Risk of advanced proximal neoplasms in asymptomatic adults according to the distal colorectal findings

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Profile of colorectal polyps in young patients: A retrospective study

There is an increased incidence of colorectal cancer in young patients, however, the relationship between polyp characteristics and histology is not clearly understood. This study aimed to investigate the prevalence of different histological types of polyps in young patients and risk factors associated with advanced histology. Young patients (aged <45) who underwent polypectomy at Sir Run Run Shaw Hospital (2015-2017, Zhejiang, China) and West China Xiamen Hospital (2023-2024, Xiamen, China) were included. A database of endoscopes was accessed to classify polyps according to endoscopic features. The distribution of polyps and the risk factors associated with advanced histology were reported. The detection rate of polyps among the young adults was 20%, with 47.6% of adenoma. Hyperplastic polyps were second only to tubular adenomas in frequency. Of the 2776 polyps, nearly 85% were sessile, 29.4% were located in the sigmoid colon, and 25.4% were located in the rectum. Among polyps, 87.3% were <10 mm in diameter. Histological features of advanced adenoma were found in 5.3% of patients. Of these, 30.4% occurred in polyps <10 mm. Furthermore, 69.6% were distributed in the distal colorectum. Multivariate logistic regression analysis demonstrated that polyp size and morphology were independent predictors of advanced adenomas. In young patients, polyps are mainly located in the distal colorectum, with tubular adenoma being the predominant type. Large size and pedunculated morphology were independent predictors of advanced polyp histology in young patients. Nearly one-third of the advanced histology cases were associated with small polyps. It is recommended that endoscopists resect all neoplastic polyps found during colonoscopy, especially pedunculated polyps, and submit them for histology.

Colonoscopy Remains an Important Option for Primary Screening for Colorectal Cancer

Colonoscopy remains the most commonly used colorectal cancer screening test in the United States. A substantial portion of the screening population value the high sensitivity of colonoscopy for precancerous colorectal lesions of all sizes, which allows it to be performed at 10 year intervals in average-risk persons with negative examinations. Emerging evidence supports the eventual endorsement of 15 year intervals for patients with normal examinations. Considerable evidence supports an impact of colonoscopy on colorectal cancer incidence and mortality, including a randomized controlled trial of colonoscopy vs. no screening, numerous case-control and cohort studies, an impact of fecal blood testing on cancer incidence, and the impact of one randomized controlled trial of flexible sigmoidoscopy on proximal colon cancer incidence. Colonoscopy is the gold standard for detection of colorectal precancerous lesions, and continues to evolve with regard to sensitivity for precancerous lesions and the effectiveness and safety of precancerous lesion resection. Gains in detection of precancerous lesions have followed from a robust movement to improve colonoscopy quality, and development of non-device techniques such as patient rotation during withdrawal, water exchange colonoscopy, and double examination of one or more colonic segments. Further, development of devices to improve mucosal exposure during withdrawal (e.g. Endocuff Vision, distal cap attachment, and Computer-Aided Quality), and devices that highlight flat lesions (e.g. chromoendoscopy, electronic chromoendoscopy, and Computer-Aided Detection) have created opportunities to achieve very high levels of detection and thereby increase the protective benefits of colonoscopy. Further, colonoscopy resection safety has improved via the widespread use of cold resection for lesions < 10 mm in size, as well as sessile serrated lesions of all sizes. Colonoscopy can be offered to patients as one of multiple options for screening, or as the test of choice for patients with the highest pre-screening probability of cancer and precancerous lesions, or as the first test offered followed by offers of other screening tests if colonoscopy is declined (sequential offers of screening). Sequential offers of screening result in overall adherence to screening similar to offering multiple options, but with a higher fraction of patients undergoing colonoscopy. Given the long-lasting protective effects of colonoscopy and its improving effectiveness and safety, colonoscopy remains a useful option for primary average-risk colorectal cancer screening.

Impact of racial disparities in follow-up and quality of colonoscopy on colorectal cancer outcomes

BACKGROUND

The benefits of colorectal cancer (CRC) screening programs rely on completing follow-up colonoscopy when a noncolonoscopy test is abnormal and on quality of colonoscopy screening as measured by the endoscopists' adenoma detection rate. Existing data demonstrate substantially lower follow-up colonoscopy rates and adenoma detection rate for Black Americans than White Americans. However, the contributions of racial differences in follow-up colonoscopy and adenoma detection rate on CRC outcomes have not been rigorously evaluated.

METHODS

We used established and validated CRC-Adenoma Incidence and Mortality (CRC-AIM) model as our analysis platform, with inputs from published literature that report lower follow-up colonoscopy rates and adenoma detection rate in Black adults compared with White adults (15% and 10% lower, respectively). We simulated screening with annual fecal immunochemical test, triennial multitarget stool DNA, and colonoscopy every 10 years between ages 45 and 75 years using real-world utilization of the screening modalities vs no screening. We reported lifetime outcomes per 1000 Black adults.

RESULTS

Elimination of Black-White disparities in follow-up colonoscopy rates would reduce CRC incidence and mortality by 5.2% and 9.3%, respectively, and improve life-years gained with screening by 3.4%. Elimination of Black-White disparities in endoscopists' adenoma detection rate would reduce CRC incidence and mortality by 9.4% and improve life-years gained by 3.7%. Elimination of both disparities would reduce CRC incidence and mortality by 14.6% and 18.7%, respectively, and improve life-years gained by 7.1%.

CONCLUSIONS

This modeling study predicts eliminating racial differences in follow-up colonoscopy rates, and quality of screening colonoscopy would substantially reduce Black-White disparities in CRC incidence and mortality.

Fecal Immunochemical Test Screening and Risk of Colorectal Cancer Death

Importance

The fecal immunochemical test (FIT) is widely used for colorectal cancer (CRC) screening, but evidence of its effectiveness is limited.

Objective

To evaluate whether FIT screening is associated with a lower risk of dying from CRC overall, according to cancer location, and within demographic groups.

Design, Setting, and Participants

This nested case-control study in a cohort of screening-eligible people was conducted in 2 large, integrated health systems of racially, ethnically, and socioeconomically diverse members with long-term programs of mailed FIT screening outreach. Eligible participants included people aged 52 to 85 years who died from colorectal adenocarcinoma between 2011 and 2017 (cases); cases were matched in a 1:8 ratio based on age, sex, health-plan membership duration, and geographic area to randomly selected persons who were alive and CRC-free on case's diagnosis date (controls). Data analysis was conducted from January 2002 to December 2017.

Exposures

Completing 1 or more FIT screenings in the 5-year period prior to the CRC diagnosis date among cases or the corresponding date among controls; in secondary analyses, 2- to 10-year intervals were evaluated.

Main Outcomes and Measures

The primary study outcome was CRC death overall and by tumor location. Secondary analyses were performed to assess CRC death by race and ethnicity.

Results

From a cohort of 2 127 128 people, a total of 10 711 participants (3529 aged 60-69 years [32.9%]; 5587 male [52.1%] and 5124 female [47.8%]; 1254 non-Hispanic Asian [11.7%]; 973 non-Hispanic Black [9.1%]; 1929 Hispanic or Latino [18.0%]; 6345 non-Hispanic White [59.2%]) was identified, including 1103 cases and 9608 controls. Among controls during the 10-year period prior to the reference date, 6101 (63.5%) completed 1 or more FITs with a cumulative 12.6% positivity rate (768 controls), of whom 610 (79.4%) had a colonoscopy within 1 year. During the 5-year period, 494 cases (44.8%) and 5345 controls (55.6%) completed 1 or more FITs. In regression analysis, completing 1 or more FIT screening was associated with a 33% lower risk of death from CRC (adjusted odds ratio [aOR], 0.67; 95% CI, 0.59-0.76) and 42% lower risk in the left colon and rectum (aOR, 0.58; 95% CI, 0.48-0.71). There was no association with right colon cancers (aOR, 0.83; 95% CI, 0.69-1.01) but the difference in the estimates between the right colon and left colon or rectum was statistically significant (P = .01). FIT screening was associated with lower CRC mortality risk among non-Hispanic Asian (aOR, 0.37; 95% CI, 0.23-0.59), non-Hispanic Black (aOR, 0.58; 95% CI, 0.39-0.85) and non-Hispanic White individuals (aOR, 0.70; 95% CI, 0.57-0.86) (P for homogeneity = .04 for homogeneity).

