Clinical and Biological Features of Interval Colorectal Cancer

Serrated colorectal cancer: preclinical models and molecular pathways

Serrated lesions are histologically heterogeneous, and detection can be challenging as these lesions have subtle features that may be missed by endoscopy. Furthermore, while approximately 30% of colorectal cancers (CRCs) arise from serrated lesions, only 8-10% of invasive serrated CRCs exhibit serrated morphology at presentation, suggesting potential loss of apparent characteristics with increased malignancy. Thus, understanding the genetic basis driving serrated CRC initiation and progression is critical to improve diagnosis and identify therapeutic biomarkers and targets to guide disease management. This review discusses the preclinical models of serrated CRCs reported to date and how these systems have been used to provide mechanistic insights into tumor initiation, progression, and novel treatment targets.

Improved use of faecal immunochemical tests for haemoglobin in the Scottish bowel screening programme

OBJECTIVES

This study aimed to develop a risk-scoring model in the Scottish Bowel Screening Programme incorporating faecal haemoglobin concentration with other risk factors for colorectal cancer.

METHODS

Data were collected for all individuals invited to participate in the Scottish Bowel Screening Programme between November 2017 and March 2018 including faecal haemoglobin concentration, age, sex, National Health Service Board, socioeconomic status, and screening history. Linkage with The Scottish Cancer Registry identified all screening participants diagnosed with colorectal cancer. Logistic regression was performed to identify which factors demonstrated significant association with colorectal cancer and could be used in the development of a risk-scoring model.

RESULTS

Of 232,076 screening participants, 427 had colorectal cancer: 286 diagnosed following a screening colonoscopy and 141 arising after a negative screening test result giving an interval cancer proportion of 33.0%. Only faecal haemoglobin concentration and age showed a statistically significant association with colorectal cancer. Interval cancer proportion increased with age and was higher in women (38.1%) than men (27.5%). If positivity in women were mirrored in men at each age quintile interval cancer proportion would still have remained higher in women (33.2%). Moreover, an additional 1201 colonoscopies would be required to detect 11 colorectal cancers.

CONCLUSIONS

Development of a risk scoring model using early data from the Scottish Bowel Screening Programme was not feasible due to most variables showing insignificant association with colorectal cancer. Tailoring the faecal haemoglobin concentration threshold according to age could help to diminish some of the disparity in interval cancer proportion between women and men. Strategies to achieve sex equality using faecal haemoglobin concentration thresholds depend considerably on which variable is selected for equivalency and this requires further exploration.

Postcolonoscopy Colorectal Cancer in a Referral Center for Colorectal Cancer: Prevalence and Risk Factors

Background and Aims

Colonoscopy is effective to detect and remove colorectal lesions. However, after a negative colonoscopy, cancers could be detected during the interval follow-up. This study was designed to identify characteristics and risk factors for postcolonoscopy colorectal cancer - interval type.

Methods

Medical records of individuals who were newly diagnosed with colorectal cancer between January 2018 and December 2019 were reviewed. Clinical, demographic, and endoscopic variables were analyzed. Those with the diagnosis of colorectal cancer between two consecutive colonoscopies performed within the appropriated surveillance range were considered to have postcolonoscopy colorectal cancer - interval type. A comparison between the group of patients with non-postcolonoscopy colorectal cancer - interval type and the group of patients with postcolonoscopy colorectal cancer - interval type was then performed.

Results

During the study period, 491 patients were newly diagnosed with colorectal cancer. Among them, 61 (12.4%) had postcolonoscopy colorectal cancer - interval subtype. Postcolonoscopy colorectal cancer - interval type was three times more prevalent on the proximal colon (p = 0.014) and was associated with the presence of two or more cardiovascular risk factors (aOR = 4.25; p = 0.016), cholecystectomy in the past (aOR = 10.09; p = 0.019), and family history of colorectal cancer on a first-degree relative (aOR = 4.25; p = 0.006). Moreover, isolated cardiovascular risk factors revealed a protective effect for the absence of all cardiovascular risk factors (aOR = 20; p = 0.034). The ROC curve associated with the multivariate model revealed a predictive power of 77.8% (p < 0.001).

Conclusions

Postcolonoscopy colorectal cancer - interval type is more common in the proximal colon and in patients with a family history (first-degree relative) of colorectal cancer, two or more cardiovascular risk factors, and a history of cholecystectomy. All of these are easily detectable in clinical practice and may be of extreme importance in the control of postcolonoscopy colorectal cancer in the near future.

