Prevention of interval colorectal cancers: what every clinician needs to know

Risk factors for synchronous high-risk polyps in patients with colorectal cancer

Purpose

Colorectal cancer (CRC) patients may experience inadequate preoperative colonoscopy due to bowel obstruction or inadequate bowel preparation, leading to potential oversight of other polyps. We aimed to identify risk factors for CRC complicated with synchronous high-risk polyps.

Methods

A retrospective analysis of 6,674 CRC patients from December 2014 to September 2018 was conducted. High-risk polyps were defined as adenomas or serrated polyps that were ≥10 mm, or with tubulovillous/villous components or high-grade dysplasia. All other polyps were defined as low-risk polyps. Patients with complete pathological and clinical information were categorized into three groups: the no polyp group, the low-risk polyp group, and the high-risk polyp group. Univariate and multivariate logistic regression analyses were performed to calculate the odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for all potential risk factors.

Results

Among the 4,659 eligible patients, 848 (18.2%) were found to have low-risk polyps, while 675 (14.5%) were diagnosed with high-risk polyps. In a multivariate logistic regression model, compared to patients without polyps, those with synchronous high-risk polyps were more likely to be male (OR = 2.07), aged 50 or older (OR = 2.77), have early-stage tumors (OR = 1.46), colon tumors (OR = 1.53), NRAS mutant tumors (OR = 1.66), and BRAF wild-type tumors (OR = 2.43).

Conclusion

Our study has identified several risk factors associated with the presence of synchronous high-risk polyps in CRC patients. Based on these findings, we recommend that patients who exhibit these high-risk factors undergo early follow-up of colonoscopy to detect synchronous polyps early.

The role of cap-assisted endoscopy and its future implications

Cap-assisted endoscopy refers to a procedure in which a short tube made of a polymer (mostly transparent) is attached to the distal tip of the endoscope to enhance its diagnostic and therapeutic capabilities. It is reported to be particularly useful in: (1) minimizing blind spots during screening colonoscopy, (2) providing a constant distance from a lesion for clear visualization during magnifying endoscopy, (3) accurately assessing the size of various gastrointestinal lesions, (4) preventing mucosal injury during foreign body removal, (5) securing adequate workspace in the submucosal space during endoscopic submucosal dissection or third space endoscopy, (6) providing an optimal approach angle to a target, and (7) suctioning mucosal and submucosal tissue with negative pressure for resection or approximation. Here, we review various applications of attachable caps in diagnostic and therapeutic endoscopy and their future implications.

Artificial intelligence fails to improve colonoscopy quality: A single centre retrospective cohort study

BACKGROUND

Limited data currently exists on the clinical utility of Artificial Intelligence Assisted Colonoscopy (AIAC) outside of clinical trials.

AIM

To evaluate the impact of AIAC on key markers of colonoscopy quality compared to conventional colonoscopy (CC).

METHODS

This single-centre retrospective observational cohort study included all patients undergoing colonoscopy at a secondary centre in Brisbane, Australia. CC outcomes between October 2021 and October 2022 were compared with AIAC outcomes after the introduction of the Olympus Endo-AID module from October 2022 to January 2023. Endoscopists who conducted over 50 procedures before and after AIAC introduction were included. Procedures for surveillance of inflammatory bowel disease were excluded. Patient demographics, proceduralist specialisation, indication for colonoscopy, and colonoscopy quality metrics were collected. Adenoma detection rate (ADR) and sessile serrated lesion detection rate (SSLDR) were calculated for both AIAC and CC.

RESULTS

The study included 746 AIAC procedures and 2162 CC procedures performed by seven endoscopists. Baseline patient demographics were similar, with median age of 60 years with a slight female predominance (52.1%). Procedure indications, bowel preparation quality, and caecal intubation rates were comparable between groups. AIAC had a slightly longer withdrawal time compared to CC, but the difference was not statistically significant. The introduction of AIAC did not significantly change ADR (52.1% for AIAC vs 52.6% for CC, P = 0.91) or SSLDR (17.4% for AIAC vs 18.1% for CC, P = 0.44).

CONCLUSION

The implementation of AIAC failed to improve key markers of colonoscopy quality, including ADR, SSLDR and withdrawal time. Further research is required to assess the utility and cost-efficiency of AIAC for high performing endoscopists.

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.

Recent advances in nanomedicine preparative methods and their therapeutic potential for colorectal cancer: a critical review

Colorectal cancer (CRC) is a prevalent malignancy that affects a large percentage of the global population. The conventional treatments for CRC have a number of limitations. Nanoparticles have emerged as a promising cancer treatment method due to their ability to directly target cancer cells and regulate drug release, thereby enhancing therapeutic efficacy and minimizing side effects. This compilation examines the use of nanoparticles as drug delivery systems for CRC treatment. Different nanomaterials can be used to administer anticancer drugs, including polymeric nanoparticles, gold nanoparticles, liposomes, and solid lipid nanoparticles. In addition, we discuss recent developments in nanoparticle preparation techniques, such as solvent evaporation, salting-out, ion gelation, and nanoprecipitation. These methods have demonstrated high efficacy in penetrating epithelial cells, a prerequisite for effective drug delivery. This article focuses on the various targeting mechanisms utilized by CRC-targeted nanoparticles and their recent advancements in this field. In addition, the review offers descriptive information regarding numerous nano-preparative procedures for colorectal cancer treatments. We also discuss the outlook for innovative therapeutic techniques in the management of CRC, including the potential application of nanoparticles for targeted drug delivery. The review concludes with a discussion of current nanotechnology patents and clinical studies used to target and diagnose CRC. The results of this investigation suggest that nanoparticles have great potential as a method of drug delivery for the treatment of colorectal cancer.

Early gastric neoplasms are significant risk factor for colorectal adenoma: A prospective case-control study

Although gastric cancer patients have a high incidence and risk of colorectal cancer, evidence is lacking regarding whether early gastric neoplasms (EGNs), such as gastric adenomas and early gastric cancer, are risk factors for colorectal adenoma. This study aimed to investigate the incidence of colorectal adenomas in patients with EGN. This prospective study was conducted between January 2015 and December 2016. Of the 307 patients who underwent gastric endoscopic submucosal dissection for EGN, 110 patients were enrolled in the EGN group, and 110 age- and sex-matched healthy persons from the screening population were included in the control group in a 1:1 ratio. Demographic factors and results of colonoscopy, including quality assessment, were collected, and analyzed. No significant differences in the quality of colonoscopy, including bowel preparation, cecal intubation rate, and withdrawal time between the 2 groups, were observed. The incidence of colorectal adenoma was significantly higher in the EGN group than in the control group (55.5% vs 26.4%, P = .001). Multivariate analysis confirmed that old age (odds ratio: 1.04, 95% confidence interval: 1.01-1.08, P = .005) and a history of EGN (odds ratio: 4.99, 95% confidence interval: 2.60-9.57, P = .001) were independent risk factors for colorectal adenoma. This is the first prospective study to reflect the quality indicator of colonoscopy and confirmed that old age and a history of EGN are significant risk factors for colorectal adenomas. Therefore, more stringent colonoscopy surveillance should be considered in elderly patients with EGN.

