Initial Screening Colonoscopy Research Articles

The Association between Red Meat Consumption and Advanced Colorectal Adenomas in a Population Undergoing a Screening-Related Colonoscopy in Alberta, Canada

The association between red meat consumption and colorectal cancer has been rigorously examined. However, a more comprehensive understanding of how the intake of unprocessed red meat contributes to the development of early precancerous colorectal lesions, such as advanced colorectal adenomas (ACRAs), requires further investigation. We examined the associations between different types of red meat intake and ACRAs in a sample population of 1083 individuals aged ≥ 50 years undergoing an initial screening colonoscopy in Calgary, Alberta, Canada. Associations between grams per day of total, processed, and unprocessed red meat from diet history questionnaires and ACRAs were evaluated with multivariable logistic regression models. We also applied cubic spline models fitted with three knots (10th, 50th, and 90th percentiles) to identify potential nonlinear associations. We did not observe a meaningful association between unprocessed red meat intake and the presence of ACRAs. In contrast, for every 10 g/d increase in total and processed meat intake, we observed an increase in the odds of ACRAs at the screening colonoscopy (adjusted odds ratio (OR) = 1.05, 95% [CI = 1.01–1.09], p = 0.04) and (adjusted OR = 1.11, 95% [CI = 1.02–1.20], p = 0.02), respectively. This study highlights the importance of differentiating between types of red meat consumption in the context of dietary risks associated with ACRAs.

S386 Assessing for Racial and Ethnic Disparities in Initial Average Risk Screening Colonoscopy Quality Metrics in a Large Military Gastroenterology Fellowship Program

S386 Assessing for Racial and Ethnic Disparities in Initial Average Risk Screening Colonoscopy Quality Metrics in a Large Military Gastroenterology Fellowship Program

Older Age at First Screening Colonoscopy is Associated With an Increased Risk of Colorectal Adenomas and Cancer.

The goal of colorectal cancer (CRC) screening is to detect precancerous polyps before cancer development or identification of cancer at an early stage. Guidelines have recommended screening colonoscopy to start at age 45. Our aim was to determine the impact of delays in performing the first screening colonoscopy on the risk of adenoma or CRC detection. We analyzed colonoscopy and histopathology data of average CRC risk patients who had their first screening colonoscopy between 2010 and 2017. Univariate and multivariable logistic regression was performed to determine the association between demographic variables and the risk of adenomas or CRC. A total of 1155 average risk patients underwent their initial screening colonoscopy during the study period. Median age was 54 years (range of 45-87) and 58.2% were females. In multivariable analysis, older age at first screening colonoscopy was significantly associated with the detection of adenomatous polyps (odds ratio 1.05, 95% confidence interval 1.04-1.07, P<0.001) and CRC (odds ratio 1.11, 95% confidence interval 1.06-1.16, P<0.001). The association between age and risk of adenomatous polyps (F-test 35.43, P=0.0019) and CRC (F-test 36.94, P=0.0017) fit an exponential growth model. It was estimated that the detection rate doubled every 14.20 years and 4.75 years for adenomas and CRC, respectively. We found that older age at the initial performance of a screening colonoscopy was associated with increased detection of adenomatous polyps and CRC. This work highlights the need for guideline adherence for the prevention of CRC development.

Colorectal cancer screening with blood-based tests: Estimated impact of a 1-, 2-, or 3-year screening interval compared with annual FIT and triennial mt-sDNA strategies.

10580 Background: Blood-based tests are an emerging option for non-invasive colorectal cancer (CRC) screening for which the Centers for Medicare &amp; Medicaid Services (CMS) has proposed coverage every 3 years for average-risk individuals. Analyses with the CRC-AIM microsimulation model demonstrated that triennial screening with blood-based tests with CMS minimum performance often yields inferior outcomes to stool-based CRC screening (fecal immunochemical test [FIT] and multi-target stool DNA [mt-sDNA]). CRC-AIM was used to explore the impact of blood-based screening intervals, using reported performance characteristics from the ECLIPSE study (Guardant Health, Inc.)1, on estimated clinical outcomes vs FIT and mt-sDNA screening. Methods: Outcomes were simulated for average-risk individuals screened between ages 45-75 years. Intervals were set at 1, 2, or 3 years for blood-based, 3 years for mt-sDNA and annually for FIT screening. The blood-based test was modeled at 83% CRC sensitivity, 13% advanced adenoma sensitivity, and 90% specificity. Perfect adherence (100%) was modeled for blood-based tests and real-world adherence rates used for CRC initial screening tests (mt-sDNA=65.6%; FIT=42.6%) and follow-up colonoscopy (mt-sDNA=72.1%; FIT=46.0%). Primary outcomes were life-years gained (LYG) and colonoscopies (COL) per 1000 individuals for blood-based screening compared to mt-sDNA and FIT. As a secondary analysis, estimates were generated with perfect (100%) adherence assumed for initial screening and follow-up colonoscopy for mt-sDNA and FIT as well. Results: Blood-based testing at a 3-year interval with 100% adherence led to 11% fewer LYG than mt-sDNA at RWE adherence (240 vs 270, respectively), and 9% more COL (1402/1000 vs 1288/1000). Meanwhile, blood-based testing at a 1-year interval and perfect adherence (best case scenario) resulted in the lowest LYG per COL ratio across all scenarios (16% more LYG and 87% more COL compared to mt-sDNA at RWE adherence). Blood-based test results showed similar trends when compared to FIT. Conclusions: Outcomes for blood-based screening every 3 years based on reported test performance characteristics and unrealistic perfect adherence demonstrate fewer LYG as compared to either mt-sDNA or FIT. When compared to real-world adherence for mt-sDNA and FIT, blood-based tests with 1- and 2-year intervals and perfect adherence had higher LYG with the tradeoff of a greater number of diagnostic colonoscopies. [Table: see text]

