Colorectal Cancer Colonoscopy Research Articles

444 Post Colonoscopy Colorectal Cancer, Are We Compliant? A Year in Review

Abstract Post Colonoscopy Colorectal Cancer (PCCRC) is defined as a Colorectal Cancer (CRC) that is diagnosed after a colonoscopy in which no cancer was found. Aim To identify the incidence of PCCRC at a district hospital trust and to check our compliance with national guidance (audit against Joint Advisory Group on GI Endoscopy standards). We review the performance in our second cycle and take lessons forward. Method Phase 1 collected data from January 2016 to June 2019 following approval. Patients with colorectal cancer were identified from the MDT pathway. Those newly diagnosed with CRC who had colonoscopy within 6-36 months prior to their diagnosis were included. Patients with appendiceal tumours, anal SCC, small bowel GIST, carcinoid tumours or those who had surveillance endoscopies were excluded. Hospital records were used to collect data retrospectively on patient demographics and comorbid diseases. Phase 2 collected data from 01/09/2021 to 01/09/2022 with similar criteria. Results The first phase of the study identified 1334 patients. Those not meeting the inclusion criteria as set out from the World Endoscopy Organisation (WEO), or those with non-primary CRC were excluded. Histologically confirmed CRC from phase one yielded 1323 cases. The rate of PCCRC according to the WEO classification was 3%. Phase 2 identified 330 patients with histologically proven CRC, the rate of PCCRC in phase 2 was a marginal decrease to 2%. Conclusions Our rate of PCCRC is compliant with national guidance, however key learning points and recommendations are drawn to help NHS services to reach national targets and improve care.

Higher Serrated Polyp Detection Rates Are Associated With Lower Risk of Postcolonoscopy Colorectal Cancer: Data From the New Hampshire Colonoscopy Registry.

We used New Hampshire Colonoscopy Registry data to examine the association between postcolonoscopy colorectal cancer (PCCRC) and sessile serrated detection rates (SSLDRs). We included patients with either a colonoscopy or a CRC diagnosis in the NH State Cancer Registry. PCCRC was any CRC diagnosed ≥ 6 months after index examination. Of 26,901 patients, 162 were diagnosed with PCCRC. The hazard ratio for PCCRC was lowest for patients whose endoscopists had the highest SSLDR quintile (≥6%) (hazard ratio 0.29; 95% confidence interval 0.16-0.50). Endoscopists with higher SSLDRs had lower risks of PCCRC. These data validate SSLDR as a clinically relevant quality measure.

Independent prognostic value of method of detection in lung cancer: Analysis of the PLCO lung screening trial.

e22526 Background: Prognostic models in cancer use patient and tumor characteristics to predict survival and disease progression. Many tumors are detected as part of screening programs such as colonoscopy for colorectal cancer, mammograms for breast cancer, and pap tests for cervical cancer. Past work in breast cancer has shown that screen detected tumors exhibit better prognosis than symptom detected tumors. The prognostic significance of method of detection in other types of cancers is less well understood. Further, the importance of method of detection, relative to other prognostic variables such as sex, age, cancer stage at diagnosis, and histology, is largely unknown. Methods: The prognostic significance of method of detection in the PLCO Lung cancer screening trial was investigated. PLCO randomized patients to intervention, with four annual chest x-ray (CXR) screenings, or control, usual care. Patients were followed for a total of approximately 13 years. All patients diagnosed with non-small cell lung cancer within 4 years of randomization were considered in the analysis (N = 934). Cox proportional hazards model and Random Survival Forests were used to build prognostic models to predict overall survival. The importance of each variable in prognostic models was assessed using hazard ratios and Random Forest variable importance measures. Results: Screen detected tumors exhibit stage shift and have better prognosis than interval and control detected tumors. The improved prognosis remains significant after controlling for stage at diagnosis and other variables commonly used in prognostic models (e.g., age, histology, sex). Variable importance measures show that method of detection is a more important prognostic indicator than sex and histology. Results are robust to different methods for cohort selection. Conclusions: Method of cancer detection should be considered when developing prognostic models in lung cancer studies. Cancer registries should routinely collect method of cancer detection.

