Postoperative Colonoscopy Research Articles

A case of early gastric cancer with a single giant lymph node metastasis

BackgroundEarly gastric cancer (EGC) is often associated with lymphatic metastasis, but it is extremely rare to be found as a single giant lymph node. Cancer often becomes more malignant in metastatic lesions than in primary lesions, and retrodifferentiation to the fetal gastrointestinal tract during the metastatic process has been reported in gastric cancer. We report an extremely rare case of EGC with a 13-cm giant lymph node metastasis in which an adenocarcinoma with enteroblastic differentiation and yolk sac tumor-like components was observed.Case presentationThe case was a 70-year-old man who visited his local doctor with right hypochondrial pain, which was identified by computed tomography (CT) as a giant mass. Upper endoscopy revealed a 30-mm-sized 0-IIc lesion in the greater curvature of the angular incisure and a 15-mm-sized 0-IIa lesion in the anterior wall of the lower body of the gastric body. Endoscopic biopsy revealed tubular adenocarcinoma in both lesions. The gastric lesion and the giant tumor were clinically regarded as independent lesions (gastrointestinal stromal tumor, [GIST], and EGCs), and distal gastrectomy and D1 + dissection were performed to comprehensively treat all lesions. Pathological examination revealed that the giant tumor was tubular adenocarcinoma with an intestinal phenotype and was considered a lymph node metastasis of EGCs. To exclude the possibility of metastasis of adenocarcinoma other than EGCs, postoperative positron emission tomography-computed tomography (PET-CT) and colonoscopy were performed; however, no primary site other than the stomach was found. Metastatic lymph nodes have an increased degree of atypia compared with the primary tumor, and yolk sac tumor-like carcinoma morphology was observed along with α-fetoprotein (AFP) and Spalt-like 4 (SALL4) expression in this case. It was considered that retrodifferentiation to a fetal phenotype occurred during the metastatic process. Liver metastasis occurred 6 months after surgery, and chemotherapy is currently being introduced.ConclusionsWe experienced a case of EGC with a single giant lymph node metastasis. Retrodifferentiation to the fetal gastrointestinal tract during metastasis was speculated to be involved in the formation of giant lymph node metastasis and liver metastasis in this case.

A Role for CXCR3 Ligands as Biomarkers of Post-Operative Crohn's Disease Recurrence.

Crohn's disease [CD] recurrence following ileocolic resection [ICR] is common. We sought to identify blood-based biomarkers associated with CD recurrence. CD patients undergoing ICR were recruited across six centres. Serum samples were obtained at post-operative colonoscopy. A multiplex immunoassay was used to analyse 92 inflammation-related proteins [Olink Proteomics]. Bayesian analysis was used to identify proteins associated with increasing Rutgeerts score. Identified proteins were used in receiver operating characteristic [ROC] analysis to examine the ability to identify CD recurrence [Rutgeerts score ≥i2]. Existing single cell data were interrogated to further elucidate the role of the identified proteins. Data from 276 colonoscopies in 213 patients were available. Median time from surgery to first and second colonoscopy was 7 (interquartile range [IQR] 6-9) and 19 [IQR 16-23] months, respectively. Disease recurrence was evident at 60 [30%] first and 36 [49%] second colonoscopies. Of 14 proteins significantly associated with Rutgeerts score, the strongest signal was seen for CXCL9 and MMP1. Among patients on anti-tumour necrosis factor drugs, CXCL9 and CXCL11 were most strongly associated with Rutgeerts score. Both are CXCR3 ligands. Incorporation of identified proteins into ROC analysis improved the ability to identify disease recurrence as compared to C-reactive protein alone: area under the curve [AUC] 0.75 (95% confidence interval [CI]: 0.66-0.82] vs 0.64 [95% CI 0.56-0.72], p = 0.012. Single cell transcriptomic data provide evidence that innate immune cells are the primary source of the identified proteins. CXCR3 ligands are associated with CD recurrence following ICR. Incorporation of novel blood-based candidate biomarkers may aid in identification of CD recurrence.

S699 Isolated Anastomotic Lesions Do Not Increase Risk for Severe Endoscopic Disease Progression in Postoperative Crohn’s Disease