Elevated Adenomatous Polyp Detection Rate Among Alaska Native and American Indian People in Interior Alaska, 2018-2022.

Colorectal cancer (CRC) incidence and mortality are twice as high among Alaska Native people as among non-Hispanic White people in the United States; as such, colonoscopy is a recommended screening test for Alaska Native people. Adenoma detection rate (ADR) is measured in patients at average risk of CRC undergoing initial screening colonoscopy and reflects the prevalence of precancerous polyps in a screened population. We evaluated the ADR among Alaska Native people living in Interior Alaska. This project evaluated the ADR among Alaska Native and American Indian adults aged ≥40 years (N = 460) living in Interior Alaska, using a retrospective medical record review of patients referred for screening colonoscopy from February 1, 2018, through March 31, 2022. The main outcome measure was ADR, stratified by age and sex. The ADR was 45.0% overall: 43.0% among women and 47.1% among men. Among patients aged ≥50 years, the ADR was 67.1%: 62.7% among women and 70.7% among men. Among patients aged 40-49 years, the ADR was 34.4%: 35.3% among women and 33.3% among men. Measured ADR was high among Alaska Native men and women aged ≥50 years in Interior Alaska and in all age groups that were screened. These findings have implications for which CRC screening methods, intervals, and age to begin screening are most appropriate for Alaska Native people, as well as the need for future research on the pathology, etiology, and natural history of CRC in this population.

Growth hormone and gastrointestinal malignancy: An intriguing link.

Growth hormone (GH) excess is associated with several systemic complications, one of which is the increased risk of neoplastic processes particularly of the gastrointestinal (GI) tract. Among the GI neoplasms, the most reported association is with benign and malignant neoplasms of the colon. In the majority of published literature, an increased incidence of GI neoplasms, both colonic adenomas as well as colorectal carcinoma is reported. However, the studies on colon cancer-specific mortality rate are conflicting with recent studies reporting similar cancer-specific mortality rates in comparison to controls. Many studies have reported an association of colorectal neoplasms with GH levels. Pathogenic mechanisms put forward to explain this association of GH excess and GI neoplasms primarily involve the increased GH-insulin-like growth factor 1 (IGF-1) signaling. Both GH and IGF-1 have proliferative, anti-apoptotic, and angiogenic effects on the systemic tissues leading to cellular proliferation. Other contributing factors to the increased risk of GI neoplasms include slow intestinal transit with a redundant large bowel, altered bile acids, deranged local immune response, shared genetic susceptibility factors and hyperinsulinemia. In view of the increased risk association, most guidelines for the care of acromegaly patients recommend an initial screening colonoscopy. Recommendations for further follow-up colonoscopy differ but broadly, the guidelines agree that it depends on the findings at first colonoscopy and state of remission of GH excess. Regarding the concern about the risk of colorectal cancers in patients receiving recombinant GH therapy, most cohort studies do not show an increased risk.

A sex-specific propensity-adjusted analysis of colonic adenoma detection rates in a screening cohort

