Society: ASGE

[Introduction] Early detection of gastric cancer offers favorable treatment outcomes. Second-generation narrow-band imaging (NBI) is expected to improve the detection of early gastric cancer (EGC); however, the detection rate is not superior to that of white light imaging (WLI). The latest endoscopic system EVIS X1 (Olympus, Tokyo, Japan) includes a higher-definition WLI, third generation (3G)-NBI, and texture and color enhancement imaging (TXI). We conducted a randomized phase II trial to compare the ability of 3G-NBI, TXI, and WLI to detect gastric neoplasms (GN) (jRCT1032210213).
[Methods] The eligibility criteria included patients aged 20–85 years with either of the following: 1) scheduled surveillance endoscopy after endoscopic resection for GN, or endoscopic resection, chemotherapy, or radiotherapy for esophageal cancer, or 2) scheduled preoperative endoscopy for known GN or esophageal cancer. Written informed consent was obtained from all participants. The EVIS X1 system and a high-definition gastroscope with an optical zoom (GIF-XZ1200) were used. Patients were randomly assigned in a 1:1:1 ratio to the 3G-NBI (primary 3G-NBI and secondary WLI), TXI (primary TXI and secondary WLI), and WLI (primary and secondary WLI) arms, with the WLI arm set as the reference arm. Non-magnifying primary observation was performed to detect the GN lesions. After completing the primary observation of the entire stomach, a secondary WLI was immediately performed by the same endoscopist. All suspected GN lesions were biopsied at the end of the examination. Pathological diagnoses were made based on biopsied tissue or specimens obtained from endoscopic or surgical resection by expert pathologists at each institution. The primary endpoint was GN detection rate in the primary observation, including cancer and adenoma. The other endpoints were the miss rate for GN, EGC detection rate, and positive predictive value (PPV) for the diagnosis of GN in the primary observation. We assumed that the primary endpoint would be 3.0% for one image-enhanced endoscopy (IEE) and > 4.3% for the other. The sample size was set to 300 per arm to ensure that 80% or more of the participants correctly selected the most promising IEE.
[Results] 901 patients were enrolled from six institutions and assigned to the 3G-NBI, TXI, and WLI arms (300/300/301). Of these, 222 (24.6%) underwent preoperative examination. The GN detection rate in the 3G-NBI, TXI, and WLI arms were 7.3%, 5.0%, and 5.6%, respectively, with the 3G-NBI showing the highest detection rate. In addition, the miss rates for GN were 1.0%, 0.7%, and 1.0%, the EGC detection rates were 5.7%, 4.0%, and 5.6%, and the PPVs for the diagnosis of GN were 36.5%, 21.3%, and 36.8% in the 3G-NBI, TXI, and WLI arms, respectively.
[Conclusion] 3G-NBI is the most promising modality for the detection of GN when compared with TXI and WLI.

Background & Aims:
Gastrointestinal (GI) bleeding is a significant complication of left ventricular assist device (LVAD) placement and can be life-threatening. If LVAD patients at higher risk of bleeding could be identified, increased efforts to prevent and manage GI bleeding could be instituted. In this study we aimed to derive a GI-bleed risk prediction model in patients with LVAD, by means of supervised machine learning, using a large retrospective data from the University of Utah heart-transplantation database.

Methods:
We utilized prospectively maintained database comprising 491 LVAD patients between 2004-2022. Institutional review board approval was obtained prior to data collection. The penalized Least Absolute Shrinkage and Selection Operator (LASSO) regression was used to select the best predictors of GI bleeding in LVAD patients, using 10-fold cross validation to develop a practical estimation of the predictive performance, by means of the area under the curve (AUC). Bootstrapped Bias corrected 95% confidence intervals (CI) for the AUC were generated. Thirty potential clinical predictors were introduced in the model. The model disagreement between the predicted and the observed outcomes were evaluated using the Brier score and calibration belt.