Introduction: The impact of isolated postoperative anastomotic lesions on future Crohn’s disease (CD) progression is controversial. This study aimed to evaluate the risk of severe disease progression in postoperative CD patients with isolated anastomotic disease. Methods: Retrospective cohort study of adult CD patients who underwent ileocolonic resection (ICR) between the years 2009-2020. Patients with bowel continuity restoration, a postoperative colonoscopy ≤ 18 months from surgery, and ≥ 1 subsequent colonoscopy were included. Disease activity was assessed utilizing retrospective application of modified Rutgeerts’ score (RS) by a centralized reader. Primary outcome was severe endoscopic progression, defined as i3 or i4 disease. Secondary outcome was surgical recurrence defines as repeat ICR. Results: 199 CD patients (median age 34 years, 47.7% stricturing, 33.2% ≥1 prior ICR) with index postoperative colonoscopy RS of i0-i2b were included. Study population RS distribution was 28.8% (n=69) i0, 13.3% (n=32) i1, 20.4% (n=49) i2a, 20.4% (n=49) i2b. Median time from ICR to index colonoscopy (260 days [195,377.5]; p=0.83) and time to follow up endoscopy (441 days [335,746.5]; p=0.65) did not differ by index RS. Overall, 26.1% of patients experienced severe endoscopic disease progression and was associated with index RS (p< 0.001) (Figure 1). During entire follow up, adjusting for index RS, tobacco use, ≥2 prior ICR, and initiation of biologics after index ileocolonoscopy, i2b disease was associated with severe endoscopic progression compared to i0 or i1 (aOR:5.53 95% CI [2.50-12.76]; p< 0.001) and i2a disease (aOR: 2.63 [1.12-6.4];p=0.03). Conversely, i2a disease did not confer increased risk compared to patients in endoscopic remission (2.11 [0.89-4.97]; p=0.087) (Table 1). On multivariable Cox proportional hazard model, adjusting for risk factors, i2b disease was associated with decrease time to severe endoscopic disease progression relative to i0 or i1 disease (aHR: 4.68 [2.42-9.02]; p< 0.001) and i2a (aHR: 3.02 [1.50-6.09]; p=0.002). i2a was not associated with decreased time to endoscopic progression relative to i0 or i1 (p=0.25) (Table 1). Surgical recurrence was not associated with index RS (p=0.86). Conclusion: Mild ileal postoperative recurrence, not isolated anastomotic lesions, is associated with increased risk for severe endoscopic disease progression. Prospective studies are needed to further elucidate impact of isolated anastomotic inflammation.Figure 1.: Anti-receptor binding domain (RBD) antibody levels among IBD patients in PREVENT-COVID study. Box and whisker plots show mean (X), median, interquartile range, overall range of anti-RBD antibody levels (ug/mL), and proportion of participants with detectable anti-RBD antibody stratified by A) age group, B) vaccination type, C) IBD medication use (all participants), and D) medication use among patients not taking corticosteroids. Abbreviations: RBD = receptor binding domain, TNFi = tumor necrosis factor inhibitor, Immune = immunomodulator, 6-MP = mercaptopurine, AZA = azathioprine, MTX = methotrexate, 5ASA = mesalamine, vedo = vedolizumab, uste = ustekinumab.Table 1.: Baseline Demographics and Characteristics and Treatment adverse events throughout 8 weeks.

The necessity of intensive surveillance colonoscopy for patients with a remaining right colon after resection of colorectal cancer: a retrospective cohort study.

To clarify how often postoperative surveillance colonoscopy should be undertaken based on the risk factors for the development of metachronous cancer (MC) and advanced adenoma (AA) after surgery for colorectal cancer. We collected data of consecutive patients who underwent curative resection for primary colorectal cancer between 2005 and 2012, with preoperative colonoscopy and surveillance colonoscopy at 1year after surgery (406 patients, mean age: 69years, 59% male). The detection rates of AA (with villous features, > 10mm or high-grade dysplasia) and MC by surveillance colonoscopy were the primary outcomes. At 5years, colonoscopy was performed as postoperative surveillance an average of 3.2 times. AA and MC were detected in 57 (14.0%) and 18 patients (4.4%), respectively. Both lesions were more common in the right colon (n = 43) than in the left colon (n = 28). The detection rate did not differ to a statistically significant extent according to the number of colonoscopies performed for surveillance (p = 0.21). However, after left-sided colectomy, both types of lesions were more commonly detected in those who received ≥ 3 colonoscopies than in those with one or two colonoscopies (p = 0.04). A remaining right colon after left-sided colectomy was associated with a higher risk of developing AA and MC. Physicians should consider performing surveillance colonoscopy more frequently if the right colon remains after surgery.

Incidental Polyp on Colectomy Specimen is Linked with Higher Odds of Polyp on Interval Colonoscopy

Incidentally found polyps on surgical pathology after colectomy is an underreported phenomenon, and management guidelines are lacking. Elucidation of the significance of incidental polyps is needed to determine if post-operative endoscopic surveillance modification is warranted. We sought to determine the relationship between incidental polyp on colectomy specimen and findings on post-operative colonoscopy. A multi-institutional retrospective review was performed on patients that underwent colorectal resection from 2018-2019. Surgical pathology was reviewed for polyps and assigned as expected or incidental based on pre-operative colonoscopy. If performed, post-operative colonoscopy was reviewed for new lesion identification. The odds of detecting new lesion on post-operative colonoscopy was compared between cases with incidental polyp on surgical specimen and patients without incidental findings. In 243 colorectal resections, incidental polyps were identified in 55 cases (22.6%). Post-operative colonoscopy was completed in 65 cases (26.7%) with new polyp detected in 24 cases (9.88%). Of those, 10 had an incidental polyp previously identified on surgical specimen while 14 did not. The presence of incidental surgical specimen polyp was associated with a greater than two-fold higher odds of detecting new polyp on post-operative colonoscopy (odds-ratio 2.76, 95% confidence interval 1.15-6.63;P=0.023). This analysis revealed a high frequency of incidental polyps on surgical specimens with an increased rate of newly found lesions on post-operative colonoscopy. Incidental polyps may be a risk factor for other missed lesions still within the patient. Therefore, providers should consider surveillance interval modification on an individual basis in the setting of incidental surgical specimen polyps.

