Undergoing Surveillance Colonoscopy Research Articles

Surveillance colonoscopy findings in asymptomatic participants over 75 years of age.

Surveillance colonoscopy for colorectal cancer (CRC) is generally not recommended beyond 75 years of age. The study determined incidence and predictors of advanced adenoma and CRC in older individuals undergoing surveillance colonoscopy. This was a retrospective cohort study of asymptomatic older participants (≥75 years), enrolled in a South Australian CRC surveillance program who underwent colonoscopy (2015-2020). Clinical records were extracted for demographics, personal or family history of CRC, comorbidities, polypharmacy, and colonoscopy findings. The associations between clinical variables and advanced adenoma or CRC at surveillance were assessed with multivariable Poisson regression analysis. Totally 698 surveillance colonoscopies were analyzed from 574 participants aged 75-91 years (55.6% male). The incidence of CRC was 1.6% (11/698), while 37.9% (260/698) of procedures had advanced adenoma detected. Previous CRC (incidence rate ratio [IRR] 5.9, 95% CI 1.5-22.5), age ≥85 years (IRR 5.8, 95% CI 1.6-20.1) and active smoking (IRR 4.9, 95% CI 1.0-24.4) were independently associated with CRC diagnosis, while advanced adenoma at immediately preceding colonoscopy (IRR 1.6, 95% CI 1.3-2.0) and polypharmacy (IRR 1.2, 95% CI 1.0-1.5) were associated with advanced adenoma at surveillance colonoscopy in asymptomatic older participants (≥75 years). Advanced neoplasia was found in more than one third of the surveillance procedures completed in this cohort. Continuation of surveillance beyond age 75 yeasrs may be considered in participants who have previous CRC or are active smokers (provided they are fit to undergo colonoscopy). In other cases, such as past advanced adenoma only, the need for ongoing surveillance should be considered alongside participant preference and health status.

A238 BEST APPROACH TO SURVEILLANCE COLONOSCOPY FOR COLORECTAL CANCER IN PATIENTS WITH PRIMARY SCLEROSING CHOLANGITIS AND INFLAMMATORY BOWEL DISEASE

Abstract Background Primary sclerosing cholangitis (PSC) is a chronic, cholestatic liver disease and it has been recognized as a risk factor for hepatobiliary and colorectal carcinoma (CRC). Inflammatory bowel disease (IBD) is associated with a 6-fold increased risk of CRC as compared to the general population but with co-existing PSC, this risk rises to 30-fold and hence CRC surveillance is critical in these patients. Aims We performed a systematic review of the literature on surveillance colonoscopy for CRC in patients with PSC-IBD, with the aim of identifying the most effective approach. Methods The protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO) under ID 472215. The search was executed in the databases Medline, EMBASE, Cochrane, Web of science, Scopus and Google Scholar databases from 1947 to May 2023. Observational or randomized controlled studies were included if patients had PSC-IBD (paediatric or adult) undergoing surveillance colonoscopy. There was no restriction for language. We used a modified version of the Newcastle–Ottawa Quality Assessment Scale to assess the risk of bias. Neoplasia was defined as the presence of low-grade dysplasia, high grade dysplasia or colorectal carcinoma. Results Amongst 2900 studies identified, 7 studies met the inclusion criteria with a total number of 379 PSC-IBD patients and 1884 IBD patients (all adult). The median frequency of surveillance colonoscopy was every 0-2 years. The most common endoscopic presentation of dysplasia in PSC-IBD was a normal appearing mucosa or subtle abnormalities such as mild inflammation. Three studies performed random and targeted biopsies and only one study did quadruple random biopsy (every 10 cm of the colon). Two studies used chromoendoscopy and high-definition endoscopy whereas another two studies used white light colonoscopy. Studies varied in terms of the number of biopsies taken and timing for the frequency and initiation of surveillance. Outcomes included intensive surveillance, resection, and colectomy. Our meta-analysis of 2 studies that reported the prevalence of colorectal dysplasia in PSC-IBD patients revealed a pooled prevalence of 21% (95% CI 1.4%-28%, I2 = 0%, Pampersand:003C0.597, shown in Figure 1) Conclusions Colorectal dysplasia is prevalent in patients with PSC-IBD and is associated with worse disease outcomes. As a result, PSC-IBD patients should be screened annually from the diagnosis of PSC. However, there is variation in practice, and no clear consensus on the best approach to perform screening colonoscopy in this population. Literature comparing various approaches is very sparse. Additional high-quality studies on this subject are needed to guide practice, particularly in paediatrics where data are non-existent. Figure 1: Forest plot for meta-analysis of CRC dysplasia prevalence in PSC-IBD Funding Agencies None

A123 THE EFFECTS OF INFLAMMATORY BOWEL DISEASE ON THE MANAGEMENT AND OUTCOMES OF COMPLEX POLYPS IN PATIENTS UNDERGOING SURVEILLANCE COLONOSCOPY: A RETROSPECTIVE COHORT STUDY

