Average-risk Colorectal Cancer Screening Research Articles

Deep learning in CT colonography: differentiating premalignant from benign colorectal polyps

ObjectivesTo investigate the differentiation of premalignant from benign colorectal polyps detected by CT colonography using deep learning.MethodsIn this retrospective analysis of an average risk colorectal cancer screening sample, polyps of all size categories and morphologies were manually segmented on supine and prone CT colonography images and classified as premalignant (adenoma) or benign (hyperplastic polyp or regular mucosa) according to histopathology. Two deep learning models SEG and noSEG were trained on 3D CT colonography image subvolumes to predict polyp class, and model SEG was additionally trained with polyp segmentation masks. Diagnostic performance was validated in an independent external multicentre test sample. Predictions were analysed with the visualisation technique Grad-CAM++.ResultsThe training set consisted of 107 colorectal polyps in 63 patients (mean age: 63 ± 8 years, 40 men) comprising 169 polyp segmentations. The external test set included 77 polyps in 59 patients comprising 118 polyp segmentations. Model SEG achieved a ROC-AUC of 0.83 and 80% sensitivity at 69% specificity for differentiating premalignant from benign polyps. Model noSEG yielded a ROC-AUC of 0.75, 80% sensitivity at 44% specificity, and an average Grad-CAM++ heatmap score of ≥ 0.25 in 90% of polyp tissue.ConclusionsIn this proof-of-concept study, deep learning enabled the differentiation of premalignant from benign colorectal polyps detected with CT colonography and the visualisation of image regions important for predictions. The approach did not require polyp segmentation and thus has the potential to facilitate the identification of high-risk polyps as an automated second reader.Key Points• Non-invasive deep learning image analysis may differentiate premalignant from benign colorectal polyps found in CT colonography scans.• Deep learning autonomously learned to focus on polyp tissue for predictions without the need for prior polyp segmentation by experts.• Deep learning potentially improves the diagnostic accuracy of CT colonography in colorectal cancer screening by allowing for a more precise selection of patients who would benefit from endoscopic polypectomy, especially for patients with polyps of 6–9 mm size.

Abstract PO-253: Overcoming barriers to colorectal cancer screening for underserved patients: Lessons from the COVID-19 pandemic

Abstract Introduction This patient navigation initiative works to address cancer health disparities by improving education and access to screening and cancer care. This initiative includes partnerships with local Federally Qualified Health Centers (FQHCs) and primary care physicians (PCPs), primarily focused on increasing colorectal cancer (CRC) screening rates among underserved populations in Western New York (WNY) who may have low health literacy. Grounded in health services research, we aimed to improve clinical care by implementing evidence-based guidelines into practice by working directly with underserved communities in our area to improve CRC screening rates at an urban FQHC. Methods Throughout the COVID-19 pandemic, our navigators pivoted to a hybrid schedule with remote access to health systems, splitting time between our cancer center and remotely at home until allowed back on-site to work at the FQHC. Colonoscopy halted in NY between March and June 2020, resulting in scheduling challenges due to significant backlogs of cancelled procedures during the shutdown and regional hold on elective procedures. Endoscopists across WNY had reduced capacity for postponed procedures, leading to the prioritization of scheduling for symptomatic patients. Therefore, navigators focused screening efforts on widely disseminating stool-based tests to patients due for average-risk CRC screening and prioritizing patients with positive screening results to coordinate colonoscopy appointments. Results Between April 2020 through March 2021, our pre-pandemic goal was to educate 550 patients and screen 300 patients. During this timeframe, navigators provided screening education to 632 patients and screened 232 patients despite significant challenges presented by the COVID-19 pandemic. With many colonoscopy procedures being cancelled and/or rescheduled, stool-based tests were widely available and became a more common choice for patients. To date, since April 2020, navigators have educated 807 patients and have navigated 306 patients to complete CRC screening. Of those 306 patients, 234 chose to complete at-home stool-based testing. In 2020, CRC screening rates remained over 50%, exceeding national FQHC targets. This was achieved through targeted patient outreach, education, and navigation, despite significant challenges with the shutdown and the COVID-19 pandemic. Conclusions Stool-based tests paired with targeted outreach and education were an efficient tool for CRC screening during this challenging time. Navigators regularly cross-check records to be sure results are received by ordering physicians and properly coded for accurate data reporting. This is especially important for positive test results and timely follow up, which may lead to improved health outcomes. Moving forward, this paired approach may be an effective strategy for improving screening rates among hard-to-reach patient populations and patients facing substantial barriers to accessing routine medical care. Citation Format: Kathryn M. Glaser, Christina Crabtree-Ide, Alyssa McNulty, Ellis Gomez, Nicole Donofrio, Tessa Flores, Mary E. Reid. Overcoming barriers to colorectal cancer screening for underserved patients: Lessons from the COVID-19 pandemic [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-253.