Results:
The GI bleeding risk in patients with LVAD was 26.06% (n=128) in the current sample. Three out of the 30 predictors were retained by the prediction model. These were: duration of LVAD implantation (<12 months, 13-24 months, >24 months), anticoagulant use, and LVAD as destination therapy. The model's ability to distinguish LVAD patients at high risk of GI-bleed was outstanding based on the AUC=0.9 (95%CI 0.82-0.92) (Figure 1A). There was no evidence of miscalibration for this model (test statistic=4.61; p=0.10), demonstrating good performance (Brier score=0.05).
A score was assigned to each predictor with a maximum score of 6. Destination therapy as an indication for LVAD transplant =1, LVAD implantation duration =1 if the duration was <12 months, 2 if the duration was 13-24 months, and 3 if the duration was >24 months. A score of 2 was assigned to anticoagulant use. The purpose of score derivation from LASSO regression predictors was to facilitate an understanding, applicability, and practicality for the proposed risk prediction model. The AUC of the Score was 0.90 (95% CI 0.87-0.93) and showed no statistical difference from the AUC of the LASSO model (P=0.49) (Figure 1B). The Youden index determined that cut-off score of 3 had a sensitivity of 69.5% and specificity of 99.1% (Table 1).

Conclusions:
The proposed model presents prediction variables in identifying patients at risk of GI bleeding post LVAD placement. Duration of LVAD implantation, anticoagulant use, and LVAD as destination therapy were the top variables retained. Additional studies are warranted to validate our findings externally.

<br /> <b>Figure 1: (A) ROC curve with mean cross validated area under the curve (CvAUC) after 10 fold cross validation. AUC: 0.92 (Bootstrap Bias Corrected 95%CI: 0.82, 0.92) and (B) comparison with AUC 0.90 (Bootstrap Bias Corrected 95% CI 0.87-0.93) of proposed score generated from lasso-generated predictors</b>

Figure 1: (A) ROC curve with mean cross validated area under the curve (CvAUC) after 10 fold cross validation. AUC: 0.92 (Bootstrap Bias Corrected 95%CI: 0.82, 0.92) and (B) comparison with AUC 0.90 (Bootstrap Bias Corrected 95% CI 0.87-0.93) of proposed score generated from lasso-generated predictors

<br /> <b>Table 1: GI bleeding risk post LVAD placement and point specific sensitivity/specificity of proposed score</b>

Table 1: GI bleeding risk post LVAD placement and point specific sensitivity/specificity of proposed score

Background: Gastric per-oral endoscopic myotomy (GPOEM) is a recently developed minimally invasive procedure for the treatment of refractory gastroparesis. Gastroparesis post-lung transplant is a frequent debilitating complication affecting 20% to 90% of lung transplant recipients, as it can increase the risk for gastro-esophageal reflux disease and subsequent graft dysfunction. We performed a systematic review and meta-analysis to evaluate the efficacy and safety of GPOEM in lung transplant patients with refractory gastroparesis.
Methods: The present systematic review and meta-analysis was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. PubMed, Cochrane and Embase databases were searched for relevant studies published from inception through November 2022. We selected studies reporting clinical efficacy rates and gastroparesis cardinal symptom index (GCSI) in the pre- and post-GPOEM period in lung transplant patients with refractory gastroparesis. Pooled effect estimates were calculated for clinical efficacy, defined as no residual gastroparesis symptoms requiring prokinetic agents or reintervention. Hedges’ g test was used to calculate the standard mean difference of GCSI in the pre- and post-GPOEM period. Random effects model was used and analysis was performed with STATA 17.
Results: Four observational studies (one conference abstract) with 104 patients were included in the meta-analysis. Prior treatments for gastroparesis included prokinetic agents and botulinum toxin in 78% (78/104) and 66.7% (66/99) respectively (Table 1). Pooled estimates for clinical efficacy of GPOEM was 83% (95% CI, 76%-90%) (Figure 1). The pooled mean reduction in GCSI following the procedure was -2.01 (-2.35, -1.65, p=0.014) (Figure 2). Three studies reported statistically significant improvement of gastro-esophageal retention or emptying in the post-GPOEM period; however analysis was not feasible due to a non-uniform reporting of results. 30-day postoperative complications included minor or major bleeding (11.6%), severe reflux (1.2%) and pyloric stenosis (1.2%) requiring re-intervention. 90-day mortality was 2.6% with one patient dying from severe allograft rejection.
Conclusion: Our study showed that GPOEM is an effective and safe strategy for lung transplant patients with refractory gastroparesis and should be considered as a therapeutic strategy in this population. Larger multicenter trials are needed in the future to further evaluate the effect of GPOEM on allograft function and rates of rejection.

