Endoscopic submucosal dissection for early gastric cancer: a large-scale feasibility study

Novel gastric endoscopic submucosal dissection training model enhances the endoscopic submucosal dissection skills of trainees: a multicenter comparative study

BACKGROUND

Endoscopic submucosal dissection (ESD) requires high endoscopic technical skills, and trainees should develop effective training methods. In collaboration with KOTOBUKI Medical, we developed the G-Master, which is a non-animal training model that can simulate various parts of gastric ESD. We aimed to clarify the usefulness of the G-Master for inexperienced ESD trainees.

METHODS

We collected data from the first 5 gastric ESD cases conducted by 15 inexperienced ESD trainees at 5 participating centers between 2018 and 2022. The participants were divided into two groups: the G-Master training and non-G-Master training groups. Outcome measurements, such as procedural speed, perforation rate, self-completion rate, and en bloc resection rate, were compared between the two groups retrospectively.

RESULTS

A total of 75 gastric ESD cases were included in this study. The G-Master training group included 25 cases performed by 5 trainees, whereas the non-G-Master training group included 50 cases performed by 10 trainees. The median procedural speed for all cases was significantly faster in the G-Master training group than in the non-G-Master training group. Moreover, the procedural speed was linearly improved from the initial to the last cases in the lower location in the G-Master training group compared with the non-G-Master training group. In addition, although there was no significant difference, the G-Master training group showed lower rates of perforation and a lesser need to transition to expert operators than the non-G-Master training group.

CONCLUSION

The G-Master could improve the ESD skills of inexperienced ESD trainees.

A Prospective Observational Study on Gastric Endoscopic Submucosal Dissection under Continuous Administration of Antithrombotic Agents

Background: This study aimed to assess the completion rate and postoperative bleeding incidence of endoscopic submucosal dissection (ESD) for gastric tumors under continuous antithrombotic therapy. Methods: A prospective observational study was conducted including 88 patients with 100 gastric lesions who underwent gastric endoscopic submucosal dissection (ESD) and received continuous antithrombotic therapy. Additionally, retrospective data on gastric ESD in 479 patients with 534 lesions who did not receive antithrombotic therapy were collected for comparison. Results: The en bloc resection rates (100% in the continuous antithrombotic therapy group vs. 100% in the non-antithrombotic therapy group) and complete resection rates (97.0% vs. 96.3%, respectively) were high and comparable between the groups. No significant differences were found in the specimen size or procedure time. Perforation rates were low (0% vs. 2.3%, respectively) and were not significantly different between the groups. However, postoperative bleeding occurred significantly more frequently in the continuous antithrombotic therapy group (10.2% vs. 4.2%, respectively) than in the non-antithrombotic therapy group. The subgroup analysis revealed a higher incidence of postoperative bleeding in patients receiving thienopyridine derivatives. Conclusions: Continuous administration of antithrombotic agents, especially thienopyridines, increased the risk of postprocedural hemorrhage following gastric ESD. These findings support the need for careful consideration of pharamcological management before ESD, aligning with the current guidelines.

A genome-wide study of gastric intramucosal neoplasia based on somatic copy number alterations, gene mutations, and mRNA expression patterns