Conclusions and Relevance

In this nested case-control study, completing FIT was associated with a lower risk of overall death from CRC, particularly in the left colon, and the associations were observed across racial and ethnic groups. These findings support the use of FIT in population-based screening strategies.

Screening for Colorectal Cancer

Colorectal cancer (CRC) is the second leading cause of cancer death. Screening has been proven to reduce both cancer incidence and cancer-related mortality. Various screening tests are available, each with their own advantages and disadvantages and varying levels of evidence to support their use. Clinicians should offer CRC screening to average-risk persons aged 50 to 75 years; starting screening at age 45 years remains controversial. Screening may be beneficial in select persons aged 76 to 85 years, based on their overall health and screening history. Offering a choice of screening tests or sequentially offering an alternate test for those who do not complete screening can significantly increase participation.

Effects of sigmoidoscopy screening (including colonoscopy) on colorectal cancer: A meta-analysis based on randomized controlled trials

Background

This study aimed to investigate the role of endoscopy screening in colorectal cancer (CRC).

Methods

Up to January 2023, databases were searched for studies related to sigmoidoscopy and colonoscopy screening. The incidence of CRC, and/or CRC mortality were the main observation outcomes.

Results

A total of 5 randomized controlled trials (RCTs) published from 2017 to 2022 were included. Among them, four studies used sigmoidoscopy screening and one study involved colonoscopy screening. Statistical results showed that the incidence (RR: 0.78, p < 0.001) and mortality (RR: 0.75, p < 0.001) of CRC were significantly lower in the screening group than in the control group. Further, a subgroup analysis of CRC site indicated that the incidence and mortality of CRC in the screening group were significantly lower than those in the non-screened group, regardless of distal CRC (Incidence: RR: 0.66, p < 0.001; Mortality: RR: 0.62, p < 0.001) or proximal CRC (Incidence: RR: 0.94, p = 0.038; Mortality: RR: 0.89, p = 0.038). In terms of gender, compared with the non-screening group, both males (Incidence: RR: 0.73, p < 0.001; Mortality: RR: 0.68, p < 0.001) and females (Incidence: RR: 0.85, p < 0.001; Mortality: RR: 0.85, p = 0.017), the screening group had a significant decrease in the incidence and mortality of CRC.

Conclusion

This meta-analysis demonstrated that sigmoidoscopy screening (including colonoscopy) could effectively reduce the incidence and mortality of CRC.

Population-based screening for colorectal cancer in Wuhan, China

Fecal DNA test has emerged as a non-invasive alternative for colorectal cancer (CRC) screening in average-risk population. However, there is currently insufficient evidence in China to demonstrate the effectiveness of population-based CRC screening using fecal DNA based test. Here, a large-scale real-world study for CRC screening was implemented in Wuhan, Hubei province, China. A total of 98,683 subjects aged between 45 and 60 years were screened by a fecal DNA test (ColoTect®) which detected methylation status of SDC2, ADHFE1, and PPP2R5C. Participants who tested positive were advised to receive diagnostic colonoscopy. 4449 (4.5%) subjects tested positive for fecal DNA test, and 3200 (71.9%) underwent colonoscopy. Among these, 2347 (73.3%) had abnormal colonoscopy findings, of which 1330 (56.7%) subjects received pathological diagnosis. Detection rates for CRC and advanced precancerous lesions were 1.3% and 2.3%, respectively. Detection rates for nonadvanced adenomas and polyps were 14.0% and 21.6%, respectively. 28.0% of all colonoscopies showed colorectal neoplasm but lack pathological diagnosis. 6.1% showed other abnormalities such as enteritis. In conclusion, preliminary real-world evidence suggested that fecal DNA tests had promising diagnostic yield in population-based CRC screening.

Clinical trial registration

https://www.chictr.org.cn/showproj.html?proj=192838, identifier ChiCTR2300070520.

Canadian Association of Radiologists Practice Guidelines for Computed Tomography Colonography

Colon cancer is the third most common malignancy in Canada. Computed tomography colonography (CTC) provides a creditable and validated option for colon screening and assessment of known pathology in patients for whom conventional colonoscopy is contraindicated or where patients self-select to use imaging as their primary modality for initial colonic assessment. This updated guideline aims to provide a toolkit for both experienced imagers (and technologists) and for those considering launching this examination in their practice. There is guidance for reporting, optimal exam preparation, tips for problem solving to attain high quality examinations in challenging scenarios as well as suggestions for ongoing maintenance of competence. We also provide insight into the role of artificial intelligence and the utility of CTC in tumour staging of colorectal cancer. The appendices provide more detailed guidance into bowel preparation and reporting templates as well as useful information on polyp stratification and management strategies. Reading this guideline should equip the reader with the knowledge base to perform colonography but also provide an unbiased overview of its role in colon screening compared with other screening options.

Automated Detection of Anatomical Landmarks During Colonoscopy Using a Deep Learning Model

BACKGROUND AND AIMS

Identification and photo-documentation of the ileocecal valve (ICV) and appendiceal orifice (AO) confirm completeness of colonoscopy examinations. We aimed to develop and test a deep convolutional neural network (DCNN) model that can automatically identify ICV and AO, and differentiate these landmarks from normal mucosa and colorectal polyps.

METHODS

We prospectively collected annotated full-length colonoscopy videos of 318 patients undergoing outpatient colonoscopies. We created three nonoverlapping training, validation, and test data sets with 25,444 unaltered frames extracted from the colonoscopy videos showing four landmarks/image classes (AO, ICV, normal mucosa, and polyps). A DCNN classification model was developed, validated, and tested in separate data sets of images containing the four different landmarks.

RESULTS

After training and validation, the DCNN model could identify both AO and ICV in 18 out of 21 patients (85.7%). The accuracy of the model for differentiating AO from normal mucosa, and ICV from normal mucosa were 86.4% (95% CI 84.1% to 88.5%), and 86.4% (95% CI 84.1% to 88.6%), respectively. Furthermore, the accuracy of the model for differentiating polyps from normal mucosa was 88.6% (95% CI 86.6% to 90.3%).

CONCLUSION

This model offers a novel tool to assist endoscopists with automated identification of AO and ICV during colonoscopy. The model can reliably distinguish these anatomical landmarks from normal mucosa and colorectal polyps. It can be implemented into automated colonoscopy report generation, photo-documentation, and quality auditing solutions to improve colonoscopy reporting quality.

Calibration and Validation of the Colorectal Cancer and Adenoma Incidence and Mortality (CRC-AIM) Microsimulation Model Using Deep Neural Networks

OBJECTIVES

Machine learning (ML)-based emulators improve the calibration of decision-analytical models, but their performance in complex microsimulation models is yet to be determined.

METHODS

We demonstrated the use of an ML-based emulator with the Colorectal Cancer (CRC)-Adenoma Incidence and Mortality (CRC-AIM) model, which includes 23 unknown natural history input parameters to replicate the CRC epidemiology in the United States. We first generated 15,000 input combinations and ran the CRC-AIM model to evaluate CRC incidence, adenoma size distribution, and the percentage of small adenoma detected by colonoscopy. We then used this data set to train several ML algorithms, including deep neural network (DNN), random forest, and several gradient boosting variants (i.e., XGBoost, LightGBM, CatBoost) and compared their performance. We evaluated 10 million potential input combinations using the selected emulator and examined input combinations that best estimated observed calibration targets. Furthermore, we cross-validated outcomes generated by the CRC-AIM model with those made by CISNET models. The calibrated CRC-AIM model was externally validated using the United Kingdom Flexible Sigmoidoscopy Screening Trial (UKFSST).