Background:
Although gastric cancer (GC) incidence is higher in high human development index (HDI) countries, mortality is lower compared to those with low and medium HDI. It is the fourth leading cause of death worldwide, but the first in some countries in Latin America, for example. It is reported that up to 25.8% GC cases are missed during endoscopy exams. Recently, Artificial Intelligence (AI) diagnostic tools have been reported to have high performance for detecting GC and to help overcome this issue. However, AI is trained with images obtained from high end equipment, which makes the generalizability of the diagnostic performance on outdated equipment an important question to be addressed. Therefore, the aim of this study is to evaluate the performance of a convolutional neural network-based AI tool in images retrieved from older endoscopes and processors in Brazil.
Methods:
The test dataset consisted of 420 images (standard white light) from 111 patients that were retrospectively collected from two hospitals in Brazil. Images were captured using the following endoscopic video systems: CV-150, CV-160, CV-170 and CV-180 Olympus Medical Systems and 4400, 4450 and 600 Fujifilm. All lesions were histology proven. The dataset was processed by a previously described convolutional neural network-based model (1), trained with high quality Japanese endoscopic images to differentiate early gastric cancer (EGC) from benign lesions or normal mucosa. For patient analysis, an answer was defined as correct when CNN detected one EGC image in multiple images of the same lesion.
Results:
The CNN detected 119 of 150 images of EGC with an overall sensitivity of 79.3%, and 50 non-neoplastic lesions resulting in a positive predictive value of 70.4%. Specificity and accuracy were 81.4% and 80.7%, respectively. Neoplastic lesions varied from 5 to 35 millimeters. Per patient analysis sensitivity was 85.7%, resulting from a correct diagnosis of 14 of 16 cases of EGC (Figure 1).
Discussion and Conclusion:
We reported the first external validation of AI in the Endoscopy field focused on using images retrieved from outdated equipment. Although the retrospective design has intrinsic limitations such as selection bias, many of the selected images would have been excluded in other studies due to the lower quality resolution and lightning. Despite that, CNN-based AI tool was able to detect early gastric cancer with acceptable performance, which suggests that this diagnostic tool can potentially be used in practices with lower resources.
(1) Ikenoyama Y, et al. Dig Endosc. 2021;33(1):141-150.

Figure 1. Detail of the two false negative cases with corresponding image examples.

Figure 1. Detail of the two false negative cases with corresponding image examples.

Figure 2. Exemplary cases of lesions from the validation set.<br /> (A)True positive: 14 mm adenocarcinoma diffuse type, Paris Classification 0-IIc<br /> (B)True positive: 30 mm adenocarcinoma intestinal type, Paris Classification 0-IIa+IIb<br /> (C)False negative: scar<br /> (D)False negative: metaplasia

Figure 2. Exemplary cases of lesions from the validation set.
(A)True positive: 14 mm adenocarcinoma diffuse type, Paris Classification 0-IIc
(B)True positive: 30 mm adenocarcinoma intestinal type, Paris Classification 0-IIa+IIb
(C)False negative: scar
(D)False negative: metaplasia

INTRODUCTION
Electrocautery-based polypectomy is commonly used for resection of non-ampullary duodenal adenomas but it is associated with an increased risk for adverse events. Cold snare endoscopic mucosal resection (EMR) has been shown to be safe and effective for resection of colon polyps, though data regarding its use in the duodenum is scarce. We aimed to evaluate the safety and efficacy of cold snare EMR for resection of non-ampullary duodenal adenomas.