We performed comprehensive analyses of somatic copy number alterations (SCNAs) and gene expression profiles of gastric intramucosal neoplasia (IMN) using array-based methods in 97 intestinal-type IMNs, including 39 low-grade dysplasias (LGDs), 37 high-grade dysplasias (HGDs), and 26 intramucosal carcinomas (IMCs) with stromal invasion of the lamina propria to identify the molecular mechanism of IMN. In addition, we examined gene mutations using gene panel analyses. We used cluster analyses for exclusion of arbitrariness to identify SCNA patterns and expression profiles. IMNs were classified into two distinct subgroups (subgroups 1 and 2) based on SCNA patterns. Subgroup 1 showed a genomic stable pattern due to the low frequency of SCNAs, whereas subgroup 2 exhibited a chromosomal instability pattern due to the high frequencies of SCNAs and TP53 mutations. Interestingly, although the frequencies of LGD and HGD were significantly higher in subgroup 1 than in subgroup 2, IMC was commonly found in both types. Although the expression profiles of specific mRNAs could be used to categorise subgroups 1 and 2, no clinicopathological findings correlated with either subgroup. We examined signalling pathways specific to subgroups 1 and 2 to identify the association of each subgroup with signalling pathways based on gene ontology tree visualisation: subgroups 1 and 2 were associated with haem metabolism and chromosomal instability, respectively. These findings reveal a comprehensive genomic landscape that highlights the molecular complexity of IMNs and provide a road map to facilitate our understanding of gastric IMNs.

Potential of Direct Oral Anticoagulant in Bleeding After Gastric Endoscopic Submucosal Dissection: A Systematic Review and Meta-Analysis

BACKGROUND AND AIMS

An increasing number of patients are undergoing gastric endoscopic submucosal dissection (ESD) with active prescriptions of direct oral anticoagulants (DOACs). Only a few reports have described the effects of DOAC intake on postoperative bleeding. We aimed to investigate the bleeding risk associated with DOACs after gastric ESD.

METHODS

Clinical studies published up to April 2022 showing bleeding rates after gastric ESD in patients taking DOACs were identified using electronic searches. The primary outcome was the rate of bleeding after gastric ESD in patients receiving DOACs compared to those not receiving antithrombotic therapy. In this meta-analysis, odds ratios (ORs) were calculated and pooled using a random effects model. The secondary outcome was the difference in the bleeding rate between patients treated with DOACs and those treated with warfarin and antiplatelet drugs.

RESULTS

Seven studies were included in this meta-analysis. The pooled analysis showed that DOACs had a higher bleeding rate than non-thrombotic therapy (17.0% vs. 3.4%; OR 5.72; 95% confidence interval [CI], 4.33-7.54; I2 = 0%). The bleeding risk associated with DOAC administration was similar to that associated with warfarin (17.0% vs. 20.0%; OR 0.83; 95% CI 0.59-1.18; I2 = 0%), whereas it was higher than that associated with antiplatelet administration (16.9% vs. 11.0%; OR 1.63; 95% CI 1.14-2.34; I2 = 8%).

CONCLUSIONS

This meta-analysis reveals that the bleeding risk of DOACs is higher than that of non-antithrombotics and antiplatelets, whereas it is comparable to that of warfarin. Gastric ESD in patients on anticoagulants requires careful postoperative management.

Sprayable tissue adhesive microparticle-magnetic nanoparticle composites for local cancer hyperthermia

Incomplete removal of early-stage gastrointestinal cancers by endoscopic treatments often leads to recurrence induced by residual cancer cells. To completely remove or kill cancer tissues and cells and prevent recurrence, chemotherapy, radiotherapy, and hyperthermia using biomaterials with drugs or nanomaterials are usually administered following endoscopic treatments. However, there are few biomaterials that can be applied using endoscopic devices to locally kill cancer tissues and cells. We previously reported that decyl group-modified Alaska pollock gelatin-based microparticles (denoted C10MPs) can adhere to gastrointestinal tissues under wet conditions through the formation of a colloidal gel driven by hydrophobic interactions. In this study, we combined C10MPs with superparamagnetic iron oxide nanoparticles (SPIONs) to develop a sprayable heat-generating nanomaterial (denoted SP/C10MP) for local hyperthermia of gastrointestinal cancers. The rheological property, tissue adhesion strength, burst strength, and underwater stability of SP/C10MP were improved through decyl group modification and SPION addition. Moreover, SP/C10MP that adhered to gastrointestinal tissues formed a colloidal gel, which locally generated heat in response to an alternating magnetic field. SP/C10MP successfully killed cancer tissues and cells in colon cancer-bearing mouse models in vitro and in vivo. Therefore, SP/C10MP has the potential to locally kill residual cancer tissues and cells after endoscopic treatments.