High Positive Predictive Value of Multitarget Stool DNA After Aerodigestive Tract Radiotherapy.

BACKGROUND AND AIMS:Multitarget stool DNA (mt-sDNA) is approved for average-risk colorectal cancer screening; test performance in persons with prior radiation therapy (RT) has not been studied. RT can induce gastrointestinal bleeding and alter DNA methylation, which may affect mt-sDNA accuracy. Among patients previously treated with RT, we aimed to measure the positive predictive value (PPV) of mt-sDNA and compare these results to historical estimates of mt-sDNA PPV among average-risk patients.METHODS:After institutional review board approval, we conducted a retrospective cohort study of a multisite academic and community-based practice. Patients with RT and subsequent mt-sDNA use during the study period (2014–2016) were identified. The findings at diagnostic colonoscopy were compared with published reports among average-risk patients. Nominal P values were generated by 2-tailed Fisher’s exact testing in comparisons of colorectal neoplasia (CRN) rates between groups.RESULTS:There were 220 patients who had RT before mt-sDNA testing. RT was delivered along the aerodigestive tract in 108 patients. Mt-sDNA tests were positive in 45 of 220 patients (20%), and colonoscopy findings were available for 42; 31 of 42 patients (74%) had CRN. PPV by mt-sDNA was similar when stratified by site of prior RT (along vs outside the aerodigestive tract; P = 1.00). Detection of advanced CRN (36%) was nominally higher than previously published retrospective (27%) and prospective (20%) studies. The median time from the start of RT to mt-sDNA use was 7 (interquartile range, 3–14) years.CONCLUSION:With a test positivity rate and PPV for CRN similar to reports among average-risk patients, prior RT does not appear to adversely affect mt-sDNA performance.

Gallstone Disease and Risk of Conventional Adenomas and Serrated Polyps: A Prospective Study.

Gallstone disease has been associated with colorectal cancer and some form of polyps, although the findings are inconclusive. It remains unknown whether gallstone disease influences the initiation of colorectal cancer. We prospectively assessed the association of gallstone disease with risk of colorectal cancer precursors, including conventional adenomas and serrated polyps, in the Nurses' Health Study (1992-2012), the Nurses' Health Study II (1991-2011), and the Health Professionals Follow-up Study (1992-2012). Gallstone diseases were assessed using biennial follow-up questionnaires. Self-reported polyp diagnosis was confirmed by review of medical records. Logistic regression models were used to calculate the ORs with adjustment for smoking and other potential confounders. Among participants who had undergone a total of 323,832 endoscopies, 16.5% had gallstone disease and 11.3% received cholecystectomy. We documented 1,724, 1,212, and 1,943 cases of conventional adenomas and 1,470, 1,090, and 1,643 serrated polyps in patients with gallstones, cholecystectomy, and either of them, respectively. The OR for adenomas was 1.00 [95% confidence interval (CI): 0.95-1.06] for gallstones, 0.99 (95% CI, 0.93-1.06) for cholecystectomy, and 1.00 (95% CI, 0.95-1.05) for either exposure. The corresponding ORs for serrated polyps were 0.98 (95% CI, 0.92-1.04), 0.99 (95% CI, 0.93-1.06), and 0.97 (95% CI, 0.92-1.03), respectively. Gallstone disease is not associated with colorectal polyps. Patients with gallstones appear to have similar risk of colorectal polyps compared with those without and may therefore follow average-risk colorectal cancer screening guidelines.

Updates on Age to Start and Stop Colorectal Cancer Screening: Recommendations From the U.S. Multi-Society Task Force on Colorectal Cancer.

This document is a focused update to the 2017 colorectal cancer (CRC) screening recommendations from the U.S. Multi-Society Task Force on Colorectal Cancer, which represents the American College of Gastroenterology, the American Gastroenterological Association, and the American Society for Gastrointestinal Endoscopy. This update is restricted to addressing the age to start and stop CRC screening in average-risk individuals and the recommended screening modalities. Although there is no literature demonstrating that CRC screening in individuals under age 50 improves health outcomes such as CRC incidence or CRC-related mortality, sufficient data support the U.S. Multi-Society Task Force to suggest average-risk CRC screening begin at age 45. This recommendation is based on the increasing disease burden among individuals under age 50, emerging data that the prevalence of advanced colorectal neoplasia in individuals ages 45 to 49 approaches rates in individuals 50 to 59, and modeling studies that demonstrate the benefits of screening outweigh the potential harms and costs. For individuals ages 76 to 85, the decision to start or continue screening should be individualized and based on prior screening history, life expectancy, CRC risk, and personal preference. Screening is not recommended after age 85.