Abstract Background The influence of inflammatory bowel disease (IBD) on the outcomes of complex polyps remains an area of uncertainty. Aims To investigate the impact of IBD on the management and outcomes of complex polyps during surveillance colonoscopy. Methods This retrospective cohort study utilized a prospectively collected database, involving patients who underwent surveillance colonoscopy for colorectal cancer or IBD surveillance who were identified to have complex polyps between February 2019 and December 2020 in Southwestern Ontario. Patient demographics, disease characteristics, medication history, polyp description and management were analyzed. The data were summarized in median and interquartile range for continuous variable and frequency and percentage for categorical variables. Characteristics between IBD and non-IBD were compared using the Wilcoxon rank sum test and Fisher’s exact test, as appropriate. Results 383 patients were included in the study, of which 27 individuals had IBD (5 Crohn's disease, 13 ulcerative colitis, and 9 indeterminate colitis). Patients with IBD were generally younger than their non-IBD counterparts (median age 61 vs 67 respectively). No significant differences were identified in terms of rates of complete polyp removal (17.70 % vs 22.22 %, pampersand:003C0.602), residual polyps after resection (76.97% vs 70.37%, pampersand:003C0.476), repeat removal attempts (84.27% vs 74.07%, pampersand:003C0.179), or surgical intervention (88.76% vs 88.89%, pampersand:003C0.99). A higher proportion of IBD patients were managed by gastroenterologists vs other endoscopists (81.48% vs. 40.17%, p ampersand:003C 0.001). No significant differences in complex polyp characteristics were observed, except in difficult locations of complex polyps were more common in the non-IBD cohort (55.34% vs 25.93%, pampersand:003C0.004). Conclusions In this retrospective cohort study, IBD does not appear to influence the management or outcome of complex polyps. Larger studies are required given the small IBD cohort size in this study. Funding Agencies None

DOP28 Yield of surveillance colonoscopy in patients with Primary Sclerosing Cholangitis

Abstract Background Patients with primary sclerosing cholangitis (PSC) have a higher risk of developing colorectal cancer (CRC), in particular in patients with concurrent diagnosis of inflammatory bowel disease (IBD). Therefore, strict surveillance colonoscopy in patients with PSC and PSC-IBD is recommended with consideration of random biopsies. The aim of this study was to assess the method and yield of surveillance colonoscopy in patients with PSC and PSC-IBD in routine practice in the Netherlands. Methods An observational cohort study was performed within the EpiPSC2 cohort in The Netherlands. Patients with a confirmed PSC diagnosis were included from January 2008 onwards. Data were collected retrospectively from the date of diagnosis until inclusion, and prospectively from that date forward. Patient demographics, PSC and IBD disease characteristics were collected at study inclusion and during annual follow-up. For this study, data collection was expanded retrospectively with colonoscopy and pathology reports. Outcomes were endoscopic surveillance technique, whether random or targeted biopsies were taken, if polypectomy was performed, dysplasia detection rate and type of dysplasia. Results The study population included 1,203 PSC patients, of whom 82.1% had large duct PSC, and 70.6% concomitant IBD (table 1). A total of 4,099 colonoscopies were performed in 759 individual patients, with a median of 4 colonoscopies per patient (IQR 2 – 8). The median follow-up duration was 11 years (IQR 12 – 17). In total, 11.5% (n=473) of colonoscopies were performed with chromo-endoscopy. Among the conducted colonoscopies, 2,543 included biopsies, 355 involved polypectomies, and 86 comprised both biopsies and polypectomies. Dysplasia was identified in 11.4% (341 out of 2,984) of the colonoscopies, including 14.1% indefinite for dysplasia (n=48), 75.1% low grade dysplasia (n=256), 7.6% high grade dysplasia (n=26), and 5.9% adenocarcinoma (n=20). The detection of dysplasia occurred through random biopsies in 89 colonoscopies (26.1%), targeted biopsies in 114 colonoscopies (33.4%) and polypectomy in 153 colonoscopies (44.9%) (figure 1). Dysplasia was observed in 195 (26%) individual patients, of whom 80.5% had PSC-IBD. Conclusion Our data highlights the importance of colonoscopic surveillance in PSC and PSC-IBD patients. Dysplasia was detected in over a quarter of patients undergoing surveillance colonoscopy. Notably, 26.1% of dysplasia cases were identified through random biopsies, emphasizing the importance of incorporating random biopsies into surveillance protocols for this specific patient population.

Dye Chromoendoscopy Outperforms High-Definition White Light Endoscopy in Dysplasia Detection for Patients With Inflammatory Bowel Disease: An Updated Meta-Analysis of Randomized Controlled Trials.