Implication of FDG-PET/CT without synchronous colonic lesion in patients with stenotic left-sided colorectal cancer

Although 18-fluoro-2-deoxy-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) is useful for detecting synchronous colorectal cancer (CRC) in stenotic CRC, long-term outcomes of patients without synchronous FDG-avid lesions are not well reported. We investigated postoperative colonoscopy results in patients with left-sided stenosing CRC without synchronous FDG-avid lesions. In this retrospective review, 754 patients with left-sided CRC without synchronous FDG-avid lesions on preoperative 18F-FDG PET/CT were divided into two groups based on the completeness of preoperative colonoscopy. Propensity score matching was performed to balance baseline characteristics. Results of postoperative colonoscopy were compared in both the unmatched and matched cohorts. At 1 and 5 years after surgery, the cumulative risk of advanced adenoma (AA) or carcinoma (CA) in all patients, risk of CA, and additional surgical risk were 1.8% and 10.1%, 0.1% and 0.4%, and 0% and 0.5%, respectively. In both cohorts, the AA risk was significantly higher in the incomplete colonoscopy group. However, the risk of CA showed no between-group difference in the matched cohort. Additional surgical risk did not differ between the two groups. Thus, the finding of negative FDG-avid lesions in the proximal colon in addition to the target CRC ensures the absence of additional lesions warranting surgical plan changes.

Tumour-to-tumour metastasis: metastatic rectal adenocarcinoma within adenocarcinoma of the lung, and a review of the literature

Background: Tumour-to-tumour metastasis (TTM) is a rare but well-recognised phenomenon. When presented with a case of synchronous colon and pulmonary adenocarcinoma in the lung, one must consider the differential diagnosis of TTM and exclude a tumour with divergent phenotype because of difference in clinical management. Aims: Herein, we present a rare case of TTM, in which a rectal adenocarcinoma has metastasised to a pulmonary adenocarcinoma. We illustrate how morphologic, immunohistochemical, and molecular analyses can help in the pathological diagnosis of TTM. Methods: A case of TTM with a review of the literature is presented. Results and conclusions: A 67-year-old male with a history of metastatic rectal adenocarcinoma to the liver has been in regular follow-up since 2012. Post-operative colonoscopy was normal and a computer tomography scan in 2015 revealed a 0.6 cm subpleural nodule in the left upper lobe of the lung. For the next 3 years, the nodule only showed mild interval enlargement, until a follow-up CT scan in 2019 revealed sudden increase in size to 1.5 cm. Suspicious of lung metastasis, the nodule was resected and histopathological analysis unexpectedly revealed a malignant tumour composed of a pulmonary and metastatic rectal adenocarcinoma. IHC for Napsin A, TTF-1, and CK7 was positive in the pulmonary adenocarcinoma, while CK20 and CDX-2 were positive in the metastatic rectal adenocarcinoma. KRAS mutation was identified in the pulmonary but not in the metastatic carcinoma. The latter was wild-type for KRAS and had TP53 mutation similar to the original rectal tumour. A review of the literature identified some 165 cases, of which only one previous case of colon adenocarcinoma metastasizing to lung adenocarcinoma has been reported. Diagnosis of TTM requires histomorphologic assessment and is aided by immunohistochemical and molecular analysis. Awareness of TTM is important because of the significant difference in clinical management.

DOP17 In high-risk Crohn’s Disease patients, anastomosis configuration types have similar rates of endoscopic recurrence

