Post-colonoscopy colorectal cancer in Belgium: characteristics and influencing factors

Post-colonoscopy colorectal cancers in a national fecal immunochemical test-based colorectal cancer screening program

BACKGROUND

Post-colonoscopy colorectal cancers (PCCRCs) decrease the effect of colorectal cancer (CRC) screening programs. To enable PCCRC incidence reduction in the long-term, we classified PCCRCs diagnosed after colonoscopies performed in a fecal immunochemical test (FIT)-based screening program.

METHODS

PCCRCs diagnosed after colonoscopies performed between 2014-2016 for a positive FIT in the Dutch CRC screening program were included. PCCRCs were categorized according to the World Endoscopy Organization consensus statement into (a) interval PCCRC (diagnosed before the recommended surveillance); (b) non-interval type A (diagnosed at the recommended surveillance interval); (c) non-interval type B (diagnosed after the recommended surveillance interval); or (d) non-interval type C (diagnosed after the intended recommended surveillance interval, with surveillance not implemented owing to co-morbidity). The most probable etiology was determined by root-cause analysis. Tumor stage distributions were compared between categories.

RESULTS

116362 colonoscopies were performed after a positive FIT with 9978 screen-detected CRCs. During follow-up, 432 PCCRCs were diagnosed. The 3-year PCCRC rate was 2.7%. PCCRCs were categorized as interval (53.5%), non-interval type A (14.6%), non-interval type B (30.6%), and non-interval type C (1.4%). The most common etiology for interval PCCRCs was possible missed lesion with adequate examination (73.6%); they were more often diagnosed at an advanced stage (stage III/IV; 53.2%) compared with non-interval type A (15.9%; P<0.001) and non-interval type B (40.9%; P=0.03) PCCRCs.

CONCLUSIONS

The 3-year PCCRC rate was low in this FIT-based CRC screening program. Approximately half of PCCRCs were interval PCCRCs. These were mostly caused by missed lesions and were diagnosed at a more advanced stage. This emphasizes the importance of high quality colonoscopy with optimal polyp detection.

Post-colonoscopy rectal cancer in Swedish patients with Crohn's disease 2001-2015: a population-based case review study

OBJECTIVE

Post-colonoscopy colorectal cancer (PCCRC) is a key quality indicator of colonoscopy, and PCCRC rates are high in the IBD population. Rectal cancer, an important risk factor for PCCRC among patients with Crohn's disease (CD), has not previously been examined.

METHODS

Swedish adult patients with CD who underwent a colonoscopy within 36 months before a rectal cancer diagnosis between 2001 and 2015 were identified through the National Patient and Cancer registers. Their medical records were reviewed and a root-cause analysis and a sub-categorization according to the World Endoscopic Organization (WEO) were performed.

RESULTS

Of 24 patients with CD and PCCRC in the rectum, 79% were men and the median age was 50 (IQR 45-59) years. The median disease duration was 21.5 (IQR 19-30) years. The cancer was located in the distal 5 cm of the rectum in 63% of the cases. Retroversion in the rectum was reported in only one case. The most common plausible explanation for PCCRC was 'possible missed lesion, prior examination adequate' (63%); when adding retroversion in the rectum, instead 77% of examinations were considered negative but deemed as inadequate. The most common PCCRC sub-category was non-interval type C (54%) and B (37%). Among those with type C, 38% should have been included in surveillance according to present guidelines.

CONCLUSION

Better adherence to surveillance guidelines and more meticulous follow-up is warranted. The importance of performing rectal palpation and retroversion in the rectum is underscored and we suggest that this is included in the WEO algorithm.

DECIDE: Delphi Expert Consensus Statement on Inflammatory Bowel Disease Dysplasia Shared Management Decision-Making

BACKGROUND AND AIMS

Inflammatory bowel disease colitis-associated dysplasia is managed with either enhanced surveillance and endoscopic resection or prophylactic surgery. The rate of progression to cancer after a dysplasia diagnosis remains uncertain in many cases and patients have high thresholds for accepting proctocolectomy. Individualised discussion of management options is encouraged to take place between patients and their multidisciplinary teams for best outcomes. We aimed to develop a toolkit to support a structured, multidisciplinary and shared decision-making approach to discussions about dysplasia management options between clinicians and their patients.

