The updated Asia-Pacific consensus statement on the role of endoscopic management in malignant hilar biliary obstruction.

The first Asia-Pacific consensus recommendations for endoscopic and interventional management of hilar cholangiocarcinoma were published in 2013. Since then, new evidence on the role of endoscopy for management of malignant hilar biliary obstruction (MHBO) has emerged. To update the recommendation, we reviewed the literature using a PICO (population/intervention/comparison/outcomes) framework and created consensus statements. The expert panel voted anonymously using the modified Delphi method and all final statements were evaluated for the quality of evidence and strength of recommendation. The important points with inadequate supporting evidence were classified as key concepts. There were seven statements and five key concepts that reached consensus. The statements and key concepts dealt with multiple aspects of endoscopy-based management in MHBO starting from diagnosis, strategies and options for biliary drainage, management of recurrent biliary obstruction, management of cholecystitis after biliary stenting, and adjunctive treatment before stenting. Although the recommendations may assist physicians in planning the treatment for MHBO patients, they should not replace the decision of a multidisciplinary team in the management of individual patients.

International Digestive Endoscopy Network Consensus on the Management of Antithrombotic Agents in Patients Undergoing Gastrointestinal Endoscopy.

Antithrombotic agents, including antiplatelet agents and anticoagulants, are widely used in Korea because of the increasing incidence of cardiocerebrovascular disease and the aging population. The management of patients using antithrombotic agents during endoscopic procedures is an important clinical challenge. The clinical practice guidelines for this issue, developed by the Korean Society of Gastrointestinal Endoscopy, were published in 2020. However, new evidence on the use of dual antiplatelet therapy and direct anticoagulant management has emerged, and revised guidelines have been issued in the United States and Europe. Accordingly, the previous guidelines were revised. Cardiologists were part of the group that developed the guideline, and the recommendations went through a consensus-reaching process among international experts. This guideline presents 14 recommendations made based on the Grading of Recommendations, Assessment, Development, and Evaluation methodology and was reviewed by multidisciplinary experts. These guidelines provide useful information that can assist endoscopists in the management of patients receiving antithrombotic agents who require diagnostic and elective therapeutic endoscopy. It will be revised as necessary to cover changes in technology, evidence, or other aspects of clinical practice.

[IDEN Consensus on Management of Antithrombotic Agents in Patients Undergoing Gastrointestinal Endoscopy].

Antithrombotic agents, including antiplatelet agent and anticoagulants are widely used in Korea due to increasing incidence of cardio-cerebrovascular disease and aging population. The management of patients using antithrombotic agents during endoscopic procedures is an important clinical challenge. Clinical practice guideline regarding this issue which was developed by the Korean Society of Gastrointestinal Endoscopy was published in 2020. However, since then, new evidence has emerged for the use of dual antiplatelet therapy and direct anticoagulant management, and revised guidelines were issued in the US and Europe. Accordingly, the previous guidelines were revised, cardiologists also participated in the development group, and the recommendations went through a consensus process among international experts. This guideline presents 14 recommendations made according to the Grading of Recommendations, Assessment, Development, and Evaluation methodology, and was reviewed by multidisciplinary experts. This guideline provides useful information that can assist endoscopists in the management of patients on antithrombotic agents who require diagnostic and elective therapeutic endoscopy. It will be revised as necessary to cover changes in technology, evidence, or other aspects of clinical practice.

CEACAM5 and TROP2 define metaplastic and dysplastic transitions in human antral gastric precancerous lesions and tumors.

BACKGROUND: Mucosal gastric atrophy and intestinal metaplasia (IM) increase the risk for the development of gastric cancer (GC) as they represent a field for development of dysplasia and intestinal-type gastric adenocarcinoma. METHODS: We have investigated the expression of two dysplasia markers, CEACAM5 and TROP2, in human antral IM and gastric tumors to assess their potential as molecular markers. RESULTS: In the normal antral mucosa, weak CEACAM5 and TROP2 expression was only observed in the foveolar epithelium, while inflamed antrum exhibited increased expression of both markers. Complete IM exhibited weak CEACAM5 expression at the apical surface, but no basolateral TROP2 expression. On the other hand, incomplete IM demonstrated high levels of both CEACAM5 and TROP2 expression. Notably, incomplete IM with dysplastic morphology (dysplastic incomplete IM) exhibited higher levels of CEACAM5 and TROP2 expression compared to incomplete IM without dysplastic features (simple incomplete IM). In addition, dysplastic incomplete IM showed diminished SOX2 and elevated CDX2 expression compared to simple incomplete IM. CEACAM5 and TROP2 positivity in incomplete IM was similar to that of gastric adenomas and GC. Significant association was found between CEACAM5 and TROP2 positivity and histology of GC. CONCLUSIONS: These findings support the concept that incomplete IM is more likely associated with GC development. Overall, our study provides evidence of the heterogeneity of gastric IM and the distinct expression profiles of CEACAM5 and TROP2 in dysplastic incomplete IM. Our findings support the potential use of CEACAM5 and TROP2 as molecular markers for identifying individuals with a higher risk of GC development in the context of incomplete IM.