Abstract Background There is conflicting data on the influence of surgical anastomosis configuration on endoscopic postoperative recurrence (POR) of Crohn’s disease (CD) following ileocolonic resection (ICR). Furthermore, whether this relationship differs by preoperative risk factors for POR has not been studied. We aimed to assess the role of ileocolonic anastomosis type on the rate and time to POR by preoperative POR risk. Methods Retrospective cohort study of adult CD patients who underwent ICR between 2009–2020 at a quaternary IBD referral center. Patients with a primary or secondary anastomosis and ≥1 postoperative colonoscopy were included. Endoscopic activity was assessed by modified Rutgeerts’ scoring. POR was defined as Rutgeerts’ ≥ i2b. Patients were categorized by anastomosis type: end-to-end (ETE), end-to-side (ETS), or side-to-side (STS). High-risk CD patients were defined by ≥1: age ≤ 30 years, active smoker, or ≥2 ICR for penetrating disease. Results 548 CD patients (52.6% female, age 35 y, 15.5% &amp;gt; 1 prior ICR, 19.7% on biologic prophylaxis, 74.8% high-risk for POR) were included in the study (Figure 1). The majority received a STS (52.0%, N=285), 27.2% ETS, and 20.8% ETE. Patients with an ETE were diagnosed with CD at a younger age (p=0.04), had more penetrating disease (p=0.01), hand-sewn anastomoses (p &amp;lt;0.001), and diverting loop ileostomies (p=0.02). There were no differences in prior ICR, smoking, biologic prophylaxis, or in median time from ICR to first post-operative colonoscopy (388.5 days, p=0.41) or POR detection (905 days, p=0.8) by anastomosis type. ETS patients had a shorter median follow-up time (3.9 y, p=0.02). The majority (55.7%) of all patients experienced POR (57% ETS; 55.4% STS; 54.4% ETE). Overall, there was no significant association between anastomosis type and POR rate (p=0.91) or time to POR (p=0.32). However, in high-risk CD patients, ETS was significantly associated with more rapid time to POR on log-rank (p=0.03) and multivariable Cox modeling (HR=1.51; p=0.04). Postoperative prophylactic biologic therapy initiated within 3 months of ICR significantly delayed POR in the overall cohort (HR=0.64; p=0.012) and the high-risk CD subgroup (HR=0.67; p=0.047). High-risk CD patients on prophylactic biologics had no difference in time to POR by anastomosis type (p=0.66). Conclusion In post-operative CD patients, there is no difference in rates of endoscopic recurrence by anastomosis configuration regardless of risk stratification. In high-risk patients, ETS was associated with more rapid endoscopic recurrence compared to other configurations, however prophylactic postoperative biologics may protect against this effect. Figure 2: KM Survival analysis of time (days) to POR

P571 Optimal biologic management of endoscopic postoperative recurrence following ileocecal resection in Crohn’s disease

Abstract Background Endoscopic postoperative recurrence (POR) of Crohn’s Disease (CD) following ileocolonic resection (ICR) is common; however, optimal treatment strategies of identified POR are unknown. We assessed the role of biologic therapy to treat endoscopic POR in a real-world cohort. Methods Retrospective cohort study of adult CD patients who underwent ICR from 2009–2020 at a tertiary center. Patients with endoscopic POR detected on postoperative colonoscopy and a subsequent follow-up colonoscopy were included. Patients were categorized by biologic therapy at time of POR and further sub-grouped by therapy modification after POR detection (no change, therapy optimization, or change in biologic class). Therapy optimization included: starting or modifying immunomodulator therapy, corticosteroids, or budesonide. POR was defined by Rutgeerts’ ≥ i2b. Results 203 CD patients (49.8% female, 15.4% &amp;gt; 1 prior ICR, 49.0% pre-operative biologic exposure) were included. Of these, 137 (67%) patients were not on biologic therapy at POR detection: 43% subsequently started a biologic, 23% optimized therapy, and 34% had no change. 66 (33%) patients were on anti-TNF at POR identification: 24% subsequently changed biologic class, 48% optimized anti-TNF, and 27% had no change (Figure 1). There was no difference in median time from ICR to POR detection (483 days, p=0.08) or inter-colonoscopy interval (483 days, p=0.25) between groups. In patients not on biologics at POR detection, those who started a biologic saw a 21% increase in subsequent endoscopic remission compared to those who optimized therapy (49.2% vs 28.1%, p=0.09) and a 12% increase compared to those who received no change (49.2% vs 37%). In patients not on biologics with severe POR (i3/i4, n=62), there was significantly higher remission rate by starting biologic therapy compared to optimizing existing therapy (53.3% vs 16.7%) or no change (53.3% vs 35.7%), p=0.04. In individuals receiving anti-TNF at time of POR, there was a 25% increase in endoscopic remission in patients who switched biologic class compared to those who optimized therapy (56.2% vs 31.2%) and a 34% increase compared to those with no change (56.2% vs 22.2%), p=0.1. Furthermore, significantly higher rates of improved Rutgeerts’ score were observed in switching biologic class compared to therapy optimization (68.8% vs 43.8%) or no change (68.8% vs 27.8%), p=0.04. Conclusion After endoscopic POR detection following ICR, initiating biologic therapy in individuals not previously receiving it, and changing mechanism of action in those already receiving anti-TNF, may improve clinical outcomes compared to alternative management strategies. If confirmed, these findings may inform optimal management strategies for endoscopic POR.