The prevalence of colorectal adenoma and advanced adenoma (AA) differs between sexes. Also, the optimal age for the first screening colonoscopy is under debate. We, therefore, performed a sex-specific and age-adjusted comparison of adenoma, AA and advanced neoplasia (AN) rates in a real-world screening cohort. In total, 2824 asymptomatic participants between 45- and 60-years undergoing screening colonoscopy at a single-centre in Austria were evaluated. 46% were females and mean age was 53 ± 4 years. A propensity score for being female was calculated, and adenoma, AA and AN detection rates evaluated using uni- and multivariable logistic regression. Sensitivity analyses for three age groups (group 1: 45 to 49 years, n = 521, 41% females, mean age 47 ± 1 years; group 2: 50 to 54 years, n = 1164, 47% females, mean age 52 ± 1 years; group 3: 55 to 60 years, n = 1139, 46% females, mean age 57 ± 2 years) were performed. The prevalence of any adenoma was lower in females (17% vs. 30%; OR 0.46, 95% CI 0.38–0.55; p < 0.001) and remained so after propensity score adjustment for baseline characteristics and lifestyle factors (aOR 0.52, 95% CI 0.41–0.66; p < 0.001). The same trend was seen for AA with a significantly lower prevalence in females (3% vs. 7%; OR 0.38, 95% CI 0.26–0.55; p < 0.001) that persisted after propensity score adjustment (aOR 0.54, 95% CI 0.34–0.86; p = 0.01). Also, all age-group sensitivity analyses showed lower adenoma, AA and AN rates in females. Similar numbers needed to screen to detect an adenoma, an AA or AN were found in female age group 3 and male age group 1. Colorectal adenoma, AA and AN were consistently lower in females even after propensity score adjustment and in all age-adjusted sensitivity analyses. Our study may add to the discussion of the optimal age for initial screening colonoscopy which may differ between the sexes.

Characteristics of Serrated Adenomas in Non-Hispanic Whites and African Americans Undergoing Screening Colonoscopy.

Background and aimAdenomatous polyps are precursor lesions for colorectal cancer (CRC). Serrated adenomas/polyps are considered a risk factor for the development of proximal and interval CRC. African-Americans are at higher risk for right-sided CRC. Minimal data evaluating serrated adenoma characteristics by race/ethnicity on initial screening colonoscopy (SC) exist. The aim of this investigation was to compare the characteristics of serrated adenomas found in non-Hispanic whites (nHw) and African-Americans (AA) undergoing initial SC.MethodsThe University of Florida-Jacksonville endoscopy database was searched for all SC performed between January 2000 and December 2014. Inclusion criteria were nHw or AA race/ethnicity and histologically proven serrated adenoma found at SC. Data were collected for all included age at SC, sex, number, location, and size of serrated adenomas found.ResultsA total of 8693 individuals (nHw - 4199 and AA - 4494) underwent SC between January 2000 and December 2014. Serrated adenomas were found in 479 individuals (nHw, n=294; AA, n=185), and AA were significantly less likely than nHw to have serrated adenomas on SC (AA 4.1% vs nHw 7%; p< 0.0001). No difference was observed in mean age, location, or size between nHw and AA with serrated adenomas.ConclusionsSerrated adenomas are more frequent in nHw compared to AA at initial SC. No difference was seen in size or location of serrated adenomas, as well as patient age, between AA and nHw. A study of genetic factors predisposing to serrated adenoma formation and the impact of socioeconomic disparities should be performed across ethnic groups to understand this difference.

Risk of metachronous neoplastic lesions during post-polypectomy surveillance in individuals with advanced colorectal neoplasia at initial screening colonoscopy.

The evidence of associations between some types of advanced colorectal neoplasia (ACN) at baseline and the risk of metachronous neoplasia is inconsistent. This study aimed to elucidate the incidence of metachronous neoplasia during post-polypectomy surveillance in individuals with ACN at baseline and examine the risk factors for its high incidence. Data from individuals who underwent endoscopic resection for ACN and received surveillance colonoscopy were analyzed. Data from individuals with no neoplastic lesions at baseline were used as reference. The incidence of metachronous ACN and clinically significant neoplasia (ACN and nonadvanced adenomas sized ≥5mm) were evaluated. Risk factors for the higher incidence of these lesions were examined in individuals with ACN at baseline. During the median follow-up period of 61.8months, metachronous ACN and nonadvanced adenomas sized ≥5mm were detected in 9.6% and 32.4% of individuals with ACN at baseline (n=136), respectively. The cumulative incidence of metachronous ACN and clinically significant neoplasia in individuals with ACN at baseline (3-year incidence: 5.5% and 16.9%, respectively) was higher than that in individuals with no neoplastic lesions at baseline (P<0.01 for both). The presence of advanced histology at baseline, ≥5 neoplastic lesions at baseline, and family history of colorectal cancer were identified as risk factors for the higher incidence of clinically significant neoplasia. The relatively high incidence of metachronous neoplasia in individuals with ACN at baseline was confirmed; careful surveillance is required for these individuals, particularly in those with the risk factors.

Are the current colonoscopy recommendations for interval surveillance in patients with polyps enough? Machine learning-augmented propensity score cohort analysis of 1840 patients.