A retrospective analysis of the histology of resected polyps and colonoscopy quality parameters in Belgium.

adenoma detection rate is a well known quality parameter for colonoscopy. However recently other quality parameters have emerged. We wanted to evaluate the histology of the resected polyps, different quality indicators of colonoscopy and post colonoscopy colorectal cancer (PCCRC) in Belgium and analyzed data about colonoscopies performed between 2008-2015. Reimbursement data on colorectal related medical procedures from the Intermutualistic Agency were linked with data on clinical and pathological staging of colorectal cancer and with histologic data of resected polyps available at the Belgian Cancer Registry over a period covering 8 years (2008-2015). 298,246 polyps were resected in 294,923 colonoscopies, of which 275,182 were adenomas (92 %) and 13,616 were SSLs (4%). There was a significant but small correlation between the different quality parameters and PCCRC. Post colonoscopy colorectal cancer rate after 3 years was 7.29 %. There were marked geographic differences in Belgium concerning adenoma detection rate, sessile adenoma detection rate and post colonoscopy colorectal cancer. Most resected polyps were adenomas, only a small percentage involved sessile serrated lesions. There was a significant correlation between adenoma detection rate and other quality parameters, and a small but significant correlation between PCCRC and the different quality parameters. The lowest post colonoscopy colorectal cancer rate was reached with an ADR of 31.4 % and a SSL-DR of 1.2 %.

Colonoscopy Colorectal Cancer Screening Programme in Southern Iraq: Challenges, Knowledge Gaps and Future Potential.

Data on current colorectal cancer screening practices in Iraq are limited. This study aimed to better understand the current colorectal cancer screening practice and perceived barriers. The project also aimed to use UK expertise to introduce Bowel Cancer Screening Programme (BCSP) in Basra, Iraq. The study consisted of two parts: A pre-visit online survey of clinicians to test the project's feasibility. A public survey was conducted to understand and gauge the general knowledge and perceived barriers to having colorectal cancer screening. The second phase included a short visit to Basra and the delivery of a multidisciplinary meeting for bowel screening colonoscopists. Fifty healthcare providers completed the survey. Basra has no established bowel cancer screening programme, let alone the country. Opportunistic colonoscopy surveillance is done on an ad hoc base. A total of 350 individuals completed the public survey. The survey showed that more than 50% of participants were not familiar with the concept of a BCSP and less than 25% were aware of "red flag" symptoms of bowel cancer. The short visit to Basra included a roundtable discussion and delivered a training workshop for screening colonoscopists using UK training materials in conjunction with the Iraqi Medical Association. Feedback from the course was extremely positive. Several potential barriers were identified to participate in BCSP. The study highlighted potential barriers, including a lack of public awareness and insufficient training resources to be addressed in future screening programmes. The study has identified several potential areas for future collaboration to support the development of a BCSP centre in Basra.

Reasons for No Colonoscopy After an Unfavorable Screening Result in Dutch Colorectal Cancer Screening: A Nationwide Questionnaire.

We aimed to assess participant-reported factors associated with non-follow-up with colonoscopy in colorectal cancer (CRC) screening. In May 2019, we distributed a nationwide cross-sectional questionnaire (n = 4,009) to participants in the Dutch CRC screening program who received a positive fecal immunochemical test (FIT). Among respondents who reported no colonoscopy, we assessed the presence of a contraindication, and those without were compared with those who reported colonoscopy by logistic regression analysis. Of 2,225 respondents (56% response rate), 730 (33%) reported no colonoscopy. A contraindication was reported by 55% (n = 404). Decisional difficulties (odds ratio [OR] = 0.29; 95% CI, 0.18-0.47), lacking the opportunity to discuss the FIT outcome (OR = 0.45; 95% CI, 0.28-0.72), and a low estimated risk of CRC (OR = 0.45; 95% CI, 0.26-0.76) were negatively associated with follow-up. Knowledge items negatively associated with follow-up included having an alternative explanation for the positive FIT (OR = 0.3; 95% CI, 0.21-0.43), having trust in the ability to self-detect CRC (OR = 0.42; 95% CI, 0.27-0.65), and thinking that polyp removal is ineffective (OR = 0.59; 95% CI, 0.43-0.82). The belief that the family physician would support colonoscopy showed the strongest positive association with follow-up (OR = 2.84; 95% CI, 2.01-4.02) CONCLUSIONS: Because decisional difficulties and certain convictions regarding CRC and screening are associated with non-follow-up, personalized screening counseling might be an intervention worth exploring as a means of improving follow-up in the Dutch CRC screening program. Involving family physicians might also prove beneficial.