AB187. SOH21AS230. Use of diagnostic imaging and post-operative colonoscopy to evaluate elderly patients with acute appendicitis: a 5-year single centre cohort study

Background: Acute appendicitis (AA) is relatively uncommon in patients over the age of 50 and may represent a first presentation of colorectal carcinoma. AA represents approximately 15% of abdominal pain presentations in patients over the age of 50, compared to almost 30% in younger patients. Rates of complicated appendicitis are also higher amongst this cohort. The objectives of this this study were two-fold: firstly to evaluate the use and accuracy of pre-operative diagnostic imaging in evaluating patients over the age of 50 with suspected AA. Secondly, to evaluate the detection rate of colorectal cancer on colonoscopy following diagnosis of AA

Fibromuscular dysplasia of mesenteric arteries: a rare cause of multiple bowel resections\u2014a case report and literature review

BackgroundFibromuscular dysplasia (FMD) is a type of unexplained nonatherosclerotic vascular disease that usually involves the renal and internal carotid arteries and rarely involves the mesenteric artery. Mesenteric artery FMD is difficult to distinguish from Crohn’s disease (CD) and Behcet’s disease (BD) solely based on symptoms. Patients with mesenteric artery FMD can present with an acute abdomen, but case reports of patients who have a long medical history and undergo multiple bowel resections are extremely rare.Case presentationThe patient was a 45-year-old woman with an 11-year history of intermittent lower abdominal pain and fever. At the age of 34 years, she underwent right hemicolectomy and appendectomy due to an acute abdomen. She suffered from oral ulcers between 34 and 36 years old. A clinical diagnosis of presumed CD was made by the age of 41, and she was treated with mesalazine; however, the effect was poor. At the age of 42, she came to our centre, and based on her atypical symptoms and examination results, we thought she had CD. Hence, she was treated with glucocorticoids for 3 years. However, when she was 45, due to steroid dependence, thalidomide tablets were added. Unfortunately, she suffered from another episode of intestinal obstruction. Therefore, she underwent enterectomy. The postoperative histopathological diagnosis was mesenteric artery FMD. She no longer underwent pharmacotherapy after the surgery. Although she did not have any of her previous symptoms and postoperative colonoscopy showed no signs of recurrence, splenomegaly and abnormal routine blood results were still present.ConclusionsPatients with mesenteric artery FMD can present with an acute abdomen. In addition, the symptoms and endoscopic manifestations of mesenteric artery FMD may appear similar to CD and BD. Hence, it is difficult to make a clear clinical diagnosis and proceed with treatment. Mesenteric artery FMD often requires surgical pathology to confirm its diagnosis. For patients who suffer from this disorder, surgery may be the best choice to improve the patient’s quality of life.

Recurrence, death risk, and related factors in patients with stage 0 colorectal cancer: A nationwide population-based study.

In this study, the National Health Insurance Research Database of Taiwan was used to examine the recurrence and death risk for stage 0 colorectal cancer patients. We examined stage 0 colorectal cancer patients to identify factors causing recurrence and death.This is a retrospective study, and stage 0 colorectal cancer patients that are registered in the Taiwan Cancer Registry of the Health Promotion Administration in 2007 to 2012 were included. The database was linked to the National Health Insurance Research Database, and subjects were followed up until the end of 2016. The mean follow-up period was 69 months. Bivariate analysis methods (log-rank test) and Cox proportional hazards model were used to evaluate the risk of recurrence and death and demographic characteristics, economic factors, environmental factors, health factors, treatment and hospitals, and absence/presence of postoperative tests were used to examine related risk factors.Our study showed that the 5-year recurrence rate and 5-year mortality rate for stage 0 colorectal cancer are 1.68% and 0.6%, respectively. For stage 0 colorectal cancer, age (61–74 years) is the only factor affecting recurrence in patients (hazard ratio (HR) = 2.44; 95% CI: 1.41–4.22), while age >75 years (HR = 4.35; 95% CI: 1.14–16.68) and Charlson Comorbidity Index >4 points (HR = 7.20, 95% CI: 2.60–19.94) can increase the risk of death. In contrast, patients who underwent one (HR = 0.27, 95% CI: 0.10–0.71) and two or more colonoscopies (HR = 0.26, 95% CI: 0.10–0.70) within 2 years after surgery can reduce the risk of death from stage 0 colorectal cancer. In addition, the risk of recurrence is higher in patients who underwent colonoscopic polypectomy (HR = 2.07, 95% CI: 0.98–4.33) and patients with rectal cancer (HR = 2.74, 95% CI: 0.96–7.83), but these differences are not statistically significant (P > .05).From this study, we can see that age and comorbidity index increase the risk of recurrence and death for stage 0 colorectal cancer, while postoperative colonoscopy can decrease the risk of death.