Colonoscopy remains the gold standard for screening and surveillance of colorectal neoplasms, and is associated with a lower risk of colorectal cancer (CRC)-related mortality. The current interval surveillance recommendations in patients with previous adenomas lack sufficient evidence. The prevalence of subsequent adenomas, and especially high-risk adenomas, during surveillance is not well known. The primary outcome of this study was to determine the prevalence of polyps upon surveillance colonoscopy in patients who have a history of adenomas on initial average-risk-screening colonoscopy, but then have a normal initial surveillance (second) colonoscopy between 2003 and 2017. This is the first known retrospective cohort study of adenoma detection rate (ADR) with sub-group analysis of patients with serial surveillance colonoscopies by abnormal and high-risk surveillance findings separately by prior abnormal colonoscopies and correct surveillance strategies based on the recent March 2020 updated guidelines. After ADR calculation, machine learning-augmented propensity score adjusted multivariable regression with augmented inverse-probability weighting propensity (AIPW) score analysis was used to assess the relationship between guideline adherence, as well as abnormal and high-risk surveillance findings. A total of 1840 patients with pathologically confirmed adenomas or cancer on an initial average-risk-screening (first) colonoscopy met study criteria. 837 (45.5%) had confirmed adenomas on second colonoscopy, and 1003 (54.5%) had normal findings. Of 837 patients with polyps on both first and second colonoscopy, 423 (50.5%) had adenomas on third colonoscopy. Of the 1003 patients without polyps on second colonoscopy, 406 (40.5%) had confirmed adenomas on third colonoscopy. Guideline adherence was low at 9.18%, though was associated in propensity score adjusted multivariable regression with increased odds of an abnormal third (but not high-risk) colonoscopy, with comparable AIPW results. This 14-year study demonstrates the ADR to be > 40% on the third colonoscopy for patients with adenomas on initial screening colonoscopy, who then have a normal second colonoscopy. Through advanced machine learning and propensity score analysis, we showed that correct adherence is associated with higher odds of abnormal, but not high-risk abnormal 3rd colonoscopy, with evidence that high-risk surveillance findings are reduced by providers shortening the time between surveillance colonoscopies in contrast to the guidelines for those for whom there is presumed greater clinical suspicion of eventual cancer. Larger prospective trials are needed to guide optimal surveillance for these patients.

A145 ENDOSCOPICALLY NON-VISIBLE INTERVAL COLONIC ADENOCARCINOMA DESPITE HIGH-QUALITY SURVEILLANCE.

Abstract Background Colonoscopy remains the gold-standard for screening and surveillance of colorectal cancer (CRC). Regular colonoscopy with polypectomy has been associated with reduced CRC incidence and mortality. However, interval CRC, defined as cancer diagnosed between initial screening and subsequent surveillance colonoscopies, occurs at rates of 2–14%. Identified risk factors for interval cancers include patient-related factors (older age, diverticular disease, proximal CRC), endoscopy-related factors (colonoscopy by non-gastroenterologists or in an outpatient setting; endoscopists with low rates of completion, adenoma detection or polypectomy) and biologic factors (microsatellite instability (MSI), CpG island methylation). We report a patient with interval metastatic ileo-cecal adenocarcinoma despite multiple, high-quality surveillance colonoscopies, not endoscopically visible as no visible intra-luminal mucosal component was present. Aims To describe a case of an interval CRC without an endoscopically visible intra-luminal component. Methods Case description and literature review. Results A 69-year-old male, with a history of multiple advanced colonic polyps requiring multiple surveillance colonoscopies and polypectomies, presented with symptoms of bowel obstruction. An abdominal CT scan revealed findings of terminal ileitis and upstream small bowel obstruction. Colonoscopy was performed, revealing obstruction of the ileo-cecal valve with a firm cecal submucosal lesion without abnormal overlying mucosal abnormalities. Exploratory laparoscopy revealed a mass at the ileo-cecal valve with associated peritoneal deposits. A right hemicolectomy was performed, and pathological examination demonstrated metastatic invasive adenocarcinoma involving the cecum, the terminal ileum and ileo-cecal valve without extension into the lumen or formation of an overt polypoid mass. The tumour extended into the wall of the distal ileum in a circumferential fashion, involving the immediate deep serosa, but with only minimal, focal mucosal ileal involvement and no overt polypoid mass. An independent review of the case and resection specimen by a second pathologist confirmed absence of significant ileal or colonic mucosal involvement and no obstructing intraluminal component. Conclusions This case illustrates a rare presentation of an interval CRC that was not identified despite several high-quality surveillance colonoscopies, as only minimal mucosal involvement was present. As endoscopy remains the gold-standard for early detection and removal of pre-malignant lesions and early malignancy, the patient’s presentation with interval malignant bowel obstruction and metastatic disease, despite adequate quality surveillance, demonstrates an inherent limitation of colonoscopy. To our knowledge, this is only the third documented case of endoscopically non-visible interval CRC. Funding Agencies NoneNone

