Treatment Of Early Gastric Cancer Research Articles

Endoscopic treatment for early gastric cancer

Background: In Korea, the number of screening endoscopies to detect early stage gastric neoplasms has increased exponentially following the active implementation of the National Cancer Screening Program.Current Concepts: Endoscopic treatment, including endoscopic mucosal resection and endoscopic submucosal dissection, is recognized as a minimally invasive treatment method with low morbidity and mortality for gastric dysplasia or early gastric cancer. Owing to improvement in the detection of early gastric cancer and advances in techniques, cases of endoscopic resection have increased and indications have been expanded. Endoscopic resection can preserve gastric function with excellent maintenance of the patient’s quality of life, and previous studies have shown better long-term follow-up outcomes compared to those with surgery. However, the fundamental limitation of endoscopic procedures is that gastric lymph-node dissection is not possible using endoscopic resection.Discussion and Conclusion: Although the usefulness of endoscopic resection is proven for tumors with a very low risk of lymph-node metastasis, follow-up examination using endoscopy and computed tomography should be performed for at least 5 years after curative resection of early gastric cancer.

Therapeutic approach to non-curative resection after endoscopic treatment in early gastric cancer

Background: Endoscopic resection is indicated for early or superficial gastrointestinal neoplasms with a negligible risk of lymph node metastasis. This procedure could preserve the organ while allowing en bloc resection of tumors, irrespective of the size and location of the lesion. Histological evaluation of the resected specimen determines whether curative resection, which implies a favorable long-term outcome, was achieved. If the resected specimen reveals non-curative, additional treatment is necessary as it is strongly associated with recurrence.Current Concepts: Surgical resection is recommended after non-curative resection of gastrointestinal neoplasms. However, rather than surgical resection, additional endoscopic treatment can be recommended if non-curative resection is solely because of the positive involvement at the horizontal resection margin without any other findings compatible with the non-curative resection criteria.Discussion and Conclusion: Adopting precise indications of endoscopic resection is important to reduce the risk of non-curative resection. If curative resection is not achieved after endoscopic resection, additional treatment should be considered to prevent local recurrence as well as lymph node metastasis.

Endoscopic diagnosis of early gastric cancer

Background: Among the types of gastric cancer, the proportion of early gastric cancer has shown a steady increase because the national screening programs have been conducted in Korea. Accordingly, the paradigm shift of the treatment procedure from surgical gastrectomy to endoscopic resection for selected early gastric cancer has accelerated recently. For successful treatment of early gastric cancer, early detection is essential to accurately predict the histological type, depth of invasion, and horizontal margins of the tumor.Current Concepts: The diagnosis of early gastric cancer and selection of treatment procedures comprises the following steps: (1) presence diagnosis, (2) qualitative diagnosis, and (3) quantitative diagnosis. Presently, early gastric cancer diagnosis is based on the endoscopic detection of a demarcated lesion and irregularity of the mucosal surface or color pattern. If a lesion is diagnosed as early gastric cancer, qualitative and quantitative diagnostic processes should be conducted. Qualitative diagnosis predicts the histological type (differentiated vs. undifferentiated), whereas quantitative diagnosis predicts the invasion depth and horizontal margins of the lesion. The diagnostic processes are based on the macroscopic morphology and color of the lesion, while sometimes using chromoendoscopy, image-enhanced endoscopy, and magnifying endoscopy.Discussion and Conclusion: If gastric cancer is detected at an early stage, most cases can be treated only by endoscopic resection. Therefore, endoscopists should have systematic knowledge regarding the findings of early gastric cancer for timely detection and appropriate selection of the treatment procedure.

Management of elderly patients with early gastric cancer in Japan.

