Usefulness of magnifying endoscopy with narrow-band imaging for determining the horizontal extent of early gastric cancer when there is an unclear margin by chromoendoscopy (with video)

Endoscopic Resection of Malignancies in the Upper GI Tract: A Clinical Algorithm

Background

Malignancies in the upper gastrointestinal tract are amenable to endoscopic resection at an early stage. Achieving a curative resection is the most stringent quality criterion, but post-resection risk assessment and aftercare are also part of a comprehensive quality program.

Summary

Various factors influence the achievement of curative resection. These include endoscopic assessment prior to resection using chromoendoscopy and HD technology. If resectability is possible, it is particularly important to delineate the lateral resection margins as precisely as possible before resection. Furthermore, the correct choice of resection technique depending on the lesion must be taken into account. Endoscopic submucosal dissection is the standard for esophageal squamous cell carcinoma and gastric carcinoma. In Western countries, it is becoming increasingly popular to treat Barrett's neoplasia over 2 cm in size and/or with suspected submucosal infiltration with en bloc resection instead of piece meal resection. After resection, risk assessment based on the histopathological resection determines the patient's individual risk of lymph node metastases, particularly in the case of high-risk lesions. This is categorized according to the current literature.

Key Messages

This review presents clinical algorithms for endoscopic resection of esophageal SCC, Barrett's neoplasia, and gastric neoplasia. The algorithms include the pre-resection assessment of the lesion and the resection margins, the adequate resection technique for the respective lesion, as well as the post-resection risk assessment with an evidence-based recommendation for follow-up therapy and surveillance.

Surveillance esophagogastroduodenoscopy using linked color imaging and narrow-band imaging: A multicenter randomized controlled trial

BACKGROUND AND AIM

There has been no report on a direct comparison between linked color imaging (LCI) and second-generation narrow-band imaging (2G-NBI) for surveillance of epithelial neoplasms in the upper gastrointestinal tract (UGIT). The aim of this study was to verify the superiority of LCI to 2G-NBI for surveillance esophagogastroduodenoscopy and to clarify how each endoscopic system should be used.

METHODS

This study was conducted as an open-label, two-arm-parallel (1:1), multicenter, randomized controlled trial at six institutions. Patients aged 20-85 years with a treatment history of epithelial neoplasms in the UGIT were recruited. Patients were assigned to a 2G-NBI group and an LCI group, and esophagogastroduodenoscopy was performed with primary image-enhanced endoscopy followed by white light imaging (WLI). The primary endpoint was the detection rate of one or more epithelial neoplasms in the primary image-enhanced endoscopy. A WLI-detected epithelial neoplasm was defined as a lesion that was detected in only WLI.

RESULTS

A total of 372 patients in the 2G-NBI group and 378 patients in the LCI group were analyzed. Epithelial neoplasms in the UGIT were detected by 2G-NBI in 18 patients (4.6%) and were detected by LCI in 20 patients (5.3%) (P = 0.87). WLI-detected epithelial neoplasms were in 11 patients in the 2G-NBI group (3.0%) and in 1 patient in the LCI group (0.27%) (P = 0.003).

CONCLUSIONS

Linked color imaging did not show superiority to 2G-NBI for the detection of epithelial neoplasms. Also, the percentage of WLI-detected epithelial neoplasms in primary NBI was significantly higher than that in primary LCI.

Landscape of Innovative Methods for Early Diagnosis of Gastric Cancer: A Systematic Review

From a global perspective, gastric cancer (GC) persists as a significant healthcare issue. In the Western world, the majority of cases are discovered at late stages, when the treatment is generally unsuccessful. There are no organized screening programs outside of Asia (Japan and Republic of Korea). Traditional diagnosis techniques (such as upper endoscopy), conventional tumor markers (CEA, CA19-9, and CA72-4), radiographic imaging, and CT scanning all have drawbacks. The gold standard for the earliest detection of cancer and related premalignant lesions is still endoscopy with a proper biopsy follow-up. Since there are currently no clinically approved biomarkers for the early diagnosis of GC, the identification of non-invasive biomarkers is expected to help improve the prognosis and survival rate of these patients. The search for new screening biomarkers is currently underway. These include genetic biomarkers, such as circulating tumor cells, microRNAs, and exosomes, as well as metabolic biomarkers obtained from biofluids. Meanwhile, cutting-edge high-resolution endoscopic technologies are demonstrating promising outcomes in the visual diagnosis of mucosal lesions with the aid of linked color imaging and machine learning models. Following the PRISMA guidelines, this study examined the articles in databases such as PubMed, resulting in 167 included articles. This review discusses the currently available and emerging methods for diagnosing GC early on, as well as new developments in the endoscopic detection of early lesions of the stomach.

Endoscopic submucosal dissection for early gastric cancer: It is time to consider the quality of its outcomes

Endoscopic resection, particularly endoscopic submucosal dissection (ESD), is widely used as a standard treatment modality for early gastric cancer (EGC) when the risk of lymph node metastasis is negligible. Compared with surgical gastrectomy, ESD is a minimally invasive procedure with additional advantages, such as preservation of the entire stomach and maintenance of the patient's quality of life. However, not all patients achieve curative resection after ESD of EGC. Several patients require surgical gastrectomy after ESD to achieve a curative treatment. Additional surgery after ESD, owing to non-curative resection, places considerable emotional and financial burdens on patients. Recently, as the number of endoscopists performing ESD has increased, the rate of non-curative resection after ESD has increased correspondingly. In order to decrease the non-curative resection rate, as well as determine the ideal rate of non-curative resection after ESD, it is time to consider quality indicators for the outcomes of ESD for EGC.

Clinical strategies for securing negative proximal margin in early gastric cancer

Securing an appropriate proximal resection margin (PRM) is crucial for oncological safety in treating gastric cancer. This study investigated the clinicopathological characteristics of patients with incomplete PRM length of <2 cm in early gastric cancer. Clinicopathological data of 1,493 patients who underwent subtotal gastrectomy for early gastric cancer in 2012 to 2021 were retrospectively reviewed. Patients were divided into the PRM length of <2 cm and ≥2 cm groups based on pathological results. Univariate and multivariate analyses evaluated factors for incomplete PRM length. Factors related to patients with a relative PRM positive were also analyzed. The proportion of patients with a PRM length of <2 cm was 17.9% (267/1,493). Multivariate regression analysis revealed that age <50, preoperative endoscopic size of ≥3 cm, size discrepancy of ≥2 cm, and midbody tumor with a lesser curvature significantly contributed to the PRM length of <2 cm. Twenty-four patients had a relative PRM positive (24/1493, 1.6%). An incomplete PRM was the only risk factor for a positive relative PRM. Surgical treatment for early gastric cancer requires an accurate preoperative endoscopic tumor size and location evaluation. A more aggressive resection is recommended for patients with age <50, preoperative endoscopic size of ≥3 cm, size discrepancy of ≥2 cm, and midbody tumor with a lesser curvature.

American Society for Gastrointestinal Endoscopy guideline on endoscopic submucosal dissection for the management of early esophageal and gastric cancers: methodology and review of evidence

This document from the American Society for Gastrointestinal Endoscopy (ASGE) provides a full description of the methodology used in the review of the evidence used to inform the final guidance outlined in the accompanying Summary and Recommendations document regarding the role of endoscopic submucosal dissection (ESD) in the management of early esophageal and gastric cancers. This guideline used the Grading of Recommendations, Assessment, Development and Evaluation framework and specifically addresses the role of ESD versus EMR and/or surgery, where applicable, for the management of early esophageal squamous cell carcinoma (ESCC), esophageal adenocarcinoma (EAC), and gastric adenocarcinoma (GAC) and their corresponding precursor lesions. For ESCC, the ASGE suggests ESD over EMR for patients with early-stage, well-differentiated, nonulcerated cancer >15 mm, whereas in patients with similar lesions ≤15 mm, the ASGE suggests either ESD or EMR. The ASGE suggests against surgery for such patients with ESCC, whenever possible. For EAC, the ASGE suggests ESD over EMR for patients with early-stage, well-differentiated, nonulcerated cancer >20 mm, whereas in patients with similar lesions measuring ≤20 mm, the ASGE suggests either ESD or EMR. For GAC, the ASGE suggests ESD over EMR for patients with early-stage, well or moderately differentiated, nonulcerated intestinal type cancer measuring 20 to 30 mm, whereas for patients with similar lesions <20 mm, the ASGE suggests either ESD or EMR. The ASGE suggests against surgery for patients with such lesions measuring ≤30 mm, whereas for lesions that are poorly differentiated, regardless of size, the ASGE suggests surgical evaluation over endosic approaches.