RESULTS

The DNN with proper preprocessing outperformed other tested ML algorithms and successfully predicted all 8 outcomes for different input combinations. It took 473 s for the trained DNN to predict outcomes for 10 million inputs, which would have required 190 CPU-years without our DNN. The overall calibration process took 104 CPU-days, which included building the data set, training, selecting, and hyperparameter tuning of the ML algorithms. While 7 input combinations had acceptable fit to the targets, a combination that best fits all outcomes was selected as the best vector. Almost all of the predictions made by the best vector laid within those from the CISNET models, demonstrating CRC-AIM's cross-model validity. Similarly, CRC-AIM accurately predicted the hazard ratios of CRC incidence and mortality as reported by UKFSST, demonstrating its external validity. Examination of the impact of calibration targets suggested that the selection of the calibration target had a substantial impact on model outcomes in terms of life-year gains with screening.

CONCLUSIONS

Emulators such as a DNN that is meticulously selected and trained can substantially reduce the computational burden of calibrating complex microsimulation models.

HIGHLIGHTS

Calibrating a microsimulation model, a process to find unobservable parameters so that the model fits observed data, is computationally complex.We used a deep neural network model, a popular machine learning algorithm, to calibrate the Colorectal Cancer Adenoma Incidence and Mortality (CRC-AIM) model.We demonstrated that our approach provides an efficient and accurate method to significantly speed up calibration in microsimulation models.The calibration process successfully provided cross-model validation of CRC-AIM against 3 established CISNET models and also externally validated against a randomized controlled trial.

Risk of colorectal advanced neoplasia in patients with acute diverticulitis with and without previous colonoscopy

BACKGROUND AND AIM

Guidelines recommend a colonoscopy after an episode of complicated diverticulitis and after a first episode of uncomplicated diverticulitis. The influence of a previous colonoscopy on postdiverticulitis colonoscopic findings has not been studied. The aim of this work was to examine the incidence of adenoma detection rate (ADR), advanced adenoma (AA) and colorectal cancer (CRC) in patients with diverticulitis with and without previous colonoscopy.

METHOD

This was a retrospective case-control study of subjects with acute diverticulitis. Subsequent and previous colonoscopies were abstracted for ADR, AA and CRC diagnoses. The incidence of neoplasia was compared between patients with and without previous colonoscopy and also with that of a screening population.

RESULTS

Compared with a healthy control group (n = 975), diverticulitis patients without prior colonoscopy (n = 325) had a significantly higher ADR (26.8% vs. 20.5%, p = 0.019) and invasive CRC rate (0.9% vs. 0%, p = 0.016). Risk factors for advanced neoplasia included age ≥ 70 years and complicated diverticulitis. Among subjects with diverticulitis and previous colonoscopy (n = 124), only one patient developed AA and there were no cancer cases.

CONCLUSIONS

A previous normal colonoscopy within 5 years before diverticulitis probably overshadows other risk factors for findings of advanced neoplasia and should be considered in the decision to repeat a colonoscopy.

Characteristics of adenomatous colorectal polyps among a Saudi population

Objectives

Colorectal cancer is a common cause of cancer-related mortality in KSA with a rising incidence. Although adenomatous polyps are well-recognized as precursors of colorectal cancer, local data are scarce. Therefore, in this study, we aimed to evaluate the characteristics of adenomatous colon polyps in the Saudi population.

Methods

We retrospectively reviewed the electronic databases of all patients who underwent colonoscopy for any indication between January 2015 and December 2019 at a tertiary care hospital. This study included adult patients who were found to have colorectal polyps with identified histopathology reports. We collected clinical and pathological data, including patient age, sex, and histopathological polyp characteristics. A p-value <0.05 was considered significant for descriptive and analytical statistics.

Results

A total of 184 patients with colorectal polyps with identified histopathology reports were included in the analysis. Of these, 130 (70.6%) patients were aged 50 years or older, and 135 (73.3%) were male. Among all polyps, 127 (69%) were adenomatous, 31 (16.8%) were hyperplastic, and 24 (13%) were inflammatory. For adenomatous polyps, 31 (24.4%) were observed in patients younger than 50 years, and high-grade dysplasia was observed in 23 (18%) polyps. Among patients with adenomatous polyps, the anatomical location was as follows: 27 (23%) in the cecum/ascending colon, 12 (9%) in the transverse colon, 45 (35%) in the descending/sigmoid colon, 25 (19%) in the rectum, and 18 (14%) at multiple sites. Age >50 years was significantly associated with adenomatous polyps (P = 0.03).

Conclusion

Approximately one-third of adenomatous polyps were detected proximal to the splenic flexure. Although adenomatous polyps were significantly associated with increasing age, 24% were observed in patients younger than 50 years of age. This finding supports the current recommendation to start screening at the age of 45.

Association of CDH1 Germline Variants and Colon Polyp Phenotypes in Patients with Hereditary Diffuse Gastric Cancer

Background and Aims

Germline CDH1 variants resulting in E-cadherin loss of function result in an increased risk of diffuse type gastric cancer and lobular type breast cancer. However, the risk of developing other epithelial neoplasms, specifically colorectal cancer, is unknown.

Methods

Patients enrolled in a prospective natural history study of hereditary gastric cancer who underwent at least one colonoscopy were evaluated.

Results

Out of 300 patients with CDH1 pathogenic or likely pathogenic variants, 85 underwent colonoscopy. More than half of patients (56%, 48/85) had at least one colorectal polyp. Most of those patients (83%, 40/48) had at least one precancerous polyp (adenoma or sessile serrated lesion). More than half (56%) of patients younger than age 45 had a colorectal polyp. Of those with polyps, the most frequent CDH1 variant type was canonical splice site (27%, 13/48) followed by nonsense (21%, 10/48). There was no association between CDH1 variant type and increased likelihood of colorectal polyps.

Conclusions

In summary, a majority of CDH1 variant carriers who underwent colonoscopy had colorectal polyps detected, and most subjects were less than 45 years old. This study of colorectal cancer risk based on the prevalence of colorectal polyps in the CDH1 population requires further investigation to appropriately counsel patients on colorectal cancer screening. Clinical trial registry website: https://clinicaltrials.gov/. Clinical trial number: NCT03030404.

Risk factors and prediction algorithm for advanced neoplasia on screening colonoscopy for average-risk individuals

BACKGROUND

Screening with colonoscopy for all average-risk population is probably not cost-effective due to the limited sources and over-generalization of the risk, and risk stratification can be used to optimize colorectal cancer screening.

OBJECTIVES

We aimed to assess risk factors for advanced neoplasia (AN) and a classification tree algorithm to predict the risk.

DESIGN

This is a retrospective cross-sectional study.

METHODS

This study was composed of consecutive asymptomatic average-risk individuals undergoing first screening colonoscopy between 2008 and 2019. Detailed characteristics including background diseases, habits, and medications were collected. We used multivariable logistic regression to investigate the associations between clinical variables and the presence of AN and built a classification algorithm to predict AN.

RESULTS

A total of 3856 patients were included (73.2% male, median age 55). Adenoma and AN detection rate were 15.8% and 3.4%, respectively. On multivariable analysis, predictors of AN [odds ratio (OR), 95% confidence interval (CI)] were age (1.04, 1.01-1.06, p = 0.003), male sex (2.69, 1.56-4.64, p < 0.001), and smoking (1.97, 1.38-2.81, p  < 0.001). A classification tree algorithm showed that smoking was the most important risk factor for prediction of AN (4.9% versus 2.4%, p < 0.001), followed by age with a cutoff value of 60 in the smokers (8.4% versus 3.8%, p = 0.001) and 50 in the non-smokers (2.9% versus 0.9%, p = 0.004).

CONCLUSION

Smoking habits, old age, and male gender are highly associated with an increased risk for AN and should be incorporated in the individualized risk-assessment to adapt a screening program.

Sequentially calibrating a Bayesian microsimulation model to incorporate new information and assumptions

BACKGROUND

Microsimulation models are mathematical models that simulate event histories for individual members of a population. They are useful for policy decisions because they simulate a large number of individuals from an idealized population, with features that change over time, and the resulting event histories can be summarized to describe key population-level outcomes. Model calibration is the process of incorporating evidence into the model. Calibrated models can be used to make predictions about population trends in disease outcomes and effectiveness of interventions, but calibration can be challenging and computationally expensive.