S1987 Go With Your Gut Feeling: A Case of Invasive Colonic Squamous Cell Carcinoma Not Detected by DNA-Based Stool Testing

Introduction: Though less common, colonic squamous cell carcinoma is a type of colorectal cancer. Current colorectal cancer screening recommendations for average-risk patients include the use of stool DNA-based testing as an alternative to screening colonoscopy. This clinical vignette is an example of colonic squamous cell carcinoma that went undetected by a stool DNA-based colorectal cancer screening test. Case Description/Methods: 57 year-old female with no prior medical history presented to outpatient gastroenterology office for evaluation of tenesmus, mucus in stool with associated diarrhea and LLQ pain of 3 months duration. Physical exam was unremarkable. Recent CBC, BMP, and albumin were within normal limits. Patient had undergone average-risk colorectal cancer screening with a stool DNA-based test 11 months prior to presentation (8 months prior to symptom onset) with a negative result. Patient was asymptomatic at the time of the screening test. Due to her new symptoms, it was recommended she undergo infectious stool studies and colonoscopy. C difficile screen, bacterial stool culture and parasitology exam were negative. Colonoscopy revealed a 6-cm partially circumferential frond-like/villous, infiltrative and ulcerated partially obstructing large mass 4-11cm from the anal verge (Figure 1A, B). Biopsy was positive for invasive squamous cell carcinoma. The patient was referred to oncology and completed definitive chemo-radiation therapy with no evidence on residual disease on most recent imaging. Discussion: This case demonstrates an average-risk patient who underwent stool DNA-based testing for colorectal cancer screening that was negative with subsequent presentation and diagnosis of invasive squamous cell carcinoma of the colon in less than one year’s time. It highlights the importance of colorectal cancer screening and the ability of colonoscopy to detect and diagnosis colorectal cancer. DNA-based stool testing is an alternative non-invasive screening test to colonoscopy in average-risk patients. The current data supports a false negative rate of DNA-based stool testing to be less than 1 in 1500. However, the presence of a false negative test provides patients with a false sense of confidence and reassurance that they do not have cancer. It is imperative that for any new lower GI symptoms or other clinical suspicion for colorectal malignancy, the patient should still undergo evaluation with colonoscopy – endoscopic evaluation should not be deferred because of a recent negative DNA-based stool test.Figure 1.: A. Colon with mass, B. Detailed view of ulcerated mas.

Comparison of colorectal cancer location and metastasis site in patients aged 50 to 75 versus age 75 and older in community and academic practice.

e15595 Background: Current guidelines recommend cessation of average risk colorectal cancer screening at age 75, after which a more individualized approach is endorsed. There is limited data on characteristics of colorectal cancer in patients over the age of 75. We aimed to determine if colorectal cancer site and metastasis is greater in the community vs academic setting in patients aged 50-75 compared to those age 75 or older. Methods: Data were analyzed from the National Cancer Database (NCDB) between 2010-2014. Results were divided into two categories (50-75 year old, >75 year old) and included number of patients, site of cancer and site of metastasis. Patient characteristics and survival were compared with Mann-Whitney U, Pearson’s Chi-square, and the Kaplan-Meier method. Results: 167, 059 patients were included in the analysis. In the academic setting, group A (age 50-75) contained 36, 298 patients and group B (>75) contained 13,253 patients. In the community setting, group A involved 77, 657 patients and group B, 39,851 patients. In the academic setting, group A identified 57.7% of cases involving the colon vs 42.3% involving the rectum. In group B, 71.4% cases involved the colon vs 28.6% involving the rectum. In the community setting, group A identified 64.4% of cases involving the colon compared to 35.6% involving the rectum. For group B, 76.2% of cases diagnosed were in the colon vs. 23.8% of cases involving the rectum. Overall, indicating a statistically significant increase seen in colon involvement in the older age group (<0.001). In community and academic practice, there is a statistically significant increase in the cases involving metastasis for group A, compared to group B (p<0.001) This is seen for specific sites as well, including bone, liver and lung, (p< 0.001) but not brain involvement in academic practice. Conclusions: In this study, we found a statistically greater number of cases of involving metastasis in patients aged 50-75 compared to patients aged 75 and older in both academic and community practices. In both the academic and community setting, older patients demonstrated statistically greater involvement of the colon compared to patients aged 50-75. Overall, there were more cases of colon and rectal cancer for both age groups seen in the community setting compared to the academic setting.

Multimodal circulating tumor DNA (ctDNA) colorectal neoplasia detection assay for asymptomatic and early-stage colorectal cancer (CRC).