American Society for Gastrointestinal Endoscopy guideline on endoscopic submucosal dissection for the management of early esophageal and gastric cancers: summary and recommendations

This clinical practice guideline from the American Society for Gastrointestinal Endoscopy (ASGE) provides an evidence-based summary and recommendations regarding the role of endoscopic submucosal dissection (ESD) in the management of early esophageal and gastric cancers. It is accompanied by the document subtitled "Methodology and Review of Evidence," which provides a detailed account of the methodology used for the evidence review. This guideline was developed using the Grading of Recommendations, Assessment, Development and Evaluation framework and specifically addresses the role of ESD versus EMR and/or surgery, where applicable, for the management of early esophageal squamous cell carcinoma (ESCC), esophageal adenocarcinoma (EAC), and gastric adenocarcinoma (GAC) and their corresponding precursor lesions. For ESCC, the ASGE suggests ESD over EMR for patients with early-stage, well-differentiated, nonulcerated cancer >15 mm, whereas in patients with similar lesions ≤15 mm, the ASGE suggests either ESD or EMR. The ASGE suggests against surgery for such patients with ESCC, whenever possible. For EAC, the ASGE suggests ESD over EMR for patients with early-stage, well-differentiated, nonulcerated cancer >20 mm, whereas in patients with similar lesions measuring ≤20 mm, the ASGE suggests either ESD or EMR. For GAC, the ASGE suggests ESD over EMR for patients with early-stage, well- or moderately differentiated, nonulcerated intestinal type cancer measuring 20 to 30 mm, whereas for patients with similar lesions <20 mm, the ASGE suggests either ESD or EMR. The ASGE suggests against surgery for patients with such lesions measuring ≤30 mm, whereas for lesions that are poorly differentiated, regardless of size, we suggest surgical evaluation over endoscopic approaches.

Computer-aided demarcation of early gastric cancer: a pilot comparative study with endoscopists

BACKGROUND

Precise area diagnosis of early gastric cancer (EGC) is critical for reliable endoscopic resection. Computer-aided diagnosis (CAD) shows strong potential for detecting EGC and reducing cancer-care disparities caused by differences in endoscopists' skills. To be used in clinical practice, CAD should enable both the detection and the demarcation of lesions. This study proposes a scheme for the detection and delineation of EGC under white-light endoscopy and validates its performance using 1-year consecutive cases.

METHODS

Only 300 endoscopic images randomly selected from 68 consecutive cases were used for training a convolutional neural network. All cases were treated with endoscopic submucosal dissection, enabling the accumulation of a training dataset in which the extent of lesions was precisely determined. For validation, 462 cancer images and 396 normal images from 137 consecutive cases were used. From the validation results, 38 randomly selected images were compared with those delineated by six endoscopists.

RESULTS

Successful detections of EGC in 387 cancer images (83.8%) and the absence of lesions in 307 normal images (77.5%) were achieved. Positive and negative predictive values were 81.3% and 80.4%, respectively. Successful detection was achieved in 130 cases (94.9%). We achieved precise demarcation of EGC with a mean intersection over union of 66.5%, showing the extent of lesions with a smooth boundary; the results were comparable to those achieved by specialists.

CONCLUSIONS

Our scheme, validated using 1-year consecutive cases, shows potential for demarcating EGC. Its performance matched that of specialists; it might therefore be suitable for clinical use in the future.

Recent advances in endoscopic management of gastric neoplasms

The development and clinical application of new diagnostic endoscopic technologies such as endoscopic ultrasonography with biopsy, magnification endoscopy, and narrow-band imaging, more recently supplemented by artificial intelligence, have enabled wider recognition and detection of various gastric neoplasms including early gastric cancer (EGC) and subepithelial tumors, such as gastrointestinal stromal tumors and neuroendocrine tumors. Over the last decade, the evolution of novel advanced therapeutic endoscopic techniques, such as endoscopic mucosal resection, endoscopic submucosal dissection, endoscopic full-thickness resection, and submucosal tunneling endoscopic resection, along with the advent of a broad array of endoscopic accessories, has provided a promising and yet less invasive strategy for treating gastric neoplasms with the advantage of a reduced need for gastric surgery. Thus, the management algorithms of various gastric tumors in a defined subset of the patient population at low risk of lymph node metastasis and amenable to endoscopic resection, may require revision considering upcoming data given the high success rate of en bloc resection by experienced endoscopists. Moreover, endoscopic surveillance protocols for precancerous gastric lesions will continue to be refined by systematic reviews and meta-analyses of further research. However, the lack of familiarity with subtle endoscopic changes associated with EGC, as well as longer procedural time, evolving resection techniques and tools, a steep learning curve of such high-risk procedures, and lack of coding are issues that do not appeal to many gastroenterologists in the field. This review summarizes recent advances in the endoscopic management of gastric neoplasms, with special emphasis on diagnostic and therapeutic methods and their future prospects.

Update on diagnosis and treatment of early signet-ring cell gastric carcinoma: A literature review

Gastric signet-ring cell gastric carcinoma (GSRC) is an unfavorable subtype of gastric cancer (GC) that presents with greater invasiveness and poorer prognosis in advanced stage than other types of GC. However, GSRC in early stage is often considered an indicator of less lymph node metastasis and more satisfying clinical outcome compared to poorly differentiated GC. Therefore, the detection and diagnosis of GSRC at early stage undoubtedly play a crucial role in the management of GSRC patients. In recent years, technological advancement in endoscopy including narrow-band imaging and magnifying endoscopy has significantly improved the accuracy and sensitivity of the diagnosis under endoscopy for GSRC patients. Researches have confirmed that early stage GSRC that meets the expanded criteria of endoscopic resection showed comparable outcomes to surgery after receiving endoscopic submucosal dissection (ESD), indicating that ESD could be considered standard treatment for GSRC after thorough selection and evaluation. This article summarizes the current knowledge and updates pertaining to the endoscopic diagnosis and treatment of early stage signet-ring cell gastric carcinoma.

Comparison Trial between I-SCAN-Optical Enhancement and Chromoendoscopy for Evaluating the Horizontal Margins of Gastric Epithelial Neoplasms

Background/Aims

Endoscopic submucosal dissection is a widely used treatment for gastric epithelial neoplasms. Accurate delineation of the horizontal margins is necessary for the complete resection of gastric epithelial neoplasms. Recently, image-enhanced endoscopy has been used to evaluate horizontal margins of gastric epithelial neoplasms. The aim of this study was to investigate whether I-SCAN-optical enhancement (I-SCAN-OE) is superior to chromoendoscopy in evaluating the horizontal margin of gastric epithelial neoplasms.

Methods

This was a multicenter, prospective, and randomized trial. The participants were divided into two groups: I-SCAN-OE and chromoendoscopy. For both groups, we first evaluated the horizontal margins of early gastric cancer or high-grade dysplasia using white-light imaging, and then evaluated, the horizontal margins using I-SCAN-OE or chromoendoscopy. We devised a unique scoring method based on the pathological results obtained after endoscopic submucosal dissection to accurately evaluate the horizontal margins of gastric epithelial neoplasms. The delineation scores of both groups were compared, as were the ratios of positive/negative horizontal margins.