Anesthesia Assistance in Colonoscopy: Impact on Quality Indicators

Background

Adenoma detection rate (ADR) and polyp detection rate (PDR) are both indicators for colonoscopy quality. Improving ADR or PDR is critical for reducing the incidence and mortality of colorectal cancer (CRC). Although several studies have focused on identifying the factors that may influence ADR or PDR, the evidence remains limited and inconclusive. We conducted a retrospective study to evaluate the effect of anesthesia assistance (AA) on ADR or PDR in patients undergoing colonoscopy screening and identify risk factors affecting ADR or PDR.

Methods

We reviewed electronic medical records of patients who underwent colonoscopy screening between May 2019 and August 2020. Patients were divided into two groups according to whether they received AA: patients in Group A underwent colonoscopy screening with AA, whereas patients in Group O underwent colonoscopy screening without AA. Propensity score matching (PSM) was utilized to account for differences in baseline characteristics. After, ADR and PDR were compared between the two groups. Binary logistic regression was employed to identify risk factors that affected ADR or PDR.

Results

Of 9432 patients who underwent colonoscopy examination during the study period, 7170 were included in the final analyses (Group A = 5756 and Group O = 1414). After PSM, 736 patients remained in each group for analyses. There was no significant difference between groups A and O (P &gt; 0.05) in ADR or PDR. Binary logistic regression indicated that the endoscopic device version (Olympus HQ290), equipment image-based technique and number of images were independent risk factors that affected ADR, and the age (50–59 years and 60–69 years), gender (male), high-risk status, endoscopist seniority (senior endoscopist), equipment image-based technique and number of images were all independent risk factors that affected PDR.

Conclusions

We discovered that AA does not affect ADR or PDR. Despite improved patient satisfaction, using AA is unnecessary for improving colonoscopy quality. Endoscopists should consider all these factors as much as possible when performing colonoscopy screening.

Atypical Presentation of Interval Colorectal Cancer/Post-Colonoscopy Colorectal Cancer in a Nursing Home Patient

The Centers for Disease Control and Prevention estimates that there are around 1.7 million beds in certified nursing homes across the United States and approximately 1.3 million residents in long-term and end-of-life care. There could be several factors causing a delayed recovery in such patients, such as decreased ambulation, multiple comorbidities, and polypharmacy.

An 83-year-old Caucasian woman sustained a fall resulting in compression fractures of the thoracic and lumbar spine. She had multiple comorbidities, including anemia of chronic disease, malnutrition, and a significant weight loss of 30 lbs over the four months prior to hospitalization. She was on antihypertensives, antidepressants, vitamin D, and calcium supplementation. Her medical history was significant for constipation with the passage of stools once in three days. Her family history was significant for colorectal cancer (CRC) and her screening colonoscopy three years ago was normal. Physical examination revealed no abdominal tenderness or distention. Subsequently, she developed edema in the left lower extremity. She underwent a venous Doppler/ultrasound study, which showed an occlusive thrombus from the common femoral vein to the popliteal vein. She was started on anticoagulants and supportive therapy. Four months later, while at the nursing home, she developed bloating and flatulence, in addition to pre-existing constipation. Examination revealed a 6 x 7 cm mass in the right lower quadrant without peritoneal signs. Bowel sounds were significantly decreased. CT imaging showed a 6-cm diameter cecal mass. The tumor was a low-grade 4 x 9 cm T4N0M0 cecal cancer, and she underwent placement of a Greenfield filter and subsequent hemicolectomy. She had methicillin-resistant Staphylococcus aureus infection and right upper extremity deep vein thrombosis (DVT), urinary tract infection, Clostridium difficile colitis, and depression, all managed successfully and without sequelae in the post-operative period. Treatment on discharge comprised Coumadin maintenance for nine months with an international normalized ratio goal of 2-3, a back brace, antidepressants, and antihypertensive medications. She received follow-up care at home.

Maintaining a high degree of suspicion for new and persistent symptoms in the elderly is essential to identify the underlying cause. One of the leading causes of post-colonoscopy CRC is a missed lesion. Careful attention to all cases of anemia as well as DVT in the elderly is also imperative to diagnose such missed cases. Future research should focus on the methods of CRC diagnosis in elderly patients with comorbidities apart from using colonoscopy alone.

Urinary Volatile Organic Compound Testing in Fast-Track Patients with Suspected Colorectal Cancer

Simple Summary

The current pathway for the investigation of possible colorectal cancer includes the use of colonoscopy. This is an invasive and unpleasant procedure, and currently, a large number of those performed are normal. Previous research has demonstrated that urinary volatile organic compounds (VOCs) can be used to detect cancer, including colorectal cancer. However, these studies have only taken place in patients already known to have cancer. This study aimed to assess the role of urinary VOC analysis in the NHS two weeks wait for cancer pathway. Three analytical techniques were used to analyze urine samples of 558 patients during the standard NHS assessment pathway. It demonstrated that gas chromatography-mass spectrometry (GCMS) has excellent sensitivity and specificity for the identification of cancer and polyps in this patient group. These results show a potential role for urinary VOC analysis in the NHS cancer screening pathway, to reduce the need for invasive colonoscopy testing.

Abstract

Colorectal symptoms are common but only infrequently represent serious pathology, including colorectal cancer (CRC). A large number of invasive tests are presently performed for reassurance. We investigated the feasibility of urinary volatile organic compound (VOC) testing as a potential triage tool in patients fast-tracked for assessment for possible CRC. A prospective, multi-center, observational feasibility study was performed across three sites. Patients referred to NHS fast-track pathways for potential CRC provided a urine sample that underwent Gas Chromatography-Mass Spectrometry (GC-MS), Field Asymmetric Ion Mobility Spectrometry (FAIMS), and Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) analysis. Patients underwent colonoscopy and/or CT colonography and were grouped as either CRC, adenomatous polyp(s), or controls to explore the diagnostic accuracy of VOC output data supported by an artificial neural network (ANN) model. 558 patients participated with 23 (4%) CRC diagnosed. 59% of colonoscopies and 86% of CT colonographies showed no abnormalities. Urinary VOC testing was feasible, acceptable to patients, and applicable within the clinical fast track pathway. GC-MS showed the highest clinical utility for CRC and polyp detection vs. controls (sensitivity = 0.878, specificity = 0.882, AUROC = 0.896) but it is labour intensive. Urinary VOC testing and analysis are feasible within NHS fast-track CRC pathways. Clinically meaningful differences between patients with cancer, polyps, or no pathology were identified suggesting VOC analysis may have future utility as a triage tool.