Polygenic risk score is a predictor of adenomatous polyps at screening colonoscopy

BackgroundSingle nucleotide polymorphism (SNP)-based polygenic risk scoring is predictive of colorectal cancer (CRC) risk. However, few studies have investigated the association of genetic risk score (GRS) with detection of adenomatous polyps at screening colonoscopy.MethodsWe randomly selected 1769 Caucasian subjects who underwent screening colonoscopy from the Genomic Health Initiative (GHI), a biobank of NorthShore University HealthSystem. Outcomes from initial screening colonoscopy were recorded. Twenty-two CRC risk-associated SNPs were obtained from the Affymetrix™ SNP array and used to calculate an odds ratio (OR)-weighted and population-standardized GRS. Subjects with GRS of < 0.5, 0.5–1.5, and > 1.5 were categorized as low, average and elevated risk.ResultsAmong 1,769 subjects, 520 (29%) had 1 or more adenomatous polyps. GRS was significantly higher in subjects with adenomatous polyps than those without; mean (95% confidence interval) was 1.02 (1.00–1.05) and 0.97 (0.95–0.99), respectively, p < 0.001. The association remained significant after adjusting for age, gender, body mass index, and family history, p < 0.001. The detection rate of adenomatous polyps was 10.8%, 29.0% and 39.7% in subjects with low, average and elevated GRS, respectively, p-trend < 0.001. Higher GRS was also associated with early age diagnosis of adenomatous polyps, p < 0.001. In contrast, positive family history was not associated with risk and age of adenomatous polyps.ConclusionsGRS was significantly associated with adenomatous polyps in subjects undergoing screening colonoscopy. This result may help in stratifying average risk patients and facilitating personalized colonoscopy screening strategies.

Real-world cost-effectiveness of stool-based colorectal cancer screening in a Medicare population

Aim Multiple screening strategies are guideline-endorsed for average-risk colorectal cancer (CRC). The impact of real-world adherence rates on the cost-effectiveness of non-invasive stool-based CRC screening strategies remains undefined. Methods This cost-effectiveness analysis from the perspective of Medicare as a primary payer used the Colorectal Cancer and Adenoma Incidence and Mortality Microsimulation Model (CRC–AIM) to estimate cost and clinical outcomes for triennial multi-target stool DNA (mt-sDNA), annual fecal immunochemical test (FIT) and annual fecal occult blood test (FOBT) screening strategies in a simulated cohort of US adults aged 65 years, who were assumed to either be previously unscreened or initiating screening upon entry to Medicare. Reported real-world adherence rates for initial stool-based screening and colonoscopy follow up (after a positive stool test result) were defined as 71.1% and 73.0% for mt-sDNA, 42.6% and 47.0% for FIT, and 33.4% and 47.0% for FOBT, respectively. The incremental cost-effectiveness ratio using quality-adjusted life years (QALY) was defined as the primary outcome of interest; other cost and clinical outcomes were also reported in secondary analyses. Multiple sensitivity and scenario analyses were conducted. Results When reported real-world adherence rates were included only for initial stool-based screening, mt-sDNA was cost-effective versus FIT ($62,814/QALY) and FOBT ($39,171/QALY); mt-sDNA also yielded improved clinical outcomes. When reported real-world adherence rates were included for both initial stool-based screening and follow-up colonoscopy (when indicated), mt-sDNA was increasingly cost-effective compared to FIT and FOBT ($31,725/QALY and $28,465/QALY, respectively), with further improved clinical outcomes. Limitations Results are based on real-world cross-sectional adherence rates and may vary in the context of other types of settings. Only guideline-recommended stool-based strategies were considered in this analysis. Conclusion Comparisons of the effectiveness and benefits of specific CRC screening strategies should include both test-specific performance characteristics and real-world adherence to screening tests and, when indicated, follow-up colonoscopy.

Timeliness of Surveillance Colonoscopy in Underserved Populations: Association with Patient Navigation for Initial Screening Colonoscopy

Patient navigation (PN) improves initial colorectal cancer (CRC) screening in underserved populations. Whether the impact persists and improves the timeliness of follow-up screening colonoscopy (FSC) is not known. Patients receiving PN at initial colonoscopy between 2010-2011 with findings requiring FSC were matched to unnavigated patients requiring FSC. The primary outcome was proportion of patients with timely FSC, defined as colonoscopy within six months of recommendation. Of 216 patients in the study 103 (48%) completed FSC: 33 of 62 (53%) who received PN compared with 70 of 154 (45%) in the control group (p=.30). After adjusting for insurance, education, language and visits, navigated patients had higher odds (AOR=1.53, 95% CI 0.80-2.92) of timely FSC completion compared with unnavigated patients. Timely FSC completion in underserved patients is low. Patients navigated for initial colonoscopy or not had similar rates of FSC completion. Future studies should investigate navigation for FSC to improve equity in CRC.