Results

In total, 124 patients were evaluated for gastric epithelial neoplasms, of whom 112 were enrolled in the study. A total of 112 patients participated in the study, and 56 were assigned to each group (1:1). There was no statistically significant difference in the delineation scores between the groups (chromoendoscopy, 7.80±1.94; I-SCAN-OE, 8.23±2.24; p=0.342).

Conclusions

I-SCAN-OE did not show superiority over chromoendoscopy in delineating horizontal margins of gastric epithelial neoplasms.

Endoscopic Submucosal Dissection in the Stomach and Duodenum: Techniques, Indications, and Outcomes

Gastric endoscopic submucosal dissection (ESD) is established for management of early gastric cancer (EGC). Diagnosis of EGC relies on adequate endoscopic assessment involving lesion size, histopathology, presence of ulceration, and depth of invasion. Absolute indications for endoscopic resection of EGC are if patients are presumed to have a less than 1% risk of lymph node metasta endoscopic submucosal dissectionsis, and long-term outcomes are similar to those with surgical gastrectomy. Duodenal ESD is more technically difficult and requires expertise in ESD in other locations.

Use of advanced endoscopic technology for optical characterization of neoplasia in patients with ulcerative colitis: Systematic review

OBJECTIVES

Advances in endoscopic technology, including magnifying and image-enhanced techniques, have been attracting increasing attention for the optical characterization of colorectal lesions. These techniques are being implemented into clinical practice as cost-effective and real-time approaches. Additionally, with the recent progress in endoscopic interventions, endoscopic resection is gaining acceptance as a treatment option in patients with ulcerative colitis (UC). Therefore, accurate preoperative characterization of lesions is now required. However, lesion characterization in patients with UC may be difficult because UC is often affected by inflammation, and it may be characterized by a distinct "bottom-up" growth pattern, and even expert endoscopists have relatively little experience with such cases. In this systematic review, we assessed the current status and limitations of the use of optical characterization of lesions in patients with UC.

METHODS

A literature search of online databases (MEDLINE via PubMed and CENTRAL via the Cochrane Library) was performed from 1 January 2000 to 30 November 2021.

RESULTS

The database search initially identified 748 unique articles. Finally, 25 studies were included in the systematic review: 23 focused on differentiation of neoplasia from non-neoplasia, one focused on differentiation of UC-associated neoplasia from sporadic neoplasia, and one focused on differentiation of low-grade dysplasia from high-grade dysplasia and cancer.

CONCLUSIONS

Optical characterization of neoplasia in patients with UC, even using advanced endoscopic technology, is still challenging and several issues remain to be addressed. We believe that the information revealed in this review will encourage researchers to commit to the improvement of optical diagnostics for UC-associated lesions.

Clinical outcome of the delineation-without-negative-biopsy strategy in magnifying image-enhanced endoscopy for identifying the extent of differentiated-type early gastric cancer

BACKGROUND

The histologic evaluation of biopsy samples collected from the surrounding mucosa has conventionally been used to determine the horizontal extent of early gastric cancer. Recently, optical delineation using magnifying image-enhanced endoscopy (IEE) has been considered an alternative method to histologic evaluation. This study aimed to assess the clinical outcome and efficacy of this method in identifying cancer margins.

METHODS

Overall, 921 patients with 1018 differentiated-type early gastric tumors who underwent endoscopic submucosal dissection (ESD) were examined. Before ESD, the lesions were classified based on whether they have clear or unclear margins on magnifying IEE. When the lesions had clear margins, the marking dots were placed outside the margins without a negative biopsy. Successful delineation was defined as lesions with clear margins and accurate delineation based on histopathological examination. The primary outcome was the accuracy of optical delineation without a negative biopsy compared with histopathological diagnosis. Moreover, the clinicopathological factors associated with an unsuccessful delineation were assessed.

RESULTS

Of 1018 lesions, 820 had a clear margin and 198 an unclear margin. Of 820 lesions with a clear margin, 817 and 3 had an accurate and inaccurate delineation, respectively, according to the histological examination. Accordingly, the accuracy rate of optical delineation was 99.6% (817/820). The significant independent factors associated with an unsuccessful delineation were absence of Helicobacter pylori infection after eradication, tumor size > 20 mm, and moderate differentiation.

CONCLUSIONS

Optical delineation may be an alternative method to histological evaluation in lesions with a clear margin on magnifying IEE.

Endoscopic Treatment of Superficial Gastric Cancer: Present Status and Future

Although the mortality rates of gastric cancer (GC) are gradually declining, gastric cancer is still the fourth leading cause of cancer-related death worldwide. This may be due to the high rate of patients who are diagnosed with GC at advanced stages. However, in countries such as Japan with endoscopic screening systems, more than half of GCs are discovered at an early stage, enabling endoscopic resection (ER). Especially after the introduction of endoscopic submucosal dissection (ESD) in Japan around 2000, a high en bloc resection rate allowing pathological assessment of margin and depth has become possible. While ER is a diagnostic method of treatment and may not always be curative, it is widely accepted as standard treatment because it is less invasive than surgery and can provide an accurate diagnosis for deciding whether additional surgery is necessary. The curability of ER is currently assessed by the completeness of primary tumor removal and the possibility of lymph node metastasis. This review introduces methods, indications, and curability criteria for ER of EGC. Despite recent advances, several problems remain unsolved. This review will also outline the latest evidence concerning future issues.

A comparative study of demarcation line diagnostic performance between non-magnifying observation with white light and non-magnifying observation with narrow-band light for early gastric cancer

BACKGROUND AND AIMS

With the improvement in endoscopic equipment functions, narrow-band imaging (NBI) for endoscopic observation of the stomach, which is an organ with a large lumen, is now feasible. Studies evaluating the NBI utility without magnifying endoscopy to diagnose the invasion extent for the demarcation line identification in early gastric cancer have not been reported. This study aimed to investigate the demarcation line diagnostic performance of NBI in early gastric cancer compared to that of white-light imaging (WLI) using prospectively collected consecutive specimens from early gastric cancer patients.

METHODS

Thirty consecutive lesions were collected from patients who underwent endoscopic submucosal dissection for early gastric cancer. Next, 30 NBI and 30 WLI images, each with the same degree of gastric wall extension, angle, and layout for one lesion, were selected, and a total of 60 images were prepared for testing. The early gastric cancer invasion ranges in the endoscopic images was plotted using the web-developed software, and 264 independent endoscopists, unaware of the diagnosis, performed the web tests, with the concordance rates between the ranges of responses. After estimating the actual early gastric cancer invasion ranges, the NBI and WLI results were compared.

RESULTS

The concordance rates for NBI and WLI images were 43.1% (95% confidence interval [CI] 42.5-43.7%) and 37.2% (95% CI 36.6-37.7%), respectively, showing that the concordance rate for NBI was significantly higher than that for WLI.

CONCLUSION

This study suggested that NBI was more useful for identifying demarcation lines than WLI.

Influence of hospital volume on bleeding after endoscopic submucosal dissection for early gastric cancer in Japan: a multicenter propensity score-matched analysis

BACKGROUND

Information on whether there is a relationship between hospital volume and bleeding after endoscopic submucosal dissection (ESD) for early gastric cancer (EGC) is limited. This study aimed to compare the bleeding rates after ESD for EGC according to the hospital volume.

METHODS

Patients who underwent ESD for EGC at 33 institutions in Japan between November 2013 and October 2016 were included in this multicenter retrospective study. Hospital volume was categorized into three groups, based on the average annual number of ESD procedures: low- and medium-volume group (LMVG), high-volume group (HVG), and very high-volume group (VHVG). The bleeding rate after ESD for EGC was compared between the three hospital volume groups after propensity score matching.