Whether dye spray chromoendoscopy (DCE) adds value in surveillance colonoscopy with high-definition (HD) scopes remains controversial. This updated meta-analysis compares dysplasia detection using DCE and high-definition white light endoscopy (HD-WLE) in patients with inflammatory bowel disease (IBD) undergoing surveillance colonoscopy. A comprehensive search was performed for randomized controlled trials (RCT) comparing HD-WLE and DCE in patients with IBD. The primary outcome was to compare the proportion of patients with at least 1 dysplastic lesion detected by DCE vs HD-WLE. Odds ratios (OR) and 95% confidence intervals (CI) were pooled using the random-effects model, with I2 > 60% indicating substantial heterogeneity. The Grading of Recommendations, Assessment, Development, and Evaluation approach was used to assess the certainty of evidence (CoE). Six RCT involving 978 patients were analyzed (DCE = 479 vs HD-WLE = 499 patients). DCE detected significantly more patients with dysplasia than HD-WLE (18.8% vs 9.4%), OR 1.94 (95% CI 1.21-3.11, I2 = 28%, P = 0.006, high CoE). This remained significant after excluding 2 RCT published as abstracts. A sensitivity analysis excluding a noninferiority RCT with a single experienced operator eliminated the results' heterogeneity, OR 2.46 (95% CI 1.56-3.90, I2 = 0%). Although high-grade dysplasia detection was numerically higher in the DCE group (2.8% vs 1.1%), the difference was statistically insignificant, OR 2.21 (95% CI 0.64-7.62, I2 = 0%, low CoE). Our updated meta-analysis supports DCE as a superior strategy in overall dysplasia detection in IBD, even with HD scopes. When expertise is available, DCE should be considered for surveillance colonoscopy in patients with high-risk IBD, with the acknowledgment that virtual chromoendoscopy shows equivalence in recent studies. Further multicenter trials with multiple endoscopists with varying expertise levels and longer-term outcome data showing a reduction in cancer or cancer-related death are needed.

Neoplasia risk in patients with Lynch syndrome treated with immune checkpoint blockade.

Metastatic and localized mismatch repair-deficient (dMMR) tumors are exquisitely sensitive to immune checkpoint blockade (ICB). The ability of ICB to prevent dMMR malignant or pre-malignant neoplasia development in patients with Lynch syndrome (LS) is unknown. Of 172 cancer-affected patients with LS who had received ≥1 ICB cycles, 21 (12%) developed subsequent malignancies after ICB exposure, 91% (29/32) of which were dMMR, with median time to development of 21 months (interquartile range, 6-38). Twenty-four of 61 (39%) ICB-treated patients who subsequently underwent surveillance colonoscopy had premalignant polyps. Within matched pre-ICB and post-ICB follow-up periods, the overall rate of tumor development was unchanged; however, on subgroup analysis, a decreased incidence of post-ICB visceral tumors was observed. These data suggest that ICB treatment of LS-associated tumors does not eliminate risk of new neoplasia development, and LS-specific surveillance strategies should continue. These data have implications for immunopreventative strategies and provide insight into the immunobiology of dMMR tumors.

Gastrointestinal: Weight gain increases the risk of metachronous advanced colorectal neoplasm observed in post-polypectomy surveillance colonoscopy.

Although obesity is a known risk factor for colorectal neoplasms, the correlation between weight change and colorectal neoplasm is unclear. Thus, we aim to evaluate the association between weight change and advanced colorectal neoplasm (ACRN) recurrence during post-polypectomy surveillance colonoscopy. This retrospective cohort study included 7473 participants diagnosed with colorectal neoplasms between 2003 and 2010 who subsequently underwent surveillance colonoscopies until 2020. We analyzed the association between the risk of metachronous ACRN and weight change, defining stable weight as a weight change of <3% and weight gain as a weight increase of ≥3% from baseline during the follow-up period. During a median 8.5years of follow-up, 619 participants (8.3%) developed ACRN. Weight gain was reported as an independent risk factor for metachronous ACRN in a time-dependent Cox analysis. A weight gain of 3-6% and ≥6% had adjusted hazard ratios (AHRs) of 1.48 (95% confidence interval [CI]: 1.19-1.84) and 2.14 (95% CI: 1.71-2.69), respectively. Participants aged 30-49 and 50-75years with weight gain of ≥6% showed AHRs of 2.88 (95% CI: 1.96-4.21) and 1.90 (95% CI: 1.43-2.51), respectively. In men and women, weight gain of ≥3% was significantly correlated with metachronous ACRN. Weight gain is associated with an increased risk of metachronous ACRN. Furthermore, weight gain is associated with the recurrence of ACRN in both men and women regardless of age.