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.

Single-cell Transcriptomics Reveals Early Molecular and Immune Alterations Underlying the Serrated Neoplasia Pathway Toward Colorectal Cancer

BACKGROUND & AIMS

Approximately one-third of colorectal cancers develop from serrated lesions (SLs), including hyperplastic polyp (HP), sessile serrated lesion (SSL), traditional serrated adenoma (TSA), and SSL with dysplasia (SSLD) through the serrated neoplasia pathway, which progresses faster than the conventional adenoma-carcinoma pathway. We sought to depict the currently unclarified molecular and immune alterations by the single-cell landscape in SLs.

METHODS

We performed single-cell RNA sequencing of 16 SLs (including 4 proximal HPs, 5 SSLs, 2 SSLDs, and 5 TSAs) vs 3 normal colonic tissues.

RESULTS

A total of 60,568 high-quality cells were obtained. Two distinct epithelial clusters with redox imbalance in SLs were observed, along with upregulation of tumor-promoting SerpinB6 that regulated ROS level. Epithelial clusters of SSL and TSA showed distinct molecular features: SSL-specific epithelium manifested overexpressed proliferative markers with Notch pathway activation, whereas TSA-specific epithelium showed Paneth cell metaplasia with aberrant lysozyme expression. As for immune contexture, enhanced cytotoxic activity of CD8⁺ T cells was observed in SLs; it was mainly attributable to increased proportion of CD103⁺CD8⁺ tissue-resident memory T cells, which might be regulated by retinoic acid metabolism. Microenvironment of SLs was generally immune-activated, whereas some immunosuppressive cells (regulatory T cells, anti-inflammatory macrophages, MDK⁺IgA⁺ plasma cells, MMP11-secreting PDGFRA⁺ fibroblasts) also emerged at early stage and further accumulated in SSLD.

CONCLUSION

Epithelial, immune, and stromal components in the serrated pathway undergo fundamental alterations. Future molecular subtypes of SLs and potential immune therapy might be developed.

Patient attitudes towards changes in colorectal cancer surveillance: An application of the Health Belief Model

OBJECTIVE

This is to determine whether health beliefs regarding colorectal cancer (CRC) screening could predict discomfort with a change to CRC surveillance proposing regular faecal immunochemical tests (FIT) instead of colonoscopy.

METHODS

Eight hundred individuals enrolled in a South Australian colonoscopy surveillance programme were invited to complete a survey on surveillance preferences. Responses were analysed using binary logistic regression predicting discomfort with a hypothetical FIT-based surveillance change. Predictor variables included constructs based on the Health Belief Model: perceived threat of CRC, perceived confidence to complete FIT and colonoscopy (self-efficacy), perceived benefits from current surveillance and perceived barriers to FIT and colonoscopy.

RESULTS

A total of 408 participants (51%) returned the survey (complete data n = 303; mean age 62 years, 52% male). Most participants (72%) were uncomfortable with FIT-based surveillance reducing colonoscopy frequency. This attitude was predicted by a higher perceived threat of CRC (OR = 1.03 [95% CI 1.01-1.04]), higher colonoscopy self-efficacy (OR = 1.34 [95% CI 1.13-1.59]) and lower perceived barriers to colonoscopy (OR = 0.92 [95% CI 0.86-0.99]).

CONCLUSIONS

Health beliefs regarding colonoscopy and perceived threat of CRC may be important to consider when changing CRC surveillance protocols. If guideline changes were introduced, these factors should be addressed to provide patients reassurance concerning the efficacy of the alternative protocol.

Most large colorectal polyps missed by gastroenterology fellows at colonoscopy are sessile serrated lesions

Background and study aims  Data on adenoma and sessile serrated lesion (SSL) miss rates for gastroenterology fellows during colonoscopy are limited. We aimed to describe the miss rate of fellows based on a second examination by a colonoscopist with a high rate of detection. Patients and methods  Second- and third-year gastroenterology fellows at a single, tertiary center performed initial examinations. A single experienced attending doctor then performed a complete examination of the colon. We recorded the size and pathology of all lesions found at both examinations and calculated the adenoma and SSL miss rates for fellows. Results  Ten trainees performed 100 examinations. Miss rates for conventional adenomas and SSLs were 30.5 % and 85.7 %, respectively. Among pre-cancerous polyps ≥ 10 mm, 10 of 14 lesions missed were SSLs. Conclusions  While conventional adenoma detection skills of gastroenterology fellows are acceptable, SSL detection is poor.