3536 Background: To improve average risk CRC screening compliance, additional options are needed, especially options that address patient and provider reported barriers such as time and convenience. LUNAR-2 is a multimodal blood-based colorectal neoplasia detection assay incorporating ctDNA assessment of somatic mutations and tumor derived methylation and fragmentomic patterns, aimed to maximize sensitivity for early stage CRC detection. We evaluated this test in a large patient cohort with newly diagnosed CRC. Methods: Individuals diagnosed with CRC between 2013-2016 consented to provide blood samples prior to surgical resection. Those treated with neoadjuvant chemotherapy were excluded. Isolated plasma samples (median 3mL from EDTA) from 434 individuals were analyzed with LUNAR-2 (Guardant Health, USA) and included in the analysis. Median age at CRC diagnosis was 63 years (range 28 - 89) and 41% were female. Control samples were from 271 age-matched cancer free individuals. “ctDNA detected” and “ctDNA not detected” results were generated by a model trained on a separate sample set (N=614) from both cancer free individuals and those with CRC. Calling threshold was determined based on this held-out set to target 90% specificity. ctDNA results and clinical characteristics were correlated. Results: Overall CRC sensitivity was 91% (393/434), with high sensitivity across all stages; 88% Stage I/II, 93% Stage III (Table). Specificity was 94% (255/271). There was no difference in sensitivity when excluding those with early (<45 years) or late (>84 years) onset CRC (90% sensitivity; 388/429; p=0.95; 88% Stage I/II, 93% Stage III). There were no differences in sensitivity for asymptomatic CRC (88%) compared to symptomatic CRC (91%; p=0.4; Table). However, higher cell-free DNA tumor fractions were observed in the symptomatic cohort. Sensitivity for detection of right-sided and left-sided CRC was similar (93% vs. 90%; p=0.5; Table). Conclusions: In this large early-stage CRC cohort, multimodal ctDNA assessment has high sensitivity for CRC detection with high specificity. Equivalent sensitivity in the asymptomatic cohort suggests this test will have clinically meaningful performance in an average risk screening population. A prospective registrational study is ongoing to evaluate the test in an average risk CRC screening cohort.[Table: see text]

Cross-sectional adherence with the multitarget stool DNA test for colorectal cancer screening in a large, national study of insured patients.

27 Background: Colorectal cancer (CRC) is the second most deadly and fourth most frequently diagnosed cancer in the United States. Early detection can improve CRC outcomes, but overall screening rates (62%) remain below the 80% goal set by the National Colorectal Cancer Roundtable. Multiple options are endorsed for average-risk CRC screening, including the multi-target stool DNA (mt-sDNA) test, which includes patient and provider navigation support. Cross-sectional adherence with the mt-sDNA test was previously reported in a large Medicare population (71%). In the current study we investigated cross-sectional adherence with the mt-sDNA test in a broader, national sample of insured patients. Methods: Aggregate data from Exact Sciences Laboratories LLC (ESL; Madison, WI) were retrospectively analyzed in compliance with HIPAA requirements. Study participants included individuals ages 50 years and older who were covered by commercial insurance or Medicare, had a valid mt-sDNA test order placed between January 1–December 31, 2018, and received a test kit shipped from ESL. Cross-sectional adherence, defined as successful completion and return of the test kit within 365 days of the shipment date, was assessed overall and by patient- and provider-level factors. Results: In total, 1,420,460 participants met the study criteria (61.2% women; mean age 65.7 years). Overall cross-sectional adherence was 66.8%. Adherence was 72.1% in participants with Traditional Medicare, 69.1% in participants with Medicare Advantage, and 61.9% in participants with commercial insurance (p<0.001). Adherence increased by participant age (p<0.001): 60.8% for ages 50-64, 71.3% for ages 65-75, and 74.7% for ages 76+ years. For Traditional Medicare patients, ages 65-75, adherence was 73.6%. Participants with mt-sDNA tests ordered placed by gastroenterologists had a higher adherence rate (78.3%) than those with orders placed by primary care clinicians (67.2%) (p<0.001). Adherence rates were highest among patients with ordering providers in the Pacific region (71.4%) and West North Central region (70.1%), and lowest in the Mid-Atlantic region (65.7%), New England (65.2%), West South Central region (64.6%), and Puerto Rico and US territories (60.7%). Conclusions: Novel data from this large, national sample of insured patients demonstrate high cross-sectional adherence with the mt-sDNA test (66.8%), supporting the substantial contribution this guideline-endorsed option plays in average-risk CRC screening. At the patient-level, adherence increased with patient age, and was highest in those covered by Traditional Medicare. Provider-level stratification showed the highest adherence for mt-sDNA tests ordered by gastroenterologists. This study adds to data regarding the impact of accompanying navigation support and at-home convenience of mt-sDNA on screening completion rates.

Feasibility and performance of the fecal immunochemical test (FIT) for average-risk colorectal cancer screening in Nigeria.