Risk of post colonoscopy colorectal cancer according to physician adenoma detection rates

Colonoscopies, which enable detection and removal of pre-cancerous polyps, are an effective method to reduce the incidence of and mortality associated with colorectal cancer. Adenoma detection rate (ADR) is validated for measuring quality of colonoscopy. Here we summarize the @GIJournal discussion held on July 3, 2022, during which we discussed the article by Schottinger et al. titled Association of physician adenoma detection rates with postcolonoscopy colorectal cancer (JAMA 2022; 327:2114–2122)1. The session was moderated by Dr. Mariam Naveed (MN [@MN_GIMD]) and the key findings were critically reviewed by Dr. Aasma Shaukat (AS [@AasmaShaukatMD]) and Dr. Rajesh N. Keswani (RK [@RKeswaniMD]).

Improved risk scoring systems for colorectal cancer screening in Shanghai, China

BackgroundAn optimal risk‐scoring system enables more targeted offers for colonoscopy in colorectal cancer (CRC) screening. This analysis aims to develop and validate scoring systems using parametric and non‐parametric methods for average‐risk populations.MethodsScreening data of 807,695 subjects and 2806 detected cases in the first‐round CRC screening program in Shanghai were used to develop risk‐predictive models and scoring systems using logistic‐regression (LR) and artificial‐neural‐network (ANN) methods. Performance of established scoring systems was evaluated using area under the receiver operating characteristic curve (AUC), calibration, sensitivity, specificity, number of high‐risk individuals and potential detection rates of CRC.ResultsAge, sex, CRC in first‐degree relatives, chronic diarrhoea, mucus or bloody stool, history of any cancer and faecal‐immunochemical‐test (FIT) results were identified as predictors for the presence of CRC. The AUC of LR‐based system was 0.642 when using risk factors only in derivation set, and increased to 0.774 by further incorporating one‐sample FIT results, and to 0.808 by including two‐sample FIT results, while those for ANN‐based systems were 0.639, 0.763 and 0.805, respectively. Better calibrations were observed for the LR‐based systems than the ANN‐based ones. Compared with the currently used initial tests, parallel use of FIT with LR‐based systems resulted in improved specificities, less demands for colonoscopy and higher detection rates of CRC, while parallel use of FIT with ANN‐based systems had higher sensitivities; incorporating FIT in the scoring systems further increased specificities, decreased colonoscopy demands and improved detection rates of CRC.ConclusionsOur results indicate the potentials of LR‐based scoring systems incorporating one‐ or two‐sample FIT results for CRC mass screening. External validation is warranted for scaling‐up implementation in the Chinese population.

Odds of Incomplete Colonoscopy in Colorectal Cancer Screening Based on Socioeconomic Status

The aim of this study is to investigate the association between socioeconomic status (SES) and the risk of having an incomplete colonoscopy (IC) in the Danish Colorectal Cancer (CRC) Screening Program. In this register-based study we included 71,973 participants who underwent colonoscopy after a positive fecal immunochemical test in the Danish CRC Screening Program. The main exposure, SES, was defined by income and education, and the outcome by complete or incomplete colonoscopy. Among the participants, 5428 (7.5%) had an incomplete colonoscopy. The odds ratio (OR) for ICs due to inadequate bowel preparation was 1.67 (95% CI: 1.46; 1.91) for income in the 1 quartile compared to income in the 4th quartile. ORs for income in the 2nd quartile was 1.38 (95% CI: 1.21; 1.56) and 1.17 (95% CI: 1.03; 1.33) for income in the 3rd quartile. For the educational level, an association was seen for high school/vocational education with an OR of 0.87 (95% CI: 0.79; 0.97) compared to higher education. For ICs due to other reasons, the level of income was associated with the risk of having an IC with an OR of 1.19 (95% CI: 1.05; 1.35) in the 1st quartile and an OR of 1.19 (95% CI: 1.06; 1.34) in the 2nd quartile. For the educational level, there were no significant associations. Low income is associated with high risk of having an IC, whereas educational level does not show the same unambiguous association.