Use of U-Net Convolutional Neural Networks for Automated Segmentation of Fecal Material for Objective Evaluation of Bowel Preparation Quality in Colonoscopy

Background: Adequate bowel cleansing is important for colonoscopy performance evaluation. Current bowel cleansing evaluation scales are subjective, with a wide variation in consistency among physicians and low reported rates of accuracy. We aim to use machine learning to develop a fully automatic segmentation method for the objective evaluation of the adequacy of colon preparation. Methods: Colonoscopy videos were retrieved from a video data cohort and transferred to qualified images, which were randomly divided into training, validation, and verification datasets. The fecal residue was manually segmented. A deep learning model based on the U-Net convolutional network architecture was developed to perform automatic segmentation. The performance of the automatic segmentation was evaluated on the overlap area with the manual segmentation. Results: A total of 10,118 qualified images from 119 videos were obtained. The model averaged 0.3634 s to segmentate one image automatically. The models produced a strong high-overlap area with manual segmentation, with 94.7% ± 0.67% of that area predicted by our AI model, which correlated well with the area measured manually (r = 0.915, p < 0.001). The AI system can be applied in real-time qualitatively and quantitatively. Conclusions: We established a fully automatic segmentation method to rapidly and accurately mark the fecal residue-coated mucosa for the objective evaluation of colon preparation.

A fecal-based test for the detection of advanced adenoma and colorectal cancer: a case-control and screening cohort study

BACKGROUND

Colorectal cancer (CRC) is the leading cause of cancer death worldwide. Screening is a confirmed way to reduce the incidence and mortality rates of CRC. This study aimed to identify a fecal-based, noninvasive, and accurate method for detection of colorectal cancer (CRC) and advanced adenoma (AA).

METHODS

Through detection in tissue (n = 96) and fecal samples (n = 88) and tested in an independent group of fecal samples (n = 294), the methylated DNA marker ITGA4 and bacterial markers Fusobacterium nucleatum (Fn) and Pepetostreptococcusanaerobius (Pa) were identified from the candidate biomarkers for CRC and AA detection. A prediction score (pd-score) was constructed using the selected markers and fecal immunochemical test (FIT) for distinguishing AA and CRC from healthy subjects by logistic regression method. The diagnostic performance of the pd-score was compared with FIT and validated in the external validation cohort (n = 117) and in a large CRC screening cohort.

RESULTS

The pd-score accurately identified AA and CRC from healthy subjects with an area under the curve (AUC) of 0.958, at a specificity of 91.37%; the pd-score showed sensitivities of 95.38% for CRC and 70.83% for AA, respectively. In the external validation cohort, the sensitivities of the pd-score for CRC and AA detection were 94.03% and 80.00%, respectively. When applied in screening, the pd-score identified 100% (11/11) of CRC and 70.83% (17/24) of AA in participants with both colonoscopy results and qualified fecal samples, showing an improvement by 41.19% compared to FIT.

CONCLUSIONS

The current study developed a noninvasive and well-validated approach for AA and CRC detection, which could be applied widely as a diagnostic and screening test.

Interval Colorectal Cancer 2006-2015: Novel Observations

BACKGROUND

Screening for colorectal cancer (CRC) with colonoscopy has been credited for the majority of the decline in mortality over the past 40 years. However, colonoscopy is hampered by frequent interval cancers (ICs) occurring within 36 months after the last examination. Risk factors for IC imply that most misses are amenable to improved colonoscopic techniques. This study had two primary objectives: (1) to determine whether the proportion of persons with ICs has declined in association with improved approaches to the quality of colonoscopy and (2) to determine unrecognized causes for missed diagnoses.

METHODS

This is a retrospective, single-center study of persons with CRC having been diagnosed within 6-36 months since the most recent colonoscopy between 2006 and 2015. Participants, ages 50 and 89 years, were evaluated specifically for technical features and findings of the most recent colonoscopy.

RESULTS

Thirty-nine persons met the inclusion criteria for IC. Mean age was 69.3 years, range 50-86 years, women were 58%, races included 95% Caucasian, 2.5% Asian, and 2.5% African-American, and history of a first-degree relative with CRC was 26%. Symptoms led to the interval diagnosis in 83%, including iron-deficient anemia (38%), bleeding (25%), abdominal/pelvic pain (18%), and change in bowel habit (2.5%). Preexisting neoplasia was present in 72%. The CRC was located in the proximal colon in 51%. Late-stage disease was present in 45%. When compared to persons with an initial diagnosis of screen-detected late-onset CRC, differences were noted for older age, more women, more with a family history of CRC, and more with late-stage disease. The ratio of interval cancers to new cancers ranged between 6 and 11.5%. Findings indicating a "difficult examination" were observed in 14 cases (36%) compared to "easy or no difficulty" examinations in 25 (65%) cases. In a biennial analysis of IC rates between 2006 and 2015, the percentage of IC remained stable between 6 and 11.5%.

CONCLUSIONS

ICs have been stable constituting 6-11.5% of all CRCs. A "difficult examination" was often associated with IC, may be a risk factor for this problem, and may be an important clue warranting further study.

ACG Clinical Guidelines: Colorectal Cancer Screening 2021

Colorectal cancer (CRC) is the third most common cancer in men and women in the United States. CRC screening efforts are directed toward removal of adenomas and sessile serrated lesions and detection of early-stage CRC. The purpose of this article is to update the 2009 American College of Gastroenterology CRC screening guidelines. The guideline is framed around several key questions. We conducted a comprehensive literature search to include studies through October 2020. The inclusion criteria were studies of any design with men and women age 40 years and older. Detailed recommendations for CRC screening in average-risk individuals and those with a family history of CRC are discussed. We also provide recommendations on the role of aspirin for chemoprevention, quality indicators for colonoscopy, approaches to organized CRC screening and improving adherence to CRC screening. CRC screening must be optimized to allow effective and sustained reduction of CRC incidence and mortality. This can be accomplished by achieving high rates of adherence, quality monitoring and improvement, following evidence-based guidelines, and removing barriers through the spectrum of care from noninvasive screening tests to screening and diagnostic colonoscopy. The development of cost-effective, highly accurate, noninvasive modalities associated with improved overall adherence to the screening process is also a desirable goal.

[Application of artificial intelligence for detection and classification of colon polyps]

Colorectal cancer is one of the most common cancers worldwide, and colonoscopy has proven to be a preferable modality for screening and surveillance of colorectal cancer. This review discusses the clinical application of artificial intelligence (AI) and computer-aided diagnosis for automated colonoscopic detection and diagnosis of colorectal polyps for better understanding of the application of AI-based computer-aided diagnosis systems especially in terms of machine learning, deep learning and convolutional neural network for screening and surveillance of colorectal cancer.