Management of elderly patients with early gastric cancer is an important issue in an aging society such as Japan. While endoscopic resection is recommended as the standard treatment for early gastric cancers with extremely low risk of lymph node metastasis (<1%), gastrectomy with lymphadenectomy is recommended for the other early gastric cancers as the standard treatment even in elderly patients. Endoscopic submucosal dissection is the most recommended endoscopic resection procedure because of its high ability for 'en bloc' resection. Endoscopic submucosal dissection can reportedly provide favorable short-term outcomes in elderly patients. In terms of patient prognosis, the importance of considering patients' physical and nutritional conditions before endoscopic submucosal dissection has recently attracted attention. With respect to gastrectomy, the nationwide data in Japan have demonstrated relatively low 5-year overall survival and non-negligible post-operative 90-day mortality in men aged ≥75years and women aged ≥80years compared with those in younger patients. Among these elderly patients, 20% or more reportedly died within 5years after gastrectomy mostly due to other diseases. These facts suggested the necessity of a less invasive management option for the elderly patients. Efforts are being made to provide a non-invasive follow-up option without gastrectomy following endoscopic resection in elderly patients. To avoid the increase in gastric cancer-related deaths, the selection of patients with relatively low lymph node metastasis risk is essential, and several tools to estimate the lymph node metastasis risk from early gastric cancers have been developed. To avoid overtreatment with gastrectomy in more elderly early gastric cancer patients, new endoscopic submucosal dissection indications for them are also warranted.

Pretreatment risk factors for endoscopic noncurative resection of gastric cancers with undifferentiated-type components.

Endoscopic submucosal dissection (ESD) is recommended for the treatment of early gastric cancers with an undifferentiated-type component, clinically diagnosed as intramucosal lesions≤2cm, without ulceration. In the JCOG1009/1010 trial, ESD could be performed with stomach preservation in 70% of such patients whose pathological findings met the curative resection criteria. However, additional gastrectomy was required for the remaining 30%. We identified the pretreatment risk factors for noncurative resection. Post-hoc analysis indicated that 336 patients were identified in the JCOG1009/1010 trial; among them, 243 and 93 patients were categorized into the curative or noncurative resection groups, respectively, based on the pathological findings of the resected specimens. We explored the pretreatment risk factors for noncurative resection and investigated their associated pathological findings. Multivariable analysis revealed that a pretreatment tumor size>1cm was an independent risk factor for noncurative resection (odds ratio, 3.538; 95% confidence interval, 2.020-6.198, P<0.0001). Patients with a pretreatment tumor size>1cm (n=172) had a histological tumor size>2cm (22.1% vs 4.3%, odds ratio, 6.313; 95% confidence interval, 2.73-14.599, P<0.0001) and submucosal invasion (17.4% vs 9.1%, odds ratio, 2.000; 95% confidence interval, 1.032-3.877, P=0.040) more frequently as noncurative resection findings compared with those with a tumor size<1cm (n=164). Because pretreatment tumor size>1cm is an independent risk factor for noncurative resection, endoscopists should be aware that noncurative resection is not uncommon in ESD and fully explain the potential necessity for additional gastrectomy to patients before the procedure.

Gastric epithelial histology and precancerous conditions

The most common histological type of gastric cancer (GC) is gastric adenocarcinoma arising from the gastric epithelium. Less common variants include mesenchymal, lymphoproliferative and neuroendocrine neoplasms. The Lauren scheme classifies GC into intestinal type, diffuse type and mixed type. The WHO classification includes papillary, tubular, mucinous, poorly cohesive and mixed GC. Chronic atrophic gastritis (CAG) and intestinal metaplasia are recommended as common precancerous conditions. No definite precancerous condition of diffuse/poorly/undifferentiated type is recommended. Chronic superficial inflammation and hyperplasia of foveolar cells may be the focus. Presently, the management of early GC and precancerous conditions mainly relies on endoscopy including diagnosis, treatment and surveillance. Management of precancerous conditions promotes the early detection and treatment of early GC, and even prevent the occurrence of GC. In the review, precancerous conditions including CAG, metaplasia, foveolar hyperplasia and gastric hyperplastic polyps derived from the gastric epithelium have been concluded, based on the overview of gastric epithelial histological organization and its renewal.