Low Incidence of Colorectal Advanced Neoplasia During Surveillance in Individuals with a Family History of Colorectal Cancer

BackgroundFamily history of colorectal cancer (CRC) is used to stratify individuals into risk categories which determine timing of initial screening and ongoing CRC surveillance. Evidence for long-term CRC risk following a normal index colonoscopy in family history populations is limited.AimsTo assess the incidence of advanced neoplasia and associated risk factors in a population undergoing surveillance colonoscopies due to family history of CRC.MethodsSurveillance colonoscopy findings were examined in 425 individuals with a family history of CRC, a normal index colonoscopy and a minimum of 10 years of follow-up colonoscopies. Advanced neoplasia risk was determined for three CRC family history categories (near-average, medium and high-risk), accounting for demographics and time after the first colonoscopy.ResultsThe median follow-up was 13.5 years (IQR 11.5–16.0), with an incidence of advanced neoplasia of 14.35% (61/425). The number of affected relatives and age of CRC diagnosis in the youngest relative did not predict the risk of advanced neoplasia (p > 0.05), with no significant differences in advanced neoplasia incidence between the family history categories (p = 0.16). Patients ≥ 60 years showed a fourfold (HR 4.14, 95% CI 1.33–12.89) higher advanced neoplasia risk during surveillance than those < 40 years at index colonoscopy. With each subsequent negative colonoscopy, the risk of advanced neoplasia at ongoing surveillance was reduced.ConclusionsThe incidence of advanced neoplasia was low (14.35%), regardless of the family history risk category, with older age being the main risk for advanced neoplasia. Delaying onset of colonoscopy or lengthening surveillance intervals could be a more efficient use of resources in this population.

Linked color imaging aids in identification of multiple rectal neuroendocrine tumors.

A 63-year-old man with a history of three synchronous primary cancers (colon, lung, and thyroid) underwent surveillance colonoscopy after his curative left hemicolectomy. A new 8 mm rectal lesion was identified and removed with hot snare polypectomy. Histology showed a grade 1 rectal neuroendocrine tumor (NET). Repeat colonoscopy 6 months later showed five new sub-centimeter rectal NETs, which were removed with cap-assisted endoscopic mucosal resection (EMR).

Age-Specific Differences in the Risk of Colorectal Precursor Lesions Among Patients with Type 2 Diabetes Undergoing Surveillance Colonoscopy.

The incidence rate of colorectal cancer (CRC) in young adults is rising in parallel with type 2 diabetes (T2D). The majority of CRC develop through two main subtypes of precursor lesions; adenomas and serrated lesions. The associations between age and T2D on development of precursor lesions remain uncertain. We studied the association of T2D with the development of adenomas and serrated lesions in individuals <50 versus ≥50 years of age, in a population undergoing long-term regular surveillance colonoscopy due to an elevated risk of CRC. A case-control study was conducted on patients who were enrolled in a surveillance colonoscopy program between 2010-2020. Findings at colonoscopy, clinical and demographic features were collected. Adjusted and unadjusted binary logistic regression assessed the association of age, T2D, sex, and other medical conditions and lifestyle-related factors with different subtypes of precursor lesions diagnosed at colonoscopy. Cox proportional hazards model analysis determined the association of T2D and other confounders with development time for precursor lesions. Cases included 412 patients <50y [mean age 38.7 (range, 24-49y)] and 824 sex-matched controls ≥50y [62.1 (50-75y)]. Individuals <50y were less likely to have been diagnosed with T2D than those ≥50y (7% vs 22%, P-value<0.001). During the follow-up period, there was no significant association between T2D and diagnosis of any precursor lesions, but when considering development time, individuals with T2D developed non-significant adenomas earlier than those without T2D (HR =1.46; 95% CI: 1.14-1.87; P-value=0.003). However, this was not independent of age or findings at index colonoscopy. T2D does not further increase the incidence of adenomas or serrated lesions in either a young or older cohort undergoing long-term surveillance colonoscopy.

Surveillance Colonoscopies of Synchronous Colorectal Cancer: What Should We Do?

The aim of this study is to investigate the occurrence of metachronous neoplasms at 2-year surveillance colonoscopy for synchronous colorectal cancer patients and the relative risk factors. Synchronous colorectal cancer patients who underwent surgery or endoscopic resection for colorectal cancer between January 2008 and December 2019 were enrolled. All patients underwent surveillance colonoscopies at least twice within 2 years after operation. Univariate and multivariate analyses were conducted to assess the risk factors for the metachronous neoplasms. Totally 38 patients (male/female: 26/12) were included, with an average age of 64.6 years (±11.5 years) and a mean surveillance interval of 23.47 ± 4.39 months. In 21 of 38 patients (55.3%), metachronous adenoma was detected, including 6 metachronous advanced adenomas. Two patients were detected with metachronous carcinomas. In univariate analysis, male sex, elderly age at diagnosis, and the presence of synchronous adenomas/synchronous advanced adenoma at baseline colonoscopy were associated with the development of metachronous adenoma (P = .037, .047, .013, .039), but not associated with metachronous advanced adenoma (P = 0.455, .746, .503, .269). Patients tends to occur less metachronous advanced adenoma if index colorectal tumors were treated by endoscopic resection (P = .010), but the tendency was not discovered in metachronous adenoma (P = .289). Tumor location (with/ without rectum cancer) was not associated with the development of metachronous lesions (P = .526, .382). On multivariate analysis, the presence of synchronous adenomas at baseline colonoscopy was an independent risk factor for MA during follow-up (odds ratio = 15.0; 95% CI: 1.55-145.22). For postoperative synchronous colorectal cancer patients, doctors should design individual surveillance strategies according to sex, baseline colonoscopy, and operative (or endoscopic) approach of resection.