Risk assessment of metachronous gastric cancer after endoscopic submucosal dissection based on endoscopic intestinal metaplasia

Background and Aim

The incidence of metachronous gastric cancer (MGC) after endoscopic treatment for early gastric cancer (EGC) is high, but a method of risk assessment for MGC based on endoscopic findings has not been established. In this study, we focused on endoscopic intestinal metaplasia (IM) and investigated the risk for MGC after endoscopic submucosal dissection (ESD) for EGC.

Methods

This retrospective observational study involved patients who underwent curative ESD for EGC from April 2015 to January 2021. We assessed endoscopic IM using the pretreatment endoscopic examination images. The severity of endoscopic IM was classified into four levels: 0 (none), 1 (mild), 2 (moderate), and 3 (severe). Four different gastric areas were evaluated. We divided the patients into a low-score group and a high-score group, and compared the cumulative incidence of MGC.

Results

In total, 156 patients who met the inclusion criteria were followed up for at least 12 months after ESD, and MGC developed in 14 patients during a mean period oof 41.5 months. The endoscopic IM scores in the lesser curvature of the antrum, lesser curvature of the corpus, and greater curvature of the corpus were higher in patients with MGC than in those without MGC. In the corpus, the 5-year cumulative incidence of MGC was significantly higher in the high-score group than in the low-score group (29.8% vs 10.0%, P = 0.004).

Conclusion

The severity of endoscopic corpus IM was associated with MGC. Thus, patients with severe corpus IM at the time of ESD require careful examination and intensive follow-up.

Treatment for T1 colorectal cancers substratified by site and size: "horses for courses"

Background

Owing to advances in diagnostic technology, the diagnosis of T1 colorectal cancers (CRCs) continues to increase. However, the optimal management of T1 CRCs in the Western Hemisphere remains unclear due to limited population-based data directly comparing the efficacy of endoscopic therapy (ET) and surgical resection (SR). The purpose of this study was to report outcome data from a large Western cohort of patients who underwent ET or SR for early CRCs.

Methods

The SEER-18 database was used to identify patients with T1 CRCs diagnosed from 2004 to 2018 treated with ET or SR. Multivariable logistic regression models were employed to identify variables related to lymph node metastasis (LNM). Rates of ET and 1-year relative survival were calculated for each year. Effect of ET or SR on overall survival and cancer-specific survival was compared using Kaplan-Meier method stratified by tumor size and site.

Results

A total of 28,430 T1 CRCs patients were identified from 2004 to 2018 in US, with 22.7% undergoing ET and 77.3% undergoing SR. The incidence of T1 CRCs was 6.15 per 100,000 person-years, with male patients having a higher incidence. Left-sided colon was the most frequent location of tumors. The utilization of ET increased significantly from 2004 to 2018, with no significant change in 1-year relative survival rate. Predictors of LNM were age at diagnosis, sex, race, tumor size, histology, grade, and location. The 5-year relative survival rates were 91.4 and 95.4% for ET and SR, respectively. Subgroup analysis showed that OS and CSS were similar between ET and SR in T1N0M0 left-sided colon cancers with tumors 2 cm or less and in rectal cancers with tumors 1 cm or less.

Conclusion

Our study showed that ET was feasible and safe for patients with left-sided T1N0M0 colon cancers and tumors of 2 cm or less, as well as T1N0M0 rectal cancers and tumors of 1 cm or less. Therefore, the over- and under-use of ET should be avoided by carefully selecting patients based on tumor size and site.