METHODS

This paper develops a technique for sequentially updating models to take full advantage of earlier calibration results, to ultimately speed up the calibration process. A Bayesian approach to calibration is used because it combines different sources of evidence and enables uncertainty quantification which is appealing for decision-making. We develop this method in order to re-calibrate a microsimulation model for the natural history of colorectal cancer to include new targets that better inform the time from initiation of preclinical cancer to presentation with clinical cancer (sojourn time), because model exploration and validation revealed that more information was needed on sojourn time, and that the predicted percentage of patients with cancers detected via colonoscopy screening was too low.

RESULTS

The sequential approach to calibration was more efficient than recalibrating the model from scratch. Incorporating new information on the percentage of patients with cancers detected upon screening changed the estimated sojourn time parameters significantly, increasing the estimated mean sojourn time for cancers in the colon and rectum, providing results with more validity.

CONCLUSIONS

A sequential approach to recalibration can be used to efficiently recalibrate a microsimulation model when new information becomes available that requires the original targets to be supplemented with additional targets.

Prevalence of colorectal cancer and its precursor lesions in symptomatic patients under 55 years of age undergoing total colonoscopy: results of a large retrospective, multicenter, controlled endoscopy study

PURPOSE

Colorectal cancer (CRC) is the second most common cancer in Germany. Around 60,000 people were diagnosed CRC in 2016 in Germany. Since 2019, screening colonoscopies are offered in Germany for men by the age of 50 and for women by the age of 55. It is recently discussed if women should also undergo a screening colonoscopy by the age of 50 and if there are any predictors for getting CRC.

METHODS

Colonoscopies of 1553 symptomatic patients younger than 55 years were compared with colonoscopies of 1075 symptomatic patients older than 55 years. We analyzed if there are any significant differences between those two groups in the prevalence of CRC and its precursor lesions or between symptomatic men and women. We evaluated if there is a correlation between abdominal symptoms and the prevalence of CRC.

RESULTS

In 164/1553 symptomatic patients, 194 (12.5%) polyps were detected. In total, six colorectal carcinomas (0.4%) were detected. There were no significant differences between men and women. In symptomatic patients ≥ 55 years, significantly more polyps were found (p<0.0001; 26.6% vs. 12.5%). Totally, 286 polyps (26.6%) were removed in 1075 symptomatic patients older than 55 years. Anorectal bleeding was the only abdominal symptom being a significant indicator for the prevalence of the occurrence of colon and rectum cancer in both groups (p=0.03, OR=2.73 95%-CI [1.11;6.70]), but with only low sensitivity (44%).

CONCLUSION

Due to no significant differences in men and women, we recommend screening colonoscopies also for women by the age of 50.

Colonoscopy quality indicators in patients with and without prior colonic resection: A single-centre prospective comparative study

AIM

Effective colonoscopy relies on meeting rigorous quality control thresholds. Some earlier studies evaluating colonoscopy key performance indicators (KPIs) have excluded patients who have previously undergone colonic resection (i.e., they have a nonintact colon); such patients also deserve high-quality colonoscopy. This study aimed to compare colonoscopy KPIs between patients with nonintact and intact colons.

METHOD

Consecutive colonoscopies performed at Whanganui Hospital (New Zealand) between September 2016 and March 2020 were included. The primary outcome was the caecal or ileal intubation rate (CIIR). Secondary outcomes were the adenoma detection rate (ADR), polyp detection rate (PDR), colonoscope withdrawal time (CWT) and caecal or ileal intubation time (CIIT).

RESULTS

In total, 3017 colonoscopies were performed: 322 in nonintact colons and 2695 in intact colons. CIIR was significantly higher in nonintact than in intact colons (98.4% vs. 95.0%; P = 0.0086). When all colonoscopies were included, the CIIR was 95.4%; this value decreased to 95.0% when nonintact colonoscopies were excluded. However, the ADR (39.9% vs. 38.8%; P = 0.77) and PDR (58.4% vs. 59.1%; P = 0.86) were similar for both nonintact and intact colons. CWT (P < 0.0001) and CIIT (P < 0.0001) were significantly shorter in participants with nonintact colons.

CONCLUSION

The CIIR exceeded recommended targets and was 3.4% higher in patients with nonintact than intact colons. Patients with nonintact colons comprise a small proportion of the overall colonoscopy cohort and it is unlikely that this small difference is relevant for most endoscopists or endoscopy units. The ADR and PDR were similar among patients with nonintact and intact colons, despite nonintact colonoscopies being significantly quicker. Patients with nonintact colons deserve high-quality colonoscopy and therefore their KPIs should be included in colonoscopy performance reports.

Association between baseline hyperplastic polyps and metachronous serrated lesions

BACKGROUND AND AIMS

Some data suggest that individuals with numerous, <10-mm, rectosigmoid hyperplastic polyps (HPs) are at average risk for the development of metachronous advanced adenomatous neoplasia. Guidelines suggest that these individuals do not need surveillance colonoscopy and should be followed akin to individuals with a normal colonoscopy. Less is known of the risk of metachronous neoplasia because of ≥1 HPs <10 mm proximal to the sigmoid colon. We compared the risk of metachronous neoplasia between individuals with small HPs and those with normal colonoscopy, specifically addressing the impact of location and number of HPs on risk.

METHODS

Colonoscopy and pathology reports from patients with ≥2 colonoscopies between 2004 and 2014 were reviewed. Exclusions included inpatients; age <40 or >75 years; and family or personal history of colorectal cancer, inflammatory bowel disease, previous colorectal surgery, or a previous colonoscopy with any adenoma, sessile serrated lesion (SSL), or HP ≥10 mm. The risk of metachronous neoplasia, including adenomas and SSLs, was compared in individuals with a normal index colonoscopy and those with <10-mm HPs stratified by location and number of HPs.

RESULTS

After exclusion, 1795 patients were included. At index colonoscopy, 82% (n = 1469) had a normal examination, 12% (219) had only 1, and 6% (107) had between 2 and 9 HPs <10 mm. Compared with patients with a normal index colonoscopy, patients with a proximal (odds ratio, 3.82; 95% confidence interval, 1.77-7.53) or distal HP (odds ratio, 2.23; 95% confidence interval, 1.18-4.00) had an increased risk of metachronous SSLs but not adenomas.

CONCLUSIONS

Patients with small proximal and distal HPs are at increased risk of metachronous SSLs. These preliminary findings warrant consideration during surveillance recommendations and future studies in larger cohorts.

Screening colonoscopy: The present and the future

In the United States, colorectal cancer (CRC) is the second leading cause of mortality in men and women. We are now seeing an increasing number of patients with advanced-stage diagnosis and mortality from colorectal cancer before 50 years of age, which requires earlier screening. With the increasing need for CRC screening through colonoscopy, and thus endoscopists, easier and simpler techniques are needed to train proficient endoscopists. The most widely used approach by endoscopists is air insufflation colonoscopy, where air distends the colon to allow visualization of the colonic mucosa. This technique is un-comfortable for patients and requires an anesthetist to administer sedation. In addition, patients commonly complain about discomfort post-op as air escapes into the small bowel and cannot be adequately removed. Current research into the use of water insufflation colonoscopies has proved promising in reducing the need for sedation, decreasing discomfort, and increasing the visibility of the colonic mucosa. Future direction into water insufflation colonoscopies which have shown to be simpler and easier to teach may increase the number of proficient endoscopists in training to serve our aging population.

Metachronous advanced neoplasia after submucosal invasive colorectal cancer resection

Little is known about the incidence of metachronous advanced neoplasia (AN) following resection of submucosal invasive colorectal cancer (SM-CRC). Here, we aimed to assess the occurrence of metachronous AN following SM-CRC resection. We retrospectively reviewed consecutive patients who underwent SM-CRC resection at an academic medical center between 2005 and 2013. Among 343 patients, 250 (72.9%) underwent surgical resection or endoscopic resection followed by surgical resection and 93 (27.1%) underwent only endoscopic resection. During a median follow-up period of 61.5 months, the overall incidence of metachronous AN was 7.6%, and the cumulative incidence at 5 years was 6.1%. The cumulative incidence was significantly higher in the endoscopic resection group than in surgical resection group, in patients with colonic disease than in those with rectal disease, and in patients with synchronous AN than in those without. Multivariate analysis revealed that synchronous AN was the only significant risk factor for metachronous AN (HR 4.35; 95% CI 1.88–10.1). These findings imply that depending on synchronous AN, a surveillance protocol following SM-CRC resection can be changed for better detection of metachronous AN.