Additional offer of sigmoidoscopy in colorectal cancer screening in Germany: rationale and protocol of the decision-analytic modelling approach in the SIGMO study

IntroductionIn Germany, statutory insured persons are entitled to a stool test (faecal immunochemical test (FIT)) or colonoscopy for colorectal cancer (CRC) screening, depending on age and sex, yet participation rates...

EP.TU.141A 5-year Post Colonoscopy Colorectal Cancer audit with focus on root cause analysis and performance at York Teaching Hospital

Abstract Introduction Post colonoscopy colorectal cancer (PC-CRC) is an important benchmark of endoscopy performance. Previous publications have reported significant variations between institutions. We chose to perform the root cause analysis (RCA) and the impact of traditional performance indicators on the likelihood of PC-CRC. Methods A retrospective analysis was performed on all PCCRC at York Hospital. Electronic endoscopic records and case-note review was performed to identify appropriate cases. Root cause analysis was performed on all identified cases. Performance data and annual procedural volumes of endoscopist were recorded. Adjusted PC-CRC/5-year period allowed endoscopist to be divided into good (<4 PC-CRC) and poor performers (³4 PC-CRC). Mann Whitney U test used to compare groups. P-value of < 0.05 deemed significant Results 32 (24 male) patients with a PC-CRC were identified . Median age was 72 (IQR 63-79) years. Table provides PCCRC rate for the 5-year period. Root cause analysis identified that most plausible cause was missed lesions despite adequate bowel preparation (76%). The commonest subtype was non interval C (38%). Three out of 18 endoscopist had a higher 5-year adjusted PC-CRC rate and were poor performers. Median withdrawal times, CIR and ADR did not differ between good and poor performers. Conclusion The overall PC-CRC rate at our institution is within an acceptable rate. We have noted significant variation of performance between endoscopist, the exact reasons for this observation require further examination.

SP1.1.6Incidence of post colonoscopy colorectal cancer, are we compliant with national guidelines?

Abstract Aims To investigate the incidence of post colonoscopy colorectal cancer (PCCRC) at a district NHS trust and assess compliance with UK key performance indicators and quality assurance standards for colonoscopy guidelines endorsed by JAG and the ACPGBI Methods We conducted a retrospective review of our trust colorectal MDT database to identify patients diagnosed with colorectal cancer in the period between January 2016 till June 2019 who underwent a colonoscopy within 6-36 month prior to their diagnosis with colorectal cancer. Patient demographics, indication of colonoscopy, date of cancer diagnosis, procedure related factors such as quality of bowel preparation, presence of diverticular disease, prior history of inflammatory bowel disease, previously diagnosed polyps and also grade of endoscopist were extrapolated. Results 1323 patients were diagnosed with colorectal cancer during the study period, out of these there were 111 patients who underwent a colonoscopy within 6-36 month prior to their diagnostic colonoscopy. After exclusion of cases with anastomotic recurrence (n = 2) and cases with no PCCRC (n = 82), there were 27 patients with confirmed PCCRC in accordance with WEO classification (PCCRC 2.8%, acceptable target 5%) Upon review of the 27 cases with PCCRC, there was equal gender distribution while the majority were 71-80 years old. There was evidence of diverticular disease in 44% and previous colonic polyps in 48%. The quality of bowel preparation was recorded as good in 25 cases while grade of endoscopist was consultant (n = 24), associate specialist (n = 1), nurse endoscopist (n = 2) Conclusions The incidence of PCCRC in our trust falls within national guidelines.