Effect of Sarcopenia on Pneumonia after Endoscopic Submucosal Resection in Patients Aged ≥65 Years: A Retrospective Study

We aimed to investigate the association between sarcopenia and incidence of pneumonia after endoscopic submucosal dissection (ESD) in patients aged ≥65 years. Patients with (n = 1571) and without sarcopenia (n = 1718) who underwent ESD for gastric neoplasm were included. Propensity score matching (PSM) was performed between the groups (n = 785) at a 1:1 ratio. The primary endpoint was the effect of sarcopenia on the incidence of pneumonia after ESD. Among the included patients, 2.2% (n = 71) developed pneumonia after ESD. After PSM, the incidence rate of pneumonia was significantly higher in patients with sarcopenia than that in patients without sarcopenia (p = 0.024). Sarcopenia and age ≥73 years were significantly associated with the incidence of pneumonia (sarcopenia and age <73 years, odd ratio (OR) = 1.22 [95% confidence interval (CI): 0.46-3.22]; sarcopenia and age ≥73 years, OR = 3.92 [95% CI: 1.79-8.74]). Patients with sarcopenia had an increased risk of developing pneumonia after ESD, even after adjusting for other factors, resulting in a higher incidence of leukocytosis and a longer duration of post-ESD hospitalization. The combination of sarcopenia and age ≥73 years could be an effective predictive factor for screening high-risk groups for pneumonia after ESD.

Clinical and endoscopic features of metachronous gastric cancer with possible lymph node metastasis after endoscopic submucosal dissection and Helicobacter pylori eradication

BACKGROUND

Several studies have reported the metachronous gastric cancers (MGCs) with possible lymph node metastasis (LNM) after endoscopic submucosal dissection (ESD) and Helicobacter pylori (H. pylori) eradication in which a curative ESD had not been achieved. There have been no published reports of evaluations of the features of patients with MGC with possible LNM after ESD and H. pylori eradication.

METHODS

We identified 264 patients with 369 MGCs after H. pylori eradication among the 4354 patients with 5059 early gastric cancers (EGCs) who underwent ESD between 1999 and 2017 and divided them into two groups: patients with MGCs with possible LNM (Group I) and patients with MGCs undergone curative ESD (Group II). We retrospectively compared the features of patients with MGCs and patients with EGCs at index ESD in the two groups.

RESULT

Group I consisted of 20 patients with 21 MGCs, and Group II consisted of 244 patients with 348 MGCs. Group I lesions were significantly more common in the posterior wall than in the lesser curvature (odds ratio [OR] = 3.97; 95% confidence intervals [CI] 1.20-13.10). Development of Group I was significantly more common in patients with a body mass index (BMI) < 19.0 kg/m2 than in patients with a BMI ≥ 19.0 kg/m2 at index ESD (OR = 4.44; 95% CI 1.30-15.20).

CONCLUSIONS

During surveillance endoscopy after gastric ESD and H. pylori eradication, the posterior wall should be carefully examined to detect MGCs early. Lower BMI may be associated with the development of MGCs with possible LNM.

Diagnostic accuracy of frozen section biopsy for early gastric cancer extent during endoscopic submucosal dissection: a prospective study

BACKGROUND

Accurate diagnosis of the lateral extent of early gastric cancer during endoscopic submucosal dissection (ESD) is crucial to achieve negative resection margins. Similar to intraoperative consultation with a frozen section in surgery, rapid frozen section diagnosis with endoscopic forceps biopsy may be useful in assessing tumor margins during ESD. This study aimed to evaluate the diagnostic accuracy of frozen section biopsy.

METHODS

We prospectively enrolled 32 patients undergoing ESD for early gastric cancer. Biopsy samples for the frozen sections were randomly collected from fresh resected ESD specimens before formalin fixation. Two different pathologists independently diagnosed 130 frozen sections as "neoplasia," "negative for neoplasia," or "indefinite for neoplasia," and the frozen section diagnosis was compared with the final pathological results of the ESD specimens.