Low Rate of Cancer Detection by Colonoscopy in Asymptomatic, Average-Risk Subjects with Negative Results From Fecal Immunochemical Tests

BACKGROUND & AIMS

Screening colonoscopies are of uncertain benefit for persons with negative results from a fecal immunochemical test (FIT). We investigated detection of CRC by colonoscopy in asymptomatic, average-risk, FIT-negative subjects.

METHODS

We conducted a retrospective, population-based cohort study of 96,804 subjects with an initial negative result from a FIT at ages 50-75 years, from 2008 through 2014, who then underwent colonoscopy, using the Kaiser Permanente California databases. We identified participants diagnosed with CRC from January 1, 2008 through December 31, 2015 from a cancer registry. Subjects were followed until initial colonoscopy, health plan disenrollment, death, or December 31, 2015. We reviewed records from 400 randomly selected persons without CRC (controls) for risk features to estimate the proportion who underwent screening colonoscopy. We performed logistic regression to identify variables associated with CRC detection.

RESULTS

Of 257 subjects with a diagnosis of CRC, 102 did not have a record of CRC risk factors; 86 of these patients (84.3%) had non-advanced-stage CRC (no regional node spread/distant metastases). Of the 400 controls, 299 (74.75%; 95% CI, 70.49%-79.01%) lacked CRC risk features, enabling estimation that 72,263 (mean age, 57.5 ± 7.0 y; 54.5% female) had undergone screening colonoscopy. CRC was detected in 1.4 per 1000 persons after 1 FIT, without association with increasing FITs (P = .97). CRC was detected in 1.3 per 1000 persons in 2 y or less after the last FIT and in 4.4 per 1000 persons more than 2 y after the last FIT (P < .001). When the last FIT was 2 y earlier or less, CRC increased from 0.7 per 1000 persons age 50-59 y to 3.1 per 1000 persons older than 70 y. Age and time from the last FIT were associated with CRC, with adjusted odds ratios of 1.08 (95% CI, 1.05-1.11) and 2.76 (95% CI, 1.28-5.95), respectively.

CONCLUSIONS

In asymptomatic, average-risk persons with a negative result from a FIT, CRC is infrequent within 2 y after the last FIT (especially for persons younger than 60 y), usually non-advanced, and unrelated to the number of FITs performed.

Global Prevalence of Colorectal Neoplasia: A Systematic Review and Meta-Analysis

BACKGROUND & AIMS

Most colorectal cancers (CRC) arise from colorectal adenomas, yet there is not enough information on global prevalence to inform health care policy. We examined the prevalence of any type of adenomas, advanced adenomas (AADs), and CRC according to age, sex, ethnicity, geographic regions, and anatomic location (proximal vs distal).

METHODS

MEDLINE and Embase were searched from their inception through May 1, 2018, to identify population-based, observational studies that reported the prevalence of colorectal neoplasia. Studies on participants 15 years or older, with a sample size of 500 persons or more, were included. Metaprop (College Station, TX) was used to model within-study variability by binomial distribution and Freeman-Tukey Double Arcsine Transformation to stabilize the variances. The prevalence figures were presented by proportions and their 95% CIs using random-effects models.

RESULTS

Our meta-analysis included 70 studies involving 637,414 individuals. The overall prevalence rates of adenoma (23.9%; 95% CI, 22.2%-25.8%), AAD (4.6%; 95% CI, 3.8%-5.5%), and CRC (0.4%, 95% CI, 0.3%-0.5%) were calculated. Subgroup analysis indicated that prevalence values (adenomas, AADs, and CRCs) were higher among men (29.7%, 6.5%, and 0.8%, respectively) than women (19.3%, 3.8% and 0.4%, respectively), among older adults (25.9%, 5.2%, and 0.6%, respectively) than younger adults (14.6%, 1.6%, and 0.1%, respectively), among Caucasians (23.7%, 6.6%, and 0.5%, respectively) than other ethnicities, in European countries (25.9%, 8.4%, and 0.8%, respectively) than other countries, and among patients with proximal (25.9%, 5.3%, and 0.1%, respectively) vs distal neoplasia.

CONCLUSIONS

In a systematic review and meta-analysis, we found a high prevalence of colorectal neoplasia among some populations. This indicates a need to expand CRC screening programs for these groups. The pooled prevalence estimates can be used as quality indicators for established CRC screening programs.

British Society of Gastroenterology/Association of Coloproctology of Great Britain and Ireland/Public Health England post-polypectomy and post-colorectal cancer resection surveillance guidelines

These consensus guidelines were jointly commissioned by the British Society of Gastroenterology (BSG), the Association of Coloproctology of Great Britain and Ireland (ACPGBI) and Public Health England (PHE). They provide an evidence-based framework for the use of surveillance colonoscopy and non-colonoscopic colorectal imaging in people aged 18 years and over. They are the first guidelines that take into account the introduction of national bowel cancer screening. For the first time, they also incorporate surveillance of patients following resection of either adenomatous or serrated polyps and also post-colorectal cancer resection. They are primarily aimed at healthcare professionals, and aim to address:Which patients should commence surveillance post-polypectomy and post-cancer resection?What is the appropriate surveillance interval?When can surveillance be stopped? two or more premalignant polyps including at least one advanced colorectal polyp (defined as a serrated polyp of at least 10 mm in size or containing any grade of dysplasia, or an adenoma of at least 10 mm in size or containing high-grade dysplasia); or five or more premalignant polyps The Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument provided a methodological framework for the guidelines. The BSG's guideline development process was used, which is National Institute for Health and Care Excellence (NICE) compliant.two or more premalignant polyps including at least one advanced colorectal polyp (defined as a serrated polyp of at least 10 mm in size or containing any grade of dysplasia, or an adenoma of at least 10 mm in size or containing high-grade dysplasia); or five or more premalignant polyps The key recommendations are that the high-risk criteria for future colorectal cancer (CRC) following polypectomy comprise either:two or more premalignant polyps including at least one advanced colorectal polyp (defined as a serrated polyp of at least 10 mm in size or containing any grade of dysplasia, or an adenoma of at least 10 mm in size or containing high-grade dysplasia); or five or more premalignant polyps This cohort should undergo a one-off surveillance colonoscopy at 3 years. Post-CRC resection patients should undergo a 1 year clearance colonoscopy, then a surveillance colonoscopy after 3 more years.

Use of enteroscope without the overtube in incomplete colonoscopies

Objectives: Colonoscopy is the gold standard diagnostic method for colorectal cancer (CRC) screening. Despite the progress in the endoscopy technology field, a small percentage of colonoscopies is still incomplete. The reasons for that are mostly associated with anatomic features, such as fixed, angulated, long and loopy colon, intra-abdominal adherences and female gender. To overcome such difficulties, the usefulness of scopes different from conventional adult colonoscope (CF), such as paediatric colonoscope (PCF), gastroscope (GIF), single and double balloon enteroscope (SBE and DBE, respectively), has been shown in literature. Our retrospective study aims to evaluate the caecal intubation rate using a SBE without the overtube in patients who previously underwent an incomplete procedure with a different scope.Methods: Patients with a previous incomplete colonoscopy with CF, PCF or GIF were retrospectively enrolled through the analysis of a dedicated database. The enteroscope used was the Olympus Enteropro Single Balloon SiF-Q180 with no overtube. Complete colonoscopy was defined as successful caecal intubation.Results: SBE was used to scope 47 adult patients, mostly female, and it led to a complete procedure in 91% of them. The most frequent reason for an incomplete procedure even with the use of SBE was a fixed and angulated colon.Conclusions: Colonoscopy performed with SBE was safe and no adverse events during and/or after the procedure occurred. Our results suggest that SBE with no overtube is a useful and valid alternative to other type of scopes in difficult cases, especially those related to fixed/angulated colon and in female gender.

Intraoperative colonoscopy in laparoscopic colorectal surgery: A review of recent publications

INTRODUCTION

Laparoscopic colorectal resection is becoming the gold standard for treating colorectal cancers because it offers superior short-term and comparable long-time outcomes compared to open surgery. Intraoperative colonoscopy (IOC) is increasingly performed for tumor localization and mucosal assessment. The aim of this report was to review the safety and efficacy of IOC in laparoscopic colorectal surgery.