METHODS

Evidence from systematic literature reviews, mixed-methods studies conducted with key stakeholders, and decision-making expert recommendations were consolidated to draft consensus statements by the DECIDE steering group. These were then subjected to an international, multidisciplinary modified electronic Delphi process until an a priori threshold of 80% agreement was achieved to establish consensus for each statement.

RESULTS

In all, 31 members [15 gastroenterologists, 14 colorectal surgeons and two nurse specialists] from nine countries formed the Delphi panel. We present the 18 consensus statements generated after two iterative rounds of anonymous voting.

CONCLUSIONS

By consolidating evidence for best practice using literature review and key stakeholder and decision-making expert consultation, we have developed international consensus recommendations to support health care professionals counselling patients on the management of high cancer risk colitis-associated dysplasia. The final toolkit includes clinician and patient decision aids to facilitate shared decision-making.

Inflammatory Bowel Disease-Associated Colorectal Cancer Epidemiology and Outcomes: An English Population-Based Study

INTRODUCTION

Patients with inflammatory bowel diseases (IBDs) of the colon are at an increased risk of colorectal cancer (CRC). This study investigates the epidemiology of IBD-CRC and its outcomes.

METHODS

Using population data from the English National Health Service held in the CRC data repository, all CRCs with and without prior diagnosis of IBD (Crohn's, ulcerative colitis, IBD unclassified, and IBD with cholangitis) between 2005 and 2018 were identified. Descriptive analyses and logistic regression models were used to compare the characteristics of the 2 groups and their outcomes up to 2 years.

RESULTS

Three hundred ninety thousand six hundred fourteen patients diagnosed with CRC were included, of whom 5,141 (1.3%) also had a previous diagnosis of IBD. IBD-CRC cases were younger (median age at CRC diagnosis [interquartile range] 66 [54-76] vs 72 [63-79] years [ P < 0.01]), more likely to be diagnosed with CRC as an emergency (25.1% vs 16.7% [ P < 0.01]), and more likely to have a right-sided colonic tumor (37.4% vs 31.5% [ P < 0.01]). Total colectomy was performed in 36.3% of those with IBD (15.4% of Crohn's, 44.1% of ulcerative colitis, 44.5% of IBD unclassified, and 67.7% of IBD with cholangitis). Synchronous (3.2% vs 1.6% P < 0.01) and metachronous tumors (1.7% vs 0.9% P < 0.01) occurred twice as frequently in patients with IBD compared with those without IBD. Stage-specific survival up to 2 years was worse for IBD-associated cancers.

DISCUSSION

IBD-associated CRCs occur in younger patients and have worse outcomes than sporadic CRCs. There is an urgent need to find reasons for these differences to inform screening, surveillance, and treatment strategies for CRC and its precursors in this high-risk group.

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.

Real-time colorectal polyp detection using a novel computer-aided detection system (CADe): a feasibility study

BACKGROUND AND AIMS

Colonoscopy aims to early detect and remove precancerous colorectal polyps, thereby preventing development of colorectal cancer (CRC). Recently, computer-aided detection (CADe) systems have been developed to assist endoscopists in polyp detection during colonoscopy. The aim of this study was to investigate feasibility and safety of a novel CADe system during real-time colonoscopy in three European tertiary referral centers.

METHODS

Ninety patients undergoing colonoscopy assisted by a real-time CADe system (DISCOVERY; Pentax Medical, Tokyo, Japan) were prospectively included. The CADe system was turned on only at withdrawal, and its output was displayed on secondary monitor. To study feasibility, inspection time, polyp detection rate (PDR), adenoma detection rate (ADR), sessile serrated lesion (SSL) detection rate (SDR), and the number of false positives were recorded. To study safety, (severe) adverse events ((S)AEs) were collected. Additionally, user friendliness was rated from 1 (worst) to 10 (best) by endoscopists.

RESULTS

Mean inspection time was 10.8 ± 4.3 min, while PDR was 55.6%, ADR 28.9%, and SDR 11.1%. The CADe system users estimated that < 20 false positives occurred in 81 colonoscopy procedures (90%). No (S)AEs related to the CADe system were observed during the 30-day follow-up period. User friendliness was rated as good, with a median score of 8/10.

CONCLUSION

Colonoscopy with this novel CADe system in a real-time setting was feasible and safe. Although PDR and SDR were high compared to previous studies with other CADe systems, future randomized controlled trials are needed to confirm these detection rates. The high SDR is of particular interest since interval CRC has been suggested to develop frequently through the serrated neoplasia pathway.