Clinical Outcomes of Endoscopic Submucosal Dissection for Early Gastric Cancer in Different Indications

Gastric cancer still threatens the health of people, which is the fifth most common cancer and the fourth leading cancer-related death worldwide. The stage of the disease is critical for the 5-year survival of gastric cancer; the 5-year survival rates could reach 90% for gastric cancer detected at early stages. At present, endoscopic submucosal dissection (ESD) is the main treatment for early gastric cancer. Referring to the treatment guideline of the Japan Gastric Cancer Association, the indications for ESD mainly include absolute indications, expanded indications, and relative indications. Many studies have reported favourable long-term outcomes after undergoing ESD, and compared with surgery, ESD preserves the entire stomach and improves the quality of life of patients. However, it has also been reported that the recurrence rate of gastric cancer after ESD is high, so regular follow-up and careful examination are needed, even for patients with early gastric cancer who met absolute indications.

Lesion Segmentation in Gastroscopic Images Using Generative Adversarial Networks.

The segmentation of the lesion region in gastroscopic images is highly important for the detection and treatment of early gastric cancer. This paper proposes a novel approach for gastric lesion segmentation by using generative adversarial training. First, a segmentation network is designed to generate accurate segmentation masks for gastric lesions. The proposed segmentation network adds residual blocks to the encoding and decoding path of U-Net. The cascaded dilated convolution is also added at the bottleneck of U-Net. The residual connection promotes information propagation, while dilated convolution integrates multi-scale context information. Meanwhile, a discriminator is used to distinguish the generated and real segmentation masks. The proposed discriminator is a Markov discriminator (Patch-GAN), which discriminates each [Formula: see text] matrix in the image. In the process of network training, the adversary training mechanism is used to iteratively optimize the generator and the discriminator until they converge at the same time. The experimental results show that the dice, accuracy, and recall are 86.6%, 91.9%, and 87.3%, respectively. These metrics are significantly better than the existing models, which proves the effectiveness of this method and can meet the needs of clinical diagnosis and treatment.

Interaction of ncRNA and Epigenetic Modifications in Gastric Cancer: Focus on Histone Modification.

Gastric cancer has developed as a very common gastrointestinal tumors, with recent effective advancements in the diagnosis and treatment of early gastric cancer. However, the prognosis for gastric cancer remains poor. As a result, there is in sore need of better understanding the mechanisms of gastric cancer development and progression to improve existing diagnostic and treatment options. In recent years, epigenetics has been recognized as an important contributor on tumor progression. Epigenetic changes in cancer include chromatin remodeling, DNA methylation and histone modifications. An increasing number of studies demonstrated that noncoding RNAs (ncRNAs) are associated with epigenetic changes in gastric cancer. Herein, we describe the molecular interactions of histone modifications and ncRNAs in epigenetics. We focus on ncRNA-mediated histone modifications of gene expression associated with tumorigenesis and progression in gastric cancer. This molecular mechanism will contribute to our deeper understanding of gastric carcinogenesis and progression, thus providing innovations in gastric cancer diagnosis and treatment strategies.

Comparison of Intracorporeal Trapezoidal-shaped Gastroduodenostomy and Delta-shaped Anastomosis After Laparoscopic Distal Gastrectomy for Gastric Cancer: A Single-center Retrospective Study.

Laparoscopic/robotic distal gastrectomy (LDG/RDG) as a treatment for early gastric cancer has become increasingly and widely accepted for its minimal invasiveness and proportionate outcomes. Over the years, in addition to the LDG/RDG technique and the lymphadenectomy and gastrectomy procedures, various reconstruction methods have been developed and further improved upon. In particular, the number of minimally invasive intracorporeal anastomosis reconstruction techniques has been increasing. The medical records of 445 patients with gastric cancer who underwent reconstruction following LDG/RDG via either trapezoidal-shaped gastroduodenostomy (TAPESTRY; n=126) or delta-shaped anastomosis (DSA; n=319) at our hospital between April 2012 and May 2021 were retrospectively reviewed. Short-term surgical outcomes, including the operation time, blood loss, length of hospital stay, and complications, were compared between the 2 groups. Anastomosis-related complications, namely leakage, bleeding, stricture, and delayed gastric emptying, were monitored and graded using the Clavien-Dindo classification. All operations were either performed or supervised by qualified surgeons. Patients' characteristics in the TAPESTRY group and the DSA group were biased in terms of the surgical approach, but they were well-balanced after propensity score matching. Overall anastomosis-related complications (Clavien-Dindo grade II or above) within 30 days after surgery in the TAPESTRY group were comparable with those in the DSA group, either all patients (1.5% vs. 5.0%, P=0.115) or after propensity score-matching analysis (2.1% vs. 6.5%, P=0.134). There were no records of reoperation or mortality during hospitalization in either group. TAPESTRY was performed safely, with a low rate of anastomosis-related complications. These findings suggest that trapezoidal-shaped gastroduodenostomy could be a feasible option for reconstruction in patients undergoing LDG/RDG.