METHODS
This was a multicenter retrospective study of patients with non-ampullary duodenal adenomas ≥1 cm who underwent cold snare EMR between August 2018 and October 2022. Patients who received any form of thermal therapy were excluded. Primary outcomes were technical success and recurrent or residual adenoma (RRA) on surveillance endoscopy. Technical success was defined as ability to resect all visible adenoma using cold EMR. Secondary outcomes were adverse events including immediate and delayed bleeding, perforation, post-polypectomy syndrome, stricture, and pancreatitis.

RESULTS
A total of 40 patients across six institutions were included. 55% of patients were female and the median age was 69.5 years [Table 1]. The average polyp size was 23.7 mm and most common location was the second portion of the duodenum. Polyp and procedural characteristics are summarized in Table 2.

Technical success was 100%. 24 of 40 patients had follow-up endoscopy. RRA was present in five patients (20.8%) who underwent additional resection with cold forceps (n = 1) or cold snare polypectomy (n = 4). Lesion eradication was achieved after the second procedure in one case where follow-up endoscopy was performed.

Immediate bleeding occurred in three cases. This was managed by hemoclips in one case and the helix tack-and-suture device in another case. In the third case, intraprocedural bleeding occurred after resection of a 60 mm polyp in a patient on apixaban therapy. Bleeding initially resolved with local epinephrine injection, however, the patient developed recurrent bleeding the following day which was managed with snare tip soft coagulation and defect closure using the helix tack-and-suture device. Polyp size [OR: 1.1, (95%CI: 1.01–1.22), P=0.007] and anticoagulation use [OR: 16, 95% CI: 1.2–218, P=0.037] was associated with increased risk of immediate bleeding. There were no cases of delayed bleeding, perforation, post-polypectomy syndrome, pancreatitis, or stricture formation [Table 2].

CONCLUSION
Despite the variation in endoscopists’ experience and technique, our preliminary analysis shows that cold snare EMR is safe and effective for resection of non-ampullary duodenal adenomas ≥1 cm. The inclusion of multiple sites suggests that our results are likely generalizable. Longitudinal data from this ongoing registry should provide valuable information on long term outcomes with cold snare EMR for duodenal adenomas.