RESULTS

Among the 130 frozen sections, 35 were from cancerous areas, and 95 were from non-cancerous areas. The diagnostic accuracies of the frozen section biopsies by the two pathologists were 98.5 and 94.6%, respectively. Cohen's kappa coefficient of diagnoses by the two pathologists was 0.851 (95% confidence interval: 0.837-0.864). Incorrect diagnoses resulted from freezing artifacts, a small volume of tissue, inflammation, the presence of well-differentiated adenocarcinoma with mild nuclear atypia, and/or tissue damage during ESD.

CONCLUSIONS

Pathological diagnosis of frozen section biopsy is reliable and can be applied as a rapid frozen section diagnosis for evaluating the lateral margins of early gastric cancer during ESD.

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.

Metachronous Multiple Gastric Cancer Discovered as Endoscopic Curability C2 during Regular Follow-Up after Gastric Endoscopic Submucosal Dissection

INTRODUCTION

The objective of this study was to clarify characteristics of metachronous endoscopic curability C2 (eCura C2) cancer during post-endoscopic submucosal dissection (ESD) follow-up.

METHODS

Of 4,355 gastric lesions treated by ESD at our hospital during 2005-2021, 657 were metachronous. After excluding lesions found ≥2 years since the prior examination or in the gastric remnant, the remaining 515 were analyzed. Study 1: We compared 35 eCura C2 cancers and 480 eCura A-C1 cancers. Study 2: Endoscopic findings of the 35 lesions were examined to determine why they had been missed.

RESULTS

Mean tumor size was larger (34.0 mm vs. 12.1 mm, p < 0.01) and the proportions of mixed-type and poorly differentiated cancers were higher (highly:mixed:poorly, 34.3:57.1:8.6 vs. 94.2:5.0:0.8, p < 0.01) in the eCura C2 group. Study 2: At the prior examination, 4 lesions were noticed but considered benign, 2 lacked sufficient imaging, 19 were detectable on imaging but missed, and 10 were not detectable on imaging. Over half the lesions that were detectable but missed at the prior examination were in the lesser curvature, many being type IIa-IIb lesions with color similar to the background mucosa. All lesions not detectable on imaging at the prior examination were mixed-type or poorly differentiated type.

DISCUSSION

Metachronous cancer detected as eCura C2 cancers was significantly larger, and a significantly higher proportion was mixed-type or poorly differentiated cancers, compared with eCura A-C1 cancers. Possible reasons why these lesions were missed include rapid progression of mixed-type and poorly differentiated cancers, and poor recognition that lesions showing only slight color changes may be present at the lesser curvature.

Comparison of the clinical and prognosis risk factors between endoscopic resection and radical gastrectomy for early-stage gastric cancer

AIM

This study aimed to explore the efficacy and safety of endoscopic submucosal dissection/endoscopic mucosal resection (ESD/EMR), laparoscopic-assisted radical gastrectomy (LARG), and open radical gastrectomy (ORG) in early-stage gastric cancer.

METHODS

A total of 417 patients with early-stage gastric cancer who were admitted in two hospitals from January 1, 2014 to July 31, 2017 were selected; the patients were divided into the ESD/EMR group (139 cases), LARG group (108 cases), and ORG group (170 cases) according to the operation methods used. The baseline data, economic cost of health, oncologic characteristics, postoperative complications, 5-year overall survival and disease-free survival, and risk factors of death were compared and analyzed.