Evolving role of artificial intelligence in gastrointestinal endoscopy

Artificial intelligence (AI) is a combination of different technologies that enable machines to sense, comprehend, and learn with human-like levels of intelligence. AI technology will eventually enhance human capability, provide machines genuine autonomy, and reduce errors, and increase productivity and efficiency. AI seems promising, and the field is full of invention, novel applications; however, the limitation of machine learning suggests a cautious optimism as the right strategy. AI is also becoming incorporated into medicine to improve patient care by speeding up processes and achieving greater accuracy for optimal patient care. AI using deep learning technology has been used to identify, differentiate catalog images in several medical fields including gastrointestinal endoscopy. The gastrointestinal endoscopy field involves endoscopic diagnoses and prognostication of various digestive diseases using image analysis with the help of various gastrointestinal endoscopic device systems. AI-based endoscopic systems can reliably detect and provide crucial information on gastrointestinal pathology based on their training and validation. These systems can make gastroenterology practice easier, faster, more reliable, and reduce inter-observer variability in the coming years. However, the thought that these systems will replace human decision making replace gastrointestinal endoscopists does not seem plausible in the near future. In this review, we discuss AI and associated various technological terminologies, evolving role in gastrointestinal endoscopy, and future possibilities.

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.

Emerging artificial intelligence applications in gastroenterology: A review of the literature

Artificial intelligence (AI) allows machines to provide disruptive value in several industries and applications. Applications of AI techniques, specifically machine learning and more recently deep learning, are arising in gastroenterology. Computer-aided diagnosis for upper gastrointestinal endoscopy has growing attention for automated and accurate identification of dysplasia in Barrett’s esophagus, as well as for the detection of early gastric cancers (GCs), therefore preventing esophageal and gastric malignancies. Besides, convoluted neural network technology can accurately assess Helicobacter pylori (H. pylori) infection during standard endoscopy without the need for biopsies, thus, reducing gastric cancer risk. AI can potentially be applied during colonoscopy to automatically discover colorectal polyps and differentiate between neoplastic and non-neoplastic ones, with the possible ability to improve adenoma detection rate, which changes broadly among endoscopists performing screening colonoscopies. In addition, AI permits to establish the feasibility of curative endoscopic resection of large colonic lesions based on the pit pattern characteristics. The aim of this review is to analyze current evidence from the literature, supporting recent technologies of AI both in upper and lower gastrointestinal diseases, including Barrett's esophagus, GC, H. pylori infection, colonic polyps and colon cancer.

Application of Artificial Intelligence in the Detection and Differentiation of Colon Polyps: A Technical Review for Physicians

Research in computer-aided diagnosis (CAD) and the application of artificial intelligence (AI) in the endoscopic evaluation of the gastrointestinal tract is novel. Since colonoscopy and detection of polyps can decrease the risk of colon cancer, it is recommended by multiple national and international societies. However, the procedure of colonoscopy is performed by humans where there are significant interoperator and interpatient variations, and hence, the risk of missing detection of adenomatous polyps. Early studies involving CAD and AI for the detection and differentiation of polyps show great promise. In this appraisal, we review existing scientific aspects of AI in CAD of colon polyps and discuss the pitfalls and future directions for advancing the science. This review addresses the technical intricacies in a manner that physicians can comprehend to promote a better understanding of this novel application.

Clinicopathologic and genetic characteristics of interval colorectal carcinomas favor origin from missed or incompletely excised precursors

Interval colorectal cancers may arise from missed or incompletely excised precursors or from a unique rapid progression pathway. We compared the clinicopathologic and molecular profiles of interval and matched non-interval colorectal cancer to determine whether interval colorectal cancers harbor any unique genetic characteristics. Fifty one of 982 colorectal cancer (5.2%) were categorized as interval colorectal cancer, defined as colorectal cancer detected in a diagnostic examination prior to the next recommended colonoscopy and at least 1 year after the last colonoscopy. Clinicopathologic characteristics of interval colorectal cancer were compared to non-interval colorectal cancer matched 1:1 on age, gender, and tumor location. Molecular profile of a subset of interval colorectal cancer (n = 20) and matched (1:2) non-interval colorectal cancer (n = 40) were evaluated using next generation sequencing. Interval colorectal cancer were more likely to occur in the right colon (55% vs. 35%; p = 0.02) and in patients > 70 years of age (55% vs. 34%; p = 0.002). Clinicopathologic features and aberrant DNA mismatch repair protein expression were not significantly different between interval and matched non-interval colorectal cancer. The frequency and spectrum of genetic alterations was also similar in interval and matched non-interval colorectal cancer. Similar findings were seen when analysis was restricted to interval colorectal cancer diagnosed <5 years after last colonoscopy (n = 42). Interval and non-interval colorectal cancers share similar clinicopathologic and genetic profiles when matched for tumor location. Interval colorectal cancers and are more likely to develop from missed or incompletely excised precursors rather than a unique rapid progression pathway.

Frequency and Characteristics of Interval Colorectal Cancer in Actual Clinical Practice: A KASID Multicenter Study

Background/Aims

The aims of the present study were to determine the frequency of interval colorectal cancers (CRCs) after surveillance colonoscopy and to compare the clinicopathologic features and survival outcomes with those of non-interval CRCs.

Methods

From January 2003 to December 2013, 66,016 follow-up colonoscopies for 38,412 patients performed within recommended time were reviewed retrospectively based on data from 11 tertiary hospitals in South Korea. To compare clinicopathologic features and survival rates for interval CRC, 106 patients with non-interval CRC matched in age and gender were included.

Results

Among the 66,016 colonoscopies performed within the surveillance period, 63 cases (63/66,016) of interval CRC were detected, and 53 were finally included in the analysis. The mean age was 69.9±8.8 years, and the male to female ratio was 1.94:1. Although the occurrence rate of cancer in the right side colon was higher than that of non-interval CRC, interval CRCs were predominantly left sided. Other clinicopathologic features and overall survival were not significantly different between the two groups. Missed lesion was suspected to be the most common cause (29 cases, 54.7%).

Conclusions

The frequency of interval CRC among patients who had undergone a surveillance colonoscopy was 0.095%. While sharing some similar clinical features and survival outcomes, interval CRCs in Korea developed more often in males and on the left side in contrast to results from Western studies.

Screening Colonoscopy Withdrawal Time Threshold for Adequate Proximal Serrated Polyp Detection Rate

INTRODUCTION

For adequate adenoma detection rate (ADR), guidelines recommend a mean withdrawal time (MWT) of ≥ 6 min. ADR has been shown to correlate strongly with proximal serrated polyp detection rate (PSP-DR), which is another suggested quality measure for screening colonoscopy. However, the impact of directly measured withdrawal time on PSP-DR has not been rigorously studied. We examined the relationship between MWT to ADR and PSP-DR, with the aim of identifying a functional threshold withdrawal time associated with both increased ADR and PSP-DR.

METHODS

This was a retrospective study of endoscopy and pathology data from average-risk screening colonoscopy examinations performed at a large system with six endoscopy laboratories. A natural language processing tool was used to determine polyp location and histology. ADR and PSP-DR were calculated for each endoscopist. MWT was calculated from colonoscopy examinations in which no polyps were resected.