What Is the Risk? Epidemiology and Evidence for Surveillance Regimens.

Patients with inflammatory bowel disease (IBD) have increased risk of colorectal cancer (CRC). The risk for CRC is positively correlated to the duration of disease, extent of colonic involvement, and severity of inflammation. After 8 to 10 years of IBD diagnosis, the risk for CRC rises substantially and screening colonoscopy is recommended. Surveillance colonoscopy interval ranges from 1 to 5 years depending on patient and disease-specific risk factors. IBD patients with high risk factors such as having concomitant primary sclerosing cholangitis, moderate-to-severe inflammation, first-degree relative with CRC at early age, or history of invisible dysplasia or high-risk visible dysplasia should undergo surveillance colonoscopy in 1 year. Meanwhile, those with minimal colonic involvement or ≥2 consecutive unremarkable examinations while in continuous remission may consider extending the surveillance interval to 5 years. Advance in colonoscopy technique such as chromoendoscopy using dyes and/or image digital processing (virtual chromoendoscopy) may enhance dysplasia detection and is the preferred method for IBD surveillance. In the era of high-definition colonoscope, the practice of obtaining extensive biopsies throughout the colon remains controversial but is generally recommended to improve the detection rate of invisible dysplasia. Endoscopic surveillance in IBD has been shown to result in earlier detection of CRC and improved prognosis.

A retrospective study of colonoscopic surveillance in the elderly.

Aotearoa New Zealand (AoNZ) guidelines suggest surveillance colonoscopy should be carefully considered after age 75. The authors noted a cluster of patients presenting in their 8th and 9th decade of life with a new colorectal cancer (CRC) having previously been declined surveillance colonoscopy. A 7-year retrospective analysis was performed of patients who underwent a colonoscopy aged between 71 and 75 years in the period between 2006 and 2012. Kaplan-Meier graphs were created with survival measured from the time of index colonoscopy. Log rank tests were used to determine any difference in survival distribution. Relative risk (RR) was calculated, and 95% confidence intervals (CI) reported. A total of 623 patients met inclusion criteria; 461 (74%) had no indication for surveillance colonoscopy and 162 (26%) had an indication. Of the 162 patients with an indication, 91 (56.2%) underwent surveillance colonoscopies after the age of 75. Twenty-three (3.7%) patients were diagnosed with a new CRC. Eighteen (78.2%) patients diagnosed with a new CRC underwent surgery. The median survival overall was 12.9 years (95% CI 12.2-13.5). This did not differ between patients with (13.1, 95% CI 12.1-14.1) or without (12.6, 95% CI 11.2-14.0) an indication for surveillance. This study found one quarter of patients who had a colonoscopy between the ages of 71-75 had an indication for surveillance colonoscopy. Most patients with a new CRC underwent surgery. This study suggests it may be appropriate to update the AoNZ guidelines and consider adopting a risk stratification tool to aid decision making.

Multiple Negative Fecal Immunochemical Tests Reduce Risk of Advanced Neoplasia in a Colonoscopy Surveillance Program

In above-average-risk individuals undergoing colonoscopy-based surveillance for colorectal cancer (CRC), screening with fecal immunochemical tests (FIT) between colonoscopies might facilitate personalization of surveillance intervals. Because a negative FIT is associated with a reduced risk for CRC, we examined the relationship between number of rounds of negative FIT and risk for advanced neoplasia in individuals undergoing surveillance colonoscopy. We conducted a retrospective cohort study on 4021 surveillance intervals in 3369 individuals (50-74 years), who had completed a 2-sample FIT between colonoscopies, from 1 to 4 rounds at 1-2 yearly intervals, each with a negative result (<20 μg hemoglobin/g feces). Incidence of advanced neoplasia (CRC or advanced adenoma) was determined at the follow-up colonoscopy. Competing-risk regression was used to assess the association between multiple negative FIT results and the risk of advanced neoplasia within 2 years. The incidence of advanced neoplasia in the cohort was 9.9% and decreased with increasing numbers of rounds of negative FIT results: 11.1% after 1 negative FIT to 5.7% after 4 negative FIT. The risk of advanced neoplasia was significantly lower in participants with 3 (subdistribution hazard ratio, 0.50; 95% confidence interval, 0.24-0.97) and 4 (subdistribution hazard ratio, 0.33; 95% confidence interval, 0.15-0.73) rounds of negative FIT compared with only 1 negative FIT. There was a low risk of advanced neoplasia after multiple rounds of negative FIT in above-average-risk people undergoing surveillance with no neoplasia or nonadvanced adenoma at prior colonoscopy. This supports the use of interval FIT to personalize surveillance by lengthening colonoscopy intervals following multiple negative FIT results.