RESULTS

A total of 10,320 patients, including 2797 patients in the LMVG, 4646 patients in the HVG, and 2877 patients in the VHVG, were identified. Propensity score matching yielded 2002 patients in each hospital volume group, with an improved balance of confounding variables between the three groups. The bleeding rates in the LMVG, HVG, and VHVG were 4.3%, 3.7%, and 4.9%, respectively, and no significant difference was noted between the three groups.

CONCLUSIONS

The bleeding rate after ESD for EGC did not differ between hospitals in Japan. The finding indicated that ESD for EGC is equally feasible across Japanese hospitals of different volumes regarding bleeding after ESD.

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.

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.

Efficacy of a Third-Generation High-Vision Ultrathin Endoscope for Evaluating Gastric Atrophy and Intestinal Metaplasia in Helicobacter pylori-Eradicated Patients

BACKGROUND

Image-enhanced endoscopy methods such as narrow-band imaging (NBI) are advantageous over white-light imaging (WLI) for detecting gastric atrophy, intestinal metaplasia, and cancer. Although new third-generation high-vision ultrathin endoscopes improve image quality and resolution over second-generation endoscopes, it is unclear whether the former also enhances color differences surrounding atrophy and intestinal metaplasia for endoscopic detection. We compared the efficacy of a new third-generation ultrathin endoscope and an older second-generation endoscope.

METHODS

We enrolled 50 Helicobacter pylori-eradicated patients who underwent transnasal endoscopy with a second-generation and third-generation endoscope (GIF-290N and GIF-1200N, respectively) in our retrospective study. Color differences based on the International Commission on Illumination 1976 (L*, a*, b*) color space were compared between second-generation and third-generation high-vision endoscopes.

RESULTS

Color differences surrounding atrophy produced by NBI on the GIF-1200N endoscope were significantly greater than those on GIF-290N (19.2 ± 8.5 vs. 14.4 ± 6.2, p = 0.001). In contrast, color differences surrounding intestinal metaplasia using both WLI and NBI were similar on GIF-1200N and GIF-290N endoscopes. NBI was advantageous over WLI for detecting intestinal metaplasia on both endoscopes.

CONCLUSIONS

NBI using a third-generation ultrathin endoscope produced significantly greater color differences surrounding atrophy and intestinal metaplasia in H. pylori-eradicated patients compared with WLI.

Diffuse-type Gastric Cancer

Gastric cancer is the most prevalent malignant tumor in Korea. Histologically, it is often classified into intestinal-type and diffuse-type. Intestinal-type gastric cancer is known to occur mainly from chronic gastritis caused by Helicobacter pylori (H. pylori) through atrophic gastritis and intestinal metaplasia, a precancerous change of the mucosa, whereas diffuse-type gastric cancer is caused by H. pylori infection, wherein active inflammation of the gastric mucosa occurs without precancerous changes in the mucosa. Compared with intestinal-type gastric cancer, it occurs at a young age, there is no difference in male to female ratio, or tends to occur more in women, and is more aggressive than intestinal-type gastric cancer. Intestinal-type gastric cancer is predominant in East Asian populations such as Koreans and Japanese, whereas diffuse-type gastric cancer has more uniform geographic distribution. In the present manuscript, I have reviewed diffuse-type gastric cancer, distinct from intestinal-type gastric cancer.

Characteristic endoscopic findings of gastric adenocarcinoma of fundic-gland mucosa type

BACKGROUND AND STUDY AIMS

Gastric adenocarcinoma of fundic-gland type (GA-FG) was first proposed as a new entity of gastric adenocarcinoma in 2010. Subsequently, gastric adenocarcinoma of fundic-gland mucosa type (GA-FGM) was reported as a subtype of gastric adenocarcinoma. This study aimed to investigate the endoscopic findings of GA-FGM and to evaluate the differences between GA-FGM and GA-FG.

PATIENTS AND METHODS

This was a single-center retrospective study. Participants were selected from patients with gastric cancer treated at Fukuoka University Chikushi Hospital, between September 2007 and May 2020. Patients histologically diagnosed with GA-FGM or GA-FG were enrolled, and endoscopic findings were analyzed in detail.

RESULTS

A total of 12 GA-FGM lesions (12 patients) and 14 GA-FG lesions (13 patients) were analyzed. The two lesion types showed similar features: most lesions were of elevated type, located in the upper stomach, and developed in the stomach without Helicobacter pylori infection. On conventional endoscopy using the dye-spraying method, well-demarcated fine granular areas were observed in 7 GA-FGM lesions (58%) but not in any GA-FG lesions, with a significant difference between the two groups (P = 0.001). Magnifying endoscopy with narrow-band imaging (NBI) showed that 11 GA-FGM lesions (92%) met the diagnostic criteria for cancer according to the vessel plus surface classification system, whereas none of the GA-FG lesions met the same criteria (0%, 0/14) (P = 0.001).

CONCLUSION

Our results suggest that magnifying endoscopy with NBI is a potentially useful method for the diagnosis of GA-FGM.

Endoscopic diagnosis and treatment of gastric dysplasia and early cancer: Current evidence and what the future may hold

Gastric cancer accounts for a significant proportion of worldwide cancer-related morbidity and mortality. The well documented precancerous cascade provides an opportunity for clinicians to detect and treat gastric cancers at an endoscopically curable stage. In high prevalence regions such as Japan and Korea, this has led to the implementation of population screening programs. However, guidelines remain ambiguous in lower prevalence regions. In recent years, there have been many advances in the endoscopic diagnosis and treatment of early gastric cancer and precancerous lesions. More advanced endoscopic imaging has led to improved detection and characterization of gastric lesions as well as superior accuracy for delineation of margins prior to resection. In addition, promising early data on artificial intelligence in gastroscopy suggests a future role for this technology in maximizing the yield of advanced endoscopic imaging. Data on endoscopic resection (ER) are particularly robust in Japan and Korea, with high rates of curative ER and markedly reduced procedural morbidity. However, there is a shortage of data in other regions to support the applicability of protocols from these high prevalence countries. Future advances in endoscopic therapeutics will likely lead to further expansion of the current indications for ER, as both technology and proceduralist expertise continue to grow.

Association between mucin phenotype and lesion border detection using acetic acid-indigo carmine chromoendoscopy in early gastric cancers

BACKGROUND

For successful treatment of early gastric cancers (EGCs), it is crucial to define the horizontal border of the lesion with high accuracy. Acetic acid-indigo carmine (AI) chromoendoscopy has been used to determine the horizontal border in EGCs, but this technique is less potent in certain situations. Mucin phenotype in gastric cancers refers to biological differences in precursor lesions and differences in histopathologic findings, and it might affect AI chromoendoscopy findings. We aimed to investigate the association between mucin phenotype and AI chromoendoscopy findings in EGCs.

METHODS

We prospectively evaluated 126 lesions in 126 patients with endoscopically diagnosed EGCs. Conventional endoscopy and AI chromoendoscopy findings of these lesions before treatment were prospectively analyzed. The border distinction between the lesion and surrounding mucosa was classified as distinct or indistinct on conventional endoscopy and AI chromoendoscopy, respectively. Mucin phenotypes were classified as gastric, intestinal, gastrointestinal, or null type by immunohistochemistry.

RESULTS

The lesion borders were distinct in 46.8% (59/126) of the lesions assessed using conventional endoscopy and in 73.0% (92/126) of those assessed with AI chromoendoscopy (p < 0.001). The border distinction rate of differentiated-type cancers on AI chromoendoscopy was significantly higher than that on conventional endoscopy (66/71 [93.0%] vs. 34/71 [47.9%], p < 0.001), but the border distinction rate of undifferentiated-type cancers on AI chromoendoscopy was not different from that on conventional endoscopy (26/55 [47.3%] vs. 25/55 [45.5%], p = 0.848). Compared with conventional endoscopy, AI chromoendoscopy identified borders in a significantly higher percentage of gastric, intestinal, and gastrointestinal mucin types; however, there was no difference in AI chromoendoscopy findings according to the mucin phenotype (p = 0.271).