RESULTS

In total, 31,558 colonoscopy examinations were performed, of which 10,196 were average-risk screening colonoscopy examinations with cecal intubation and adequate prep by 24 gastroenterologists. When assessing the statistical significance of increasing MWT by minute, the first significant time mark for PSP-DR was at 11 min at a rate of 14.2% (p = 0.01). There was a significant difference comparing aggregated MWT < 11 min compared to ≥ 11 min looking at the rates of adenomas [OR 1.65 (1.09-2.51)] and proximal serrated polyps [OR 1.81 (1.06-3.08)]. While ADR linearly correlated well with MWT (R = 0.76, p < 0.001), the linear relationship with PSP-DR was less robust (R = 0.42, p = 0.043).

CONCLUSION

In this large cohort of average-risk screening colonoscopy, a MWT of 11 min resulted in a statistically significant increase in both ADR and PSP-DR. Our data suggest that a longer withdrawal time may be required to meet both quality metrics.

Deep Learning Localizes and Identifies Polyps in Real Time With 96% Accuracy in Screening Colonoscopy

BACKGROUND & AIMS

The benefit of colonoscopy for colorectal cancer prevention depends on the adenoma detection rate (ADR). The ADR should reflect the adenoma prevalence rate, which is estimated to be higher than 50% in the screening-age population. However, the ADR by colonoscopists varies from 7% to 53%. It is estimated that every 1% increase in ADR lowers the risk of interval colorectal cancers by 3%-6%. New strategies are needed to increase the ADR during colonoscopy. We tested the ability of computer-assisted image analysis using convolutional neural networks (CNNs; a deep learning model for image analysis) to improve polyp detection, a surrogate of ADR.

METHODS

We designed and trained deep CNNs to detect polyps using a diverse and representative set of 8,641 hand-labeled images from screening colonoscopies collected from more than 2000 patients. We tested the models on 20 colonoscopy videos with a total duration of 5 hours. Expert colonoscopists were asked to identify all polyps in 9 de-identified colonoscopy videos, which were selected from archived video studies, with or without benefit of the CNN overlay. Their findings were compared with those of the CNN using CNN-assisted expert review as the reference.

RESULTS

When tested on manually labeled images, the CNN identified polyps with an area under the receiver operating characteristic curve of 0.991 and an accuracy of 96.4%. In the analysis of colonoscopy videos in which 28 polyps were removed, 4 expert reviewers identified 8 additional polyps without CNN assistance that had not been removed and identified an additional 17 polyps with CNN assistance (45 in total). All polyps removed and identified by expert review were detected by the CNN. The CNN had a false-positive rate of 7%.

CONCLUSION

In a set of 8,641 colonoscopy images containing 4,088 unique polyps, the CNN identified polyps with a cross-validation accuracy of 96.4% and an area under the receiver operating characteristic curve of 0.991. The CNN system detected and localized polyps well within real-time constraints using an ordinary desktop machine with a contemporary graphics processing unit. This system could increase the ADR and decrease interval colorectal cancers but requires validation in large multicenter trials.

Interval colorectal cancer: a challenging field in colorectal cancer

Accumulated evidence has shown that colonoscopy may not be a perfect tool in screening and reducing the incidence of the colorectal cancer (CRC), because interval CRC (I-CRC), a specific subgroup of CRCs, has been challenging the traditional detection technology in recent years. I-CRC is accounting for an increasing proportion in CRCs. However, the effective procedures to prevent and supervise I-CRC need to be explored. In this review, we summarized the incidence, causes, risk factors, characteristics and management of I-CRC. It would promote the awareness of the special value in the education and training for the gastroenterologists, which plays an important role in conquering CRC.

Current standards and new developments of colorectal polyp management and resection techniques

Colonoscopy and endoscopic removal of precancerous polyps play an important role in colorectal cancer (CRC) prevention. Improved endoscopes and quality standards have led to an increasing polyp and adenoma detection rate. Optimal polyp resection techniques and management strategies are key for an effective colonoscopy practice. Areas covered: Strategies for how to improve diminutive polyp (polyps up to 5 mm in size) management are discussed because of their high prevalence. Systematic removal of diminutive polyps leads to increasing costs of colonoscopy practice, while the effect on colorectal cancer prevention might be negligible. Furthermore, polypectomy recommendations for mid-size and large polyps are provided. For all larger polyps larger, complete and safe resection is mandatory to avoid post colonoscopy cancers. The focus for managing such larger polyps is to use new techniques (i.e. cold snares) and to attempt complete removal and to reduce post-polypectomy complications. Expert commentary: The resect-and-discard strategy is a promising management strategy for diminutive polyps. However, modification of this approach might be required in order to make widespread adoption feasible. Cold snare polypectomy is a promising new approach for small polyp resection. For resection of large polyps adequate treatment recommendations with regard to endoscopic mucosal resection and complication prevention are provided.

Faecal occult blood testing screening for colorectal cancer and 'missed' interval cancers: are we ignoring the elephant in the room? Results of a multicentre study

AIM

Biennial faecal occult blood testing (FOBT) is used to screen for colorectal cancer throughout the UK. Interval cancers are tumours that develop in patients between screening rounds who have had a negative FOBT. Through a multicentre study, we compared the demographics of patients with interval cancers, FOBT screen detected cancers and cancers that developed in patients who chose not to participate in the screening programme.

METHOD

Five hundred and sixteen colorectal cancers were detected in the screening age group (60-74 years) population in three UK National Health Service hospitals over 2 years. One hundred and twenty seven (25%) were interval cancers, 161 (31%) were screen detected and 228 (44%) were cancers that developed in patients who had declined FOBT. The interval cancer group had a higher incidence of right-sided cancers (38% vs 29% and 24%), a higher proportion of high tumour stages (Dukes C and D) (70% vs 53% and 33%) and a shorter time from diagnosis to death (10 months vs 13 months and 24 months) compared to patients who had declined the FOBT and the FOBT screen detected cancers. Of all the patients studied, those with right-sided interval cancers had the worst outcome.

CONCLUSION

A quarter of the colorectal cancers diagnosed in our study were interval cancers. Patients with right-sided interval cancers had the highest proportion of Dukes C and D tumours coupled with the shortest survival time after diagnosis compared with the other groups.

Colorectal Cancer: Genetics is Changing Everything

Cancer is fundamentally a genetic disease caused by mutational or epigenetic alterations in DNA. There has been a remarkable expansion of the molecular understanding of colonic carcinogenesis in the last 30 years and that understanding is changing many aspects of colorectal cancer care. It is becoming increasingly clear that there are genetic subsets of colorectal cancer that have different risk factors, prognosis, and response to treatment. This article provides a general update on colorectal cancer and highlights the ways that genetics is changing clinical care.

Colorectal cancer development and advances in screening

Most colon tumors develop via a multistep process involving a series of histological, morphological, and genetic changes that accumulate over time. This has allowed for screening and detection of early-stage precancerous polyps before they become cancerous in individuals at average risk for colorectal cancer (CRC), which may lead to substantial decreases in the incidence of CRC. Despite the known benefits of early screening, CRC remains the second leading cause of cancer-related deaths in the United States. Hence, it is important for health care providers to have an understanding of the risk factors for CRC and various stages of disease development in order to recommend appropriate screening strategies. This article provides an overview of the histological/molecular changes that characterize the development of CRC. It describes the available CRC screening methods and their advantages and limitations and highlights the stages of CRC development in which each screening method is most effective.