There is a paucity of prospective data on the performance of the fecal immunochemical test (FIT) for colorectal cancer (CRC) screening in sub-Saharan Africa. The aim of this exploratory analysis was to evaluate the feasibility and performance of FIT in Nigeria. This was a prospective, single-arm study. A convenience sample of asymptomatic, average-risk individuals between 40-75 years of age were enrolled at Obafemi Awolowo University Teaching Hospital. Study participants returned in 48 hours with a specimen for ova and parasite (O&P) and qualitative FIT (50ug/g) testing. Participants with a positive FIT had follow-up colonoscopy and those with intestinal parasites were provided treatment. Between May-June 2019, 379 individuals enrolled with a median age of 51 years (IQR 46-58). In total, 87.6% (n = 332) returned for FIT testing. FIT positivity was 20.5% (95% CI = 16.3%-25.2%). Sixty-one (89.7%) of participants with a positive FIT had a follow-up colonoscopy (n = 61), of whom 9.8% (95%CI:3.7-20.2%) had an adenoma and 4.9% (95%CI:1.0-13.7%) had advanced adenomas. Presence of intestinal parasites was inversely related to FIT positivity (6.5% with vs. 21.1% without parasites, p = 0.05). Eighty-two percent of participants found the FIT easy to use and 100% would recommend the test to eligible family or friends if available. Asymptomatic, FIT-based CRC screening was feasible and well tolerated in this exploratory analysis. However, the high FIT positivity and low positive predictive value for advanced neoplasia raises concerns about its practicality and cost effectiveness in a low-resource setting such as Nigeria.

Prevalence and risk factors for sessile serrated lesions in an average risk colorectal cancer screening population.

The reported prevalence and risk factors for sessile serrated lesions (SSLs) show significant variation. We aimed to specifically study the prevalence and potential risk factors of SSLs in an average risk colorectal cancer (CRC) screening population of Chinese subjects. This is a case-control study of prospectively collected data from a territory-wide colorectal screening program in Hong Kong. Information on risk factors was obtained from questionnaires completed prior to screening colonoscopy. We compared subjects with SSLs against controls without these lesions to identify potential risk factors using multivariable logistic regression. Of 12039 asymptomatic screening subjects, 6011 subjects received a screening colonoscopy with 2214 subjects (36.8%) having conventional adenomas, 486 subjects (8.1%) having hyperplastic polyps, and 85 subjects (1.4%) having SSLs only. Of these subjects, three had synchronous advanced adenomas and were excluded from the analysis. More than 60% of these lesions were in the proximal colon. We compared these 82 subjects with SSLs only and 3226 controls without any polyps. After multivariable logistic regression, age ≥66years, smoking, and diabetes mellitus (DM) were significant independent risk factors for SSLs. In this study, we report the prevalence of SSLs to be 1.4%. Age ≥66years, smoking, and DM were independent risk factors for these lesions. Our findings provide relevant new data that should be taken into consideration when designing region-specific surveillance programs for SSLs with the ultimate goal of reducing the risk of CRC.

Comparable quality of bowel preparation with single-day versus three-day low-residue diet: Randomized controlled trial.

There is controversy about the length of low-residue diet (LRD) for colonoscopy preparation. The aim of the study was to compare one-day vs. three-day LRD associated to standard laxative treatment for achieving an adequate colonoscopy preparation in average risk subjects with positive fecal immunochemical test undergoing screening colonoscopy. A non-inferiority, randomized, controlled, parallel-group clinical trial was performed in the setting of average risk colorectal cancer screening program. Participants were randomized to receive 1-day vs. 3-day LRD in addition to standard polyethilenglicol treatment. Adequacy of preparation was evaluated using the Boston Bowel Preparation Scale (BBPS). Primary outcome was achieving a BBPS≥2 in all colon segments. Analysis was performed for a non-inferiority margin of 5%, a 95% statistical power and one-sided 0.05 significance level. A total of 855 patients were randomized. Adequate bowel preparation was similar between groups: 97.9% of patients in the 1-day LRD group vs 96.9% in the 3-day LRD group achieved the primary outcome (P-value for non-inferiority<0.001). The percentage of patients with BBPS scores≥8 was superior in the 1-day LRD group (254 vs 221 in the 3-day LRD group, P=0.032). The 1-day regimen was better tolerated than the 3-day diet. 47.7% (vs 28.7%, P<0.05) of patients rated the 1-day LRD as very easy to follow. The 1-day LRD is non-inferior to 3-day LRD for achieving an adequate colon cleansing before average risk screening colonoscopy and it is better tolerated.

S0542 Intraoperative Morbidity Associated With Monitored Anesthesia Care in Obese Patients Undergoing Average Risk Colorectal Cancer Screening