CLINICAL TRIAL REGISTRATION

The study was registered in the Dutch Trial Register (reference number: NL8788).

Systematic review with meta-analysis: the prevalence of post-colonoscopy colorectal cancers using the World Endoscopy Organization nomenclature

INTRODUCTION

Post-colonoscopy colorectal cancers (PCCRCs) have been proposed as a performance metric for colonoscopy quality assurance programs. Previously, there was no standardised terminology or reporting methods. In 2018, the World Endoscopy Organization (WEO) advised standardised definitions and prevalence calculation methodology.

AIMS

To assess PCCRC burden using WEO standardised methods, to explore causes of heterogeneity, and to review changes in prevalence over time METHODS: We updated a prior systematic review by searching Ovid MEDLINE and EMBASE databases from 1 January 2013 to 31 January 2021 to identify population-based studies (or multicentre studies representative of the local population) reporting PCCRC prevalence (PROSPERO [CRD42020183796]). Two authors independently determined study eligibility, assessed quality, and extracted data. We estimated the PCCRC 3-year prevalence using WEO-recommended methodologies and investigated between-study sources of heterogeneity. We examined changes in prevalence over time.

RESULTS

Fifteen studies reporting on 25 872 PCCRC cases met eligibility criteria. Pooled PCCRC 3 year prevalence was 8.2% (95% CI = 6.9%-9.4%, I²  = 98.2%) across four European studies using WEO precise methodology. Proximal PCCRC prevalence was greater than distal (9.7% [95% CI = 7.0%-12.4%] vs 5.4% [95% CI = 2.9%-7.8%], I²  = 99.2%). Seven studies reporting PCCRC rates over time showed no consistent trend: four showed a decrease, one an increase and two were unchanged. Between-study heterogeneity was high.

CONCLUSIONS

Pooled 3-year PCCRC prevalence was 8.2% (95% CI = 6.9%-9.4%). Despite WEO standardised methodology to define and calculate PCCRC rates, there was significant heterogeneity among studies. Comparing rates between populations remains challenging and additional studies are needed to better understand the global PCCRC burden to inform quality assurance programs.

A single-centre analysis of post-colonoscopy colorectal cancer

PATIENTS AND METHODS

A prospective registration of patients with colorectal cancer and a colonoscopy within the last 10 years. We tried to classify these post-colonoscopy colorectal cancers (PCCRCs) by most reasonable explanation and into subcategories suggested by the World Endoscopy Organization (WEO) and calculated the unadjusted PCCRC rate.

RESULTS

47 PCCRCs were identified. The average age at diagnosis of PCCRC was 73 years. PCCRCs were more located in the right colon with a higher percentage of MSI-positive and B-RAF mutated tumours. The average period between index colonoscopy and diagnosis of PCCRC was 4.2 years. Sixty-eight % of all PCCRCs could be explained by procedural factors. The mean PCCRC-3y of our department was 2.46%.

CONCLUSIONS

The data of our centre are in line with the data of the literature from which can be concluded that most postcolonoscopy colorectal cancers are preventable. The PCCRC-3y is an important quality measure for screening colonoscopy. Ideally all centres involved in the population screening should measure the PCCRC-3 y annually, with cooperation of the cancer registry and reimbursement data provided by the Intermutualistic Agency (IMA).

Postcolonoscopy Colorectal Cancer in Sweden From 2003 to 2012: Survival, Tumor Characteristics, and Risk Factors

BACKGROUND & AIMS

The rate of postcolonoscopy colorectal cancer (PCCRC) is a measure of colonoscopy quality, but there are conflicting results from studies of survival times of patients with PCCRC. We assessed survival times of patients with PCCRC and characterized the microscopic and macroscopic features of postcolonoscopy colorectal tumors.

METHODS

We performed a population-based cohort study using data from a database in Sweden, on 458,937 colonoscopies (54.0% women) performed from 2003 through 2012. Rates of colorectal cancer within 3 years of a colonoscopy were calculated based on the World Endoscopy Organization guidelines. Risk factors were evaluated using Poisson regression analysis. We used Cox regression models and Kaplan-Meier analyses, stratified by sex, to assess conditional survival. Logistic regression models were used to evaluate features of postcolonoscopy colorectal tumors, including stage location (right, left, or rectum) differentiation grade (high or low), synchronous tumors, perineural growth, resection margins, and mucinous and vessel characteristics.