S234 Small Low-Risk Tubular Adenomas 5-9 mm Have an Increased Risk for Post Colonoscopy Colorectal Cancer: Data From the New Hampshire Colonoscopy Registry

S234 Small Low-Risk Tubular Adenomas 5-9 mm Have an Increased Risk for Post Colonoscopy Colorectal Cancer: Data From the New Hampshire Colonoscopy Registry

Risk of post colonoscopy colorectal cancer following screening colonoscopy with low-risk or no adenomas: A population-based study.

In the Danish faecal occult blood test based bowel cancer screening programme, the first round was rolled out over 4years. After roll-out, the planned faecal test recall procedure for individuals with either no or low risk adenomas at colonoscopy is 8 and 2years, respectively. Here, we aimed to investigate the post colonoscopy colorectal cancer incidence in these two groups. All Danish screening individuals from 2014 to 2015 with a positive faecal test and either no or low risk adenomas at colonoscopy were included and followed for 3years post screening for the event of colorectal cancer through national registries. Out of 533,023 submitted faecal tests and 36,673 positive tests, 17,627 had no or low risk adenomas. We identified 60 (0.34%) individuals diagnosed with colorectal cancer within 3years, 18 (0.29%) in the low risk adenoma group, and 42 (0.37%) in the no adenomas group (p=0.44). Advancing age (HR=1.079, p<0.001) and higher faecal test value (HR=1.001, p=0.002) increased hazard of colorectal cancer occurrence, whereas male sex (HR=1.3, p=0.308) and having low risk adenomas (HR=0.729, p=0.264) did not. We found no difference in post colonoscopy colorectal cancer occurrence between individuals with either no or low risk adenomas. Instead, advancing age and increased faecal test value was associated with a higher risk of post colonoscopy colorectal cancer.

Bowel-cleansing efficacy of the 1L polyethylene glycol-based bowel preparation NER1006 (PLENVU) in patient subgroups in two phase III trials.

Background:Adequate bowel preparation prior to colonoscopy is essential for visualization of the colonic mucosa to maximize adenoma and polyp detection. The risk of inadequate bowel cleansing is heightened if the patient is older, male, overweight, and has comorbidities, such as diabetes. This post hoc analysis of the combined MORA and NOCT clinical trials explores the efficacy of evening/morning split-dose regimens of NER1006 (PLENVU®, Norgine Ltd), a 1-liter polyethylene glycol (PEG) bowel preparation, to evaluate its bowel-cleansing efficacy in patients at risk for inadequate cleansing.Methods:Patients requiring colonoscopy were randomized to receive evening/morning split-dosing of either NER1006, 2-liter (2L) PEG and ascorbate, or oral sulfate solution (OSS). Bowel-cleansing efficacy was assessed by treatment-blinded central readers using the validated Harefield Cleansing Scale (HCS).Results:Split-dose NER1006 was associated with high levels of cleansing, ranging between 87.0% and 94.0% across all patient subtypes (n = 551), including patients with obesity or diabetes. However, patients aged >65 years and <45 years showed significantly greater rates of successful cleansing than patients aged 45–65 years (94.0% versus 94.2% versus 87.0%, p = 0.002). The high-risk patient subgroup, which included obese males aged ⩾60 years, had significantly improved overall and high-quality bowel-cleansing success rates of 100% (33/33) and 72.7% (27/33) on the HCS with NER1006, compared with 86.7% (26/30) and 50% (15/30) with the comparator solutions (p = 0.015 and p = 0.033, respectively). In this high-risk subgroup, adenoma detection was greater per patient receiving NER1006 versus the comparator group (1.82 versus 0.93, p = 0.041). NER1006 was the only treatment that enabled the detection of patients with ⩾5 adenomas [9.1% (3/33) versus 0/30, p = 0.047].Conclusion:NER1006 effectively cleansed a broad range of patients and offered superior bowel cleansing versus 2LPEG/OSS in patients at increased risk of colorectal cancer. Future research should establish whether more effective cleansing also enables improved adenoma detection.Plain language summaryA low-volume bowel preparation solution to better detect lesions associated with colorectal cancer during colonoscopyColorectal cancer (CRC) is the fourth most commonly diagnosed cancer in the world. Obese men over the age of 65 years are at particularly increased risk of developing CRC. If the changes in their large intestine (colon) could be seen more clearly during a colonoscopy (where a small camera is inserted via the anus to examine the bowels from the inside), patients who need treatment would be diagnosed earlier, thus improving their chances of survival. In this paper we discuss the use of a bowel preparation solution that is more convenient for patients (less to drink) but also cleans bowels more effectively, meaning more lesions are detected than when other solutions are used. This improved cleansing, and thus better visualization, occurred in a range of patients, including those at higher risk of CRC, such as older, overweight men.