CONCLUSION

AI chromoendoscopy was effective in horizontal border delineation in differentiated-type EGCs, but not in undifferentiated-type EGCs. Mucin phenotype had no effect on border distinction using AI chromoendoscopy.

Application of Current Image-Enhanced Endoscopy in Gastric Diseases

Image-enhanced endoscopy (IEE) plays an integral role in endoscopic diagnosis and treatment. IEE enables an early and accurate detection of cancer and characterization of lesions prior to therapeutic decisions. Ideal IEE can serve as an optical or digital chromoscopic endoscopy, as well as an optical biopsy that predicts exact histopathology. Several IEE modalities have recently been developed and are used in the clinical field. The stomach is a challenging organ for imaging because of its complex secretion function and status of Helicobacter pylori infection. Therefore, understanding the current IEE modalities for their clinical applicability in an evidence-based approach is warranted. Along with technology refinements, the new paradigm will be available for the diagnosis of gastric cancer or other conditions in the stomach in the near future.

Endoscopic Advances for Gastric Neoplasia Detection

This article explores advances in endoscopic neoplasia detection with supporting clinical evidence and future aims. The ability to detect early gastric neoplastic lesions amenable to curative endoscopic submucosal dissection provides the opportunity to decrease gastric cancer mortality rates. Newer imaging techniques offer enhanced views of mucosal and microvascular structures and show promise in differentiating benign from malignant lesions and improving targeted biopsies. Conventional chromoendoscopy is well studied and validated. Narrow band imaging demonstrates superiority over magnified white light. Autofluorescence imaging, i-scan, flexible spectral imaging color enhancement, and bright image enhanced endoscopy show promise but insufficient evidence to change current clinical practice.

Endoscopic Resection of Gastric Cancer

With improvements in the early detection of early gastric cancer (EGC) and advances in therapeutic techniques, endoscopic resection (ER) for EGC has become widely adopted in East Asian and Western countries. Endoscopic submucosal dissection has higher rates of en bloc, complete, and curative resections with lower rates of local recurrence than that of endoscopic mucosal resection. ER is a minimally invasive method with low morbidity that provides excellent outcomes. ER for EGC is a safe, effective method, preserving organ function and thus maintaining the patient's quality of life, and is recognized as the first-line treatment of EGC in selected patients.

[Clinical Practice Guideline for Endoscopic Resection of Early Gastrointestinal Cancer]

Although surgery was the standard treatment for early gastrointestinal cancers, endoscopic resection is now a standard treatment for early gastrointestinal cancers without regional lymph node metastasis. High-definition white light endoscopy, chromoendoscopy, and image-enhanced endoscopy such as narrow band imaging are performed to assess the edge and depth of early gastrointestinal cancers for delineation of resection boundaries and prediction of the possibility of lymph node metastasis before the decision of endoscopic resection. Endoscopic mucosal resection and/or endoscopic submucosal dissection can be performed to remove early gastrointestinal cancers completely by en bloc fashion. Histopathological evaluation should be carefully made to investigate the presence of risk factors for lymph node metastasis such as depth of cancer invasion and lymphovascular invasion. Additional treatment such as radical surgery with regional lymphadenectomy should be considered if the endoscopically resected specimen shows risk factors for lymph node metastasis. This is the first Korean clinical practice guideline for endoscopic resection of early gastrointestinal cancer. This guideline was developed by using mainly de novo methods and encompasses endoscopic management of superficial esophageal squamous cell carcinoma, early gastric cancer, and early colorectal cancer. This guideline will be revised as new data on early gastrointestinal cancer are collected.

Three-dimensional visualization improves the endoscopic diagnosis of superficial gastric neoplasia

BACKGROUND

Three-dimensional (3D) technology has been used in many fields, including flexible endoscopy. We evaluated the usefulness of 3D visualization for endoscopically diagnosing superficial gastric neoplasia.

METHODS

Twelve participants (4 novices, 4 trainees and 4 experts) evaluated two-dimensional (2D) and 3D endoscopic still images of 28 gastric neoplasias, obtained before ESD with white-light imaging (WLI) and narrow-band imaging (NBI). Assessments of the delineation accuracy of tumor extent and tumor morphology under 2D and 3D visualization were based on the histopathological diagnosis of ESD specimens. Participants answered visual analog scale (VAS) questionnaires (0-10, worst to best) concerning the (a) ease of recognition of lesion morphology, (b) lesion extent and (c) comprehensive endoscopic cognition under 2D and 3D visualization. The endpoints were the accuracy of tumor extent and morphology type and the degree of confidence in assessing (a)-(c).

RESULTS

The delineation accuracy of lesion extent [mean (95% confidence interval)] with WLI under 3D visualization [60.2% (56.1-64.3%)] was significantly higher than that under 2D visualization [52.3% (48.2-56.4%)] (P < 0.001). The accuracy with NBI under 3D visualization [70.3% (66.8-73.7%)] was also significantly higher than that under 2D visualization [64.2% (60.7-67.4%)] (P < 0.001). The accuracy of the morphology type with NBI under 3D visualization was significantly higher than that under 2D visualization (P = 0.004). The VAS for all aspects of endoscopic recognition under 3D visualization was significantly better than that under 2D visualization (P < 0.01).

CONCLUSIONS

Three-dimensional visualization can enhance the diagnostic quality for superficial gastric tumors.

Image-Enhanced Endoscopy and Its Corresponding Histopathology in the Stomach

In recent years, the technological innovation and progress of endoscopic equipment have been remarkable, and various endoscopic observation techniques have been developed. Among them, representative techniques are magnified observation and narrow-band imaging. Magnifying endoscopy with narrow-band imaging (M-NBI) can visualize superficial microanatomies in the stomach. The normal morphology of the microanatomy visualized using M-NBI differs according to the part of the stomach. The vessel plus surface (VS) classification system has been developed as a diagnostic criterion for early gastric cancer using M-NBI, and its usefulness has been proven. Based on the VS classification system, a magnifying endoscopy simple diagnostic algorithm for early gastric cancer (MESDA-G), a simplified algorithm used for early gastric cancer diagnosis, was created. We aimed to describe the anatomic structure of the stomach that can be viewed using M-NBI and outline the principles and clinical application of the VS classification system and MESDA-G. (Gut Liver 2021;15:-337)

Diagnostic Ability of Magnifying Narrow-Band Imaging for the Extent of Early Gastric Cancer: A Systematic Review and Meta-Analysis

Background

Accurate delineation of tumor margin is essential for complete resection of early gastric cancer (EGC). The objective of this study is to assess the performance of magnifying endoscopy with narrow-band imaging (ME-NBI) for the accurate demarcation of EGC margins.

Methods

We searched PubMed, EMBASE, Web of Science, and Cochrane Library databases up to March 2020 to identify eligible studies. The diagnostic accuracy of ME-NBI for EGC margins was calculated, and subgroup analyses were performed based on tumor size, depth of tumor invasion, tumor-occupied site, macroscopic type, histological type, Helicobacter pylori (H. pylori), and endoscopists' experience. Besides, we also evaluated the negative and positive resection rates of the horizontal margin (HM) of EGC after endoscopic submucosal dissection (ESD) and surgery.