Partially covered versus uncovered pyloro-duodenal stents for unresectable malignant gastric outlet obstruction: Randomized controlled study.

OBJECTIVES: The aim of the current study was to compare the efficacy of partially covered duodenal stent (PCDS) vs. uncovered duodenal stent (UCDS) in patients suffering from unresectable primary malignant gastric outlet obstruction (GOO). METHODS: This was a prospective international randomized controlled study conducted in 10 high-volume institutions. Consecutive patients suffering from malignant GOO were recruited. The primary outcome measurement was the reintervention rate. Secondary outcomes included technical and clinical success, 30-day adverse events, 30-day mortality, causes of stent dysfunction, and the duration of stent patency. RESULTS: Between March 2017 and October 2020, 115 patients (59 PCDS, 56 UCDS) were recruited. The 1-year reintervention was not significantly different (PCDS vs. UDCS = 12/59, 20.3% vs. 14/56, 25%, P = 0.84). There was a trend to fewer patients with tumor ingrowth in the PCDS group (6/59 [10.2%]) vs. 13/56 [23.2%], P = 0.07). There were no significant differences in the technical success (100% vs. 100%, P = 1), clinical success (91.5% vs. 98.2%, P = 0.21), procedural time (21.5 [interquartile range [IQR] 17-30] vs. 20.0 [IQR 15-34.75], P = 0.62), hospital stay (4 [IQR 3-12] vs. 5 [IQR 3-8] days, P = 0.81), 30-day adverse events (18.6% vs. 14.3%, P = 0.62), or 30-day mortality (6.8% vs. 5.2%, P = 1.00). CONCLUSION: The use of PCDS was associated with a lower risk of tumor ingrowth but did not improve on reintervention rates or stent patency. Both kinds of stents could be used in this group of patients.

Spatiotemporal genomic profiling of intestinal metaplasia reveals clonal dynamics of gastric cancer progression.

Intestinal metaplasia (IM) is a pre-malignant condition of the gastric mucosa associated with increased gastric cancer (GC) risk. Analyzing 1,256 gastric samples (1,152 IMs) across 692 subjects from a prospective 10-year study, we identify 26 IM driver genes in diverse pathways including chromatin regulation (ARID1A) and intestinal homeostasis (SOX9). Single-cell and spatial profiles highlight changes in tissue ecology and IM lineage heterogeneity, including an intestinal stem-cell dominant cellular compartment linked to early malignancy. Expanded transcriptome profiling reveals expression-based molecular subtypes of IM associated with incomplete histology, antral/intestinal cell types, ARID1A mutations, inflammation, and microbial communities normally associated with the healthy oral tract. We demonstrate that combined clinical-genomic models outperform clinical-only models in predicting IMs likely to transform to GC. By highlighting strategies for accurately identifying IM patients at high GC risk and a role for microbial dysbiosis in IM progression, our results raise opportunities for GC precision prevention and interception.

Global prospective case series of ERCPs using a single-use duodenoscope.