The impact of sarcopenia on adverse events associated with gastric endoscopic submucosal dissection.

Endoscopic submucosal dissection (ESD) is one of the main methods of treatments for early gastric cancer. Sarcopenia is a known risk factor for postoperative adverse events; however, the effect of sarcopenia on gastric ESD is unclear. We investigated the impact of sarcopenia on short-term prognosis after gastric ESD. This was a retrospective cohort study. We reviewed 832 patients who underwent gastric ESD between January 2015 and December 2019 and classified them into two groups: sarcopenia and non-sarcopenia groups. The curative resection rate, adverse events, and lengths of hospital stay were evaluated. We also evaluated risk factors associated with adverse events. 700 patients were analyzed (239 in the sarcopenia group and 461 in the non-sarcopenia group). The curative resection rates were similar in both groups. Common Terminology Criteria for Adverse Events (CTCAE) grade ≥ 2 (17% vs. 10%) were significantly more common, and the length of hospital stay was longer (8 vs. 7days) in the sarcopenia group. Univariate analysis identified age ≥ 75years, antithrombotic medication, history of gastric surgery, submucosal (SM) invasion, and sarcopenia as risk factors for CTCAE grade ≥ 2. Multivariate analysis showed that sarcopenia [odds ratio (OR) 1.79, 95% confidence interval (CI) 1.11-2.89, p = 0.016], history of gastric surgery (OR 9.32, 95% CI 1.97-44.05, p = 0.005), and SM invasion (OR 2.14, 95% CI 1.24-3.70, p = 0.006) were significant independent risk factors. Sarcopenia significantly affected short-term prognosis and is a novel risk factor for gastric ESD.

Significance of Lymph Node Metastasis in the Treatment of Gastric Cancer and Current Challenges in Determining the Extent of Metastasis.

The stomach exhibits abundant lymphatic flow, and metastasis to lymph nodes is common. In the case of gastric cancer, there is a regularity to the spread of lymph node metastasis, and it does not easily metastasize outside the regional nodes. Furthermore, when its extent is limited, nodal metastasis of gastric cancer can be cured by appropriate lymph node dissection. Therefore, identifying and determining the extent of lymph node metastasis is important for ensuring accurate diagnosis and appropriate surgical treatment in patients with gastric cancer. However, precise detection of lymph node metastasis remains difficult. Most nodal metastases in gastric cancer are microscopic metastases, which often occur in small-sized lymph nodes, and are thus difficult to diagnose both preoperatively and intraoperatively. Preoperative nodal diagnoses are mainly made using computed tomography, although the specificity of this method is low because it is mainly based on the size of the lymph node. Furthermore, peripheral nodal metastases cannot be palpated intraoperatively, nodal harvesting of resected specimens remains difficult, and the number of lymph nodes detected vary greatly depending on the skill of the technician. Based on these findings, gastrectomy with prophylactic lymph node dissection is considered the standard surgical procedure for gastric cancer. In contrast, several groups have examined the value of sentinel node biopsy for accurately evaluating nodal metastasis in patients with early gastric cancer, reporting high sensitivity and accuracy. Sentinel node biopsy is also important for individualizing and optimizing the extent of uniform prophylactic lymph node dissection and determining whether patients are indicated for function-preserving curative gastrectomy, which is superior in preventing post-gastrectomy symptoms and maintaining dietary habits. Notably, advancements in surgical treatment for early gastric cancer are expected to result in individualized surgical strategies with sentinel node biopsy. Chemotherapy for advanced gastric cancer has also progressed, and conversion gastrectomy can now be performed after downstaging, even in cases previously regarded as inoperable. In this review, we discuss the importance of determining lymph node metastasis in the treatment of gastric cancer, the associated difficulties, and the need to investigate strategies that can improve the diagnosis of lymph node metastasis.