Table 1. Patient characteristics

Table 2. Polyp and procedure details

Background and Aims: Gastric intestinal metaplasia (GIM) is a well-established risk factor for non-cardia gastric cancer (GC). Given the marked geographical variation in incidence rates of GC, interest remains in determining whether a tailored approach to specific populations with risk factors such as race/ethnicity is warranted. Geographic and ethnic differences in the incidence of GC strongly suggest that environmental factors have an important role in the etiology of GC. Previous studies conducted in U.S. have not assessed environmental risk factors. We previously identified Asian ethnicity as a risk factor for neoplastic progression of GIM in a large multi-ethnic North American population cohort. We aimed to identify social and environmental factors associated with Asian ethnicity in multi-ethnic U.S. patients with GIM. Methods: This study was funded by the American Society for Gastrointestinal Endoscopy. The cohort consists of individuals who underwent EGD at our institutions and had pathologically confirmed GIM. Patients who were previously diagnosed with GC were excluded from the cohort. We sent surveys translated in the patient’s native language to all patients in the cohort and ascertain data on detailed demographic information, diet, lifestyle, social and family history. Results: 425 patients (median age 65 years [IQR 54-72], 41% male) responded to the surveys. Patients’ ethnicity was as follows; Asian 173 (41%), Caucasian 161 (38%), Hispanic 46 (11%), African American 33 (8%) and other 12 (2%). There were no baseline characteristic differences between Asian and Non-Asian patients regarding the age, gender, history of smoking, family history (at least one 1st or 2nd degree relative) of GC, and histologically confirmed gastric mucosal atrophy and autoimmune gastritis (Table 1). Asian patients were more likely 1st generation immigrants (92%). Neoplastic progression of GIM was identified more frequently in Asian (6%) than Non-Asian (2%) patients on any given surveillance EGDs (p=0.025). Asian patients with GIM reported to more frequently consume their traditional home country food/meals (p<0.01) and less frequently use NSAIDs (p<0.01) comparing to Non-Asian patients. Non-Asian patients more frequently exercised (vigorous, moderately intense and walking) per week. There was no statistical difference about the consumption of traditional salt-preserved food between the Asian and Non-Asian. Conclusions: In this cohort of well-characterized multi-ethnic patients with GIM, Asian patients who were strongly associated with neoplastic progression of GIM more frequently consumed their traditional home country food/meals and less frequently used NSAIDs and exercised. If validated, these findings could be used to develop a tailored approach consisting of dietary/behavioral interventions and chemoprevention for neoplastic progression of GIM in the U.S.

Table 1. Patient characteristics

Division of Gastroenterology and Hepatology, Stanford University, Stanford, California, USA
Introduction
Gastric cancer (GC) is the 6^th leading cause of cancer mortality in the world and is diagnosed in 27,000 Americans every year. Gastric intestinal metaplasia (GIM), characterized by the change of gastric mucosa to intestinal epithelium, is believed to be a precursor to GC. The Stanford GAstric Precancerous conditions Study (GAPS) is a case-control study of individuals with GIM compared with histologically normal controls, with an anticipated enrollment of 300 case-control pairs. These participants are recruited from the population undergoing clinically-indicated endoscopies at Stanford University. This abstract reports an interim analysis of clinical data.
Methods
Patients aged 35-84 undergoing ambulatory endoscopy for screening/surveillance of GIM or symptomatic indications (e.g. dyspepsia) were eligible. Participants completed a detailed questionnaire inquiring about medical/family history, and lifestyle/dietary patterns. Blood and saliva samples were also collected. During the scheduled endoscopy, biopsies were collected following the Sydney System biopsy protocol and assigned an operative link for GIM (OLGIM) score (scored from 0 to IV) by a gastrointestinal pathologist. Predictors of GIM were analyzed using univariable and multivariable analyses.
Results
Individuals were primarily female, non-white, and foreign born, reflective of the patient population undergoing endoscopic procedures at Stanford University. Table 1 depicts univariable and multivariable predictors of GIM. In univariable analysis, older age, Asian race, positive family history, non-native birth, and prior H. pylori infection were variables associated with greater risk for GIM. A multivariable analysis incorporating these variables showed that age, race/ethnicity, and prior H. pylori infection remained significant predictors. In a separate analysis (Figure 1), it was found that older age was significantly associated with advanced OLGIM stages (defined as OLGIM >=2).
Discussion/Conclusion
In this interim analysis of an ongoing case-control study, known risk factors for gastric cancer are also predictive of GIM. Those at greatest risk include patients older than 50 years of age, Asians, first-generation immigrants to the US, with a family history of gastric cancer, and prior H. pylori infection. In the multivariable analysis, it appears the strongest single risk factor is age. Moreover, age is the single greatest risk factor for advanced OLGIM stage, with more advanced OLGIM scores being strongly predictive of future gastric cancer risk. This abstract provides critical data describing the epidemiology and risk factors for GIM and advanced-OLGIM GIM in a North American population. We hope these data will help future risk stratification efforts focused on multi-ethnic US populations.

Joo Ha Hwang

Stanford University School of Medicine

Appearances