A Multi-Centre Study to Risk Stratify Colorectal Polyp Surveillance Patients Utilising Volatile Organic Compounds and Faecal Immunochemical Test.

Simple SummaryA total of 15% of the annual colonoscopies are undertaken for polyp surveillance, and this causes strain on already stretched endoscopy services in the U.K. Hence, there is an urgent need to triage and prioritise patients with high-risk findings. The performance of the faecal immunochemical test is not adequate to be used within polyp surveillance. In light of this, we investigated the usefulness of urinary volatile organic compounds for the detection of high-risk findings. We confirmed that urinary volatile organic compounds can be used to triage patients with high-risk findings. It can be used alone or in combination with faecal immunochemical tests.(1) Background: The service capacity for colonoscopy remains constrained, and while efforts are being made to recover elective services, polyp surveillance remains a challenge. (2) Methods: This is a multi-centre study recruiting patients already on polyp surveillance. Stool and urine samples were collected for the faecal immunochemical test (FIT) and volatile organic compounds (VOC) analysis, and all participants then underwent surveillance colonoscopy. (3) Results: The sensitivity and specificity of VOC for the detection of a high-risk finding ((≥2 premalignant polyps including ≥1 advanced polyp or ≥5 premalignant polyps) were 0.94 (95% CI, 0.88 to 0.98) and 0.69 (95% CI, 0.64 to 0.75) respectively. For FIT, the sensitivity was (≥10 µg of haemoglobin (Hb) / g faeces) 0.54 (95% CI, 0.43 to 0.65) and the specificity was 0.79 (95% CI, 0.73 to 0.84). The probability reduction for having a high-risk finding following both negative VOC and FIT will be 24% if both tests are applied sequentially. (4) Conclusion: The diagnostic performance of VOC is superior to FIT for the detection of a high-risk finding. The performance further improves when VOC is applied together with FIT sequentially (VOC first and then FIT). VOC alone or the combination of VOC and FIT can be used as a triage tool for patients awaiting colonoscopy within a polyp surveillance population, especially in resource-constrained healthcare systems.

S292 Socioeconomic Status: An Important Determinant for Follow-Up for Surveillance Colonoscopy After Endoscopic Mucosal Resection