Mo1662 PATIENT AND ENDOSCOPIC CHARACTERISTICS OF POST-COLONOSCOPY COLON CANCER: A CASE-CONTROL STUDY

There is good evidence that screening programs are successful at reducing the risk of colorectal cancer (CRC). Colonoscopy is the gold standard, however it remains imperfect and colon cancers are still detected after screening or surveillance exams. Developing CRC within 10 years of a prior colonoscopy without cancer is considered post colonoscopy colorectal cancer (PCCRC). Possible explanations include missed lesions, new lesions, incomplete resection, and aggressive biology. The aim of this study was to compare patient characteristics and endoscopic findings of PCCRC cases with those from controls who did not develop CRC. Using a tumor registry dataset, we extracted all CRCs diagnosed at our medical center from 2012–2017. We identified those with prior colonoscopy without cancer within 10 years (index colonoscopy), which were considered PCCRC cases. Major exclusions were prior CRC or hereditary CRC syndromes, IBD, colonoscopies not done at our institution and incomplete polyp resection. Controls were collected from a cohort of all colonoscopies performed from 2003–2019. They never had CRC or high risk adenomas, had colonoscopy for screening indications, and were still followed in our medical record when they were identified (3/2019). The date of index colonoscopy, age and sex for cases was matched in a 3:1 fashion with controls and data were analyzed using conditional logistic regression. Index colonoscopies of 54 PCCRCs were matched with 162 controls. Patient characteristics were similar for both groups (age, sex, smoking, EtOH). The following features were significantly associated with risk of PCCRC: ever history of polyps (OR=3.84), ever history of serrated adenomas (OR=5.33), 2 v 0 polyps (OR=4.55), having a tubular adenoma (TA) (OR=3.53) or sessile serrated adenoma (SSA) (OR=8.49) on index colonoscopy, or having a follow-up recommendation from the endoscopist that did not correlate with the AGA guidelines (OR=5.40). 61% of PCCRC cases had polyps on their index colonoscopy in the same location as their PCCRC. Features that were not significantly associated with risk of PCCRC included: first degree relative with CRC, prep quality, proximal v distal location of polyp, 1 v 0 polyp, hyperplastic polyps, and polyp size (<5mm v 5-9mm). Not surprisingly, patients with TAs/SSAs or multiple polyps have higher risk of developing cancer, including PCCRC. We also show that when comparing TAs to SSAs, there is no significantly elevated risk of developing PCCRC. Given that patient and endoscopic characteristics do not differ between the groups, these data indicate that endoscopy-related factors such as missed or incompletely resected polyps may explain most PCCRC. Increased risk of PCCRC in patients who had incorrect follow-up recommendations should be further investigated.

A142 ENDOSCOPIST EDUCATIONAL INTERVENTIONS ARE ASSOCIATED WITH IMPROVEMENTS IN ADENOMA DETECTION RATE: A SYSTEMATIC REVIEW AND META-ANALYSIS