Results

Ten studies comprising 1018 lesions were eligible in the databases. The diagnostic accuracy of ME-NBI for the demarcation of EGC margins was 92.4% (95% confidence interval (CI): 86.7%-96.8%). According to ME-NBI subgroup analyses, the rate of accurate evaluation of EGC margins was not associated with H. pylori infection status, tumor size, depth of tumor invasion, tumor-occupied site, macroscopic type, histological type, and endoscopists' experience, and no statistical differences were found in subgroup analyses. Moreover, the negative and positive resection rates of HM after ESD and surgery were 97.4% (95% CI: 92.1%-100%) and 2.6% (95% CI: 0.02%-7.9%), respectively.

Conclusions

ME-NBI enables a reliable delineation of the extent of EGC.

Systematic Endoscopic Approach to Early Gastric Cancer in Clinical Practice

Early gastric cancers (EGCs) are defined as gastric cancers confined to the mucosa or submucosa, regardless of regional lymph node metastasis. The proportion of EGCs has been increasing due to the increase in screening endoscopy for gastric cancers; therefore, the paradigm shift from surgical resection to endoscopic resection as a treatment modality for selected EGCs is accelerating. For successful endoscopic resection of EGCs, it is important to detect EGCs at an early stage and to accurately predict the histological type, depth of invasion, and horizontal margins of the tumor. The diagnostic process of EGCs can be divided into three steps: presence diagnosis, qualitative diagnosis, and quantitative diagnosis. The presence diagnosis of EGCs is mainly based on two endoscopic findings: a well-demarcated lesion and irregularity in the color/surface pattern. Qualitative diagnosis refers to the prediction of histological type, which is mainly possible based on the macroscopic shape and color of the lesion. Quantitative diagnosis of EGCs consists of predicting the depth of invasion by detailed examination of the macroscopic morphology and determining horizontal margins using chromoendoscopy. Although advanced diagnostic modalities, such as endosonography or magnifying endoscopy, are helpful for the qualitative and quantitative diagnosis of EGCs, these modalities are not available in most hospitals. Therefore, it is still very important to evaluate EGCs systematically during conventional endoscopy for successful endoscopic treatment.

Quality in diagnostic upper gastrointestinal endoscopy for the detection and surveillance of gastric cancer precursor lesions: Position paper of AEG, SEED and SEAP

This position paper, sponsored by the Asociación Española de Gastroenterología [Spanish Association of Gastroenterology], the Sociedad Española de Endoscopia Digestiva [Spanish Gastrointestinal Endoscopy Society] and the Sociedad Española de Anatomía Patológica [Spanish Anatomical Pathology Society], aims to establish recommendations for performing an high quality upper gastrointestinal endoscopy for the screening of gastric cancer precursor lesions (GCPL) in low-incidence populations, such as the Spanish population. To establish the quality of the evidence and the levels of recommendation, we used the methodology based on the GRADE system (Grading of Recommendations Assessment, Development and Evaluation). We obtained a consensus among experts using a Delphi method. The document evaluates different measures to improve the quality of upper gastrointestinal endoscopy in this setting and makes recommendations on how to evaluate and treat the identified lesions. We recommend that upper gastrointestinal endoscopy for surveillance of GCPL should be performed by endoscopists with adequate training, administering oral premedication and use of sedation. To improve the identification of GCPL, we recommend the use of high definition endoscopes and conventional or digital chromoendoscopy and, for biopsies, NBI should be used to target the most suspicious areas of intestinal metaplasia. Regarding the evaluation of visible lesions, the risk of submucosal invasion should be evaluated with magnifying endoscopes and endoscopic ultrasound should be reserved for those with suspected deep invasion. In lesions amenable to endoscopic resection, submucosal endoscopic dissection is considered the technique of choice.

Guidelines for endoscopic submucosal dissection and endoscopic mucosal resection for early gastric cancer (second edition)

In response to the rapid and wide acceptance and use of endoscopic treatments for early gastric cancer, the Japan Gastroenterological Endoscopy Society, in collaboration with the Japanese Gastric Cancer Association, produced "Guidelines for Endoscopic Submucosal Dissection and Endoscopic Mucosal Resection for Early Gastric Cancer" in 2014, as a set of basic guidelines in accordance with the principles of evidence-based medicine. At the time, a number of statements had to be established by consensus (the lowest evidence level), as evidence levels remained low for many specific areas in this field. However, in recent years, the number of well-designed clinical studies has been increasing. Based on new findings, we have issued the revised second edition of the above guidelines that cover the present state of knowledge. These guidelines are divided into the following seven categories: indications, preoperative diagnosis, techniques, evaluation of curability, complications, long-term postoperative surveillance, and histology.

Early gastric cancer detection in high-risk patients: a multicentre randomised controlled trial on the effect of second-generation narrow band imaging

OBJECTIVE

Early detection of gastric cancer has been the topic of major efforts in high prevalence areas. Whether advanced imaging methods, such as second-generation narrow band imaging (2G-NBI) can improve early detection, is unknown.

DESIGN

This open-label, randomised, controlled tandem trial was conducted in 13 hospitals. Patients at increased risk for gastric cancer were randomly assigned to primary white light imaging (WLI) followed by secondary 2G-NBI (WLI group: n=2258) and primary 2G-NBI followed by secondary WLI (2G-NBI group: n=2265) performed by the same examiner. Suspected early gastric cancer (EGC) lesions in both groups were biopsied. Primary endpoint was the rate of EGC patients in the primary examination. The main secondary endpoint was the positive predictive value (PPV) for EGC in suspicious lesions detected (primary examination).

RESULTS

EGCs were found in 44 (1.9%) and 53 (2.3%; p=0.412) patients in the WLI and 2G-NBI groups, respectively, during primary EGD. In a post hoc analysis, the overall rate of lesions detected at the second examination was 25% (n=36/145), with no significant differences between groups. PPV for EGC in suspicious lesions was 13.5% and 20.9% in the WLI (50/371 target lesions) and 2G-NBI groups (59/282 target lesions), respectively (p=0.015).

CONCLUSION

The overall sensitivity of primary endoscopy for the detection of EGC in high-risk patients was only 75% and should be improved. 2G-NBI did not increase EGC detection rate over conventional WLI. The impact of a slightly better PPV of 2G-NBI has to be evaluated further.

TRIAL REGISTRATION NUMBER

UMIN000014503.

NBI utility in oncologic surgery: An organ by organ review

The main aims of the oncologic surgeon should be an early tumor diagnosis, complete surgical resection, and a careful post-treatment follow-up to ensure a prompt diagnosis of recurrence. Radiologic and endoscopic methods have been traditionally used for these purposes, but their accuracy might sometimes be suboptimal. Technological improvements could help the clinician during the diagnostic and therapeutic management of tumors. Narrow band imaging (NBI) belongs to optical image techniques, and uses light characteristics to enhance tissue vascularization. Because neoangiogenesis is a fundamental step during carcinogenesis, NBI could be useful in the diagnostic and therapeutic workup of tumors. Since its introduction in 2001, NBI use has rapidly spread in different oncologic specialties with clear advantages. There is an active interest in this topic as demonstrated by the thriving literature. It is unavoidable for clinicians to gain in-depth knowledge about the application of NBI to their specific field, losing the overall view on the topic. However, by looking at other fields of application, clinicians could find ideas to improve NBI use in their own specialty. The aim of this review is to summarize the existing literature on NBI use in oncology, with the aim of providing the state of the art: we present an overview on NBI fields of application, results, and possible future improvements in the different specialties.

Near-focus magnification and second-generation narrow-band imaging for early gastric cancer in a randomized trial

BACKGROUND

Magnifying endoscopy with narrow-band imaging (NBI) is effective for the diagnosis of early gastric cancer (EGC). However, magnifying endoscopy is not yet popular globally because of the required level of skill and lack of availability. To overcome these problems, dual-focus endoscopy (standard- and near-focus (NF) modes) has been developed. In this study, we evaluated the diagnostic performance of NF with second-generation (2G)-NBI (NF-NBI) for the diagnosis of EGC.