Weakly Supervised Polyp Segmentation in Colonoscopy Images Using Deep Neural Networks

Colorectal cancer (CRC) is a leading cause of mortality worldwide, and preventive screening modalities such as colonoscopy have been shown to noticeably decrease CRC incidence and mortality. Improving colonoscopy quality remains a challenging task due to limiting factors including the training levels of colonoscopists and the variability in polyp sizes, morphologies, and locations. Deep learning methods have led to state-of-the-art systems for the identification of polyps in colonoscopy videos. In this study, we show that deep learning can also be applied to the segmentation of polyps in real time, and the underlying models can be trained using mostly weakly labeled data, in the form of bounding box annotations that do not contain precise contour information. A novel dataset, Polyp-Box-Seg of 4070 colonoscopy images with polyps from over 2000 patients, is collected, and a subset of 1300 images is manually annotated with segmentation masks. A series of models is trained to evaluate various strategies that utilize bounding box annotations for segmentation tasks. A model trained on the 1300 polyp images with segmentation masks achieves a dice coefficient of 81.52%, which improves significantly to 85.53% when using a weakly supervised strategy leveraging bounding box images. The Polyp-Box-Seg dataset, together with a real-time video demonstration of the segmentation system, are publicly available.

ERBB2 Mutations as Potential Predictors for Recurrence in Colorectal Serrated Polyps by Targeted Next-Generation Sequencing

Background

Follow-up guidelines for serrated polyps (SPs) are mainly based on factors such as histology and size with limited evidence. The underlying genomic mechanism of SPs in relation to recurrence risks is utterly unknown.

Methods

We applied targeted next-generation sequencing (NGS) approach on two groups of SPs [polyp-relapsed SPs (PRSPs) vs. polyp-free SPs (PFSPs)] based on the surveillance outcomes to compare differences of DNA variants in 71 colorectal cancer-associated genes. A multicenter validation cohort was established longitudinally from 2016 to 2019 to confirm the relevant results.

Results

Among the 96 NGS samples, at least one mutant after filtration was detected in 90 samples (94%). Molecular profiling presented BRAF, KRAS, and APC as top 3 mutated genes. FBXW7, MSH2, and ERBB2 might be recurrence-relevant, while DMD, BRCA1, and BRCA2 might be negatively correlated with recurrence. Notably, ERBB2 mutants (R678Q and V842I) (n = 5) had higher risks of polyp recurrence than the wild types (n = 85), with a median polyp-free interval of 15 months compared to 26 months [P &lt; 0.001; hazard ratio (HR) = 4.9; 95% confidence interval (CI) = 1.9–12.8]. Furthermore, a multicenter cohort composed by 321 SPs verified that ERBB2-mutated SPs had increased risks of polyp recurrence (P &lt; 0.001; HR = 3.7; 95% CI = 2.3–6.0) and advanced neoplastic lesion (ANL) recurrence (P &lt; 0.001; HR = 10.0; 95% CI = 2.7–36.9) compared with wild-type SPs, respectively.

Conclusions

Our results are emphasizing that SP individuals with ERBB2 mutants are at higher risks of subsequent colorectal neoplasms. ERBB2 mutants might work as facilitated markers for prediction of high-risk SPs and might implicate a potential mechanism in the serrated pathway to colorectal carcinoma (CRC).

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

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

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

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

Detecting Deficient Coverage in Colonoscopies

Colonoscopy is tool of choice for preventing Colorectal Cancer, by detecting and removing polyps before they become cancerous. However, colonoscopy is hampered by the fact that endoscopists routinely miss 22-28% of polyps. While some of these missed polyps appear in the endoscopist's field of view, others are missed simply because of substandard coverage of the procedure, i.e. not all of the colon is seen. This paper attempts to rectify the problem of substandard coverage in colonoscopy through the introduction of the C2D2 (Colonoscopy Coverage Deficiency via Depth) algorithm which detects deficient coverage, and can thereby alert the endoscopist to revisit a given area. More specifically, C2D2 consists of two separate algorithms: the first performs depth estimation of the colon given an ordinary RGB video stream; while the second computes coverage given these depth estimates. Rather than compute coverage for the entire colon, our algorithm computes coverage locally, on a segment-by-segment basis; C2D2 can then indicate in real-time whether a particular area of the colon has suffered from deficient coverage, and if so the endoscopist can return to that area. Our coverage algorithm is the first such algorithm to be evaluated in a large-scale way; while our depth estimation technique is the first calibration-free unsupervised method applied to colonoscopies. The C2D2 algorithm achieves state of the art results in the detection of deficient coverage. On synthetic sequences with ground truth, it is 2.4 times more accurate than human experts; while on real sequences, C2D2 achieves a 93.0% agreement with experts.