RESULTS

No significant difference was observed in the baseline data among the three patient groups (P > 0.05). The total hospitalization days, operation time, postoperative fluid intake time, hospitalization expenses, and proportion of antibiotic use rate in the ESD/EMR group were lesser than those in other groups (P < 0.05). The LARG group has a longer operation time and higher hospitalization expenses compared with the ORG group (P < 0.05), but the total hospitalization days, postoperative fluid intake time, proportion of antibiotic use, and lung infection status were consistent. The ESD/EMR group had a lower incidence of incision site infection and postoperative abdominal distension compared with that of the surgery groups (P < 0.05). Five patients required radical surgery after undergoing ESD/EMR (The patients had residual tissue margin cancer), while none of the patients had switched to ORG during LARG. Surgery had advantages over ESD/EMR in terms of lymph node dissection (P < 0.05). No significant differences were observed in the postoperative complications such as upper gastrointestinal bleeding, perforation, incision hernia, reoperation and recurrence (P > 0.05). The 5-year postoperative survival rates of patients in the three groups were 94.2% (ESD/EMR), 93.5% (LARG), and 94.7% (ORG), respectively, with no significant differences (P > 0.05). The binary logistics multivariate analysis showed that the tumor size, invasion depth, vascular invasion, and differentiated degree were risk factors for death in patients with gastric cancer.

CONCLUSIONS

No significant difference was observed between ESD/EMR and radical surgery. However, standardized criteria for excluding metastatic lymph nodes should be established to promote ESD/EMR.

Predictive model for bleeding after gastric submucosal dissection before and after guidelines: A single‐center retrospective study

Objectives

In July 2017, supplementary guidelines on anticoagulants, including direct oral anticoagulants, were published in Japan. We investigated the changes in endoscopic submucosal dissection (ESD) of gastric mucosal lesions after the publication of the supplement, examined the risk factors, and developed a predictive model for post‐ESD bleeding.

Methods

We included 2272 gastric ESD cases from our hospital between May 2003 and June 2021 and classified them into two groups: 1789 cases before and 483 after the publication of the supplementary guidelines. A predictive model for post‐ESD bleeding was developed using the pre‐publication cohort data.

Results

The proportion of patients receiving warfarin decreased (5.0% vs. 1.4%) and those receiving direct oral anticoagulants increased (1.2% vs. 6.8%) after the publication of the supplementary guidelines. Post‐ESD bleeding occurred in 61 patients, but there was no significant difference in the bleeding rate between the groups (50 [2.8%] vs. 11 [2.3%] patients, respectively). Five risk factors (number of antithrombotic agents, dialysis, heparin replacement, resection specimen size, and procedure time) were identified for model development. The C‐statistic for the model and post‐publication cohorts were 0.83 and 0.72, respectively. In the model, each risk factor for postoperative bleeding was scored, and the risk was classified into three levels according to the total score. Bleeding rates at low, intermediate, and high risks were 1.6%, 10.3%, and 38.9%, respectively.

Conclusion

Despite changes in patient characteristics and clinical practice regarding ESD before and after the publication of the supplementary guidelines, we could still develop a simple and useful predictive model.

Prediction model of 3-year survival after endoscopic submucosal dissection for early gastric cancer in elderly patients aged ≥ 85 years: EGC-2 model

PURPOSE

Little is known about the prognostic factors for survival after endoscopic submucosal dissection (ESD) in elderly patients with early gastric cancer (EGC). The aim of this study is to determine prognostic factors and a prediction model of 3-year survival after ESD for EGC in patients aged ≥ 85 years.

METHODS

We retrospectively evaluated the clinical outcomes of 740 patients with EGC aged ≥ 85 years, who were treated by ESD at 30 institutions in Japan. Overall survival (OS) and disease-specific survival (DSS) were calculated with the Kaplan-Meier method. Prediction models for 3-year OS after ESD were estimated using the Cox proportional hazards model based on Uno's C-statistics.

RESULTS

During the follow-up period, 309 patients died of any cause and 10 patients died of gastric cancer. OS and DSS after 3 years were 82.7% and 99.2%, respectively. No significant differences in OS were found among curability categories. The Cox proportional hazards model revealed the geriatric nutritional risk index (GNRI) and the Charlson comorbidity index (CCI) to be predictors of 3-year survival. We established a final model (EGC-2 model) expressed by GNRI - (2.2×CCI) with a cutoff value of 96. The overall survival rate was significantly lower in the model value < 96 group than in the model value ≥ 96 group (P < 0.001).