Abstract Background Screening-related colonoscopy reduces the overall morbidity and mortality associated with colorectal cancer. In order for screening-related colonoscopy to be effective and safe, endoscopists must be well trained. However, a significant degree of variation exists between endoscopists in terms of adenoma detection rate (ADR) and cecal intubation rate (CIR). ADR in particular is an important colonoscopy quality metric that has been directly and inversely related to the rate of post colonoscopy colorectal cancer (PCCRC). Educational interventions aimed at endoscopists have been developed in an attempt to optimize the performance of colonoscopy. It is unknown what benefit these have on colonoscopy quality indicators or outcomes, if any. Aims We performed a systematic review and meta-analysis to determine whether there is an association between educational interventions aimed at endoscopists and improvements in colonoscopy quality indicators or outcomes. Methods An electronic search was conducted through August 2019 for studies reporting on targeted endoscopist educational interventions and associations with ADR or other colonoscopy quality indicators, or outcomes. Interventions such as hands-on training modules, skills enhancement courses were included Pooled rate ratios (RR) and weighted mean differences (WMD) were calculated using DerSimonian and Laird random effects models. A priori subgroup and sensitivity analyses were performed to assess for potential methodological or clinical factors associated with any of the outcomes of interest. Results From 2,253 initial studies, 14 were included in the systematic review, and 8 were included in the meta-analysis for ADR, representing 76,373 colonoscopies. Educational interventions were associated with improvements in ADR (RR 1.28, 95% confidence intervals, CI, 1.19–1.38). Educational interventions were also associated with improvements in overall polyp detection rate, PDR (RR 1.17, 95% confidence intervals, CI, 1.02–1.35). Educational interventions were not associated with longer withdrawal times (WMD -0.03 minutes, 95% CI, -0.57 - 0.51) or improved CIR (RR 1.00, 95% CI, 0.99 to 1.02), though unadjusted CIR was high in both the pre- and post-intervention groups, at 94.5% and 95.0%, respectively. Figure 1 shows Forest plots comparing pre-intervention and post-intervention rates for A) ADR, b) PDR and c) CIR. Conclusions Our study provides evidence that educational interventions aimed at endoscopists significantly improve ADR and overall PDR. Educational interventions did not impact withdrawal time or cecal intubation rates, and thus, the specific mechanisms for their benefit remain incompletely clear. As part of quality improvement programs to optimize colonoscopy performance, educational interventions should be considered. Funding Agencies None

Performance of Initial Screening Tests for Colorectal Cancer and Subsequent Adherence to Colonoscopy: An Ecological Study

Background: Adherence to colonoscopy in colorectal cancer (CRC) screening is at a low level and varies greatly across populations. No study has examined the influencing factors of colonoscopy adherence at a population level, and this remains to be an unaddressed knowledge gap. We therefore aimed to analyze the correlation between performance of initial CRC screening tests and subsequent adherence to colonoscopy base on an ecological evaluation. Methods: The sensitivity, specificity, and positive predictive value (PPV) of initial CRC screening tests and subsequent adherence to colonoscopy in different populations were extracted from relevant studies published in English up to December 31, 2018. The age-standardized incidences (ASR) of CRC across populations in the year of screening were obtained from the Cancer Statistics data. Locally weighted regression smoothing was used to examine the relationship between adherence to colonoscopy and ASR of CRC. Cut-off points of adherence on ASR were identified by Joinpoint Regression and used in Regression Discontinuity as potential thresholds. Spearman’s correlation analysis was used to calculate correlation coefficients. Findings: We identified 192 eligible articles. The median and interquartile range of adherence to colonoscopy was 82·5% (71·8%-90·5%). The adherence was significantly correlated with ASR of CRC in the study populations (r=0·187, p<0·001) and marginally with the PPV of initial screening tests (r=0·105, p=0·077). The change points of the adherence to colonoscopy were identified at the ASR of 32·5 and 142·5/100,000, and the ratio of adherence to colonoscopy at 143/100,000 was 0·900. In countries / areas with a moderate ASR, adherence to colonoscopy was negatively correlated with the sensitivity (r=-0·367, p=0·023) and positively with the PPV (r=0·143, p=0·040), whereas in populations with a high ASR, flexible sigmoidoscopy was more widely used as an initial screening test and achieved a high subsequent adherence to colonoscopy. Interpretation: Adherence to colonoscopy is correlated with the performance of initial screening tests, particularly among populations with moderate CRC incidence. Initial screening tests with high PPV or specificity may help to increase population adherence to colonoscopy, but different strategies should be used in countries / areas with a high or moderate incidence of CRC. Funding Statement: This study was supported by the Local High Level University Construction Project of Shanghai and the Health Commission of the Pudong New Area of Shanghai (PW2019A-5). Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: Not required.