Relationship between serrated polyps and synchronous and metachronous advanced neoplasia: A retrospective study

OBJECTIVE

Serrated polyps (SP) are regarded as precursor lesions of colorectal cancer (CRC). We conducted this single-center study aiming to investigate the relationship between SP and synchronous and metachronous advanced neoplasia in the Chinese population.

METHODS

The data for this retrospective study were collected from the Endoscopy Center and Department of Gastroenterology of Renji Hospital, School of Medicine, Shanghai Jiao Tong University between May 2012 and May 2019. Altogether 2205 patients were pathologically confirmed with colorectal SP.

RESULTS

The detection rate of SP among all polyps has gradually increased since 2014 and reached 8.74% by 2019. Among all the SP cases, 1540 (69.84%) were confirmed as having hyperplasic polyps (HP), 486 (22.04%) were having sessile serrated lesions (SSL), and 171 (7.76%) had traditional serrated adenomas (TSA). Compared with HP (2.14%), SSL and TSA were larger and more likely to be accompanied by synchronous and metachronous advanced neoplasia (6.79% and 6.08%). We next found that large SP (diameter ≥10 mm) (odds ratio [OR] 2.52, 95% confidence interval [CI] 1.40-4.55, P = 0.002) and SSL with high-grade intraepithelial neoplasia (OR 13.85, 95% CI 3.28-58.56, P < 0.001) were associated with an increased risk of synchronous advanced neoplasia. However, we failed to find a relationship between SP and metachronous advanced neoplasia because few patients had developed metachronous advanced neoplasia.

CONCLUSION

Large SP and SSL with high-grade intraepithelial neoplasia are associated with synchronous advanced neoplasia and require timely surveillance.

Association between improved adenoma detection rates and interval colorectal cancer rates after a quality improvement program

BACKGROUND AND AIMS

Although colonoscopy reduces colorectal cancer (CRC) risk, interval CRCs (iCRCs) still occur. We aimed to determine iCRC incidence, assess the relationship between adenoma detection rates (ADRs) and iCRC rates, and evaluate iCRC rates over time concomitant with initiation of an institutional colonoscopy quality improvement (QI) program.

METHODS

We performed a retrospective cohort study of patients who underwent colonoscopy at an academic medical center (January 2003 to December 2015). We identified iCRCs through our data warehouse and reviewed charts to confirm appropriateness for study inclusion. iCRC was defined as a cancer diagnosed 6 to 60 months and early iCRC as a cancer diagnosed 6 to 36 months after index colonoscopy. We measured the relationship between provider ADRs and iCRC rates and assessed iCRC rates over time with initiation of a QI program that started in 2010.

RESULTS

A total of 193,939 colonoscopies were performed over the study period. We identified 186 patients with iCRC. The overall iCRC rate was .12% and the early iCRC rate .06%. Average-risk patients undergoing colonoscopy by endoscopists in the highest ADR quartile (34%-52%) had a 4-fold lower iCRC risk (relative risk, .23; 95% confidence interval, .11-.48) than those undergoing colonoscopy by endoscopists in the lowest quartile (12%-21%). After QI program initiation, overall iCRC rates improved from .15% to .08% (P < .001) and early iCRC rates improved from .07% to .04% (P = .004).

CONCLUSIONS

We confirmed that iCRC rate is inversely correlated with provider ADR. ADRs increased and iCRC rates decreased over time, concomitant with a QI program focused on split-dose bowel preparation, quality metric measurement, provider education, and feedback. iCRC rate measurement should be considered a feasible, outcomes-driven institutional metric of colonoscopy quality.