CONCLUSIONS

The prediction model using GNRI and CCI will be useful to support decision-making for the treatment of EGC in elderly patients aged ≥ 85 years.

Surgery Matters: Progress in Surgical Management of Gastric Cancer

OPINION STATEMENT

The surgical treatment of gastric carcinoma has progressed significantly in the past few decades. A major milestone was the establishment of multimodal therapies for locally advanced tumours. Improvements in the technique of endoscopic resection have supplanted surgery in the early stages of many cases of gastric cancer. In cases in which an endoscopic resection is not possible, surgical limited resection procedures for the early stages of carcinoma are an equal alternative to gastrectomy in the field of oncology. Proximal gastrectomy is extensively discussed in this context. Whether proximal gastrectomy leads to a better quality of life and better nutritional well-being than total gastrectomy depends on the reconstruction chosen. The outcome cannot be conclusively assessed at present. For locally advanced stages, total or subtotal gastrectomy with D2 lymphadenectomy is now the global standard. A subtotal gastrectomy requires sufficiently long tumour-free proximal resection margins. Recent data indicate that proximal margins of at least 3 cm for tumours with an expansive growth pattern and at least 5 cm for those with an infiltrative growth pattern are sufficient. The most frequently performed reconstruction worldwide following gastrectomy is the Roux-en-Y reconstruction. However, there is evidence that pouch reconstruction is superior in terms of quality of life and nutritional well-being. Oncological gastric surgery is increasingly being performed laparoscopically. The safety and oncological equivalency were first demonstrated for early carcinomas and then for locally advanced tumours, by cohort studies and RCTs. Some studies suggest that laparoscopic procedures may be advantageous in early postoperative recovery. Robotic gastrectomy is also increasing in use. Preliminary results suggest that robotic gastrectomy may have added value in lymphadenectomy and in the early postoperative course. However, further studies are needed to substantiate these results. There is an ongoing debate about the best treatment option for gastric cancer with oligometastatic disease. Preliminary results indicate that certain patient groups could benefit from resection of the primary tumour and metastases following chemotherapy. However, the exact conditions in which patients may benefit have yet to be confirmed by ongoing trials.

Long-term Survival After Endoscopic Resection For Gastric Cancer: Real-world Evidence From a Multicenter Prospective Cohort

BACKGROUND & AIMS

We aimed to clarify the long-term outcomes of endoscopic resection (ER) for early gastric cancers (EGCs) based on pathological curability in a multicenter prospective cohort study.

METHODS

We analyzed the long-term outcomes of 9054 patients with 10,021 EGCs undergoing ER between July 2010 and June 2012. Primary endpoint was the 5-year overall survival (OS). The hazard ratio for all-cause mortality was calculated using the Cox proportional hazards model. We also compared the 5-year OS with the expected one calculated for the surgically resected patients with EGC. If the lower limit of the 95% confidence interval (CI) of the 5-year OS exceeded the expected 5-year OS minus a margin of 5% (threshold 5-year OS), ER was considered to be effective. Pathological curability was categorized into en bloc resection, negative margins, and negative lymphovascular invasion: differentiated-type, pT1a, ulcer negative, ≤2 cm (Category A1); differentiated-type, pT1a, ulcer negative, >2 cm or ulcer positive, ≤3 cm (Category A2); undifferentiated-type, pT1a, ulcer negative, ≤2 cm (Category A3); differentiated-type, pT1b (SM1), ≤3 cm (Category B); or noncurative resections (Category C).

RESULTS

Overall, the 5-year OS was 89.0% (95% CI, 88.3%-89.6%). In a multivariate analysis, no significant differences were observed when the hazard ratio of Categories A2, A3, and B were compared with that of A1. In all the pathological curability categories, the lower limit of the 95% CI for the 5-year OS exceeded the threshold 5-year OS.