Clinical Value of White Light Image, Endoscopic Ultrasonography and Magnifying Endoscopy with Narrow Band Imaging in Evaluation of Indications for Endoscopic Treatment of Early Gastric Cancer

To explore the application value of white light image (WLI), endoscopic ultrasonography (EUS) and magnifying endoscopy with narrow band imaging (ME-NBI) in the endoscopic treatment of early gastric cancer (EGC), and to provide basis for decision-making in clinical diagnosis and treatment. The clinicopathological data of EGC patients who underwent endoscopic submucosal dissection (ESD) at West China Hospital, Sichuan University between December 2013 and October 2020 were included. The accuracy, sensitivity, specificity, positive predictive value and negative predictive value of EGC invasive depth were compared between WLI and EUS. The role of ME-NBI in predicting the differentiation types of EGC was analyzed. A total of 280 patients (291 lesions) were enrolled in the study. Among them, 199 patients (207 lesions) received EUS and 160 patients (168 lesions) received ME-NBI. The overall accuracy of WLI in diagnosing the invasive depth of EGC was 87.0%, significantly higher than that of EUS (46.4%, P<0.001). When WLI was combined with EUS, the diagnostic accuracy (87.4%) was not significantly improved. The overall accuracy of determining the differentiation degree of EGC with ME-NBI was 92.3% (155/168), and the accuracy of determining undifferentiated EGC with ME-NBI was significantly lower than that of differentiated EGC (41.2% vs. 98.0%, P<0.001). In the evaluation of indications for endoscopic treatment of EGC, WLI showed better performance in predicting the invasive depth of EGC, while EUS demonstrated limited value. ME-NBI showed better accuracy for predicting the differentiation degree of most EGC, especially for differentiated EGC.

Second gastric cancer after curative endoscopic resection of differentiated-type early gastric cancer: post-hoc analysis of a single-arm confirmatory trial

Endoscopic resection (ER) for early gastric cancer (EGC) can preserve the stomach; however, the remaining stomach can develop second gastric cancer. Few reports have prospectively investigated the incidence and treatment outcomes of second gastric cancer. This post-hoc analysis used the dataset of the single-arm confirmatory trial, JCOG0607. The key inclusion criteria for JCOG0607 were solitary differentiated-type EGC and no previous gastrectomy or endoscopic treatment for EGC. Three hundred seventeen patients who underwent curative ER were included in this study. Surveillance endoscopy was performed 1 to 3 months after the initial ER and subsequently annually for at least 5 years. A lesion detected≤1 year and >1 year after the initial ER was defined as overlooked gastric cancer (OGC) and metachronous gastric cancer (MGC), respectively. During a median follow-up period of 6.0 years (interquartile range, 5.1-7.0), 30 OGCs and 61 MGCs were detected in 24 and 48 patients, respectively. The cumulative incidence of OGC at 1 year and MGC at 5 years was 7.6% and 12.7%, respectively. ER and gastrectomy were performed in 85 lesions and 6 lesions, respectively. Pathologic evaluation showed 78 mucosal cancers, 12 submucosal cancers, and 1 advanced cancer. Eventually, 28 OGCs and 52 MGCs fulfilled the pathologic criteria for curative ER. Our study was the first to reveal the actual incidence of second gastric cancer after curative ER for differentiated-type gastric cancer. Most lesions could be treated with ER. Continuous endoscopic surveillance after curative ER is important to detect second gastric cancer.

Function-Preserving Gastrectomy for Early Gastric Cancer.