Abstract PO-183: Pre-diabetes, diabetes and the risk for adenoma detection

Abstract Background U.S Multi-Society Task Force of Colorectal Cancer (MSTF) has suggested that screening begin at a younger age in Blacks to detect precancerous adenomas. Our group conducted a multi-institution retrospective study of clinical data collected in 2012 to identify biological factors associated with adenoma detection. However, the results of the investigation revealed that the included Urban Safety Net Hospital (USNH) had a relatively lower adenoma detection rate (ADR) that may have confounded other analysis in the study. After successful initiatives to improve ADR, this interim study compares the incidence of adenomas in non-diabetic (ND), pre- diabetic (PD) and Type II diabetic (T2DM) categories. Methods This study is a retrospective analysis of prospectively collected data from January 2017 to June 2018. Chart review was used to build a registry of subjects within ages 45 - 75 years old that completed an initial screening colonoscopy. Subjects at high risk for adenoma or colorectal cancer (hereditary syndromes, inflammatory bowel disease), symptomatic presentation, poor bowel prep, or incomplete colonoscopy were excluded from the study. ND, PD and T2DM groups were established by clinical diagnosis or HgbA1c levels according to American Diabetes Association guidelines. 12 Subjects with an unknown diabetes status were also excluded from this analysis. Chi- square analysis was performed to determine significance at a threshold of p ≤ 0.05 for unadjusted p-values. Preliminary Results As shown in Table 1, 248 patients met the inclusion criteria. 94% of patients identified as Black or African American, &amp;lt;1 % as Caucasian and 5% declined to identify with a race or was left unknown. 94 and 89 out of 248 subjects had pre-diabetes or diabetes, respectively. The overall adenoma detection rate is at 29%. The percentage of detected adenomas in the ND, PD and T2DM group were 22%, 33%, and 29% respectively. Discussion As evidence by an ADR of 29%, preliminary data from 2017 shows quality improvement in colonoscopies performed at this USNH. In this cohort that is 94% Black, the incidence of T2DM and PD is higher than the CDC’s national averages for individuals ≥ 45 years old. 62% of this population sample are diabetic or pre-diabetic. At a sample size of 284 subjects, this ongoing study is underpowered and cannot yet conclude an association between a diagnosis of PD, T2DM, and the incidence of adenomas. However, there is a trend that shows that a higher proportion of adenomas are in the PD and the T2DM groups in comparison to the ND group. The relatively high proportion of adenomas in the PD group suggests that the associated risk for colorectal cancer may occur prior to diagnosis with T2DM. Citation Format: Dimitri F. Joseph, Ellen Li, Laura Martello-Rooney, Michelle Follen, Evan Grossman. Pre-diabetes, diabetes and the risk for adenoma detection [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PO-183.

S0278 Adenoma and Sessile Serrated Detection Rates in Patients Undergoing Screening Colonoscopy Are Higher in Those Prepped With High-Volume Colonic Water Irrigation Than With Standard Oral Bowel Preparations

INTRODUCTION: Adenoma detection rate (ADR) is defined as the percentage of patients age 50 and older, with an average risk for colorectal cancer (CRC) who have adenomas detected on initial screening colonoscopy. ADR is an indicator of the adequacy of colonic preparation and skill level of the colonoscopist. Conventional adenomas have historically been considered to be the only screening-relevant CRC precursor lesion. However, sessile serrated polyps (SSPs) are considered to be a disproportionate contributor to interval CRC (subsequent to a colonoscopy). Quality of colonoscopy is critically dependent on the adequacy of colonic preparation. This study evaluated the adequacy of using high volume colonic water irrigation bowel prep (BP) on the detection rates of neoplastic polyps at the index screening exam. METHODS: ADR and detection rates of SSPs were collected at Austin Gastroenterology (Austin, TX) between October 1, 2018 and June 31, 2019. Study participants included 112 eligible and average risk patients. The high-volume colon irrigation was performed using an FDA-cleared system and under stringent standard operating procedures (SOP) by nurses and technicians trained by the managing operator. The study participants were examined by 18 gastroenterologists. RESULTS: ADRs of patients undergoing high-volume water irrigation BP was 34% in females and 60% in males. The detection rate for SSPs in patients who underwent high-volume water irrigation BP was 12.5%. The average Boston Bowel Prep Score (BBPS) was 8.3 (n = 112). CONCLUSION: When using a high-volume colonic water irrigation BP performed under stringent standard operating procedures the ADRs of patients was 34% in females and 60% for male, significantly exceeding the national guidelines for oral prep, 20% and 30%, respectively. The SSPs detection rate was also higher than the 5%–7% previously recorded in literature. Detection rate of colonic lesions is inversely related to the patient’s post-colonoscopy CRC risk, and improvement in methods and techniques to increase their detection rate will improve patient care. The FDA cleared high-volume colonic water irrigation, has outstanding BBPS scores, ADR, and SSP detection rates. Due to the increased quality of detection of neoplastic polyps, this approach should be considered a prep of choice for improved quality and outcomes.