BACKGROUND: The first commercialized single-use duodenoscope was cleared by the US Food and Drug Administration in December 2019. Data regarding endoscopic retrograde cholangiopancreatography (ERCP) using a single-use duodenoscope are needed on a broader range of cases conducted by endoscopists with varying levels of experience in a wide range of geographic areas. METHODS: 61 endoscopists at 22 academic centers in 11 countries performed ERCP procedures in adult patients aged ≥ 18. Outcomes included ERCP completion for the intended indication, rate of crossover to a reusable endoscope, device performance ratings, and serious adverse events (SAEs). RESULTS: Among 551 patients, 236 (42.8 %) were aged > 65, 281 (51.0 %) were men, and 256 (46.5 %) had their procedure as an inpatient. ERCPs included 196 (35.6 %) with American Society for Gastrointestinal Endoscopy complexity of grades 3-4. A total of 529 ERCPs (96.0 %) were completed: 503 (91.3 %) using only the single-use duodenoscope, and 26 (4.7 %) with crossover to a reusable endoscope. There were 22 ERCPs (4.0 %) that were not completed, of which 11 (2.0 %) included a crossover and 11 (2.0 %) were aborted cases (no crossover). Median ERCP completion time was 24.0 minutes. Median overall satisfaction with the single-use duodenoscope was 8.0 (scale of 1 to 10 [best]). SAEs were reported in 43 patients (7.8 %), including 17 (3.1 %) who developed post-ERCP pancreatitis. CONCLUSIONS: In academic medical centers over a wide geographic distribution, endoscopists with varying levels of experience using the first marketed single-use duodenoscope had good ERCP procedural success and reported high performance ratings for this device.

Endoscopic retrograde cholangiopancreatography-related complications: risk stratification, prevention, and management.

Endoscopic retrograde cholangiopancreatography (ERCP) plays a crucial role in the management of pancreaticobiliary disorders. Although the ERCP technique has been refined over the past five decades, it remains one of the endoscopic procedures with the highest rate of complications. Risk factors for ERCP-related complications are broadly classified into patient-, procedure-, and operator-related risk factors. Although non-modifiable, patient-related risk factors allow for the closer monitoring and instatement of preventive measures. Post-ERCP pancreatitis is the most common complication of ERCP. Risk reduction strategies include intravenous hydration, rectal nonsteroidal anti-inflammatory drugs, and pancreatic stent placement in selected patients. Perforation is associated with significant morbidity and mortality, and prompt recognition and treatment of ERCP-related perforations are key to ensuring good clinical outcomes. Endoscopy plays an expanding role in the treatment of perforations. Specific management strategies depend on the location of the perforation and the patient's clinical status. The risk of post-ERCP bleeding can be attenuated by preprocedural optimization and adoption of intra-procedural techniques. Endoscopic measures are the mainstay of management for post-ERCP bleeding. Escalation to angioembolization or surgery may be required for refractory bleeding. Post-ERCP cholangitis can be reduced with antibiotic prophylaxis in high risk patients. Bile culture-directed therapy plays an important role in antimicrobial treatment.

Real-World Validation of a Computer-Aided Diagnosis System for Prediction of Polyp Histology in Colonoscopy: A Prospective Multicenter Study.

INTRODUCTION: Computer-aided diagnosis (CADx) of polyp histology could support endoscopists in clinical decision-making. However, this has not been validated in a real-world setting. METHODS: We performed a prospective, multicenter study comparing CADx and endoscopist predictions of polyp histology in real-time colonoscopy. Optical diagnosis based on visual inspection of polyps was made by experienced endoscopists. After this, the automated output from the CADx support tool was recorded. All imaged polyps were resected for histological assessment. Primary outcome was difference in diagnostic performance between CADx and endoscopist prediction of polyp histology. Subgroup analysis was performed for polyp size, bowel preparation, difficulty of location of the polyps, and endoscopist experience. RESULTS: A total of 661 eligible polyps were resected in 320 patients aged ≥40 years between March 2021 and July 2022. CADx had an overall accuracy of 71.6% (95% confidence interval [CI] 68.0-75.0), compared with 75.2% (95% CI 71.7-78.4) for endoscopists ( P = 0.023). The sensitivity of CADx for neoplastic polyps was 61.8% (95% CI 56.9-66.5), compared with 70.3% (95% CI 65.7-74.7) for endoscopists ( P < 0.001). The interobserver agreement between CADx and endoscopist predictions of polyp histology was moderate (83.1% agreement, κ 0.661). When there was concordance between CADx and endoscopist predictions, the accuracy increased to 78.1%. DISCUSSION: The overall diagnostic accuracy and sensitivity for neoplastic polyps was higher in experienced endoscopists compared with CADx predictions, with moderate interobserver agreement. Concordance in predictions increased this diagnostic accuracy. Further research is required to improve the performance of CADx and to establish its role in clinical practice.

Motorized spiral enteroscopy versus double-balloon enteroscopy: a case-matched study.