METHOD

A MEDLINE search of studies of IOC in laparoscopic colorectal surgery was performed. We focused on three aspects of IOC use: (i) IOC for intraoperative tumor localization; (ii) colonic irrigation and IOC for obstructive left-sided colorectal cancers; and (iii) IOC for assessing colorectal anastomosis.

RESULTS

During laparoscopic colorectal surgery, IOC enables accurate localization of early mucosal tumors, detection of lesions in the proximal unexamined colon for obstructive left-sided cancer, and visual assessment of anastomosis. Additionally, IOC allows for proper surgical resection, management of concomitant lesions, immediate maintenance of hemostasis, suture repair of leaks, and the creation of a protective stoma as necessary.

CONCLUSIONS

Intraoperative colonoscopy is beneficial in laparoscopic colorectal surgery. Experienced surgical endoscopists should be trained to safely perform IOC.

Screening colonoscopy and flexible sigmoidoscopy for reduction of colorectal cancer incidence: A case-control study

BACKGROUND

Flexible sigmoidoscopy and colonoscopy are both recommended colorectal cancer screening options, but their relative effectiveness needs clarification. The aim of this study was to compare the effectiveness of colonoscopy and flexible sigmoidoscopy for reduction of colorectal cancer incidence.

METHODS

We conducted a case-control study within the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare database. Cases were subjects age 70-85 years in the SEER-Medicare database diagnosed with CRC during 2004-2013. Up to 3 controls were matched to each case by birth year, sex, race, and SEER region. Receipt of screening colonoscopy or flexible sigmoidoscopy was ascertained from Medicare claims. Conditional logistic regression models were developed to estimate the odds ratios (ORs) and 95% confidence intervals (CI) for a history of screening in cases vs. controls. We conducted secondary analyses by sex, race, endoscopist characteristics, and with varying timing and duration of the look-back period.

RESULTS

Receipt of screening colonoscopy and sigmoidoscopy was associated with a 59% (OR 0.41, 95%CI 0.39, 0.43) and 22% reduction (OR 0.78, 95%CI 0.67, 0.92) in colorectal cancer incidence, respectively. Colonoscopy was associated with greater reduction in the distal colorectal cancer incidence (OR 0.22, 95%CI 0.20, 0.24) than proximal colorectal cancer incidence (OR 0.62, 95%CI 0.59, 0.66). Sigmoidoscopy was associated with a 52% reduction in distal colorectal cancer incidence (OR 0.48, 95%CI 0.37, 0.63), but with no reduction in proximal colorectal cancer incidence. These associations were stronger in men than in women. No differences by race or endoscopist characteristics were observed.

CONCLUSION

Both screening colonoscopy and sigmoidoscopy were associated with reductions in overall colorectal cancer incidence, with a greater magnitude of reduction observed with colonoscopy.

Location of colorectal adenomas and serrated polyps in patients under age 50

BACKGROUND

The incidence of colorectal cancer, especially located in distal colorectum, is rising markedly in young patients. Conventional adenomas and serrated polyps have been widely recognized as precursors of colorectal cancer.

AIM

To investigate the correlation of polyp feature with polyp location in patients under age 50.

METHOD

Patients under age 50 who had received colonoscopy were included from 2010 to 2018. Clinical data including number, location, size, and histopathology of polyps were collected. Odd ratios and 95% confidence interval of adenomas with their location were calculated.

RESULT

In total, 25,636 patients aged 18-49 were enrolled, among which 4485 patients had polyps, with polyp detection rate of 17.5%. A total of 2484 and 2387 patients had conventional adenomas and serrated polyps, respectively. 76.0% advanced adenomas and 69.5% ≥ 10-mm serrated polyps were located in the distal colorectum. The detection rate of advanced adenomas was higher in patients aged 45-49. Patients with adenomas especially advanced adenomas in the distal colorectum were more likely to have advanced adenoma in the proximal colon.

CONCLUSION

Among patients under age 50, advanced adenomas and ≥ 10-mm serrated polyps were predominantly in the distal colorectum. Advanced adenomas tended to be found in patients aged 45-49. Our results might explain the rising trend of distal colorectal cancer and emphasize the necessity for colonoscopy screening among these populations.

MICROSIMULATION MODEL CALIBRATION USING INCREMENTAL MIXTURE APPROXIMATE BAYESIAN COMPUTATION

Microsimulation models (MSMs) are used to inform policy by predicting population-level outcomes under different scenarios. MSMs simulate individual-level event histories that mark the disease process (such as the development of cancer) and the effect of policy actions (such as screening) on these events. MSMs often have many unknown parameters; calibration is the process of searching the parameter space to select parameters that result in accurate MSM prediction of a wide range of targets. We develop Incremental Mixture Approximate Bayesian Computation (IMABC) for MSM calibration, which results in a simulated sample from the posterior distribution of model parameters given calibration targets. IMABC begins with a rejection-based ABC step, drawing a sample of points from the prior distribution of model parameters and accepting points that result in simulated targets that are near observed targets. Next, the sample is iteratively updated by drawing additional points from a mixture of multivariate normal distributions and accepting points that result in accurate predictions. Posterior estimates are obtained by weighting the final set of accepted points to account for the adaptive sampling scheme. We demonstrate IMABC by calibrating CRC-SPIN 2.0, an updated version of a MSM for colorectal cancer (CRC) that has been used to inform national CRC screening guidelines.

Synchronous Neoplastic Lesions In Referred Patients With Colorectal Cancer: A Retrospective Cohort Study

Background

Synchronous neoplastic lesions are usually present in patients with colorectal cancer (CRC) at diagnosis or postoperative follow-up endoscopy. However, few studies have been published about the clinicopathological features of synchronous lesions, especially those of synchronous advanced neoplasia. This study aimed to describe synchronous lesions in patients with CRC because this knowledge may be useful for preventing the development of metachronous cancer.

Material and methods

We retrospectively reviewed 261 primary CRC cases with synchronous lesions referred to our hospital during a 4-year period. Personal history, habits, family history, characteristics of index cancer, and synchronous lesions were assessed.

Results

In total, the 261 patients with CRC had 812 synchronous adenomas and 146 advanced neoplasia. Diminutive, small, and large polyps made up 66.7%, 20.2%, and 13.1% of all lesions, respectively; 9.3% of diminutive and small adenomas were advanced neoplasia, and 45.2% of synchronous advanced lesions were subcentimeter polyps. Both synchronous non-advanced lesions and advanced lesions developed most frequently in the distal colon, followed by the proximal colon, and were least frequently found in the rectum (P < 0.001). Older age (P = 0.04) and male gender (P = 0.001) were associated with the presence of advanced neoplasia in CRC cases with synchronous neoplastic lesions. Meanwhile, the use of aspirin may be associated with a lower incidence of advanced neoplasia (P = 0.04).

Conclusion

Patients diagnosed with CRC require detailed clearing of the remainder of the colon at baseline coloscopy or postoperative follow-up examination, and we should take a more cautious approach to synchronous subcentimeter polyps in this group of patients.

Enhancing bowel screening: Preventing colorectal cancer by flexible sigmoidoscopy in New Zealand

OBJECTIVES

The prevention of colorectal cancer (CRC) attainable from introducing once-in-a-lifetime flexible sigmoidoscopy (FSIG) screening was assessed.

STUDY DESIGN

This is a review of relevant available information for the assessment of the impact and resource demands of FSIG in New Zealand.

METHODS

The reduction in bowel cancer incidence achievable by one-off FSIG screening from 50 to 59 years of age, an age group for which bowel screening is not currently offered, was reviewed. The prevention of CRC attainable from an offer of screening at 55 years of age in New Zealand was also estimated. The number and cost of the FSIG screening procedures required and referrals for colonoscopies and the savings in treatment were calculated.