METHODS

This was a secondary analysis of a multicenter randomized controlled trial of 4523 high-risk patients who underwent gastroscopies at 13 institutions in Japan. Patients were randomly assigned to white-light imaging (WLI) followed by 2G-NBI or to 2G-NBI followed by WLI. Lesions suspicious for EGC, newly detected by non-magnifying WLI or 2G-NBI, were subsequently observed with NF-NBI. All detected lesions were biopsied or resected. The diagnostic performance of NF-NBI was compared with the final histology.

RESULTS

A total of 870 detected lesions (145 EGC, 725 non-EGC) were analyzed. Overall diagnostic performance for EGC using NF-NBI was accuracy 87.7%, sensitivity 60.7%, specificity 93.1%, positive predictive value 63.8%, and negative predictive value 92.2%. There were no significant differences in diagnostic performance between lesions detected by WLI or 2G-NBI. For lesions diagnosed with high (333 lesions) and low (537 lesions) confidences, accuracy was 92.2% and 84.9%, sensitivity was 64.7% and 58.5%, and specificity was 90.5% and 88.8%, respectively.

CONCLUSION

The diagnostic performance of NF-NBI is good and acceptable for diagnosis of EGC in combination with either WLI or 2G-NBI.

A "Just Enough" Gross Proximal Margin Length Ensuring Pathologically Complete Resection in Distal Gastrectomy for Gastric Cancer

Introduction

The objective of this study is to determine a "just enough" gross proximal margin (PM) length to ensure a pathologically negative PM in distal gastrectomy for gastric cancer. There is a discrepancy between the gross and pathological proximal boundaries of gastric cancer. We must transect the stomach maintaining some safety margins to obtain a pathologically negative PM. However, we have no standard to indicate where to transect the stomach.

Methods

Patients undergoing distal gastrectomy for gastric cancer were enrolled. A new parameter named ΔPM, which corresponded to the pathological extension proximal to the gross tumor boundary toward the resection stump, was evaluated. The number of patients was counted in each ΔPM range of 1-cm increments. The maximum ΔPM was defined as the first value at which the number of patients became 0, and it was determined as the recommended gross PM length for each disease type.

Results

In cT1, 259 and 330 patients were assigned to differentiated (Dif) and undifferentiated types (Und), respectively. The maximum ΔPM was 20 mm for Dif and 40 mm for Und. In cT2-4, 194 and 490 patients were assigned to the expansive (Exp) and infiltrative (Inf) growth types. The maximum ΔPM was 30 mm for Exp. The maximum ΔPM was 50 mm for Inf of less than 80 mm and 60 mm for Inf of 80 mm or more.

Conclusions

A newly recommended gross PM length to ensure pathologically negative PMs in distal gastrectomy for each gastric cancer type was determined.

Case series of three patients with hereditary diffuse gastric cancer in a single family: Three case reports and review of literature

BACKGROUND

Hereditary diffuse gastric cancer (HDGC) is a familial cancer syndrome often associated with germline mutations in the CDH1 gene. However, the frequency of CDH1 mutations is low in patients with HDGC in East Asian countries. Herein, we report three cases of HDGC harboring a missense CDH1 variant, c.1679C>G, from a single Japanese family.

CASE SUMMARY

A 26-year-old female (Case 1) and a 51-year-old male (father of Case 1), who had a strong family history of gastric cancer, were diagnosed with advanced diffuse gastric cancer. After genetic counselling, a 25-year-old younger brother of Case 1 underwent surveillance esophagogastroduodenoscopy that detected small signet ring cell carcinoma foci as multiple pale lesions in the gastric mucosa. Genetic analysis revealed a CDH1 c.1679C>G variant in all three patients.

CONCLUSION

It is important for individuals suspected of having HDGC to be actively offered genetics evaluation. This report will contribute to an increased awareness of HDGC.

Narrowband imaging with near-focus magnification for discriminating the gastric tumor margin before endoscopic resection: A prospective randomized multicenter trial

BACKGROUND AND AIM

This study investigated the usefulness of near-focus narrowband imaging (NF-NBI) for determining gastric tumor margins compared with indigo carmine chromoendoscopy (ICC) before endoscopic submucosal dissection (ESD).

METHODS

This prospective randomized controlled trial was conducted at seven teaching hospitals in Korea. Patients with gastric adenoma or differentiated adenocarcinoma undergoing ESD were enrolled and randomly assigned to the NF-NBI or ICC group. A marking dot was placed on the most proximal margin of the tumor before ESD. The primary endpoint was delineation accuracy, which was defined as presence of marking dots within 1 mm of the tumor margin under microscopic observation.

RESULTS

A total of 200 patients in the NF-NBI group and 195 patients in the ICC group were included. The delineation accuracy rate was 84.5% in the NF-NBI group and 81.0% in the ICC group (P = 0.44). However, the distance from the marking dot to the margin of the tumor was significantly shorter in the NF-NBI group than in the ICC group (0.8 ± 0.8 vs 1.2 ± 1.3 mm, P < 0.01). Even after adjustment of other clinicopathological factors that are associated with difficulty of tumor delineation, NF-NBI did not show significant association with accurate delineation (odds ratio of 0.86, P = 0.60).

CONCLUSIONS

This prospective multicenter study showed that NF-NBI is not superior to ICC in terms of accurately delineating gastric tumors (NCT02661945).

Clinical practice guideline for endoscopic resection of early gastrointestinal cancer

Although surgery was the standard treatment for early gastrointestinal cancers, endoscopic resection is now a standard treatment for early gastrointestinal cancers without regional lymph node metastasis. High-definition white light endoscopy, chromoendoscopy, and image-enhanced endoscopy such as narrow band imaging are performed to assess the edge and depth of early gastrointestinal cancers for delineation of resection boundaries and prediction of the possibility of lymph node metastasis before the decision of endoscopic resection. Endoscopic mucosal resection and/or endoscopic submucosal dissection can be performed to remove early gastrointestinal cancers completely by en bloc fashion. Histopathological evaluation should be carefully made to investigate the presence of risk factors for lymph node metastasis such as depth of cancer invasion and lymphovascular invasion. Additional treatment such as radical surgery with regional lymphadenectomy should be considered if the endoscopically resected specimen shows risk factors for lymph node metastasis. This is the first Korean clinical practice guideline for endoscopic resection of early gastrointestinal cancer. This guideline was developed by using mainly de novo methods and encompasses endoscopic management of superficial esophageal squamous cell carcinoma, early gastric cancer, and early colorectal cancer. This guideline will be revised as new data on early gastrointestinal cancer are collected.

Diagnostic limitations of magnifying endoscopy with narrow-band imaging in early gastric cancer

Background and study aims  Magnifying endoscopy with narrow band imaging (M-NBI) has made a huge contribution to endoscopic diagnosis of early gastric cancer (EGC). However, we sometimes encountered false-negative cases with M-NBI diagnosis (i. e., M-NBI diagnostic limitation lesion: M-NBI-DLL). However, clinicopathological features of M-NBI-DLLs have not been well elucidated. We aimed to clarify the clinicopathological features and histological reasons of M-NBI-DLLs. Patients and methods  In this single-center retrospective study, M-NBI-DLLs were extracted from 456 EGCs resected endoscopically at our hospital. We defined histological types of M-NBI-DLLs and analyzed clinicopathologically to clarify histological reasons of M-NBI-DLLs. Results  Of 456 EGCs, 48 lesions (10.5 %) of M-NBI-DLLs were enrolled. M-NBI-DLLs was classified into four histological types as follows: gastric adenocarcinoma of fundic-gland type (GA-FG, n = 25), gastric adenocarcinoma of fundic-gland mucosal type (GA-FGM, n = 1), differentiated adenocarcinoma (n = 14), and undifferentiated adenocarcinoma (n = 8). Thirty-nine lesions of M-NBI-DLLs were H. pylori -negative gastric cancers (39/47, 82.9 %). Histological reasons for M-NBI-DLLs were as follows: 1) completely covered with non-neoplastic mucosa (25/25 GA-FG, 8/8 undifferentiated adenocarcinoma); 2) well-differentiated adenocarcinoma with low-grade atypia (1/1 GA-FGM, 14/14 differentiated adenocarcinoma); 3) similarity of surface structure (10/14 differentiated adenocarcinoma); and 4) partially covered and/or mixed with a non-neoplastic mucosa (1/1 GA-FGM, 6/14 differentiated adenocarcinoma). Conclusions  Diagnostic limitations of M-NBI depend on four distinct histological characteristics. For accurate diagnosis of M-NBI-DLLs, it may be necessary to fully understand endoscopic features of these lesions using white light imaging and M-NBI based on these histological characteristics and to take a precise biopsy.