Introduction: Alabama had significantly higher incidence of colorectal cancer (CRC)at 43.5 compared to the US rate 39.5, and African Americans have higher rate of CRC compared to Caucasian individuals. There is compelling evidence that surveillance colonoscopy after high-risk adenoma polypectomy can reduce the risk of developing CRC.Our objective was to identify risk factors associated with poor follow up after undergoing colonoscopy with endoscopic mucosal resection (EMR). Methods: We performed retrospective chart review of patients who had EMR at our facility between June 2016-March 2022.Patient demographics, referral, procedural and census data were collected. Census data obtained was used to evaluate income, median household income, and educational attainment. Patients were divided into two groups; poor and good follow up. Poor follow up was defined as those who failed to follow up and/or presented for surveillance colonoscopy >1 month after the recommended timeframe. Results: Initial chart review included 520 eligible patients;73 were excluded due to lack of referral data, and 59 with recent EMR whose recommended surveillance colonoscopy has not passed. Of the included 388 patients, 293 (75.5%) had poor follow up and 95 (24.5%) had good follow up. Descriptive statistics of the various characteristics and comparisons of the of two groups is presented in Table. Compared to individuals with good follow up, there was a significant association of poor follow up with patients whose index colonoscopy was performed at an outside hospital (p=0.003) and if the index colonoscopy was their first colonoscopy (p=0.04). Additionally, census data revealed lower median home values were associated with poor follow up ($168,382) when compared to good follow up ($185,034). There was a trend to poor follow up in patients with obesity (80.5%), former alcohol use (88.9%), patients insured by Medicaid (88.9%), and minority populations including African American, and Hispanic/other ethnicities (77.1%,90.9%, respectively). Conclusion: Our study illustrates that social economic status has significant impact on surveillance colonoscopy after EMR, and outside hospital referral are more likely to have poor follow up compared to in house referrals. Given the potential impact this data has for reducing risk of developing CRC in lower social economic individuals, further studies are needed to validate this finding and stratify predictors of poor follow up. Table 1. - Descriptive characteristics and comparison of poora vs goodb follow up in patients who underwent EMR at UAB between June 2016-March 2022 Overall Follow-up p value N=388 Poor n=293 (75.5%) Good n=95 (24.5%) Age (years), mean (SD) 63 (10.4) 64 (10.4) 62 (10.4) 0.23c Sex Male 52.1% 75.3% 24.8% 0.89d Female 47.9% 75.8% 24.2% Race/Ethnicity Caucasian 67.8% 73.8% 26.2% 0.38d African American 28.1% 77.1% 22.9% Other 2.8% 90.9% 9.1% Type of insurance Private 45.9% 74.7% 25.3% 0.39d Medicare 47.4% 75.0% 25.0% Medicaid 4.6% 88.9% 11.1% Uninsured 2.1% 75.0% 25.0% BMI less than 24.9 – Underweight/ Normal 24.8% 72.8% 27.2% 0.11d between 25.0 and 29.9 – Overweight 32.4% 70.0% 30.0% more than 30.0 – Obese 42.9% 80.5% 19.5% ASA classification 1 0.8% 66.7% 33.3% 0.84d 2 60.2% 75.5% 24.5% 3 38.5% 75.8% 24.2% 4 0.5% 50.0% 50.0% Smoking Current 25.0% 76.3% 23.7% 0.79d Former 26.8% 73.1% 26.9% Never 47.7% 76.2% 23.8% Alcohol Current 46.1% 72.6% 27.4% 0.25d Former 6.9% 88.9% 11.1% Never 46.4% 76.1% 23.9% Drugs Current 3.4% 84.6% 15.4% 0.85d Former 4.4% 70.6% 29.4% Never 87.9% 75.4% 24.6% Employment Employed 29.9% 74.1% 25.9% 0.99d Unemployed 6.9% 74.1% 25.9% Retired 28.4% 75.5% 24.6% Disabled 10.1% 76.9% 23.1% First colonoscopy Yes 17.0% 75.8% 24.2% 0.04d* No 44.6% 69.9% 30.1% Outside Hospital Referral Yes 31.7% 86.2% 13.8% 0.003d* No 67.8% 70.7% 29.3% Time of procedure Morning 57.9% 72.9% 27.1% 0.16d Afternoon 42.0% 79.1% 20.9% ASA=American Society of Anesthesiologists; BMI=body mass index; EMR= endoscopic mucosal resection; SD=standard deviation; UAB=University of Alabama at Birmingham.*Statistically significant at 0.05 level (two-tailed test).aPoor follow up included patients that did not receive surveillance colonoscopy within recommended timeframe or patients who were lost to follow up.bGood follow up is defined as undergoing surveillance colonoscopy within the recommended timeframe.cUnpaired t-test.dChi-square test.

S2200 A Rare Case of Extraluminal Rectal Fecaloma

Introduction: Fecaloma is usually an intraluminal stony mass of inspissated feces covered with layers of calcified shell. It can cause obstructive or compressive symptoms and sometimes even luminal rupture. It is usually managed conservatively and surgical removal is rarely needed. Most common sites for fecaloma are sigmoid colon and rectum. It is commonly associated with inflammatory bowel disease, Hirschsprung’s disease, Chagas disease, psychiatric and bedridden patients, neoplasm or idiopathic chronic constipation. We present a unique case of extraluminal fecalith presenting as subepithelial rectal mass. Case Description/Methods: A 60-year-old male with history of colon polyps underwent surveillance colonoscopy which showed a 3-4 cm firm rectal subepithelial mass that resembled a large lipoma or GIST (Figure A) Patient denied any symptoms including constipation or abdominal pain and had no family history of colon cancer. On endoscopic ultrasound (EUS) with radial and linear probe a subepithelial mass like lesion with calcified wall (Figure B) was noted. Multiple cold snare polypectomies were performed to de-roof the lesion as well as a deep "bite on bite/well biopsy technique" in order to get through the wall when feculent material and purulent debris was noted within the cavity (Figure C). Mucosal and muscular layer biopsies showed only vegetable fiber and fecal debris focally calcified consistent with fecalith. A CD 117 immunostain was negative excluding a GIST tumor. Historically this patient had an episode of complicated diverticulitis with phlegmon and microperforation in his 40s that was treated conservatively. Few months after that episode he had sigmoid colon resection with anastomosis in order to prevent future episodes. Discussion: Although there are rare reported cases of extraluminal cecal fecalomas, to our knowledge this is the first reported case of extraluminal rectal fecaloma. We suspect that our patient developed fecal leakage through the suture line after sigmoid resection with anastomosis nearly 20 years ago. Over time, the leakage likely became a well-organized fecaloma with calcification. In summary, fecaloma is a differential diagnosis to consider when encountering a large subepithelial mass in the rectum.Figure 1.: Extraluminal Rectal Fecaloma. A. Colonoscopic imaging showing large subepithelial mass. B. Endoscopic ultrasound image showing subepithelial mass with calcified wall. C. Colonoscopic image showing feco-purulent material inside the mass.