Multi-Target Stool DNA Test: Is the Future Here?

Colorectal cancer (CRC) screening reduces CRC incidence and mortality and is widely recommended. However, despite these demonstrated benefits, a large percentage of the population remains unscreened. The multi-target stool DNA (MT-sDNA) test is a new, non-invasive option for CRC screening that has a high accuracy rate in detection of colorectal neoplasia and offers great opportunity to enhance screening uptake. This review provides the current state of the art knowledge about the use of MT-sDNA in CRC screening.

Should Assessment of Quality Indicator of Colonoscopy Be Varied Depending on the Colonoscopic Technique Level?

BACKGROUND/AIM

The purpose of this research was to evaluate if withdrawal time is a useful index in spite of differences in gastroenterologists' ability and if there are other quality indicators of colonoscopy.

METHODS

A total of 665 consecutive, asymptomatic individuals of average risk between 50 and 75 years of age who underwent screening colonoscopies performed by 12 gastroenterologists were included in this study. The endoscopists were classified to either the experienced group (group A, N = 6) or the under-experienced group (group B, N = 6). The endoscopists were unaware that they were being studied during the two-month study period.

RESULTS

In group A, adenoma detection rate was 0.56, while in group B it was 0.43 (P = 0.048). The mean withdrawal time ranged widely from 4.2 to 10.3 min per patient with a mean value of 6.83 for group A and 6.54 for group B. There was a significantly positive relationship between the number of adenomas detected and the withdrawal time for group B (r = 0.827, P = 0.005), but not for group A (r = -0.152, P = 0.584). In the case of group A, the ratio of cecal intubation time to withdrawal time (I/E ratio) less than 1 showed significantly correlated adenoma detection rate compared to I/E ratio greater than 1 (r = -0.308, P = 0.036). In the case of group B, mean I/E ratio was 1.7 and all endoscopists' I/E ratios were greater than 1.

CONCLUSIONS

For experienced endoscopists, a useful supplementary quality indicator of colonoscopy is to keep intubation/withdrawal time ratio less than 1 and it is necessary for under-experienced endoscopists to try to keep enough withdrawal time.

Stool DNA Testing for Screening Detection of Colorectal Neoplasia in Alaska Native People

OBJECTIVE

To assess the accuracy of a multitarget stool DNA test (MT-sDNA) compared with fecal immunochemical testing for hemoglobin (FIT) for detection of screening-relevant colorectal neoplasia (SRN) in Alaska Native people, who have among the world's highest rates of colorectal cancer (CRC) and limited access to conventional screening approaches.

PATIENTS AND METHODS

We performed a prospective, cross-sectional study of asymptomatic Alaska Native adults aged 40-85 years and older undergoing screening or surveillance colonoscopy between February 6, 2012, and August 7, 2014.

RESULTS

Among 868 enrolled participants, 661 completed the study (403 [61%] women). Overall, SRN detection by MT-sDNA (49%) was superior to that by FIT (28%; P<.001); in the screening group, SRN detection rates were 50% and 31%, respectively (P=.01). Multitarget stool DNA testing detected 62% of adenomas 2 cm or larger vs 29% by FIT (P=.05). Sensitivity by MT-sDNA increased with adenoma size (to 80% for lesions ≥3 cm; P=.01 for trend) and substantially exceeded FIT sensitivity at all adenoma sizes. For sessile serrated polyps larger than 1 cm (n=9), detection was 67% by MT-sDNA vs 11% by FIT (P=.07). For CRC (n=10), detection was 100% by MT-sDNA vs 80% by FIT (P=.48). Specificities were 93% and 96%, respectively (P=.03).

CONCLUSION

The sensitivity of MT-sDNA for cancer and larger polyps was high and significantly greater than that of FIT for polyps of any size, while specificity was slightly higher with FIT. These findings could translate into high cumulative neoplasm detection rates on serial testing within a screening program. The MT-sDNA represents a potential strategy to expand CRC screening and reduce CRC incidence and mortality, especially where access to endoscopy is limited.

Detection of Polyps After Resection of Colorectal Cancer

Purpose

Because colonoscopy after colorectal cancer surgery is important for detecting synchronous or metachronous colorectal neoplasms, we designed this study to investigate, by using postoperative colonoscopy, the miss rate for and the location of polyps remaining after colorectal cancer surgery.

Methods

In a prospectively-collected patient database, 264 patients were shown to have undergone a colorectal cancer resection between May 2012 and June 2013. Of these, 116 who had received a complete colonoscopy preoperatively and postoperatively were included in this study.

Results

Of these 116 patients, 68 were males and 48 were females; their mean age was 63 years. The mean time after surgery at which postoperative colonoscopy was performed was 7.1 months (range, 3-15 months). On postoperative colonoscopy, a total of 125 polyps were detected. Of these, there were no cancerous lesions; 46 (36.8%) were neoplastic polyps, and 79 (63.2%) were nonneoplastic polyps. Fifty-nine polyps (47.2%) and 15 polyps (12%) were located in the proximal and the distal parts of the anastomosis, respectively. The miss rates for the total numbers of polyps and of neoplastic polyps remaining after surgery were 37.4% and 24.2%, respectively. The incidence of neoplastic polyps increased during postoperative colonoscopy as it had during preoperative colonoscopy (r = 0.164, P = 0.048).

Conclusion

Colonoscopic surveillance after colorectal cancer resection results in the detection of pathologic polyps in one-fourth of the cases. During postoperative colonoscopy, careful examination of the proximal colon is necessary. Patients in whom multiple neoplastic polyps had been detected during preoperative colonoscopy require careful and thorough follow-up.

Physician report cards and implementing standards of practice are both significantly associated with improved screening colonoscopy quality

OBJECTIVES

Adenoma-detection rates (ADRs) are associated with decreased interval colorectal cancer (CRC) rates and CRC mortality; quality improvement strategies focus on improving physician ADRs. The objective of this study was to examine the sequential effect of physician report cards and implementing institutional standards of practice (SOP) on ADRs.

METHODS

Colonoscopy metrics were prospectively evaluated at a single academic medical center over a 23-month period (November 2012 to October 2014). ADRs were evaluated over three time periods-Period 1: Before initial report card distribution or SOP (November 2012 to March 2013); Period 2: After individualized report card distribution detailing physician and institutional ADRs (April 2013 to March 2014); Period 3: After second report card and SOP implementation (April 2014 to October 2014). The SOP required physicians to have a minimum 5-min withdrawal time in normal colonoscopies (WT) and an ADR minimum of 20%; those who did not meet benchmarks would require further training or endoscopy block time alterations. Only endoscopists averaging >15 colonoscopies/month were included in this analysis.