RESULTS

Annually, about 27,500 FSIG screening procedures would be required if 50% of those turning 55 years of age accepted an offer of once-in-a-lifetime FSIG screening. This would result in three-four-fold fewer people being referred for colonoscopy than in the national 2-yearly faecal immunochemical test (FIT) screening programme and subsequently reduce demand for colonoscopy from a false-positive FIT. The number of CRC cases prevented would increase over 17 years to more than 300 per year by 2033. After 10-15 years of screening, the annual savings in health service costs, primarily from CRC prevented, were sufficient to completely fund the FSIG screening.

CONCLUSIONS

Inclusion of FSIG screening in the national bowel screening programme would significantly reduce both the incidence and mortality of CRC in New Zealand, reduce the colonoscopy demand of current bowel screening and reduce long-term health service costs.

Outcomes at follow-up of negative colonoscopy in average risk population: systematic review and meta-analysis

OBJECTIVE

To review and summarise the evidence on the prevalence of colorectal adenomas and cancers at a follow-up screening colonoscopy after negative index colonoscopy, stratified by interval between examinations and by sex.

DESIGN

Systematic review and meta-analysis of all available studies.

DATA SOURCES

PubMed, Web of Science, and Embase. Two investigators independently extracted characteristics and results of identified studies and performed standardised quality ratings.

ELIGIBILITY CRITERIA

Studies assessing the outcome of a follow-up colonoscopy among participants at average risk for colorectal cancer with a negative previous colonoscopy (no adenomas).

RESULTS

28 studies were identified, including 22 cohort studies, five cross sectional studies, and one case-control study. Findings for an interval between colonoscopies of one to five, five to 10, and more than 10 years were reported by 17, 16, and three studies, respectively. Summary estimates of prevalences of any neoplasm were 20.7% (95% confidence interval 15.8% to 25.5%), 23.0% (18.0% to 28.0%), and 21.9% (14.9% to 29.0%) for one to five, five to 10, and more than 10 years between colonoscopies. Corresponding summary estimates of prevalences of any advanced neoplasm were 2.8% (2.0% to 3.7%), 3.2% (2.2% to 4.1%), and 7.0% (5.3% to 8.7%). Seven studies also reported findings stratified by sex. Summary estimates stratified by interval and sex were consistently higher for men than for women.

CONCLUSIONS

Although detection of any neoplasms was observed in more than 20% of participants within five years of a negative screening colonoscopy, detection of advanced neoplasms within 10 years was rare. Our findings suggest that 10 year intervals for colonoscopy screening after a negative colonoscopy, as currently recommended, may be adequate, but more studies are needed to strengthen the empirical basis for pertinent recommendations and to investigate even longer intervals.

STUDY REGISTRATION

Prospero CRD42019127842.

Gallbladder Polyps Are Associated with Proximal Colon Polyps

Background

The association between gallbladder (GB) disease and colorectal precancerous lesions remains elusive. This study sought to explore the association between GB disease and colorectal neoplasms at different locations.

Methods

Patients who received general health checkup from January to December 2008 were included and subgrouped into three groups by polyp location: proximal, distal, and whole colon. GB disease and other known risk factors for colon cancer were compared and analyzed. Different types of polyps at different locations were further investigated.

Results

Of a total of 3136 patients (1776 men and 1360 women; mean age, 49.3 years) who had colon polyps, 212 (6.8%) had GB stone and 512 (16.3%) had GB polyps. Patients in the proximal colon polyp group had higher rates of GB polyps and stones. GB polyps were independently associated with proximal colon polyps, including both hyperplastic polyps (odds ratio, 1.523; P = 0.034) and adenomatous polyps (odds ratio, 1.351; P = 0.048). No relationship between GB polyps and distal or any colon polyps was observed. Irrespective of the polyp location (i.e., proximal, distal, or any part of the colon), GB stone did not show any association with colon polyp.

Conclusions

We suggested that GB polyps are associated with proximal colon polyps. Colonoscopy may be a more effective strategy for screening proximal precancerous lesions among patients with GB polyps. The association between GB disease and colon polyps demands further prospective investigation.

Molecular characterization of colorectal adenomas reveals POFUT1 as a candidate driver of tumor progression

Removal of colorectal adenomas is an effective strategy to reduce colorectal cancer (CRC) mortality rates. However, as only a minority of adenomas progress to cancer, such strategies may lead to overtreatment. The present study aimed to characterize adenomas by in‐depth molecular profiling, to obtain insights into altered biology associated with the colorectal adenoma‐to‐carcinoma progression. We obtained low‐coverage whole genome sequencing, RNA sequencing and tandem mass spectrometry data for 30 CRCs, 30 adenomas and 18 normal adjacent colon samples. These data were used for DNA copy number aberrations profiling, differential expression, gene set enrichment and gene‐dosage effect analysis. Protein expression was independently validated by immunohistochemistry on tissue microarrays and in patient‐derived colorectal adenoma organoids. Stroma percentage was determined by digital image analysis of tissue sections. Twenty‐four out of 30 adenomas could be unambiguously classified as high risk (n = 9) or low risk (n = 15) of progressing to cancer, based on DNA copy number profiles. Biological processes more prevalent in high‐risk than low‐risk adenomas were related to proliferation, tumor microenvironment and Notch, Wnt, PI3K/AKT/mTOR and Hedgehog signaling, while metabolic processes and protein secretion were enriched in low‐risk adenomas. DNA copy number driven gene‐dosage effect in high‐risk adenomas and cancers was observed for POFUT1, RPRD1B and EIF6. Increased POFUT1 expression in high‐risk adenomas was validated in tissue samples and organoids. High POFUT1 expression was also associated with Notch signaling enrichment and with decreased goblet cells differentiation. In‐depth molecular characterization of colorectal adenomas revealed POFUT1 and Notch signaling as potential drivers of tumor progression.

What's new?

Removal of colorectal adenomas is an effective strategy to reduce colorectal cancer (CRC) mortality rates. However, as only a minority of adenomas progress to cancer, such strategies may lead to overtreatment. While high‐risk adenomas, defined by specific DNA copy number aberrations, have an increased risk of progression, the mechanisms underlying colorectal adenoma‐to‐carcinoma progression remain unclear. This molecular characterization of colorectal adenomas, CRCs, and normal adjacent colon samples demonstrates that biological processes inherent to CRC are already more active in high‐risk adenomas compared to low‐risk adenomas. Moreover, the findings highlight POFUT1 and Notch signaling as potential drivers of colorectal tumor development.

[Colorectal cancer: role of imaging in screening]

CLINICAL PROBLEM

Colorectal cancer (CRC) is a major cause of cancer-related morbidity and mortality. Most colorectal cancers derive from benign precursor lesions, so-called adenomatous polyps, over a long period of time. Colorectal cancer screening is based on the detection of precancerous polyps and early stage CRC in asymptomatic individuals to reduce CRC incidence and mortality. The protective effect of screening programs can be improved by increasing the screening rates.

PRACTICAL RECOMMENDATIONS

Apart from the established examinations, CT colonography (CTC) has been proposed as an optional test for colorectal cancer screening. The detection rates of CTC for large polyps and cancer are similar to the ones of colonoscopy and superior to stool-based tests. CTC is therefore the radiological test of choice for the detection of colorectal neoplasia. It has replaced double contrast barium enema for almost all indications. As a minimally invasive procedure, CTC has a high safety profile and good patient acceptance. The evaluation of extracolonic organs in addition to the colon can increase examination efficacy. The option to choose CTC as a CRC screening test has the potential to increase the overall screening rates.

The landscape of genomic copy number alterations in colorectal cancer and their consequences on gene expression levels and disease outcome

Aneuploidy, the unbalanced state of the chromosome content, represents a hallmark of most solid tumors, including colorectal cancer. Such aneuploidies result in tumor specific genomic imbalances, which emerge in premalignant precursor lesions. Moreover, increasing levels of chromosomal instability have been observed in adenocarcinomas and are maintained in distant metastases. A number of studies have systematically integrated copy number alterations with gene expression changes in primary carcinomas, cell lines, and experimental models of aneuploidy. In fact, chromosomal aneuploidies target a number of genes conferring a selective advantage for the metabolism of the cancer cell. Copy number alterations not only have a positive correlation with expression changes of the majority of genes on the altered genomic segment, but also have effects on the transcriptional levels of genes genome-wide. Finally, copy number alterations have been associated with disease outcome; nevertheless, the translational applicability in clinical practice requires further studies. Here, we (i) review the spectrum of genetic alterations that lead to colorectal cancer, (ii) describe the most frequent copy number alterations at different stages of colorectal carcinogenesis, (iii) exemplify their positive correlation with gene expression levels, and (iv) discuss copy number alterations that are potentially involved in disease outcome of individual patients.