INTRODUCTION: Average risk Colorectal Cancer (CRC) screening colonoscopy requires procedural sedation and monitored anesthesia care (MAC). Elevated BMI is associated with higher prevalence of comorbid conditions including obstructive sleep apnea, hypertension, and pulmonary hypertension. Pre-existing comorbidities, including obesity, may be associated with increased intraoperative cardiopulmonary (ICP) morbidity related to procedural sedation. The aim of our quality improvement project was to evaluate intraoperative morbidity associated with MAC during screening colonoscopy in obese patients. METHODS: Data were collected by retrospective chart review of 304 randomly selected patients undergoing average risk CRC screening colonoscopy at Allegheny Health Network. Demographic data for obese (n = 152) and non-obese (n = 152) cohorts were collected (Table 1). BMI and intraoperative indices including arrhythmia, hypotension, and oxygen saturation, were extracted and analyzed using Pearson’s Chi-Squared Test. Independent T-Test was performed to compare average oxygen desaturation time (ODT). RESULTS: 77.3% of patients were BMI 25–29.9 (27.3%), 30–40 (25.3%) and ≥40 (24.7%) (Table 1). 52.6% of obese patients experienced oxygen desaturation (SaO2 < 95%) as compared to 46.7% in non-obese patients, but this was not statistically significant. Obese patients did have lower mean initial SaO2 and statistically significant increased time with SaO2 < 95% (P = .007). There was no statistically significant association between obesity and intraoperative complications including hypotension, arrhythmia, and hypoxia. CONCLUSION: Our study shows no statistically significant difference in ICP morbidity related to obesity(BMI >30), except for ODT. These findings suggest that patients with obesity are at higher risk of prolonged oxygen desaturation during MAC assisted colonoscopies. Further larger studies are needed to evaluate the clinical implications of prolonged ODT in obese patients.Table 1.: Patient demographics and comorbiditiesTable 2.: Rates of intraoperative cardiopulmonary complications in obese and non-obese patients while under MAC during screening colonoscopyTable 3.: A and 3B. 3A: T-test for Equality of Means showing statistically significant increased ODT minutes in obese patients; 3B: Obese vs. Non-Obese Group Statistics for intraprocedural oxygenation status

S0286 Intra-Operative Morbidity Associated With Monitored Anesthesia Care in Obstructive Sleep Apnea Patients Undergoing Average Risk Colorectal Cancer Screening

INTRODUCTION: Screening colonoscopies are recommended for all patients who are 50 years of age and are at average risk for colorectal cancer (CRC). Monitored anesthesia care (MAC) decreases patient discomfort and improves tolerance of the procedure. Patients with obstructive sleep apnea (OSA) are considered to be at a higher risk for cardiopulmonary complications while under anesthesia. The aim of our quality improvement project is to evaluate intraoperative cardiopulmonary (ICP) morbidity associated with MAC anesthesia in patients with OSA undergoing average risk CRC screening colonoscopy. We postulated that patients with OSA would have higher ICP morbidity compared to those without OSA. METHODS: Retrospective data was collected on 304, 152 obese and 152 non-obese, randomly selected patients who underwent average risk CRC screening colonoscopy at Allegheny Health Network. Diagnostic and high-risk screening colonoscopies were excluded. Table 1 shows the overall population analysis. A total of 66 patients with documented OSA and 238 patients without OSA were included in the data analysis. Pertaining data was collected by chart review and analyzed using Pearson’s chi-squared test. Average oxygen desaturation time (ODT) was compared with ODT in patients with a diagnosis of OSA using independent T-Test. A sub-analysis of ODT in patients with OSA with and without home CPAP was performed using independent T-Test. RESULTS: Comparatively, the OSA group did not have a statistically different rate of hypoxia (P = 0.801), the need for airway change (P = 0.719), cardiac arrhythmia (P = 0.123), or hypotension (P = 0.081) (Table 2). However, total ODT was significantly higher in OSA patients compared to patients without OSA (P = 0.009) (Table 3A). Interestingly, home CPAP use in OSA did not show a significant correlation with ODT (P = 0.753) (Table 3C). CONCLUSION: Our study shows that there are no statistically significant differences in ICP morbidity based on a history of OSA, except for ODT. These findings suggest that patients with OSA are at higher risk of prolonged oxygen desaturation during MAC assisted screening colonoscopies. Further studies are required to assess if patients with OSA are preemptively placed on a higher FiO2 or level of airway than patients without OSA, which could possibly lead to statistically skewed results.Table 1.: Patient demographics and comorbiditiesTable 2.: Rates of cardiopulmonary complications in patients with and without OSA while under conscious sedation during screening colonoscopyTable 3.: A: T-test for equality of the means showing statistically significant increased average oxygen desaturation time in patients with OSA compared to patients without OSA. B: OSA vs No OSA group statistics. C: T-Test for equality of the means showing no significant difference in average oxygen desaturation time in patients with OSA on CPAP compared to patients with OSA, not on CPAP. D: CPAP vs No CPAP group statistics

COVID-19: An Opportunity to Reimagine Colorectal Cancer Diagnostic Testing—A New Paradigm Shift

ABSTRACT Colorectal cancer is the third leading cause of cancer related deaths and to date, the COVID-19 pandemic has led to major disruptions of the diagnosis and treatment pathways of this cancer, which may adversely affect survival outcomes for many years. Colorectal cancer pathways must be maintained at a near normal throughput with urgent attention to the backlog of patients to avoid a potential crisis of avoidable cancer deaths. A radical review and revamping of endoscopy services to improve efficiency during COVID-19 is urgently required. To date most endoscopy units have severely restricted their activity, except for time-critical diagnostic and therapeutic procedures. In the post- COVID-19 recovery phase, access to endoscopy services will increase but capacity will be reduced compared to before the pandemic, due to infection control measures. A pragmatic and safe strategy is urgently needed to clear the backlog of endoscopic procedures and for managing the new symptomatic referrals. We propose the use of non-invasive tests, such as FIT and mSEPT9 combined with “safety netting” to “rule out” colorectal cancer and to reduce the utilization of colonoscopy by up to 80% and limit the procedure to those patients at high risk of cancer.