Simple SummaryFor patients with early gastric cancer (EGC), a good prognosis is achieved by conventional standard gastrectomy with radical lymphadenectomy. However, postgastrectomy syndrome is often inevitable and results in decreased quality of life (QOL). To improve patients’ QOL, proximal gastrectomy instead of total gastrectomy and pylorus-preserving gastrectomy instead of distal gastrectomy have been widely accepted as function-preserving gastrectomies. Recently, personalized, minimized gastrectomy with sentinel node navigation surgery has been developed and is expected to be an ideal treatment option for patients with EGC. Herein, we review the indications, surgical techniques, and postoperative outcomes of function-preserving gastrectomy.Recently, minimally invasive (endoscopic or laparoscopic) treatment for early gastric cancer (EGC) has been widely accepted. However, a standard gastrectomy with radical lymphadenectomy is generally performed in patients with EGC who have no indications for endoscopic resection, and postgastrectomy dysfunction is one of the problems of standard gastrectomy. Function-preserving gastrectomy, such as proximal gastrectomy and pylorus-preserving gastrectomy, can be considered when attempting to preserve the patient’s quality of life (QOL) postoperatively. In addition, sentinel node navigation surgery for EGC has been applied in clinical practice in several prospective studies on function-preserving personalized minimized gastrectomy. In the near future, the sentinel lymph node concept is expected to form the basis for establishing an ideal, personalized, minimally invasive function-preserving treatment for patients with EGC, which will improve their postoperative QOL without compromising their long-term survival. In this review article, we summarize the current status, surgical techniques, and postoperative outcomes of function-preserving gastrectomy for EGC.

Application of convolutional neural networks for evaluating the depth of invasion of early gastric cancer based on endoscopic images.

Recently, artificial intelligence (AI) has been used in endoscopic examination and is expected to help in endoscopic diagnosis. We evaluated the feasibility of AI using convolutional neural network (CNN) systems for evaluating the depth of invasion of early gastric cancer (EGC), based on endoscopic images. This study used a deep CNN model, ResNet152. From patients who underwent treatment for EGC at our hospital between January 2012 and December 2016, we selected 100 consecutive patients with mucosal (M) cancers and 100 consecutive patients with cancers invading the submucosa (SM cancers). A total of 3508 non-magnifying endoscopic images of EGCs, including white-light imaging, linked color imaging, blue laser imaging-bright, and indigo-carmine dye contrast imaging, were included in this study. A total of 2288 images from 132 patients served as the development dataset, and 1220 images from 68 patients served as the testing dataset. Invasion depth was evaluated for each image and lesion. The majority vote was applied to lesion-based evaluation. The sensitivity, specificity, and accuracy for diagnosing M cancer were 84.9% (95% confidence interval [CI] 82.3%-87.5%), 70.7% (95% CI 66.8%-74.6%), and 78.9% (95% CI 76.6%-81.2%), respectively, for image-based evaluation, and 85.3% (95% CI 73.4%-97.2%), 82.4% (95% CI 69.5%-95.2%), and 83.8% (95% CI 75.1%-92.6%), respectively, for lesion-based evaluation. The application of AI using CNN to evaluate the depth of invasion of EGCs based on endoscopic images is feasible, and it is worth investing more effort to put this new technology into practical use.

Pathology Reporting of Gastric Endoscopic Resections: Recommendations From the International Collaboration on Cancer Reporting

Endoscopic resection (ER) has recently become an increasingly common treatment for early gastric cancer, despite being a relatively new approach in non–East Asian countries. Consistent, generalized data are needed for the implementation of evidence-based clinical practice in the field.

Predictors of early and late mortality after the treatment for early gastric cancers.