Abstract B102: Factors contributing to precancerous polyp detection in initial screening colonoscopies

Abstract Background: The incidence of colorectal cancer is persistently higher in Black/African Americans than other races in the United States. It is less clear whether Black/African Americans are at higher risk for colonic precancerous polyps, which represent an earlier stage in colorectal adenoma-carcinoma progression. Methods: A retrospective chart review was performed on initial average-risk screening colonoscopies on patients (age 45-75 years) during 2012 at 3 institutions. Multivariable logistic regression models were used to examine the relationship between potential risk factors and the detection of precancerous polyps. Results: Of the 2,225 initial screening colonoscopies, 1,495 (67.2%) were performed on Black/African Americans and 566 (25.4%) on Caucasian non-Hispanic patients. The mean age of initial colonoscopies was 57.1 y and 56.0 y for Black and Caucasian patients, respectively. Male patients represented 32.0% and 42.8% of the Black and Caucasian patients, respectively. Obese patients represented 41.4% and 31% of Black and Caucasian patients. A higher percentage (30%) of the Black patients were diagnosed with diabetes mellitus compared to Caucasians (11%). Multivariable logistic regression revealed that performance of the colonoscopy by academic gastroenterologists was associated with higher precancerous polyp detection compared to contractual nonacademic gastroenterologists (OR 1.69 95% CI 1.32-2.17, p&amp;lt;0.0001). Because of this observation, a physician feedback program was initiated, and as of 2017 the polyp detection rates at all three institutions reached 25%. In addition, multivariable analysis also identified older age (OR 1.03/year 95% CI 1,01-1,04 p= 0.0006), male sex (OR 1.60 95%CI 1.32-2.00 p&amp;lt;0.0001), current smoking (1.52 95% CI 1.32-2.17 p&amp;lt;0.0001) and diabetes mellitus (OR 1.27 95% CI 0.99-1.63 p = 0.062) as associated with higher precancerous colon polyp detection or adenoma detection rate (ADR). Neither race, ethnicity, BMI, nor insurance was significantly associated with detection rates. Conclusions: It is imperative that metrics of polyp detection rates be routinely monitored to ensure that all patients have access to high-quality screening colonoscopies. A prospective observational cohort study will help further identify factors associated with precancerous polyp detection, now that variations in operator detection rates have been addressed. Citation Format: Yakira David, Lorenzo Ottaviano, Jihye Park, Sadat Iqbal, Michelle Likhtshteyn, Samir Kumar, Helen Lyo, Ayanna Lewis, Brandon Lung, Jesse Frye, Li Huang, Ellen Li, Jie Yang, Laura Martello, Shivakumar Vignesh, Joshua Miller, Evan Grossman. Factors contributing to precancerous polyp detection in initial screening colonoscopies [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr B102.

Abstract C131: Patient compliance with professional society guidelines for surveillance and re-screening following initial screening colonoscopy