Abstract C006: Sociodemographic predictors of adherence to postoperative surveillance colonoscopy among patients diagnosed with nonmetastatic colorectal cancer

Abstract Background: Despite progress in colorectal cancer (CRC) screening and treatment over the past two decades, striking disparities in CRC survival persist among racial/ethnic minorities, with Blacks experiencing a 10% lower 5-year overall survival compared to Whites (American Cancer Society, 2017). One potential reason for the disparity in survival may be due to lower rates of appropriate surveillance care among racial/ethnic minorities. Among CRC patients, postoperative surveillance (PS) received at recommended intervals within 5-years following surgery improves overall survival up to 33% (Rodríguez-Moranta, 2006). Unfortunately, minority CRC survivors are approximately 30% less likely to receive PS compared to non-Hispanic Whites (NHW) (Carpentier, 2013). There are likely multiple underlying factors contributing to disparities in the timely receipt of recommended PS procedures such as colonoscopy, a PS procedure with adherence proportions as low as 18% among CRC patients. The differences in CRC patients who adhere or do not adhere to PS procedures are understudied. Purpose: Based on Andersen's (1978, 1995, 2007) Behavioral Model of Health Services Use, this study will assess the association between individual- and contextual-level factors and adherence to PS colonoscopy among Medicare beneficiaries from different racial/ethnic groups. Methods: This is a retrospective population-based cohort study using the SEER-Medicare linked database (2009-2014). Medicare beneficiaries diagnosed with CRC as their first cancer and who received surgical resection for CRC stage II and III, and who are between the ages of 66 and 85, are included in this sample. Chi-squared test will be used to assess significant differences in the distribution of patient characteristics across race/ethnicity, and analysis of variance (ANOVA) is used to assess differences for age as a continuous variable. Descriptive statistics will be presented for all demographic and socioeconomic variables to describe the characteristics of the sample population, stratified by racial/ethnic group. A hierarchical generalized linear model will be used to assess adherence to PS colonoscopy as a nonlinear function of explanatory variables defined at the individual- and contextual-levels. The adjusted odds with 95% confidence intervals of adherence to PS colonoscopy also will be presented by racial/ethnic group. Conclusions: Appropriate surveillance following a CRC diagnosis is critical for improving CRC outcomes. Characteristics that are unique to racial/ethnic minorities may contribute to lower rates of adherence to PS colonoscopy, leading to poor survival outcomes. Findings from the proposed research may help guide future public health and clinical interventions focused on improving the timely receipt of PS procedures among older adults. Citation Format: Janeth Sanchez, Veena Shankaran, Joseph Unger, Margaret Madeleine, Beti Thompson. Sociodemographic predictors of adherence to postoperative surveillance colonoscopy among patients diagnosed with nonmetastatic colorectal cancer [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 C006.

P112 CORRELATION OF FECAL CALPROTECTIN TO COLONOSCOPIC FINDINGS FOR DETECTION OF RECURRENCE OF CROHN'S DISEASE IN THE POST-OPERATIVE SETTING AT A SINGLE ACADEMIC CENTER

Patients with Crohn’s disease (CD) who undergo a first surgery are at higher risk of having a subsequent surgery in light of recurrence of disease. Significant evidence suggests that a postoperative colonoscopy evaluating recurrence at the anastomosis using the Rugeerts score (RS) can predict risk of repeat surgery. Given the invasive nature of colonoscopy, there has been increasing interest in using noninvasive biomarkers to predict disease recurrence. Studies have shown variability in the operating characteristics of the fecal calprotectin (FC) assay with sensitivities and specificities for detecting recurrence ranging widely from 48-95 and 58-79%, respectively. A recent meta-analysis demonstrated a pooled sensitivity of 70% when using an optimal FC cut-off of 150 ug/g. We sought to delineate how FC correlates with RS at our institution and to identify a cutoff for significant recurrence.

P112 CORRELATION OF FECAL CALPROTECTIN TO COLONOSCOPIC FINDINGS FOR DETECTION OF RECURRENCE OF CROHN’S DISEASE IN THE POST-OPERATIVE SETTING AT A SINGLE ACADEMIC CENTER