244 Exogenous Insulin Therapy Increases the Risk of Advanced Colorectal Adenoma Among Patients With Type 2 Diabetes Mellitus

INTRODUCTION: Endogenous hyperinsulinemia increases the risk of colorectal cancer (CRC) among patients with type 2 diabetes mellitus (T2DM). Exogenous insulin therapy, used by 30% of T2DM patients, further increases systemic levels of insulin and has been shown to increase the risk of CRC in animal models. We sought to evaluate the effect of exogenous insulin therapy on the incidence of advanced adenoma in T2DM patients. METHODS: We conducted a retrospective cohort study among patients with T2DM aged 40–80 at a tertiary healthcare center. Among other inclusion/exclusion criteria (Figure 1), eligible patients must have undergone 2 rounds of colonoscopy examinations – a baseline colonoscopy and a follow-up (index) colonoscopy ≥1 year later. Primary outcome was incident advanced adenomas at index colonoscopy. Primary exposure was long-term (≥1 year) insulin therapy before index colonoscopy. Assuming α = 0.05, background advanced adenoma incidence of 5%, and prevalence of insulin therapy among T2DM of 20%, a cohort size of 865 would be required to have 90% power to detect a 7.5 percentage point increase in advanced adenoma incidence among long-term insulin users. Multivariable logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (CI). RESULTS: Among patients with ≥1 diagnostic code for DM and ≥2 colonoscopy procedure codes, we randomly selected 1,900 patients for chart review and identified 867 eligible patients (Figure 1). Except for BMI, baseline characteristics between short-term/non-insulin users versus long-term insulin users were not significantly different (Table 1). Characteristics of the baseline and index colonoscopies were similar between the two groups (Table 1). Incidence of advanced adenoma at index colonoscopy was higher among the long-term insulin users versus short-term/non-insulin users (20% versus 4.7%, chi2 P &lt; 0.001). Multivariable adjusted OR for advanced adenoma risk associated with long-term insulin use was 6.2 (95% CI: 3.4–11.3). Long-term insulin use was also associated with increased risk of having ≥3 adenomas (adjusted OR 2.8, 95% CI 1.4–5.4) and having ≥1 right-sided advanced adenoma (adjusted OR 6.9, 95% CI 3.5–13.8) at index colonoscopy. CONCLUSION: Chronic insulin therapy was associated with increased risk of advanced adenoma occurrence in T2DM patients. This novel observation is important for developing a risk-tailored approach to the use of colonoscopy in CRC screening/surveillance in patients with T2DM.

Recommended Cancer Screening in Accountable Care Organizations: Trends in Colonoscopy and Mammography in the Medicare Shared Savings Program.

Accountable care organizations (ACOs) are a delivery and payment model designed to encourage integrated, high-value care. We designed a study to test the association between ACOs and two recommended cancer screening tests, colonoscopy for colorectal cancer and mammography for breast cancer. Using the random 20% sample of Medicare claims, beneficiaries were attributed to ACO or non-ACO cohorts on the basis of providers' enrollment in the Medicare Shared Savings Program. An inverse probability of treatment weighting was used to balance patient characteristics between ACO and non-ACO cohorts. A propensity score-weighted, difference-in-differences analysis was then performed using the same provider groups in 2010-pre-ACO-as a baseline. A secondary analysis for older-nonrecommended-age ranges was performed. Prevalence of colonoscopy in recommended age ranges in ACOs from 2010 to 2014 increased from 15.3% (95% CI, 14.9% to 15.6%) to 17.9% (95% CI, 17.3% to 18.5%). This differed significantly from the change in non-ACOs (difference in differences, 1.2%; P < .001). Among women in ACOs, mammography prevalence rose from 53.7% (95% CI, 53.0% to 54.4%) to 54.9% (95% CI, 54.2% to 55.7%). In contrast to colonoscopy, the difference in mammography prevalence was not significantly different in ACO versus non-ACOs (difference in differences, 0.49%; P < .13). A similar pattern was also observed in older-nonrecommended-age ranges with significant difference in differences (ACO v non-ACO) in colonoscopy, but not mammography. The impact of ACOs on cancer screening varies between screening tests. Our results are consistent with a greater effect of ACOs on high-cost, high-complexity screening services, which may be more sensitive to integrated care delivery models.