Abstract Background: Screening colonoscopy followed by timely surveillance and rescreening colonoscopy can prevent most colorectal cancers (CRC) by enabling removal of pre-cancerous polyps. Surveillance compliance with professional society guidelines is unknown. We examined compliance patterns of a community-based cohort screened at an endoscopy center in South Carolina with documented 83% and 89% CRC incidence and mortality reductions, respectively, validating very high polyp clearance, which supports using these data to study surveillance timing compliance relative to recommendations. Historically, data sources to study surveillance compliance have been limited because no colonoscopy series is documented with evidence of high polyp clearance at screening. Methods: Patients provided screening colonoscopy from September 4, 2001 to December 31, 2015 followed through July 31, 2016 were studied for surveillance and rescreening colonoscopy timing classified by risk status at screening and to study the impact of the 2006 surveillance guidelines - 1-year surveillance for sessile adenoma removed piecemeal, hyperplastic polyposis syndrome or &amp;gt; 10 adenomas; 3 years for 3-10 adenomas, ≥1cm adenoma, villous features or high-grade dysplasia; 5 years for 1-2 small adenomas; 10 years for no adenoma or &amp;lt; 3 small hyperplastic polyps in left colon). Surveillance was classified as appropriate, overuse and underuse within each risk category. We used Kaplan-Meier analysis with the log-rank test, and logistic regression to identify the factors associated. Findings: Of 14,048 study-eligible patients (after excluding patients aged &amp;lt;40/≥75 years, CRC at screening, 2nd colonoscopy not due during study period, attained 75 years, and missing pathology), majority were female (51.0%), aged 50-59 years (55.1%), black (51.9%), and had Medicare/private insurance (87.9%). Of 6,817 surveillance-eligible, 52.6% completed it, 17% at the appropriate time. Among 3-year- and 5-year-eligibles, overuse (39% and 36%, respectively) and underuse (48.4% and 55.8%, respectively) were widespread. Among the 10-year rescreening-eligible, 45% completed it (mean 5.08 years since screening), 39.9% too early, 5.1% timely or late. Compared to pre-guideline period, overuse decreased among the 5-year category (25.5% vs. 48.6%), and increased among the 3-year category (41.5% vs. 35.4%). Among the 10-year rescreening group, overuse increased (60.4% vs. 31.6%). Overuse more likely among the 5-year group vs. ≤3-year (OR:2.7; 95%CI: 2.1- 3.4). Other overuse predictors were: adenoma ≥1cm (OR:1.9; 95%CI: 1.3-2.7) and multiple advanced adenoma features (OR:2.1; 95%CI: 1.4-3.2). For underuse, right-sided adenoma (OR:1.6; 95%CI: 1.2-2.1) and Medicaid (OR: 3.4; 95%CI: 1.4-8.1) were significant. Conclusions: Surveillance compliance improved following the 2006 guidelines. Underuse by patients with right-sided adenoma and Medicaid insurance needs research and policy attention, as also premature rescreening among low-risk population. Citation Format: Meng-Han Tsai, Sudha Xirasagar, JiaJia Zhang. Patient compliance with professional society guidelines for surveillance and re-screening following initial screening colonoscopy [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr C131.

High-Risk Adenomas at Screening Colonoscopy Remain Predictive of Future High-Risk Adenomas Despite an Intervening Negative Colonoscopy.

Limited data inform the current postpolypectomy surveillance guidelines, which suggest a shortened interval to third colonoscopy after a negative second examination if high-risk adenomas (HRA) were present on the initial screening colonoscopy. Therefore, we examined the risk of HRA at third colonoscopy stratified by findings on 2 previous examinations in a prospective screening colonoscopy cohort of US veterans. We identified participants who had 3 or more colonoscopies from CSP#380. We examined the risk of HRA on the third examination based on findings from the previous 2 examinations. Multivariate logistic regression was used to adjust for multiple covariates. HRA were found at the third examination in 114 (12.8%) of 891 participants. Those with HRA on both previous examinations had the greatest incidence of HRA at third examination (14/56, 25.0%). Compared with those with no adenomas on both previous examinations, participants with HRA on the first examination remained at significantly increased risk for HRA at the third examination at 3 years after a negative second examination (odds ratio [OR] 3.41, 95% confidence interval [CI] 1.28-9.08), 5 years (OR 3.14, 95% CI 1.49-6.61), and 7 years (OR 2.89, 95% CI 1.08-7.74). In a screening population, HRA on the first examination identified individuals who remained at increased risk for HRA at the third examination, even after a negative second examination. This finding supports current colorectal cancer surveillance guidelines, which suggest a shortened, 5-year time interval to third colonoscopy after a negative second examination if high-risk findings were present on the baseline examination.

Type 2 diabetes impacts colorectal adenoma detection in screening colonoscopy

Background: Diabetes is associated with an increased risk of colorectal cancer (CRC). We conducted a retrospective analysis of adenoma detection rates (ADR) in initial screening colonoscopies to further investigate the role of diabetes in adenoma detection. Methods: A chart review was performed on initial average risk screening colonoscopies (ages 45–75) during 2012–2015. Data collected included basic demographics, insurance, BMI, family history of CRC, smoking, diabetes, and aspirin use. Multivariable generalized linear mixed models for binary outcomes were used to examine the relationship between diabetes and variables associated with CRC risk and ADR. Results: Of 2865 screening colonoscopies, 282 were performed on patients with type 2 diabetes (T2DM). Multivariable analysis suggested that T2DM (OR = 1.49, 95% CI:1.13–1.97, p = 0.0047) was associated with an increased ADR, as well as smoking, older age, higher BMI and male sex (all p < 0.05). For patients with T2DM, those not taking diabetes medications were more likely to have an adenoma than those taking medication (OR = 2.38, 95% CI:1.09–5.2, p = 0.03). Conclusion: T2DM has an effect on ADR after controlling for multiple confounding variables. Early interventions for prevention of T2DM and prescribing anti-diabetes medications may reduce development of colonic adenomas and may contribute to CRC prevention.