Abstract Introduction Patients with Crohn’s disease (CD) who undergo a first surgery are at higher risk of having a subsequent surgery in light of recurrence of disease. Significant evidence suggests that a postoperative colonoscopy evaluating recurrence at the anastomosis using the Rugeerts score (RS) can predict risk of repeat surgery. Given the invasive nature of colonoscopy, there has been increasing interest in using noninvasive biomarkers to predict disease recurrence. Studies have shown variability in the operating characteristics of the fecal calprotectin (FC) assay with sensitivities and specificities for detecting recurrence ranging widely from 48–95 and 58–79%, respectively. A recent meta-analysis demonstrated a pooled sensitivity of 70% when using an optimal FC cut-off of 150 ug/g. We sought to delineate how FC correlates with RS at our institution and to identify a cutoff for significant recurrence. Methods We performed a retrospective review of adult patients with CD who underwent ileocecectomy followed by a colonoscopy within 18 months of surgery, with the additional inclusion of FC testing within 2 weeks of the colonoscopy. Patients were identified at our institution via ICD 9 and 10 codes and the electronic medical record. The primary outcome of interest was a comparison of mean FC for those without endoscopic recurrence (defined as RS i0-i1) to those with significant endoscopic recurrence (defined as RS i2-i4). Other variables assessed included gender, disease location and phenotype, and extent of surgery (Table 1). Results A total of 12 patients met the inclusion criteria. 7 patients (58.3%) were female. Age at time of surgery ranged from 21 to 73 years (mean 37.9). Only 1 patient (8.3%) had a nonstricturing, nonpenetrating phenotype. After surgery, 11 patients were on biologic or combination therapy and 1 patient was not on any medical therapy. 5 patients (42%) demonstrated endoscopic recurrence by RS with mean FC of 883.7 ug/g, as compared to mean FC of 83.6 ug/g for those without recurrence. There was a positive correlation between FC and RS with a Spearman’s rank correlation coefficient of 0.86 (p = 0.0004). Conclusions Our results demonstrate a strong correlation between FC and RS. Using a cutoff for FC of 150 ug/g, we demonstrate sensitivity and specificity of 100%. This further supports the possibility of using FC as a surrogate to possibly defer colonoscopy in those post-operative CD patients with low FC. Study limitations include the retrospective nature and small sample size, recognizing that in years past FC was not as readily available or used in this setting. Future considerations include larger, prospective studies looking at FC and other noninvasive biomarkers in this post-operative setting.

P661 Post-operative prophylaxis with anti-TNF in patients with Crohn’s disease who are anti-TNF experienced is associated with higher rates of prophylaxis failure

Abstract Background Anti-TNF therapy is the most effective strategy for post-operative prophylaxis in patients with Crohn’s disease (CD) who are considered to be at high risk for recurrence. However, some patients fail to maintain long-term remission under these therapies. We aimed to assess predictors for the efficacy of post-operative anti-TNF therapy. Methods Patients with CD who underwent a curative bowel resection and were given post-operative anti-TNF prophylaxis between 2010 and 2019 were identified, and their data analysed retrospectively. Patients were assessed for disease recurrence at their first post-operative colonoscopy, a Rutgeerts score of &amp;gt;2a or clinically active disease that required a change in treatment was considered prophylaxis failure. Results Overall, 51 patients were included in our analysis. Male: 23 (45%); most of them had a penetrating complication (n = 23, 63%) that required surgery. Median age at surgery: 32 years (IQR 26–46). Anti-TNF therapy was started within a median of 9 weeks (IQR 6–14) post-surgery. Anti-TNF naïve: 14/51; 37/51 were anti-TNF experienced; of whom, 23 (62%) were treated with the same anti-TNF given before surgery. Disease recurrence occurred in 23 patients (45%) within a median follow-up of 13 months (IQR 8–26). Of the patients with disease recurrence, 10 (43%) were male, the median age of CD diagnosis was 26 years (IQR 15–49), 15 (65%) had penetrating disease, 5 (21%) had previous surgery, and 5 (21%) were active smokers. Disease recurrence was more common among patients operated at an older age (43 vs 33 years, p &amp;lt; 0.05) and in patients who had previous exposure to anti-TNF agents (56% vs. 14%, p = 0.01). In a multivariate Cox regression analysis, previous anti-TNF exposure was predictive of disease recurrence after surgery (HR 5.5, 95% CI 1.3–24, p &amp;lt; 0.05). Conclusion Post-operative prophylaxis using anti-TNF therapy in patients with CD who are anti-TNF experienced is associated with high rates of disease recurrence. This failure might be attributed to immunogenicity or pharmacodynamic failure. Closer monitoring and early treatment modifications should be considered in anti-TNF experienced patients.

DOP23 Endoscopic evaluation at 1 month after ileocolic resection for Crohn’s disease predicts postoperative recurrence and is safe

Abstract Background Endoscopic surveillance remains the gold standard for evaluating postoperative recurrence in Crohn’ disease (CD). However, the optimal timing of the first postoperative endoscopic evaluation is unclear. The commonly used strategy, first endoscopy at 3, 6, or 12 months, demonstrates high rates of endoscopic recurrence, which means this strategy may delay the detection and treatment. The aim of this study was to determine the clinical value and safety of the endoscopy at 1 month after surgery, and define the related factors. Methods This was a prospective cohort study of CD patients undergoing an ileocolic resection between 2015 and 2018, with a postoperative colonoscopy at 4–5 week after surgery. The primary outcome was endoscopic recurrence at 12 months, or clinical recurrence, or surgical recurrence within 12 months after surgery. Univariate and multivariate analyses were performed to identify related factors. Results Eighty-four eligible CD patients were included. Among 84 colonoscopies at 4–5 week, no endoscopic complication occurred. The main endoscopic findings at the first evaluation were anastomotic ulcers (45 [10 circumferential ulcers and 35 scattered ulcers], 53.6%), ulcers in the neoterminal ileum (16, 19.0%), oedema in anastomosis (50, 59.5%), mild narrowing in anastomosis (7, 8.3%), and mild narrowing in neoterminal ileum (3, 3.6%). On univariate and multivariable analysis, anastomotic scattered ulcers were associated with forward postoperative recurrence (HR, 2.532; 95% CI, 1.019–6.318; p = 0.046). We then used the modified Rutgeerts score to define endoscopic findings: i0, 26(44.0%); i1, 4(4.8%); i2a (circumferential anastomotic ulcers were not included), 40(34.5%); i2b, 11(13.1%); i3, 0; i4, 3(7.1%). Univariate and multivariable analysis showed ≥i2a were associated with forward postoperative recurrence (HR, 3.174; 95% CI, 1.218–8.273; p = 0.018). No factor was associated with ≥i2a at the first endoscopy. Conclusion Endoscopic evaluation at 4–5 weeks after surgery in CD was safe, and endoscopic findings were associated with postoperative recurrence. Earlier endoscopic examination after surgery may be useful for the adjustment of medication.