Colorectal Neoplasia among Patients with and without Human Immunodeficiency Virus.

Increasing availability of highly active antiretroviral therapy (HAART) for human immunodeficiency virus (HIV) has led to prolonged survival and rising incidence of non-HIV-defining cancers among patients with HIV. Compared with the general population, risk of colorectal cancer may differ among those with HIV due to immunosuppression, oncogenic viral coinfections, and higher prevalence of risk factors. We identified patients (age ≥50 years) diagnosed with HIV, prescribed HAART for ≥6 months, and receiving care in two large health care systems in Dallas, TX. Patients received a first colonoscopy between January 2009 and December 2017. We calculated a standardized prevalence ratio as the ratio of observed to expected number of advanced neoplasia (high-risk adenoma or colorectal cancer) using an age- and sex-matched cohort of patients without HIV (n = 10,250). Among patients with HIV (n = 839), about two thirds (60.1%) had normal findings at colonoscopy; 6.8% had hyperplastic polyps only, 20.4% had low-risk adenomas, 11.7% had high-risk adenomas, and 1.1% had colorectal cancer. Prevalence of advanced neoplasia was similar between patients with and without HIV, with a standardized prevalence ratio of 0.99 (95% confidence interval, 0.81-1.19). There was no difference in the prevalence of colorectal neoplasia between patients with and without HIV. Patients with HIV appear to have similar risk of colorectal neoplasia compared to those without HIV and can therefore follow average-risk colorectal cancer screening guidelines.

Comparison of Tissue-Based Molecular Markers in Younger versus Older Patients with Colorectal Neoplasia.

Emerging colorectal cancer trends demonstrate increased incidence and mortality in younger populations, prompting consideration of average-risk colorectal cancer screening initiation at age 45 versus 50 years. However, screening test performance characteristics in adults 45-49 years have been minimally described. To inform the biologic rationale for multi-target stool DNA (mt-sDNA) screening in younger patients, we analyzed and compared tissue levels of methylation (BMP3, NDRG4) and mutation (KRAS) markers included in the FDA-approved, mt-sDNA assay (Cologuard; Exact Sciences Corporation). Within 40-44, 45-49, and 50-64 year age groups, archived colorectal tissue specimens were identified for 211 sporadic colorectal cancer cases, 123 advanced precancerous lesions (APLs; adenomas >1 cm, high-grade dysplasia, ≥25% villous morphology, or sessile serrated polyp; 45-49 and 50-64 age groups only), and 204 histologically normal controls. Following DNA extraction, KRAS, BMP3, and NDRG4 were quantified using QuARTS assays, relative to ACTB (reference gene). None of the molecular marker concentrations were significantly associated with age (P > 0.05 for all comparisons), with the exception of NDRG4 concentration in APL samples (higher in older vs. younger cases; P = 0.008). However, NDRG4 levels were also statistically higher in APL case versus normal control samples in both the 45-49 (P < 0.0001) and 50-64 (P < 0.0001) year age groups. Overall, these findings support the potential for earlier onset of average-risk colorectal cancer screening with the mt-sDNA assay. These novel data address an identified knowledge gap and strengthen the biologic basis for earlier-onset, average-risk screening with the mt-sDNA assay.