A deep learning method for delineating early gastric cancer resection margin under chromoendoscopy and white light endoscopy

BACKGROUND

Accurate delineation of cancer margins is critical for endoscopic curative resection. This study aimed to train and validate real-time fully convolutional networks for delineating the resection margin of early gastric cancer (EGC) under indigo carmine chromoendoscopy (CE) or white light endoscopy (WLE), and evaluated its performance and that of magnifying endoscopy with narrow-band imaging (ME-NBI).

METHODS

We collected CE and WLE images of EGC lesions to train fully convolutional networks ENDOANGEL. ENDOANGEL was tested both on stationary images and endoscopic submucosal dissection (ESD) videos. The accuracy and reliability of ENDOANGEL and NBI-dependent delineation were further evaluated by a novel endoscopy-pathology point-to-point marking.

RESULTS

ENDOANGEL had an accuracy of 85.7% in the CE images and 88.9% in the WLE images under an overlap ratio threshold of 0.60 in comparison with the manual markers labeled by the experts. In the ESD videos, the resection margins predicted by ENDOANGEL covered all areas of high-grade intraepithelial neoplasia and cancers. The minimum distance between the margins predicted by ENDOANGEL and the histological cancer boundary was 3.44 ± 1.45 mm which outperformed the resection margin based on ME-NBI.

CONCLUSIONS

ENDOANGEL has the potential to assist endoscopists in delineating the resection extent of EGC under CE or WLE during ESD.

Efficacy and Feasibility of Magnifying Blue Laser Imaging without Biopsy Confirmation for the Diagnosis of the Demarcation of Gastric Tumors: A Randomized Controlled Study

BACKGROUND

Accurate diagnosis of the demarcation line (DL) of gastric tumors is essential for curative complete resection by endoscopic submucosal dissection (ESD). It is controversial to perform only magnifying endoscopy for diagnosing the DL of gastric tumors prior to ESD. This study aimed to evaluate the diagnostic accuracy for the DL of gastric adenomas and well-differentiated adenocarcinomas using only magnifying blue laser imaging (M-BLI) compared with that using both M-BLI and biopsy confirmation.

METHODS

In this prospective, single-center study, 96 well-differentiated adenocarcinomas and 32 gastric adenomas were enrolled between July 2015 and December 2016. A total of 122 lesions with a clear DL on M-BLI were randomly allocated to undergo M-BLI only (the M-BLI group) or M-BLI with biopsy confirmation (the M-BLI-BC group), performed as biopsies in 4 directions from noncancerous tissues ≈ 5 mm outside the lesion before ESD. The primary end point was to clarify the noninferiority of M-BLI without biopsy confirmation compared with that with biopsy confirmation, in terms of the diagnostic accuracy and complete resection.

RESULTS

There were no significant differences in sex, median age, color, circumference, macroscopic type, biopsy-based diagnosis, and Helicobacter pylori infection between the 2 groups. The diagnostic accuracy for the DL was 100 and 95.0% and the complete resection was 100 and 100% in the M-BLI and M-BLI-BC groups, respectively.

CONCLUSION

The diagnostic ability of M-BLI is excellent in diagnosing the demarcation of gastric adenoma and well-differentiated adenocarcinoma. Biopsy confirmation is not needed for these lesions with a clear DL by M-BLI.

Clinical applicability of gastroscopy with narrow-band imaging for the diagnosis of Helicobacter pylori gastritis, precancerous gastric lesion, and neoplasia

Premalignant gastric lesions such as atrophic gastritis and intestinal metaplasia frequently occur in subjects with long-term Helicobacter pylori (H. pylori) infection. The regular arrangement of collecting venules (RAC) is seen in the normal gastric corpus, whereas mucosal swelling and redness without RAC are observed in H. pylori-infected mucosa. Despite successful H. pylori eradication, the presence of atrophic gastritis and/or gastric intestinal metaplasia (GIM) is a risk factor for gastric cancer. With the development of advanced imaging technologies, recent studies have reported the usefulness of narrow-band imaging (NBI) for endoscopic diagnosis of atrophic gastritis and GIM. Using NBI endoscopy with magnification (M-NBI), atrophic gastritis is presented as irregular coiled microvessels and loss of gastric pits. Typical M-NBI endoscopic findings of GIM are a light blue crest and a white opaque substance. Based on the microvascular patterns, fine network, core vascular, and unclear patterns are useful for predicting gastric dysplasia in polypoid lesions. For diagnosis of early gastric cancer (EGC), a systematic classification using M-NBI endoscopy has been proposed on the basis of the presence of a demarcation line and an irregular microvascular/microsurface pattern. Furthermore, M-NBI endoscopy has been found to be more accurate for determining the horizontal margin of EGC compared to conventional endoscopy. In this review, we present up-to-date results on the clinical usefulness of gastroscopy with NBI for the diagnosis of H. pylori gastritis, precancerous gastric lesion, and neoplasia.

Guidelines for endoscopic diagnosis of early gastric cancer

The Japan Gastroenterological Endoscopy Society developed the Guideline for Endoscopic Diagnosis of Early Gastric Cancer based on scientific methods. Endoscopy for the diagnosis of early gastric cancer has been acknowledged as a useful and highly precise examination, and its use has become increasingly more common in recent years. However, the level of evidence in this field is low, and it is often necessary to determine recommendations based on expert consensus only. This clinical practice guideline consists of the following sections to provide the current guideline: [I] Risk stratification of gastric cancer before endoscopic examination, [II] Detection of early gastric cancer, [III] Qualitative diagnosis of early gastric cancer, [IV] Diagnosis to choose the therapeutic strategy for gastric cancer, [V] Risk stratification after endoscopic examination, and [VI] Surveillance of early gastric cancer.

Clinical Practice Guideline for Endoscopic Resection of Early Gastrointestinal Cancer

Although surgery was the standard treatment for early gastrointestinal cancers, endoscopic resection is now a standard treatment for early gastrointestinal cancers without regional lymph node metastasis. High-definition white light endoscopy, chromoendoscopy, and image-enhanced endoscopy such as narrow band imaging are performed to assess the edge and depth of early gastrointestinal cancers for delineation of resection boundaries and prediction of the possibility of lymph node metastasis before the decision of endoscopic resection. Endoscopic mucosal resection and/or endoscopic submucosal dissection can be performed to remove early gastrointestinal cancers completely by en bloc fashion. Histopathological evaluation should be carefully made to investigate the presence of risk factors for lymph node metastasis such as depth of cancer invasion and lymphovascular invasion. Additional treatment such as radical surgery with regional lymphadenectomy should be considered if the endoscopically resected specimen shows risk factors for lymph node metastasis. This is the first Korean clinical practice guideline for endoscopic resection of early gastrointestinal cancer. This guideline was developed by using mainly de novo methods and encompasses endoscopic management of superficial esophageal squamous cell carcinoma, early gastric cancer, and early colorectal cancer. This guideline will be revised as new data on early gastrointestinal cancer are collected.