BACKGROUND AND AIMS: Motorized spiral enteroscopy (MSE) has been postulated to ease the complexities of the standard-of-care double-balloon enteroscopy (DBE). However, there are no comparative studies between MSE and DBE. This study aimed to compare the therapeutic outcomes and safety between MSE and DBE. METHODS: In this case-matched study, patients were matched 1:2 (MSE/DBE) by age, sex, body mass index, and American Society of Anesthesiology scores. Thirty-one patients who underwent MSE were compared with 62 patients who underwent DBE from 2014 to 2022. Our primary outcomes were to compare the technical and diagnostic success rates between DBE and MSE. Our secondary outcomes were to compare the therapeutic success and adverse event rates. RESULTS: The main indications for enteroscopy were suspected GI bleeding and positive radiologic findings. Prior abdominal surgery was reported in 35.5% and 22.6% of DBE and MSE patients, respectively. Most were antegrade enteroscopy (71%). We found no significant difference in the technical success (DBE 98.4% vs MSE 96.8%, P = .62), diagnostic success (DBE 66.1% vs MSE 54.8%, P = .25), and therapeutic success rates (DBE 62.8% vs MSE 52.9%, P = .62) between the groups. Adverse events occurred in 1 DBE and 11 MSE patients. Most were minor (n = 10, 25.6%). Two patients (5.1%) in the MSE group sustained deep lacerations in the proximal esophagus requiring hospitalization. One developed ileal perforation after MSE needing surgical repair. CONCLUSIONS: In patients requiring enteroscopy, the diagnostic and therapeutic performance of MSE is similar to DBE. An increased frequency of adverse events was observed with MSE. There are some restrictions in the indication because of the design of MSE.

Integrated environmental, lifestyle, and epigenetic risk prediction of primary gastric neoplasia using the longitudinally monitored cohorts.

BACKGROUND: DNA methylation accumulates in non-malignant gastric mucosa after exposure to pathogens. To elucidate how environmental, methylation, and lifestyle factors interplay to influence primary gastric neoplasia (GN) risk, we analyzed longitudinally monitored cohorts in Japan and Singapore. METHODS: Asymptomatic subjects who underwent a gastric mucosal biopsy on the health check-up were enrolled. We analyzed the association between clinical factors and GN development using Cox hazard models. We further conducted comprehensive methylation analysis on selected tissues, including (i) mucosae from subjects developing GN later, (ii) mucosae from subjects not developing GN later, and (iii) GN tissues and surrounding mucosae. We also use the methylation data of mucosa collected in Singapore. The association between methylation and GN risk, as well as lifestyle and methylation, were analyzed. FINDINGS: Among 4234 subjects, GN was developed in 77 subjects. GN incidence was correlated with age, drinking, smoking, and Helicobacter pylori (HP) status. Accumulation of methylation in biopsied gastric mucosae was predictive of higher future GN risk and shorter duration to GN incidence. Whereas methylation levels were associated with HP positivity, lifestyle, and morphological alterations, DNA methylation remained an independent GN risk factor through multivariable analyses. Pro-carcinogenic epigenetic alterations initiated by HP exposure were amplified by unfavorable but modifiable lifestyle choices. Adding DNA methylation to the model with clinical factors improved the predictive ability for the GN risk. INTERPRETATION: The integration of environmental, lifestyle, and epigenetic information can provide increased resolution in the stratification of primary GN risk. FUNDING: The funds are listed in Acknowledgements section.

Academy of Medicine, Singapore clinical guideline on endoscopic surveillance and management of gastric premalignant lesions.

Gastric cancer (GC) has a good prognosis, if detected at an early stage. The intestinal subtype of GC follows a stepwise progression to carcinoma, which is treatable with early detection and intervention using high-quality endoscopy. Premalignant lesions and gastric epithelial polyps are commonly encountered in clinical practice. Surveillance of patients with premalignant gastric lesions may aid in early diagnosis of GC, and thus improve chances of survival. An expert professional workgroup was formed to summarise the current evidence and provide recommendations on the management of patients with gastric premalignant lesions in Singapore. Twenty-five recommendations were made to address screening and surveillance, strategies for detection and management of gastric premalignant lesions, management of gastric epithelial polyps, and pathological reporting of gastric premalignant lesions.

Evaluation of the ex-vivo porcine simulator on EUS-guided cystogastrostomy using lumen-apposing metal stent training.