Although many patients with early gastric cancers (EGCs) die of non-gastric cancer-related causes, the association of the risk categories of lymph node metastasis (LNM) with all-cause mortality remains unclear. We aimed to clarify the predictors of early and late mortality, separately. Patients with endoscopic resection or gastrectomy for EGCs between 2003 and 2017 were retrospectively enrolled. We analyzed predictors for early and late mortality, including risk categories of LNM, treatment method, and nine non-cancer-related indices, separately, with a cut-off value of 3 years. We enrolled 1439 patients with a median follow-up period of 79 months. The 5-year overall survival rate was 86.8%. In the multivariate Cox analysis, the most important predictors for early and late mortality were age ≥85 years (hazard ratio [HR] 2.88 and 4.54, respectively) and Eastern Cooperative Oncology Group Performance Status ≥2 (HR 3.00 and 4.19, respectively). Charlson comorbidity index ≥2 (HR 2.76 and 1.99, respectively), American Society of Anesthesiologists Physical Status ≥3 (HR 2.35 and 1.79, respectively), and C-reactive protein/albumin ratio ≥0.028 (HR 2.30 and 1.58, respectively) were also predictors for both early and late mortality. Male (HR 2.26), intermediate- (HR 2.12)/high-risk (HR 1.85) of LNM in eCura system, and sarcopenia evaluated by the psoas muscle mass index (HR 1.70) were predictors for early mortality. The combined assessment of multiple predictors might help to predict early and/or late mortality in patients with EGCs. The eCura system was associated with early mortality.

Gastric endoscopic submucosal dissection in Western countries: Indications, applications, efficacy and training perspective.

Endoscopic submucosal dissection was introduced in Japan for the mini-invasive treatment of early gastric cancer, as part of national screening program considering high prevalence of disease in these latitudes. This technique allows en-bloc curative oncological excision and to obtain in a single step R0-resection, characterization, histological staging and potential cure of the tumor with a very high cost-benefit balance. Over the years, Western endoscopists have adopted endoscopic submucosal dissection, achieving good rates of efficacy, long-term improved outcomes and safety, with low risk of local recurrence comparable to those obtained in Asian institutes. However, according to some authors, the excellent outcomes from East country could not be representative of the Western experience. Despite epidemiological differences of early gastric cancer, scant volume data and limitations in training opportunities between Western and Eastern countries, European Society of Gastrointestinal Endoscopy have adopted Japanese guidelines and developed a European core curriculum for endoscopic submucosal dissection training. Endoscopists should be able to estimate the probability of performing a curative resection by considering the benefit/risk relationship case-by-case in order to implement a correct decision-making process.

S993 Continued Aspirin Use and Bleeding Risk After Endoscopic Submucosal Dissection of Gastric Neoplasms: A Meta-Analysis

Introduction: With the development of endoscopic technologies, the detection rate of early gastric cancer (EGC) and precancerous lesions is gradually increasing. As an effective minimally invasive therapy, endoscopic submucosal dissection (ESD) has been accepted as a standard treatment for EGC and dysplasia. However, postprocedural bleeding is one of the most common complications of ESD, with a reported incidence of 5.1%. Moreover, the effect of continued low-dose aspirin (LDA) on bleeding during the peri-ESD period is not clear. Methods: We searched the OVID/Medline and Google Scholar databases through June 2021 to find studies relating to continued LDA use in patients undergoing ESD. Studies reporting bleeding rates in patients undergoing ESD with and without continued LDA were included. Postoperative bleeding rates were compared between those who continued LDA during the procedure and those who did not; a random-effects model was used to calculate pooled odds ratio for bleeding risk with continued LDA use. A p-value < 0.05 was considered statistically significant. Results: The initial search identified 2023 studies; after excluding duplicates, review articles, and studies not meeting inclusion criteria, 9 studies (all were retrospective observational studies) were finally included in the analysis. The total number of patients undergoing ESD procedure was 7978, out of which 703 continued LDA during the procedure. Pooled analysis comparing the post-operative bleeding rates between people with and without continued use of LDA revealed that aspirin use during ESD translated into higher postoperative bleeding rates compared to those who did not. (Pooled OR 1.720 , 95%CI: 1.121-2.641, P= 0.01). No interstudy heterogeneity was observed (I2=0). Conclusion: The results of our meta-analysis demonstrated that LDA continuation significantly increased the risk of post-ESD bleeding. Therefore, the physicians should individualize the decision of continuing LDA in patients undergoing ESD based on their thrombotic risk.Figure 1.: Forest plot of gastric neoplasm studies with and without continuation of low-dose aspirin.Table 1.: Baseline Characteristics of Included Studies.