Appendiceal Diverticular Disease: A 10-year Retrospective Study of Cases from Tertiary Hospitals in Western Australia.

Background: Appendiceal diverticular disease (ADD) is typically a histological diagnosis. Our paper aims to investigate the implications of ADD compared to acute appendicitis (AA). Methods: We conducted a retrospective data collection of patients who had undergone an appen dicectomy in three tertiary hospitals across Western Australia between 2009-2019 and included patients with histopathological diagnoses of ADD and AA. Results: Thirty-seven patients with ADD and forty with AA were included. The mean age in the ADD group was significantly older (p 0.001) at 50.1 compared to the AA group (37.3). The mean white cell count (WCC) in the ADD group was lower than the AA group (11x109/L vs. 13.3x109/L, p 0.001), whereas the C-Reactive Protein (CRP) level was greater, although not statistically significant. The ADD group had a greater risk of major surgery (p 0.05) and complications such as appendiceal perforation and appendiceal mass (p 0.05). Post-operative colonoscopy also demon strated a higher incidence of polyps in patients with ADD (19% vs. 2.5%, p 0.001). Conclusion: ADD frequently presents with clinical features indiscernible from AA. Our study demonstrates that ADD is associated with higher rates of appendiceal perforation, polyps and malignancy. We recommend that patients with ADD be advised to have a colonoscopy post-opera tively to rule out underlying malignancy.

Quality of Preoperative Colonoscopy Affects Missed Postoperative Adenoma Detection in Colorectal Cancer Patients.

Despite thorough preoperative screening, 19-30% of synchronous polyps or adenomas are detected after colon cancer surgery. Remnant synchronous lesions require additional colonoscopy procedures or surgery. To investigate factors of preoperative colonoscopy potentially affecting the detection of missed lesions in patients subjected to colorectal cancer surgery. Of 1147 colorectal cancer patients subjected to curative open or laparoscopic colectomy and colonoscopy at the Chungnam National University Hospital from January 2012 to December 2016, 518 patients underwent pre- and postoperative colonoscopy. The index colonoscopy was defined as the last preoperative endoscopy performed. We analyzed pre- and postoperative medical charts for colonoscopy and pathological data. The effects of patient, procedure, and tumor factors on the postoperative adenoma detection rate, advanced adenoma detection rate, and adenoma miss rate (AMR) were analyzed. The overall AMR was 25.7% (95% confidence interval, 22.2-29.8%). Comparing optimal and non-optimal bowel preparation groups, the latter had greater postoperative polyp missed rate (PMR), AMR (p < 0.01), and AAMR (p = 0.272). The optimal preparation group allowed identification of more synchronous adenomas than in the fair (OR 5.72) and poor (OR 11.39) preparation groups. On univariate analysis, patient age and left-sided colectomy (p < 0.01) influenced AMR. Multivariate analysis showed that age, preoperative bowel preparation, and left colon resection influenced postoperative AMR. A better quality of index colonoscopy had a positive effect on lowering the detection rate of postoperative adenoma. Older age and suboptimal bowel preparation at the index colonoscopy and left-sided colectomy had negative effects on lowering the postoperative AMR.

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

Guidelines recommend perioperative complete colonoscopy in patients with colorectal cancer (CRC) to reduce the risk of metachronous carcinoma. Our aim was to verify these recommendations by examining the residual colon of patients with incomplete preoperative colonoscopy. This retrospective analysis included patients with the initial diagnosis of CRC and preoperative incomplete or no colonoscopy. Postoperative colonoscopies were investigated to identify synchronous lesions. In two-thirds of the patients, synchronous lesions could be detected. In 78% of the cases, the lesion was located proximal of the endpoint of the initial colonoscopy and therefore undiscovered. Two-thirds of the synchronous lesions were adenomata. Complete perioperative colonoscopy in patients with CRC should be performed to reduce the rate of metachronous carcinoma. Postoperative completion of preoperative insufficiently colonoscoped patients is recommended.