RESULTS

Within 36 months after a colonoscopy, there were 19,184 individuals who had received a diagnosis of CRC; 1384 of these were PCCRCs (7.2%). The proportion of individuals with PCCRC decreased from 9.4% in 2003 to 6.1% in 2012. The largest risk factors for PCCRC were a prior diagnosis of CRC (relative risk [RR], 3.31; 95% CI, 2.71-4.04), ulcerative colitis (RR, 5.44; 95% CI, 4.75-6.23), Crohn's disease (RR, 3.81; 95% CI, 2.98-4.87), and prior polypectomy (RR, 2.32; 95% CI, 1.97-2.72). Individuals with PCCRCs had shorter survival times than individuals with CRCs detected during the index colonoscopy. Multivariate hazard ratios for PCCRC were 2.75 for men (95% CI, 2.21-3.42) and 2.00 for women (95% CI, 1.59-2.52), respectively. Individuals with left-side PCCRC had shorter survival times than patients with CRC detected during the index colonoscopy. Postcolonoscopy colorectal tumors had increased odds of low differentiation grade (odds ratio, 1.27; 95% CI, 1.09-1.49) compared with colorectal tumors detected during the index colonoscopy.

CONCLUSIONS

In an analysis of colonoscopies in Sweden, the rate of PCCRCs decreased from 9.4% in 2003 to 6.1% in 2012. Diseases that require surveillance (such as prior colorectal neoplasms and inflammatory bowel diseases) are the largest risk factors for PCCRC. Patients with PCCRC have shorter survival times than patients with CRC detected during their initial colonoscopy-especially women and patients with left-side tumors.

Causes of Post-Colonoscopy Colorectal Cancers Based on World Endoscopy Organization System of Analysis

BACKGROUND & AIMS

Postcolonoscopy colorectal cancer (PCCRC) is CRC diagnosed after a colonoscopy in which no cancer was found. A consensus article from the World Endoscopy Organization (WEO) proposed an approach for investigating and categorizing PCCRCs detected within 4 years of a colonoscopy. We aimed to identify cases of PCCRC and the factors that cause them, test the WEO system of categorization, quantify the proportion of avoidable PCCRCs, and propose a target rate for PCCRCs detected within 3 years of a colonoscopy that did not detect CRC.

METHODS

We performed a retrospective analysis of 107 PCCRCs identified at a single medical center in England from January 1, 2010, through December 31, 2017 using coding and endoscopy data. For each case, we reviewed clinical, pathology, radiology, and endoscopy findings. Using the WEO recommendations, we performed a root-cause analysis of each case, categorizing lesions as follows: possible missed lesion, prior examination adequate; possible missed lesion, prior examination inadequate; detected lesion, not resected; or likely incomplete resection of previously identified lesion. We determined whether PCCRCs could be attributed to the colonoscopist for technical or decision-making reasons, and whether the PCCRC was avoidable or unavoidable, based on the WEO categorization and size of tumor. The endoscopy reporting system provided performance data for individual endoscopists.

RESULTS

Of the PCCRCs identified, 43% were in high-risk patients (those with inflammatory bowel disease, previous CRC, previous multiple large polyps, or hereditary cancer syndromes) and 66% were located distal to the hepatic flexure. There was no correlation between postcolonoscopy colorectal tumor size and time to diagnosis after index colonoscopy. Bowel preparation was poor in 19% of index colonoscopies, and only 36% of complete colonoscopies had adequate photodocumentation of completion. Development of 73% of PCCRCs was determined to be affected by technical endoscopic factors, 17% of PCCRCs by administrative factors (follow-up procedures delayed/not booked by administrative staff), and 27% of PCCRCs by decision-making factors. Twenty-seven percent of PCCRCs were categorized as possible missed lesion, prior examination adequate; 58% as possible missed lesion, prior examination inadequate; 8% as detected lesion, not resected; and 7% as incomplete resection of previously observed lesion; 89% were deemed to be avoidable.

CONCLUSIONS

In a retrospective analysis of PCCRCs, using the WEO system of categorization, we found 43% to occur in high-risk patients; this might be reduced with more vigilant surveillance. Measures are needed to reduce technical, decision-making, and administrative factors. We found that 89% of PCCRCs may be avoidable. If half of avoidable PCCRCs could be prevented, the target rate of 2% for the PCCRC-3y (cancer diagnosed between 6 and 36 months after index colonoscopy) benchmark would be achievable.