RESULTS

Twenty endoscopists met the inclusion criteria, performing 12,894 screening colonoscopies over the 23-month period. Following report card distribution, physician ADRs increased by 3% (P<0.001). SOP implementation resulted in a further significant increase in mean physician ADR of 8% (P<0.0001). Overall, mean ADR increased by 11% from Period 1 to Period 3 (P<0.0001). All physicians met the minimum 20% ADR benchmark during Period 3. Although ADRs significantly correlated with WT overall (r=0.45; 95% CI 0.01, 0.75; P=0.04), mean WT did not significantly increase from Period 1 to Period 3.

CONCLUSIONS

Our data suggest that distributing colonoscopy quality report cards resulted in a significant ADR improvement. Further, we report evidence that implementing SOP significantly improved ADRs beyond report card distribution and resulted in all endoscopists meeting minimum benchmarks. This suggests that report cards and SOPs may have an additive effect in improving colonoscopy quality, and their implementation in endoscopy labs should be encouraged.

Risk factors of developing interval early gastric cancer after negative endoscopy

BACKGROUND

New or missed gastric cancer rates after negative endoscopy are high. However, the clinicopathologic characteristics of missed or interval early gastric cancer (EGC) are not well known. The aim of this study was to evaluate clinicopathologic and endoscopic characteristics of missed or interval EGC after negative endoscopy.

METHODS

We retrospectively analyzed 1,055 patients with EGC confirmed by endoscopic resection or surgery between June 2006 and July 2013. Referred patients with diagnosed or suspected gastric neoplasms were excluded (n = 771). Interval EGC was defined as gastric cancer diagnosed within 2 years of negative endoscopy. Clinicopathologic characteristics of patients with initially detected and interval EGC and risk factors for interval EGC were investigated.

RESULTS

Of 284 patients, 52 had interval EGC (18.3 %; mean age 65.4 years; average interval between diagnosis and previous endoscopy, 12.6 months). Tumors were significantly smaller (1.3 vs. 1.8 cm, P < 0.001), and the incidence of metaplasia was significantly higher (90.4 vs. 65.9 %, P < 0.001) for interval EGC than for initially detected EGC. And no symptoms (50 vs. 17.7 %, P < 0.001) were significantly associated with interval EGC. However, tumor location, differentiation, gross morphology, and Helicobacter pylori infection status did not differ significantly.

CONCLUSIONS

Subtle mucosal lesions with surrounding intestinal metaplasia were associated with interval EGC. Careful endoscopic screening for patients with intestinal metaplasia at short-term interval would be beneficial for decreasing interval EGC rates.

Multi-target stool DNA test: a new high bar for noninvasive screening

Stool DNA testing has evolved into what is now a highly accurate and well-validated test for the screen detection of colorectal neoplasia. An optimized and automated multi-target stool DNA test (MT-sDNA) has achieved the same high point-sensitivities as reported for colonoscopy and significantly higher sensitivity than by fecal immunochemical blood testing for detection of early-stage cancer and advanced precancer. Thus, MT-sDNA sets a new high criterion standard for the noninvasive screen detection of colorectal neoplasia. With clinical application, MT-sDNA has potential to meaningfully address current gaps in our approach to CRC screening through benefits of its high accuracy on screening effectiveness, user-friendly features on patient compliance, and easy mail-out distribution on test access. The US Food and Drug Administration and Center for Medicaid and Medicare Services have recently completed their parallel reviews of MT-sDNA, which has just become available for clinical use. This review summarizes the recent clinical validation data on MT-sDNA, addresses central clinical questions at this front end of implementation, and touches on innovative future applications of stool DNA testing.

Interval cancers in a population-based screening program for colorectal cancer in catalonia, Spain

Objective. To analyze interval cancers among participants in a screening program for colorectal cancer (CRC) during four screening rounds. Methods. The study population consisted of participants of a fecal occult blood test-based screening program from February 2000 to September 2010, with a 30-month follow-up (n = 30,480). We used hospital administration data to identify CRC. An interval cancer was defined as an invasive cancer diagnosed within 30 months of a negative screening result and before the next recommended examination. Gender, age, stage, and site distribution of interval cancers were compared with those in the screen-detected group. Results. Within the study period, 97 tumors were screen-detected and 74 tumors were diagnosed after a negative screening. In addition, 17 CRC (18.3%) were found after an inconclusive result and 2 cases were diagnosed within the surveillance interval (2.1%). There was an increase of interval cancers over the four rounds (from 32.4% to 46.0%). When compared with screen-detected cancers, interval cancers were found predominantly in the rectum (OR: 3.66; 95% CI: 1.51-8.88) and at more advanced stages (P = 0.025). Conclusion. There are large numbers of cancer that are not detected through fecal occult blood test-based screening. The low sensitivity should be emphasized to ensure that individuals with symptoms are not falsely reassured.

Sessile serrated polyps: detection, eradication, and prevention of the evil twin

OPINION STATEMENT

The sessile serrated polyp (SSP), also known as sessile serrated adenoma, is the evil twin among the colorectal cancer precursors. As will be described, these lesions have multiple aliases (serrated adenoma, serrated polyp, or serrated lesion among others), they hang out in a bad neighborhood (the poorly prepped right colon), they hide behind a mask of mucus, they are difficult for witnesses (pathologists) to identify, they are difficult for police (endoscopists) to find, they are difficult to permanently remove from the society (high incomplete resection rate), they can be impulsive (progress rapidly to colorectal cancer (CRC)), and enforcers (gastroenterologists) do not know how best to control them (uncertain surveillance recommendations). There is no wonder that there is a need to understand these lesions well, learn how best to prevent the colonic mucosa from going down this errant path or, if that fails, detect these deviants and eradicate them from the colonic society. These lesions should be on endoscopists' most wanted list.

Diverticulosis and the risk of interval colorectal cancer

BACKGROUND

Diverticulosis, a prevalent condition at screening colonoscopy, has been associated with colorectal cancers that develop after a clearing colonoscopy, or interval cancers.

AIMS

To quantify the overall risk of diverticulosis in the development of interval cancers and examine this association in relevant subgroups.

METHODS

Using a linked database containing SEER tumor registry data and Medicare claims, we identified patients aged ≥69 years with colorectal cancer who underwent colonoscopy within 6 months of diagnosis. Patients with an additional colonoscopy from 36 to 6 months prior to cancer diagnosis were characterized as having interval cancers. We compared characteristics of patients with interval cancers and detected cancers according to a diagnosis of diverticulosis not associated with a colonoscopy procedure from 1991 through the date of the most recent colonoscopy in both univariate and multivariate models.

RESULTS

A previous diagnosis of diverticulosis was documented in 14,452 (26.9 %) patients with detected cancers compared to 2,905 (69.3 %) patients with interval cancers (p < 0.001); these results were consistent in multivariable analysis. Moreover, the association was found as well in the proximal colon (OR 2.88, 95 % CI 2.66, 3.12), distal colon (OR 3.56, 95 % CI 3.09, 4.11), and rectum (OR 4.07, 95 % CI 3.34, 4.95). The vast majority of diverticulosis diagnoses were without complications such as hemorrhage or diverticulitis.