Implementing visual cues to improve the efficacy of screening colonoscopy: exploiting the Hawthorne effect

Background:

Colonoscopy is the gold standard for colon cancer screening. Adenoma detection rate and a withdrawal time of 6 min are quality metrics to measure the efficacy of colonoscopy in colon cancer screening. The aim of our study was to exploit the Hawthorne effect in an effort to ensure adherence to a minimum 6-min withdrawal time and subsequently increase adenoma detection rate.

Methods:

This was a retrospective single-center study where we reviewed the records of patients who underwent screening colonoscopy in 2015 and 2017. We divided our patient population into 2 groups. The first group of patients from 2015 underwent screening colonoscopy with no visual cues on the colonoscopy monitor. The second group of patients from 2017 had visual cues indicating withdrawal time on the colonoscopy monitor.

Results:

Screening colonoscopy had a statistically significantly higher adenoma detection rate when performed with visual cues compared to without visual cues (25.3% vs. 19.45, P=0.04). Polyp detection rate was also higher in the group where visual cueing was used (52.9% vs. 22.9%, P<0.001). There were no statistically significant differences in actual withdrawal time or cecal intubation rates.

Conclusions:

Visual cues indicating withdrawal time are a useful intervention that results in an increased adenoma detection rate. Given its practicality and cost effectiveness, we recommend universally implementing visual cues to ensure adherence to a minimum 6-min withdrawal time.

Prevalence of 'one and done' in adenoma detection rates: results from the New Hampshire Colonoscopy Registry

Background and study aims  Adenoma detection rate (ADR), the proportion of an endoscopist's screening colonoscopies in which at least one adenoma is found, is an established quality metric. Several publications have suggested that a technique referred to as "one and done," where less attention is paid to additional polyp detection following discovery of one likely adenoma, may be occurring 1 2 3 . To investigate whether this practice occurs and provide additional context to the significance of ADR, we examined ADR by single and multiple adenomas in the statewide New Hampshire Colonoscopy Registry (NHCR). Patients and methods  A total of 25,324 NHCR patients receiving screening colonoscopies between 2009 and 2014 by 69 endoscopists were analyzed. ADR was dichotomized into high (≥ 20 %) and low (< 20 %) based on 2006 recommended targets in place during the time of the study. ADR-plus (the average number of adenomas in colonoscopies with > 1 adenoma) was dichotomized at mean values into high (≥ 1.5) and low (< 1.5). As suggested by others, a high ADR but low ADR-plus was used to indicate the "one and done" approach. Results  Among endoscopists with an ADR ≥ 20 %, only 5 (7.2 %) had low ADR-plus values and were classified as "one and done." Results for serrated polyp detection were similar. ADR and ADR-plus decreased monotonically with increasing years since residency ( P values for trend ADR = 0.02; ADR-plus = 0.003) after adjusting for patient risk factors. Conclusion  "One and done" infrequently occurred among endoscopists with high ADR in a large statewide registry. The need to replace ADR with other polyp detection metrics (such as ADR-plus) to accurately ascertain performance quality is not supported by these findings.

Serrated Colorectal Cancer: The Road Less Travelled?

Studies of colorectal cancer (CRC) originating through the conventional adenoma-carcinoma sequence have provided insight into the molecular mechanisms controlling its initiation and progression. Less is known about the alternative 'serrated' pathway, which has been associated with BRAF mutation and microsatellite instability. Recent transcriptomics approaches to classify human CRC revealed that mesenchymal and/or desmoplastic features combined with an immunosuppressive microenvironment are key determinants of CRC with the poorest prognosis. Importantly, these aggressive CRCs harbor the characteristics of serrated tumors, suggesting that initiation through this alternative pathway determines how aggressive the CRC becomes. Here, we review recent evidence on how serrated carcinogenesis contributes to the subtype of CRC with the poorest prognosis.

DNA methylation changes that precede onset of dysplasia in advanced sessile serrated adenomas

Background

Sessile serrated adenomas (SSAs) are common polyps which give rise to 20–30% of colorectal cancer (CRC). SSAs display clinicopathologic features which present challenges in surveillance, including overrepresentation in young patients, proclivity for the proximal colon and rarity of histologic dysplasia (referred to then as SSAs with dysplasia, SSADs). Once dysplasia develops, there is rapid progression to CRC, even at a small size. There is therefore a clinical need to separate the “advanced” SSAs at high risk of progression to SSAD and cancer from ordinary SSAs. Since SSAs are known to accumulate methylation over time prior to the development of dysplasia, SSAD backgrounds (the remnant SSA present within an SSAD) likely harbour additional methylation events compared with ordinary SSAs. We therefore performed MethyLight and comprehensive methylation array (Illumina MethylationEPIC) on 40 SSAD backgrounds and 40 matched ordinary SSAs, and compared the methylation results with CRC methylation, CRC expression and immunohistochemical data.