Tu1116 DISPARITIES IN HEALTH: LOWER COLORECTAL CANCER SCREENING RATES AMONG LGBTQ PATIENTS

Colorectal cancer (CRC) screening via colonoscopy can prevent CRC. Socially neglected populations such as ethnic and racial minorities have consistently lower CRC screening rates when compared to the general population. While lesbian, gay, bisexual, transgender, and queer (LGBTQ) patients represent a population who are at risk for CRC screening disparities, an estimate of the existence and magnitude of the disparity remains unknown. The aim of this study is to analyze the rate of CRC screening between the LGBTQ population and the general population to determine if a disparity exists along with the possible magnitude. Data was extracted from our tertiary care medical center’s de-identified patient database (SD) between 2014 and 2018. Search terms for the LGBTQ population included self-identification in the EMR as “lesbian”, “gay”, “bisexual”, “transgender”, “transsexual”, “queer”, “questioning”, or “intersex” or had an associated ICD 9 or 10 code. The 2008 USPSTF criteria for CRC screening were utilized for identification of patients eligible for screening. Search terms for average risk CRC screening included “colonoscopy”, “FOBT”, “FIT”, “flexible sigmoidoscopy”, and ICD 9/10 codes v76.51, v76.41, z12.11, and z12.12. Patients considered as increased risk for CRC were excluded (family history of CRC or advanced polyp; personal history of IBD). Based on the magnitude of data for the general population, the Center for Disease Control (CDC) and Prevention database for our state was utilized in publication years to calculate the CRC screening rate of the state-wide population. Students t-test for was utilized to assess for differences between the groups. A total of 117 LGBTQ patients were found in the SD. 15% were lesbian, 44% gay, 18% bisexual, 23% transgender, and 0% queer/questioning or intersex with a mean age of 58 [50-76] years-old. 85% were Caucasian (90% non-Hispanic; 3% Hispanic; 7% not identified), 11% African-American, 0% Asian, and 4% unknown. Of the LGBTQ patients identified, 35 met 2008 USPSTF eligibility criteria for average risk CRC screening. The LGBTQ CRC screening rate compared to the state population rate was 29.3% v. 64.9% (p<0.01) in 2014, 34.8% v. 66.4% (p<0.01) in 2016, and 29.9% v. 69.1% (p<0.01) in 2018. Despite increased CRC screening rates for the state population over the years of the study, the rate among the LGBTQ population remained low. Although this is a single center study, our data may serve to highlight low CRC screening rates among the LGBTQ population. Future studies to evaluate the etiology of the low rate, barriers to screening in this marginalized population, and implementation of strategies to improve screening rates are underway.

Simulation modeling validity and utility in colorectal cancer screening delivery: A systematic review.

ObjectiveThis study sought to assess the impact and validity of simulation modeling in informing decision making in a complex area of healthcare delivery: colorectal cancer (CRC) screening.Materials and MethodsWe searched 10 electronic databases for English-language articles published between January 1, 2008, and March 1, 2019, that described the development of a simulation model with a focus on average-risk CRC screening delivery. Included articles were reviewed for evidence that the model was validated, and provided real or potential contribution to informed decision making using the GRADE EtD (Grading of Recommendations Assessment, Development, and Evaluation Evidence to Decision) framework.ResultsA total of 43 studies met criteria. The majority used Markov modeling (n = 31 [72%]) and sought to determine cost-effectiveness, compare screening modalities, or assess effectiveness of screening. No study reported full model validation and only (58%) reported conducting any validation. Majority of models were developed to address a specific health systems or policy question; few articles report the model’s impact on this decision (n = 39 [91%] vs. n = 5 [12%]). Overall, models provided evidence relevant to every element important to decision makers as outlined in the GRADE EtD framework.Discussion and ConclusionSimulation modeling contributes evidence that is considered valuable to decision making in CRC screening delivery, particularly in assessing cost-effectiveness and comparing screening modalities. However, the actual impact on decisions and validity of models is lacking in the literature. Greater validity testing, impact assessment, and standardized reporting of both is needed to understand and demonstrate the reliability and utility of simulation modeling.

Multitarget Stool DNA Test Performance in an Average-Risk Colorectal Cancer Screening Population.

INTRODUCTION:We set out to evaluate the performance of a multitarget stool DNA (MT-sDNA) in an average-risk colonoscopy-controlled colorectal cancer (CRC) screening population. MT-sDNA stool test results were evaluated against fecal immunochemical test (FIT) results for the detection of different lesions, including molecularly defined high-risk adenomas and several other tumor characteristics.METHODS:Whole stool samples (n = 1,047) were prospectively collected and subjected to an MT-sDNA test, which tests for KRAS mutations, NDRG4 and BMP3 promoter methylation, and hemoglobin. Results for detecting CRC (n = 7), advanced precancerous lesions (advanced adenoma [AA] and advanced serrated polyps; n = 119), and non-AAs (n = 191) were compared with those of FIT alone (thresholds of 50, 75, and 100 hemoglobin/mL). AAs with high risk of progression were defined by the presence of specific DNA copy number events as measured by low-pass whole genome sequencing.RESULTS:The MT-sDNA test was more sensitive than FIT alone in detecting advanced precancerous lesions (46% (55/119) vs 27% (32/119), respectively, P < 0.001). Specificities among individuals with nonadvanced or negative findings (controls) were 89% (791/888) and 93% (828/888) for MT-sDNA and FIT testing, respectively. A positive MT-sDNA test was associated with multiple lesions (P = 0.005), larger lesions (P = 0.03), and lesions with tubulovillous architecture (P = 0.04). The sensitivity of the MT-sDNA test or FIT in detecting individuals with high-risk AAs (n = 19) from individuals with low-risk AAs (n = 52) was not significantly different.DISCUSSION:In an average-risk screening population, the MT-sDNA test has an increased sensitivity for detecting advanced precancerous lesions compared with FIT alone. AAs with a high risk of progression were not detected with significantly higher sensitivity by MT-sDNA or FIT.