CONCLUSIONS

Diverticulosis was strongly associated with interval colorectal cancers in all segments of the colon. Given its known predominance in the left colon, the findings argue against impaired visualization of lesions at colonoscopy as the only pathogenic factor.

Genetic mechanisms in interval colon cancers

BACKGROUND AND AIM

The factors underlying the development of interval colon cancers are not well defined and are likely heterogeneous. We sought to determine whether there are distinct molecular properties associated with interval colon cancers.

METHODS

Colon cancers diagnosed within 5 years of a complete and well-prepped colonoscopic examination were identified over a 7-year period at a single institution. The clinical and pathological features of the tumors were defined. Analysis of DNA mismatch repair (MMR) and genotyping of a panel of oncogenes associated with colon cancer were performed.

RESULTS

Forty-two interval colon cancers were diagnosed at an average age of 70 years. 69 % of tumors were located in the right colon. 41 % of tumors exhibited DNA microsatellite instability (MSI). Loss of staining of DNA MMR proteins by immunohistochemistry (IHC) was confirmed in 82 % of the MSI-positive tumors. Among tumors with abnormal MSI and IHC, 54 % exhibited somatic methylation of the MLH1 promoter, but the remaining 43 % exhibited molecular features indicative of underlying Lynch syndrome (LS). The frequency of somatic mutations in the KRAS, BRAF, NRAS, and PIK3CA oncogenes was similar between interval cancer cases and controls.

CONCLUSIONS

Interval colon cancers are not distinguished by the activation of the KRAS, NRAS, BRAF, or PIK3CA oncogenic pathways. However, MSI pathway defects are present in a significant proportion of interval colon cancers. Underlying LS may explain nearly half of these MSI-positive cases, and the remaining cases appear to represent sporadic serrated pathway tumors.

Endoscopic surveillance of gastrointestinal premalignant lesions: current knowledge and future directions

PURPOSE OF REVIEW

Provide an evidence-based resource for the surveillance of gastrointestinal premalignant lesions, focusing on the scientific articles reported recently.

RECENT FINDINGS

No randomized controlled clinical trials exist to definitively support the efficacy of surveillance programs for Barrett's esophagus and gastric intestinal metaplasia. However, surveillance of these premalignant lesions is recommended by some of the leading organizations. To optimize the usefulness of surveillance programs, targeting high-risk patients might maximize its benefits. A Barrett's esophagus segment of at least 3 cm and evidence of intestinal metaplasia can help stratify those patients at highest risk for progression to esophageal adenocarcinoma. The location, extent, and severity of intestinal metaplasia are indicators of risk of developing gastric cancer. Patients with extensive intestinal metaplasia should be offered endoscopic surveillance. Quality in the baseline colonoscopy is crucial to decrease the risk of interval colorectal cancers. The importance of serrated polyps, as well as their surveillance intervals, is emphasized.

SUMMARY

To optimize the usefulness of surveillance programs, targeting high-risk patients might maximize its benefits. Future research is needed to design more effective surveillance strategies. Recently, emerging imaging techniques hold promise for improving sensitivity of endoscopic surveillance of premalignant conditions in the gastrointestinal tract.

Prevalence, risk factors, and outcomes of interval colorectal cancers: a systematic review and meta-analysis

OBJECTIVES

We performed meta-analysis to estimate pooled prevalence, risk factors, and outcomes of interval colorectal cancers (CRCs).

METHODS

Systematic literature search through October 2013, identified population-based studies, reporting prevalence of interval CRCs (CRCs diagnosed within 6-36 months of colonoscopy). We estimated the pooled prevalence, patient, endoscopist, and tumor-related risk factors, as well as outcomes of interval CRCs, as compared with detected CRCs (CRCs diagnosed at or within 6 months of colonoscopy).

RESULTS

Twelve studies reporting on 7,912 interval CRCs were included. Pooled prevalence of interval CRCs was 3.7% (95% confidence interval (CI)=2.8-4.9%). These cancers were 2.4 times more likely to arise in the proximal colon (6.5%; 95% CI=4.9-8.6%) as compared with distal colon (2.9%; 95% CI=2.0-4.2%). Patients with interval CRCs were older (age >65-70 years vs. <65-70 years: odds ratio (OR)=1.15; 95% CI=1.02-1.30), have more comorbidities (high Charlson comorbidity index: OR=2.00; 95% CI=1.77-2.27), and have diverticular disease (OR=4.25; 95% CI=2.58-7.00). There was a nonsignificant time trend of declining prevalence of interval CRCs from 4.8% in 1990s to 4.2% between 2000 and 2005 and 3.7% beyond 2005. Patients with interval CRCs were less likely to present at an advanced stage (OR=0.79; 95% CI=0.67-0.94), although there was no survival benefit. Considerable heterogeneity was observed in most of the analyses.

CONCLUSIONS

Based on meta-analysis, approximately 1 in 27 CRCs are interval CRCs, although the confidence in these estimates is low because of the heterogeneity among the studies. These are more likely to arise in the proximal colon and are diagnosed in older patients, patients with comorbidities or diverticular disease.

Excess of proximal microsatellite-stable colorectal cancer in African Americans from a multiethnic study

PURPOSE

African Americans (AA) have the highest incidence of colorectal cancer compared with other U.S. populations and more proximal colorectal cancers. The objective is to elucidate the basis of these cancer disparities.

EXPERIMENTAL DESIGN

Of note, 566 AA and 328 non-Hispanic White (NHW) colorectal cancers were ascertained in five Chicago hospitals. Clinical and exposure data were collected. Microsatellite instability (MSI) and BRAF (V600E) and KRAS mutations were tested. Statistical significance of categorical variables was tested by the Fisher exact test or logistic regression and age by the Mann-Whitney U test.

RESULTS

Over a 10-year period, the median age at diagnosis significantly decreased for both AAs (68-61; P < 0.01) and NHWs (64.5- 62; P = 0.04); more AA patients were diagnosed before age 50 than NHWs (22% vs. 15%; P = 0.01). AAs had more proximal colorectal cancer than NHWs (49.5% vs. 33.7%; P < 0.01), but overall frequencies of MSI, BRAF and KRAS mutations were not different nor were they different by location in the colon. Proximal colorectal cancers often presented with lymphocytic infiltrate (P < 0.01) and were diagnosed at older ages (P = 0.02). Smoking, drinking, and obesity were less common in this group, but results were not statistically significant.

CONCLUSIONS

Patients with colorectal cancer have gotten progressively younger. The excess of colorectal cancer in AAs predominantly consists of more proximal, microsatellite stable tumors, commonly presenting lymphocytic infiltrate and less often associated with toxic exposures or a higher BMI. Younger AAs had more distal colorectal cancers than older ones. These data suggest two different mechanisms driving younger age and proximal location of colorectal cancers in AAs.