Results

SSAD backgrounds demonstrated significant hypermethylation of CpG islands compared with ordinary SSAs, and the proportion of hypermethylated probes decreased progressively in the shore, shelf and open sea regions. Hypomethylation occurred in concert with hypermethylation, which showed a reverse pattern, increasing progressively away from the island regions. These methylation changes were also identified in BRAF-mutant hypermethylated CRCs. When compared with CRC expression data, SV2B, MLH1/EPM2AIP1, C16orf62, RCOR3, BAIAP3, OGDHL, HDHD3 and ATP1B2 demonstrated both promoter hypermethylation and decreased expression. Although SSAD backgrounds were histologically indistinguishable from ordinary SSAs, MLH1 methylation was detectable via MethyLight in 62.9% of SSAD backgrounds, and focal immunohistochemical MLH1 loss was seen in 52.5% of SSAD backgrounds.

Conclusions

Significant hyper- and hypomethylation events occur during SSA progression well before the development of histologically identifiable changes. Methylation is a heterogeneous process within individual SSAs, as typified by MLH1, where both MLH1 methylation and focal immunohistochemical MLH1 loss can be seen in the absence of dysplasia. This heterogeneity is likely a generalised phenomenon and should be taken into account in future methylation-based studies and the development of clinical methylation panels.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0691-4) contains supplementary material, which is available to authorized users.

Characteristics and consequences of missed gastric cancer: A multicentric cohort study

BACKGROUND

Missed gastric cancer (MGC) is poorly documented in Mediterranean populations.

AIMS

(1) To assess the rate, predictors and survival of MGC. (2) To compare MGC and non-MGC tumors.

METHODS

This is a retrospective-cohort study conducted at four centers. MGC was defined as cancer detected within three years after negative esophagogastroduodenoscopy. Gastric adenocarcinomas diagnosed between 2008-2015 were included. Patients with no follow-up were excluded.

RESULTS

During the study period 123,395 esophagogastroduodenoscopies were performed, with 1374 gastric cancers being diagnosed (1.1%). A total of 1289 gastric cancers were finally included. The overall rate of MGC was 4.7% (61/1289, 3.7-6%). A negative esophagogastroduodenoscopy in MGC patients was independently associated with PPI therapy (p < 0.001), previous Billroth II anastomosis (p = 0.002), and lack of alarm symptoms (p < 0.001). The most frequent location for MGC was the gastric body(52.4%). MGCs were smaller than non-MGCs (31 vs 41 mm, p = 0.047), more often flat or depressed (p = 0.003) and less likely to be encountered as advanced disease. Overall 2-year survival was similar between MGC (34.1%) and Non-MGC (35.3 %) (p = 0.59).

CONCLUSION

MGC accounted for nearly five percent of newly-diagnosed gastric adenocarcinomas. Overall survival was poor and not different between MGC and non-MGC.

Quality measures improving endoscopic screening of colorectal cancer: a review of the literature

INTRODUCTION

Colorectal cancer (CRC) is a major health-care problem all over the world and CRC screening is effective in reducing mortality and increasing the 5-year survival. Colonoscopy has a central role in CRC screening. It can be performed as a primary test, as a recall policy after a positive result of another screening test, and for surveillance. Since effectiveness of endoscopic screening depends on adequate detection and removal of colonic polyps, consistent quality measures, which are useful in enhancing the diagnostic yield of examination, are essential. Areas covered: The aim of this review is to analyze current evidence from literature supporting quality measures able to refine endoscopic screening of colorectal cancer. Expert commentary: Quality measures namely a) time slot allotted to colonoscopy, b) assessment of indication, c) bowel preparation, d) Cecal intubation, e) withdrawal time, f) adenoma detection rate, g) proper management of lesions (polypectomy technique, polyps retrieval rate and tattooing of resection sites), and h) adequate follow-up intervals play a key role in identifying malignant and at-risk lesions and improving the outcome of screening. Adherence to these quality measures is critical to maximize the effectiveness of CRC screening, as well as, a proper technique of colonoscopy and a quality report of the procedure. Among all recommended measures, adenoma detection rate is the most important and must be kept above the recommended quality threshold by all physicians practicing in the setting of screening.