Erosive footprints

Sodium sulfate/magnesium sulfate/potassium chloride is an osmotic pill laxative recently approved by the U.S. Food and Drug Administration for colonoscopy preparation in adults. During our first week of using this agent, 3 patients undergoing endoscopy and colonoscopy were found to have caustic-appearing gastric ulcers. Two patients had chronic heartburn and associated risk factors. The third case was of a patient with Lynch syndrome undergoing surveillance colonoscopy. No patients had previously known gastric pathologic conditions or use of nonsteroidal anti-inflammatory agents.

The frequency of second primary malignancies and colonic polyps in Lynch syndrome with MSI tumors following immune checkpoint blockade.

10505 Background: Lynch syndrome (LS) is caused by germline mutations in DNA mismatch repair genes and is characterized by microsatellite instability (MSI) status of associated tumors. MSI sensitizes tumors to immune checkpoint inhibition (ICI). The incidence of second primary malignancies and colonic polyps in LS patients with MSI tumors following ICI has not been evaluated. Methods: The Memorial Sloan Kettering LS database was queried for all patients with cancer who received ≥1 cycle of ICI using an IRB approved protocol. LS was confirmed by presence of a germline pathogenic/likely pathogenic alteration in a DNA mismatch repair gene ( MLH1, MSH2, MSH6, PMS2, EPCAM). Tumor and matched normal DNA sequencing was performed via MSK-IMPACT, an IRB approved protocol (NCT01775072). MSI status was assessed using MSIsensor. Results: At our center, 131 patients with LS received ICI mostly (73.3%) in the context of metastatic cancer. While 108 patients received ICI for an MSI tumor, 23 LS patients received ICI for a MSS (Microsatellite Stable) tumor (4 hepatobiliary, 3 colorectal, 3 CNS, 2 endometrial, 2 gastroesophageal, 2 renal, 2 sarcoma, 5 other). Five patients (3.8%) developed ≥1 second primary malignancy while on or following ICI comprised of an MSI small bowel adenocarcinoma, MSI upper tract urothelial cancer, 2 MSS prostate cancers, MSS HCC and MSI sebaceous neoplasm; 1 patient developed both MSS prostate cancer and MSI urothelial cancer on ICI. All five patients’ primary malignancy was MSI. Only a minority of patients underwent surveillance colonoscopies post completion of ICI (31.3%, (41/131)). Of these 41, nine (22%, (9/41)) were identified to have polyps including 8 tubular adenomas and 1 tubulo-villous adenoma. Median time to development of a polyp was 22 months (95% CI 16.82-27.18) from last colonoscopy and 13 months (95% CI 4-25 months) from last ICI. Notably amongst the 23 LS patients whose tumors were MSS, 14 had progression on ICI. Conclusions: Herein, we demonstrate that in LS-patients in receipt of ICI for cancer treatment, the risk of a second primary cancer and polyps remain high following treatment with ICI. Biological mechanisms underlying immune escape warrant further investigation. Surveillance strategies should be continued for LS patients post ICI.

Faecal immunochemical test mitigates risk of delayed colonoscopy in people with elevated risk of colorectal neoplasia

Surveillance colonoscopies may be delayed because of pressure on resources, such as the COVID-19 pandemic. This study aimed to determine whether delayed surveillance colonoscopy increases the risk for advanced neoplasia and whether interval screening with faecal immunochemical tests (FITs) and other known risk factors can mitigate this risk. A retrospective cohort study of individuals undergoing surveillance colonoscopy for personal or family history of colorectal neoplasia was being provided with FIT between colonoscopies. Colonoscopy≥6months after the guideline-recommended interval was considered "delayed." Individuals were stratified based on prime colonoscopy findings to nonneoplastic findings, non-advanced adenoma, and advanced adenoma. The relative risk (RR) for developing advanced neoplasia was determined using a robust multivariable modified Poisson regression. Of 2548 surveillance colonoscopies, 1457 (57.18%) were delayed. Prior advanced adenoma, older age (>60years) and nonparticipation in interval FIT were associated with increased risk for advanced neoplasia (P<0.05). There was a trend to increased risk in those with prior advanced adenoma with an increasing colonoscopy delay (P trend=0.01). In participants who did not complete interval FIT and having advanced adenoma in the prime colonoscopy, risk of advanced neoplasia was 2.48 times higher (RR=2.48, 95% confidence interval: 1.20-5.13) in participants who had beyond 2years of delayed colonoscopy compared with those with on-time colonoscopy. Colonoscopy delay did not increase the risk of advanced neoplasia in participants with negative interval FIT results. Surveillance colonoscopy can be safely extended beyond 6months in elevated colorectal cancer risk patients who do not have prior advanced adenoma diagnosis, particularly if interval FIT is negative.