia. Recent advances in endoscopy techniques and molecular imaging permit microscale visualization of the colonic mucosa. These technologies can be combined with various molecular probes that recognize and target heterogenous lesion surfaces to achieve early, real-time, and potentially non-invasive, detection of pre-cancerous lesions. The primary goal of this review is to contextualize existing and emergent CRC surface biomarkers and assess each’s potential as a candidate marker for early marker-based detection of CRC lesions. CRC markers that we include were stratified by the level of support gleaned from peer-reviewed publications, abstracts, and databases of both CRC and other cancers. The selected biomarkers, accessible on the cell surface and preferably on the luminal surface of the colon tissue, are organized into three categories: (1) established biomarkers (those with considerable data and high confidence), (2) emerging biomarkers (those with increasing research interest but with less supporting data), and (3) novel candidates (those with very recent data, and/or supportive evidence from other tissue systems). We also present an overview of recent advances in imaging techniques useful for visual detection of surface biomarkers, and discuss the ease with which these methods can be combined with microscopic visualization.

Expression of Parkin, APC, APE1, and Bcl-xL in Colorectal Polyps

Colorectal cancer can develop through molecular, chromosomal, and epigenetic cumulative changes that transform the normal intestinal epithelium into the colorectal polyps, called conventional adenomas (CAs) or serrated polyps (SPs), recognized as precursors of invasive colorectal neoplasia. These benign lesions need to explore the morphology, histological diagnosis, and biomarkers profile to accurately characterize lesions with potential for evolution to cancer. This study aimed to correlate the immunohistochemical expression of Parkin and Adenomatous Polyposis Coli (APC; tumor suppressors), Human Apurinic/Apyrimidinic endonuclease 1 (APE1), and B-cell lymphoma-extra-large (Bcl-xL; oncogenic proteins) in sporadic colorectal polyps with clinical, endoscopic, and diagnostic data. Immunohistochemical analysis was performed on tissue microarray samples of 306 polyps. Based on the Allred score, the expressions were graduated in the cytoplasm and nucleus of superficial and cryptic cells. There was higher Parkin nuclear expression (p=0.006 and 0.010) and APC cytoplasmic expression in cryptic cells (p<0.001) in SPs. CAs, APE1 (p<0.001) and Bcl-xL (p<0.001) were more expressed in the nuclei and cytoplasms, respectively. These results are related to the biological role proposed for these proteins in cellular functions. They can contribute to the diagnosis criteria for polyps and improve the knowledge of biomarkers that could predict cancer development.

Application of Next Generation Quality/Statistical Process Control and Expert-Led Case Review to Increase the Consistency of Diagnostic Rates in Precancerous Colorectal Polyps

BACKGROUND

Prior work suggests high interrater variability in the pathologist diagnostic rate (PDR) of the precancerous polyp sessile serrated adenoma (SSA).

OBJECTIVES

To improve the diagnostic consistency in the pathological evaluation of colorectal polyp specimens with diagnostic rate awareness, using funnel plots (FPs)/control charts (CCs), and a focused group case review.

METHODS

All colorectal polyp specimen (CRPS) reports September 2015 to August 2017 were analyzed at one institution. PDRs were extracted using a hierarchical free-text string matching algorithm and visualized using FPs, showing pathologist specimen volume versus PDR, and CCs, showing pathologist versus normed PDR. The FPs/CCs were centered on the group median diagnostic rate (GMDR). Pathologists were shown their baseline SSA diagnostic rate in relation to the practice, and in January 2017, there was a focused group case review/open discussion of approximately 40 sequential cases signed as SSA with a gastrointestinal pathology expert.

RESULTS

Nine pathologists interpreted more than 250 CRPSs per year. FPs/CCs for the first and second years showed 6/4 and 3/1 P < .05/P < .001 pathologist outliers, respectively, in relation to the GMDR for SSA and 0/0 and 0/0 P < .05/P < .001 pathologist outliers, respectively, in relation to the GMDR for tubular adenoma (TA). An in silico kappa (ISK) for SSA improved from 0.52 to 0.62.

CONCLUSION

Diagnostic rate awareness facilitated by FPs/CCs coupled with focused expert-led reviews may help calibrate PDR. Variation in SSA PDRs still remains high in relation to TA. ISK represents an intuitive, useful metric and Next Generation Quality/Statistical Process Control a promising approach for objectively increasing diagnostic consistency.

Serrated polyps of the colon and rectum: a concise review

"Serrated polyps" is the term used for epithelial lesions of the colon and rectum that have a "sawtooth" pattern on the polyp's surface and crypt epithelium. The so-called serrated pathway describes the progression of sessile serrated adenomas and traditional serrated adenomas to colorectal cancer. Said pathway is well recognized as an alternative mechanism of carcinogenesis and accounts for 15-30% of the cases of colorectal cancer. It also explains a large number of the cases of interval colorectal cancer. Thus, due to their usually aggressive and uncertain behavior, serrated polyps are of the utmost importance in colorectal cancer screening. Our aim was to review the history, current nomenclature, pathophysiology, morphology, treatment, and surveillance of serrated polyps.