Bckground and Objectives: EUS-guided cystogastrostomy is a well-established advanced endoscopic technique with a steep-learning curve which necessitates an ex-vivo simulator that would allow for adequate training. The aim of this study is to evaluate the feasibility of the model in allowing training for EUS-guided cystogastrostomy using lumen-apposing metal stent (LAMS). Subjects and Methods: The model was created by ROEYA Training Center, Egypt, using native porcine tissue to create fluid collections simulating both cystic and solid lesions. It was designed and tested in advance while the hydrogel was added on-site. The simulator was evaluated prospectively in five training sessions involving 17 international experts. The task was to successfully deploy the LAMS to drain the created cyst. After using the simulator, the experts were asked to fill a questionnaire to assess their experience. The primary endpoint was overall satisfaction with the model as a training tool. Results: All of the experts were satisfied with the model as a tool to train endoscopists for the technique. 76.5% (n = 11) of the experts thought the model to be moderately realistic. Proper visualization was reported by 94.1% of the experts. All experts believed the lesions to be either slightly like or very similar to real lesions. The model was graded "easy" in difficulty by 11 of the experts. Conclusions: In all parameters assessed, the experts thought the model to be a useful tool for future training. This preliminary study suggests that the aforementioned simulator can be used to train endoscopists on using LAMS in a risk-free environment.

Severity of gastric intestinal metaplasia predicts the risk of gastric cancer: a prospective multicentre cohort study (GCEP).

OBJECTIVE: To investigate the incidence of gastric cancer (GC) attributed to gastric intestinal metaplasia (IM), and validate the Operative Link on Gastric Intestinal Metaplasia (OLGIM) for targeted endoscopic surveillance in regions with low-intermediate incidence of GC. METHODS: A prospective, longitudinal and multicentre study was carried out in Singapore. The study participants comprised 2980 patients undergoing screening gastroscopy with standardised gastric mucosal sampling, from January 2004 and December 2010, with scheduled surveillance endoscopies at year 3 and 5. Participants were also matched against the National Registry of Diseases Office for missed diagnoses of early gastric neoplasia (EGN). RESULTS: There were 21 participants diagnosed with EGN. IM was a significant risk factor for EGN (adjusted-HR 5.36; 95% CI 1.51 to 19.0; p<0.01). The age-adjusted EGN incidence rates for patients with and without IM were 133.9 and 12.5 per 100 000 person-years. Participants with OLGIM stages III-IV were at greatest risk (adjusted-HR 20.7; 95% CI 5.04 to 85.6; p<0.01). More than half of the EGNs (n=4/7) attributed to baseline OLGIM III-IV developed within 2 years (range: 12.7-44.8 months). Serum trefoil factor 3 distinguishes (Area Under the Receiver Operating Characteristics 0.749) patients with OLGIM III-IV if they are negative for H. pylori. Participants with OLGIM II were also at significant risk of EGN (adjusted-HR 7.34; 95% CI 1.60 to 33.7; p=0.02). A significant smoking history further increases the risk of EGN among patients with OLGIM stages II-IV. CONCLUSIONS: We suggest a risk-stratified approach and recommend that high-risk patients (OLGIM III-IV) have endoscopic surveillance in 2 years, intermediate-risk patients (OLGIM II) in 5 years.

Clinical guidance on endoscopic management of colonic polyps in Singapore.

Colonoscopy with endoscopic resection of detected colonic adenomas interrupts the adenoma-carcinoma sequence and reduces the incidence of colorectal cancer and cancer-related mortality. In the past decade, there have been significant developments in instruments and techniques for endoscopic polypectomy. Guidelines have been formulated by various professional bodies in Europe, Japan and the United States, but some of the recommendations differ between the various bodies. An expert professional workgroup under the auspices of the Academy of Medicine, Singapore, was set up to provide guidance on the endoscopic management of colonic polyps in Singapore. A total of 23 recommendations addressed the following issues: accurate description and diagnostic evaluation of detected polyps; techniques to reduce the risk of post-polypectomy bleeding and delayed perforation; the role of specific endoscopic resection techniques; the histopathological criteria for defining endoscopic cure; and the role of surveillance colonoscopy following curative resection.

Consensus guidelines on the role of cholangioscopy to diagnose indeterminate biliary stricture.