Synchronous pathologic findings in patients with colorectal cancer and preoperative incomplete colonoscopy

BACKGROUND AND PURPOSE

Guidelines recommend perioperative complete colonoscopy in patients with colorectal cancer (CRC) to reduce the risk of metachronous carcinoma. Our aim was to verify these recommendations by examining the residual colon of patients with incomplete preoperative colonoscopy.

PATIENTS AND METHODS

This retrospective analysis included patients with the initial diagnosis of CRC and preoperative incomplete or no colonoscopy. Postoperative colonoscopies were investigated to identify synchronous lesions.

RESULTS

In two-thirds of the patients, synchronous lesions could be detected. In 78% of the cases, the lesion was located proximal of the endpoint of the initial colonoscopy and therefore undiscovered. Two-thirds of the synchronous lesions were adenomata.

CONCLUSIONS

Complete perioperative colonoscopy in patients with CRC should be performed to reduce the rate of metachronous carcinoma. Postoperative completion of preoperative insufficiently colonoscoped patients is recommended.

The Yield and Safety of Screening Colonoscopy in Patients Evaluated for Liver Transplantation

Colorectal cancer (CRC) screening with colonoscopy is commonly used in patients who are candidates for liver transplantation. We initiated this study to define the risk-benefit ratio of performing screening colonoscopy in this population. A retrospective observational study of all consecutive patients undergoing colonoscopy during pre-liver transplantation screening between 2004 and 2017 was conducted. Endoscopic and pathological findings and clinical events potentially related to the colonoscopy in the 30 days after the procedure were registered and compared with a 30-day inpatient control time frame. A total of 858 colonoscopies were performed in 808 patients (65% male; median age, 55 years [interquartile range (IQR), 47-62]; median model for end-stage liver disease (MELD) score, 15 [IQR, 11-18]). CRC was found in 2 patients (0.2%), and advanced adenomas were found in 44 patients (5.4%). The only independent risk factor for an advanced neoplasm was age (odds ratio, 1.072 per year; 95% confidence interval, 1.031-1.115; P < 0.001). During the 30-day postprocedure period, 178 clinical events occurred in 128 patients compared with 101 clinical events in 72 patients in the control time frames (P < 0.001). After colonoscopy, there was a significantly increased risk for renal failure (P = 0.001) and gastrointestinal (GI) bleeding (P = 0.023). Presence of ascites and MELD score were identified as independent risk factors for acute renal failure and GI bleeding. During the study observation period, 53.5% of the screened population actually underwent liver transplantation. Conclusion: CRC screening in pre-liver transplantation patients is associated with a relatively low prevalence of CRC and an increased risk of postcolonoscopy complications such as acute renal failure and GI bleeding, especially in patients with advanced liver disease. Because the risk-benefit ratio of standard performance of a screening colonoscopy in this population appears questionable, alternative screening strategies should be considered.

Progress of colorectal cancer screening in United States: Past achievements and future challenges

The United States has seen progress with colorectal cancer with both falling incidence and mortality rates. Factoring into this decline, the significance of early detection and removal of precancerous lesions through screening must be underscored. With the advancement of screening modalities, attention has been directed towards optimizing the quality of screening and detecting adenomas. Colorectal cancer screening has been a major agenda item for national gastroenterology societies, culminating in a major victory with passage of the Balanced Budget Act that allowed for Medicare coverage of colorectal cancer screening. Colonoscopy as the primary screening modality was solidified in the 1990s after landmark studies demonstrated its superiority over modalities for detecting precancerous polyps. Despite progress, colorectal cancer screening disparities between race and gender continue to exist. Legislative efforts are on-going and include the SCREEN Act and Dent Act that aim to further improve access to screening. The National Colorectal Cancer Roundtable has launched colorectal cancer screening initiatives targeting at risk populations. Today, the current goal of these initiatives is to reach colorectal screening rate of 80% of eligible patients by 2018. With these initiatives, efforts to narrow the gaps in screening disparities and lower overall mortality have been prioritized and continued by the medical community. This review article details colorectal cancer screening progress to date and highlights major studies and initiatives that have solidified its success in the United States.

Long-term performance of colorectal cancerscreening programmes based on the faecal immunochemical test

BACKGROUND

The long-term performance of colorectal cancer (CRC) screening programmes based on a 2-year faecal immunochemical test (FIT) is still unclear.

METHODS

In a sample of 50 to 69-year-olds repeatedly screened with the FIT (OC-Hemodia latex agglutination test; cut-off: 20 µg haemoglobin/g faeces), we examined: (1) the FIT positivity rate, the CRC and advanced adenoma detection rate and the FIT's positive predictive value (PPV) for advanced neoplasia, at each round of screening and (2) the cumulative CRC and advanced adenoma detection rate after five rounds of FIT.

RESULTS

Over 12 years (2002-2014), 123 347 individuals were administered the FIT up to six times, and 781 CRCs and 4713 advanced adenomas were diagnosed. The CRC and advanced adenoma detection rates declined substantially from the first to the third (rate ratio (RR) 0.25, 95% CI 0.20 to 0.32) and second (RR 0.51, 95% CI 0.47 to 0.56) rounds, respectively, and then remained stable. The PPV for advanced neoplasia dropped by 18% in the second round (RR 0.82, 95% CI 0.77 to 0.89), with no further reduction thereafter due to a concomitant decline in the FIT positivity rate (RR first to sixth rounds: 0.56, 95% CI 0.53 to 0.60).The cumulative CRC and advanced adenoma detection rates over five consecutive rounds were 8.5‰ (95% CI 7.8 to 9.2), and 58.9‰ (95% CI 56.9 to 61.0), respectively.

CONCLUSIONS

Repeated FIT significantly reduces the burden of colorectal disease while facilitating an efficient use of colonoscopy resources. The cumulative detection rate after five rounds of FIT is similar to primary screening with colonoscopy, supporting the need to account for the cumulative sensitivity of repeated FITs when evaluating the test's efficacy.

Two-year retrospective analysis of patients undergoing direct to procedure flexible sigmoidoscopy investigation with rectal bleeding as a primary complaint

BACKGROUND AND AIMS

 Rectal bleeding affects ~15 % of the general population and is a common reason for referral to gastroenterologists by primary care physicians. Direct to procedure flexible sigmoidoscopy is an appealing modality to investigate rectal bleeding due its diagnostic yield, safety profile, and accessibility. Patients referred on a routine basis for direct to procedure clinic by primary care physicians with the sole complaint of rectal bleeding have not previously been studied. Our study aims to explore the spectrum of diagnoses and evaluate for potential clinical predictors of underlying pathology in this specific patient population.

METHODS

 In total, 528 charts of patients referred to the Kingston General Hospital and Hotel Dieu Hospital endoscopy units (Kingston, Canada) with the sole complaint of rectal bleeding were reviewed. All of these patients were referred on a routine basis to direct to procedure clinic from primary care physicians. The performance of various clinical variables in predicting significant pathology was assessed by univariate analysis.

RESULTS

 The diagnostic spectrum of the cohort studied included hemorrhoids (75.5 %), anal fissures (4 %), ulcerative colitis (3.2 %), Crohn's disease (1.1 %), indeterminate proctitis/colitis (1.7 %), and colorectal malignancy (2.7 %). Of the various clinical variables assessed, only male sex predicted significant pathology (25.2 % of males vs 17.6 % of females, P  < 0.05).

CONCLUSION

 Our study highlights the need for a thorough investigation of rectal bleeding given the lack of clinical predictors. Future prospective studies with more patients are needed to fully assess the utility of various clinical variables in predicting pathology in this patient population. This would allow for more effective triaging of a routine rectal bleeding, a very common reason for patient referral to gastroenterologists by primary care physicians. Flexible sigmoidoscopy was not associated with complications or missed diagnosis in our study. As such, the technique appears to be a suitable initial investigative modality for patients with rectal bleeding.