Oncogenic BRAF, unrestrained by TGFβ-receptor signalling, drives right-sided colonic tumorigenesis

Right-sided (proximal) colorectal cancer (CRC) has a poor prognosis and a distinct mutational profile, characterized by oncogenic BRAF mutations and aberrations in mismatch repair and TGFβ signalling. Here, we describe a mouse model of right-sided colon cancer driven by oncogenic BRAF and loss of epithelial TGFβ-receptor signalling. The proximal colonic tumours that develop in this model exhibit a foetal-like progenitor phenotype (Ly6a/Sca1⁺) and, importantly, lack expression of Lgr5 and its associated intestinal stem cell signature. These features are recapitulated in human BRAF-mutant, right-sided CRCs and represent fundamental differences between left- and right-sided disease. Microbial-driven inflammation supports the initiation and progression of these tumours with foetal-like characteristics, consistent with their predilection for the microbe-rich right colon and their antibiotic sensitivity. While MAPK-pathway activating mutations drive this foetal-like signature via ERK-dependent activation of the transcriptional coactivator YAP, the same foetal-like transcriptional programs are also initiated by inflammation in a MAPK-independent manner. Importantly, in both contexts, epithelial TGFβ-receptor signalling is instrumental in suppressing the tumorigenic potential of these foetal-like progenitor cells.

Oncogenic BRAF, unrestrained by TGFβ-receptor signalling, drives right-sided colonic tumorigenesis

Right-sided (proximal) colorectal cancer (CRC) has a poor prognosis and a distinct mutational profile, characterized by oncogenic BRAF mutations and aberrations in mismatch repair and TGFβ signalling. Here, we describe a mouse model of right-sided colon cancer driven by oncogenic BRAF and loss of epithelial TGFβ-receptor signalling. The proximal colonic tumours that develop in this model exhibit a foetal-like progenitor phenotype (Ly6a/Sca1+) and, importantly, lack expression of Lgr5 and its associated intestinal stem cell signature. These features are recapitulated in human BRAF-mutant, right-sided CRCs and represent fundamental differences between left- and right-sided disease. Microbial-driven inflammation supports the initiation and progression of these tumours with foetal-like characteristics, consistent with their predilection for the microbe-rich right colon and their antibiotic sensitivity. While MAPK-pathway activating mutations drive this foetal-like signature via ERK-dependent activation of the transcriptional coactivator YAP, the same foetal-like transcriptional programs are also initiated by inflammation in a MAPK-independent manner. Importantly, in both contexts, epithelial TGFβ-receptor signalling is instrumental in suppressing the tumorigenic potential of these foetal-like progenitor cells.

Prevalence and risk factors for sessile serrated lesions in an average risk colorectal cancer screening population

BACKGROUND AND AIM

The reported prevalence and risk factors for sessile serrated lesions (SSLs) show significant variation. We aimed to specifically study the prevalence and potential risk factors of SSLs in an average risk colorectal cancer (CRC) screening population of Chinese subjects.

METHODS

This is a case-control study of prospectively collected data from a territory-wide colorectal screening program in Hong Kong. Information on risk factors was obtained from questionnaires completed prior to screening colonoscopy. We compared subjects with SSLs against controls without these lesions to identify potential risk factors using multivariable logistic regression.

RESULTS

Of 12 039 asymptomatic screening subjects, 6011 subjects received a screening colonoscopy with 2214 subjects (36.8%) having conventional adenomas, 486 subjects (8.1%) having hyperplastic polyps, and 85 subjects (1.4%) having SSLs only. Of these subjects, three had synchronous advanced adenomas and were excluded from the analysis. More than 60% of these lesions were in the proximal colon. We compared these 82 subjects with SSLs only and 3226 controls without any polyps. After multivariable logistic regression, age ≥ 66 years, smoking, and diabetes mellitus (DM) were significant independent risk factors for SSLs.

CONCLUSION

In this study, we report the prevalence of SSLs to be 1.4%. Age ≥ 66 years, smoking, and DM were independent risk factors for these lesions. Our findings provide relevant new data that should be taken into consideration when designing region-specific surveillance programs for SSLs with the ultimate goal of reducing the risk of CRC.

Aspirin reduces the incidence of metastasis in a pre-clinical study of Braf mutant serrated colorectal neoplasia

BACKGROUND

Aspirin reduces the incidence of conventional adenomas driven by APC mutation and thus colorectal cancer. The effect of aspirin on the ~20% of colorectal cancers arising via BRAF mutation is yet to be established.

METHODS

Braf^V637E/+;Villin-Cre^ERT2/+ mice were allocated to a control (n = 86) or aspirin-supplemented (n = 83) diet. After 14 months the incidence of murine serrated lesions, carcinoma and distant metastases were measured by histological examination. RNA was extracted from carcinomas from each cohort and subjected to sequencing to identify differentially expressed genes and molecular pathways.

RESULTS

Aspirin did not reduce the incidence of murine serrated lesions or carcinoma when compared to control, however, did significantly reduce lesion size (P = 0.0042). Among the mice with carcinoma there was a significant reduction in the incidence of distant metastasis with aspirin treatment (RR 0.69, 95% CI 0.48-0.90, P = 0.0134). Key pathways underlying metastasis of carcinoma cells include NOTCH, FGFR and PI3K signalling, were significantly downregulated in carcinomas sampled from mice on an aspirin-supplemented diet.

CONCLUSIONS

Aspirin reduces the incidence of metastatic Braf mutant carcinoma, although this is not due to a reduction in primary disease. The reduction in metastasis could be attributed to a delay or prevention of molecular changes within the primary site driving metastatic growth.

Genetic engineering in organoids

Three-dimensional organoids have been widely used for developmental and disease modeling. Organoids are derived from both adult and pluripotent stem cells. Various types are available for mimicking almost all major organs and tissues in the mouse and human. While culture protocols for stepwise differentiation and long-term expansion are well established, methods for genetic manipulation in organoids still need further standardization. In this review, we summarized different methods for organoid genetics and provide the pros and cons of each method for designing an optimal strategy.

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.