CpG Island Methylation in Sessile Serrated Adenomas Increases With Age, Indicating Lower Risk of Malignancy in Young Patients

Among sessile serrated adenomas (SSAs) with identical histologic features, some never progress, whereas others become dysplastic and develop into invasive cancers. Development of the CpG island methylator phenotype is a feature of SSA progression; we examined the CIMP status of 448 SSAs and examined the association with patient clinical data. Overall, 190 SSAs were CpG island methylator phenotype-positive. CpG island methylator phenotype positivity was associated with older patient age (P < .001) and proximal polyp site (P < .001), but not with patient sex (P = .94) or polyp size (P = .34). These results might be used to improve SSA surveillance guidelines.

Rate of missed oesophageal cancer at routine endoscopy and survival outcomes: A multicentric cohort study

Background

Missed oesophageal cancer (MEC) at upper gastrointestinal endoscopy (UGE) is poorly documented.

Objective

The objectives of this study were: (1) to assess the rate, predictors and survival of MEC; (2) to compare MEC and non-MEC tumours.

Methods

This was a retrospective cohort study conducted at four tertiary centres. Oesophageal cancers (ECs) diagnosed between 2008 and 2015 were included. Patients with a premalignant condition (Barrett, achalasia), prior diagnosis of EC or oesophagogastric junction tumour of gastric origin were excluded. MEC was defined as EC detected within 36 months after negative UGE.

Results

123,395 UGEs were performed during the study period, with 502 ECs being diagnosed (0.4%). A total of 391 ECs were finally included. Overall MEC rate was 6.4% (95% confidence intervals (CI): 4.4-9.3%). The interval between negative and diagnostic UGE was less than 2 years in 84% of the cases. Multivariate analysis showed that a negative endoscopy was associated with proton pump inhibitor (PPI) therapy and less experienced endoscopists. MEC was smaller than non-MEC at diagnosis (25 versus 40 mm, p = 0.021), more often flat or depressed (p = 0.013) and less frequently diagnosed as metastatic disease (p = 0.013). Overall 2-year survival rate was similar for MEC (20%) and non-MEC (24.1%) (p = 0.95).

Conclusions

MEC accounted for 6.4% of all ECs and was associated with poor survival. High-quality UGE and awareness of MEC may help to reduce its incidence.

Does the Numerical Colour Value (NCV) correlate with preneoplastic and neoplastic colorectal lesions?

BACKGROUND

White light endoscopy (WLE) is the gold standard for detection of colorectal cancer. Autofluorescence endoscopy (AFE) is among the novel methods expected to increase the sensitivity and specificity of endoscopic diagnosis. The main objective of the study was to determine the diagnostic efficacy of AFE for the detection of preneoplastic and neoplastic colorectal lesions and to identify high-grade neoplasia using Numerical Colour Value (NCV).

METHODS

This retrospective study included 188 patients with colorectal mucosal lesions diagnosed on WLE and assessed using AFE; they were included in the study if a complete patient record was available (description of visualized colorectal lesions, NCV and histopathology report). The NCV was compared with the histological result.

RESULTS

Histology revealed 38 hyperplastic colon polyps, 77 low-grade dysplastic lesions, 17 high-grade dysplastic lesions, 24 adenocarcinomas and 32 inflammatory lesions. The mean NCVs of high-grade dysplasia (HGD) and adenocarcinoma were 2.24 ± 0.22 and 2.73 ± 0.16, respectively, significantly higher than the NCV of hyperplastic colon polyps (0.95 ± 0.06), low-grade dysplasia (LGD) (1.27 ± 0.05) and inflammatory lesions (1.26 ± 0.17). The NCV cut-off value for HGD and adenocarcinoma was set at 1.7. The sensitivity, specificity, PPV (positive predictive value) and NPV (negative predictive value) were 95.2%, 87.9%, 97.5%, 84.8%, respectively.

CONCLUSION

Our study showed that AFE could provide useful diagnostic information regarding preneoplastic and neoplastic colorectal lesions. Additionally, the NCV significantly correlated with the histopathology results.