BACKGROUND: Indeterminate strictures pose a therapeutic dilemma. In recent years, cholangioscopy has evolved and the availability of cholangioscopy has increased. However, the position of cholangioscopy in the diagnostic algorithm to diagnose malignancy have not been well established. We aim to develop a consensus statement regarding the clinical role of cholangioscopy in the diagnosis of indeterminate biliary strictures. METHODS: The international experts reviewed the evidence and modified the statements using a three-step modified Delphi method. Each statement achieves consensus when it has at least 80% agreement. RESULTS: Nine final statements were formulated. An indeterminate biliary stricture is defined as that of uncertain etiology under imaging or tissue diagnosis. When available, cholangioscopic assessment and guided biopsy during the first round of ERCP may reduce the need to perform multiple procedures. Cholangioscopy are helpful in diagnosing malignant biliary strictures by both direct visualization and targeted biopsy. The absence of disease progression for at least 6 months is supportive of non-malignant etiology. Direct per-oral cholangioscopy provides the largest accessory channel, better image definition, with image enhancement but is technically demanding. Image enhancement during cholangioscopy may increase the diagnostic sensitivity of visual impression of malignant biliary strictures. Cholangioscopic imaging characteristics including tumor vessels, papillary projection, nodular or polypoid mass, and infiltrative lesions are highly suggestive for neoplastic/malignant biliary disease. The risk of cholangioscopy related cholangitis is higher than in standard ERCP, necessitating prophylactic antibiotics and ensuring adequate biliary drainage. Per-oral cholangioscopy may not be the modality of choice in the evaluation of distal biliary strictures due to inherent technical difficulties. CONCLUSION: Evidence supports that cholangioscopy has an adjunct role to abdominal imaging and ERCP tissue acquisition in order to evaluate and diagnose indeterminate biliary strictures.

Recovery of endoscopy services in the era of COVID-19: recommendations from an international Delphi consensus.

The COVID-19 pandemic has had a profound impact on provision of endoscopy services globally as staff and real estate were repurposed. As we begin to recover from the pandemic, a cohesive international approach is needed, and guidance on how to resume endoscopy services safely to avoid unintended harm from diagnostic delays. The aim of these guidelines is to provide consensus recommendations that clinicians can use to facilitate the swift and safe resumption of endoscopy services. An evidence-based literature review was carried out on the various strategies used globally to manage endoscopy during the COVID-19 pandemic and control infection. A modified Delphi process involving international endoscopy experts was used to agree on the consensus statements. A threshold of 80% agreement was used to establish consensus for each statement. 27 of 30 statements achieved consensus after two rounds of voting by 34 experts. The statements were categorised as pre-endoscopy, during endoscopy and postendoscopy addressing relevant areas of practice, such as screening, personal protective equipment, appropriate environments for endoscopy and infection control precautions, particularly in areas of high disease prevalence. Recommendations for testing of patients and for healthcare workers, appropriate locations of donning and doffing areas and social distancing measures before endoscopy are unique and not dealt with by any other guidelines. This international consensus using a modified Delphi method to produce a series of best practice recommendations to aid the safe resumption of endoscopy services globally in the era of COVID-19.

DNA damage signalling as an anti-cancer barrier in gastric intestinal metaplasia.

OBJECTIVE: Intestinal metaplasia (IM) is a premalignant stage that poses a greater risk for subsequent gastric cancer (GC). However, factors regulating IM to GC progression remain unclear. Previously, activated DNA damage response (DDR) signalling factors were shown to engage tumour-suppressive networks in premalignant lesions. Here, we interrogate the relationship of DDR signalling to mutational accumulation in IM lesions. DESIGN: IM biopsies were procured from the gastric cancer epidemiology programme, an endoscopic surveillance programme where biopsies have been subjected to (epi)genomic characterisation. IM samples were classified as genome-stable or genome-unstable based on their mutational burden/somatic copy-number alteration (CNA) profiles. Samples were probed for DDR signalling and cell proliferation, using the markers γH2AX and MCM2, respectively. The expression of the gastric stem cell marker, CD44v9, was also assessed. Tissue microarrays representing the GC progression spectrum were included. RESULTS: MCM2-positivity increased during GC progression, while γH2AX-positivity showed modest increase from normal to gastritis and IM stages, with further increase in GC. γH2AX levels correlated with the extent of chronic inflammation. Interestingly, genome-stable IM lesions had higher γH2AX levels underscoring a protective anti-cancer role for DDR signalling. In contrast, genome-unstable IM lesions with higher mutational burden/CNAs had lower γH2AX levels, elevated CD44v9 expression and modest promoter hypermethylation of DNA repair genes WRN, MLH1 and RAD52. CONCLUSIONS: Our data suggest that IM lesions with active DDR will likely experience a longer latency at the premalignant state until additional hits that override DDR signalling clonally expand and promote progression. These observations provide insights on the factors governing IM progression.