CONCLUSION

ER can be recommended as a standard treatment for patients with EGCs fulfilling Category A2, A3, and B, as well as A1 (UMIN Clinical Trial Registry, UMIN000005871).

Establishing machine learning models to predict the early risk of gastric cancer based on lifestyle factors

BACKGROUND

Gastric cancer is one of the leading causes of death worldwide. Screening for gastric cancer greatly relies on endoscopy and pathology biopsy, which are invasive and pose financial burdens. Thus, the prevention of the disease by modifying lifestyle-related behaviors and dietary habits or even the prevention of risk factor formation is of great importance. This study aimed to construct an inexpensive, non-invasive, fast, and high-precision diagnostic model using six machine learning (ML) algorithms to classify patients at high or low risk of developing gastric cancer by analyzing individual lifestyle factors.

METHODS

This retrospective study used the data of 2029 individuals from the gastric cancer database of Ayatollah Taleghani Hospital in Abadan City, Iran. The data were randomly separated into training and test sets (ratio 0.7:0.3). Six  ML methods, including multilayer perceptron (MLP), support vector machine (SVM) (linear kernel), SVM (RBF kernel), k-nearest neighbors (KNN) (K = 1, 3, 7, 9), random forest (RF), and eXtreme Gradient Boosting (XGBoost), were trained to construct prognostic models before and after performing the relief feature selection method. Finally, to evaluate the models' performance, the metrics derived from the confusion matrix were calculated via a test split and cross-validation.

RESULTS

This study found 11 important influence factors for the risk of gastric cancer, such as Helicobacter pylori infection, high salt intake, and chronic atrophic gastritis, among other factors. Comparisons indicated that the XGBoost had the best performance for the risk prediction of gastric cancer.

CONCLUSIONS

The results suggest that based on simple baseline patient data, the ML techniques have the potential to start the prescreening of gastric cancer and identify high-risk individuals who should proceed with invasive examinations. Our model could also considerably lessen the number of cases that need endoscopic surveillance. Future studies are required to validate the efficacy of the models in a larger and multicenter population.

Cardia function-preserving surgery and anti-reflux anastomotic method after proximal gastrectomy for gastric cancer: Current status and future perspectives

The incidence and mortality of gastric cancer ranked 5th and 3rd worldwide, respectively, in 2018, and the incidence of gastroesophageal junction adenocarcinoma increased over the past 40 years. Radical resection and lymph node dissection is the preferred treatment for gastric cancer. Proximal gastrectomy or total gastrectomy is usually performed for gastroesophageal junction adenocarcinoma and upper gastric cancer. Owing to the resection of the cardia structures, the incidence of reflux esophagitis increases significantly after proximal gastrectomy and total gastrectomy, resulting in poor postoperative quality of life. To reduce the incidence of reflux esophagitis and improve patients' postoperative quality of life, various methods to preserve the function of the cardia or to perform anti-reflux reconstruction have emerged. In this manuscript, we systematically introduced the advantages and problems of various anti-reflux anastomotic method after proximal gastrectomy, and cardia-preserving gastrectomy including endoscopic resection (ER), local gastrectomy by gastroscopy combined with laparoscopy, segmental gastrectomy, subtotal gastrectomy, and cardia-preserving radical gastrectomy. Cardia-preserving radical gastrectomy has the advantage of more thorough lymph node dissection and wider indications than those for subtotal gastrectomy. However, the clinical efficacy of cardia-preserving radical gastrectomy requires verification in prospective and controlled clinical trials. Cardia-preserving radical gastrectomy is a promising approach as one of the more reasonable anti-reflux surgeries.

Endoscopic submucosal dissection for lesions involving the anastomosis after upper gastrointestinal surgery

BACKGROUND AND AIMS

Endoscopic submucosal dissection (ESD) for anastomotic lesions is technically challenging due to severe fibrosis, deformity, staples, and limited space for procedure. We aimed to characterize the clinicopathological characteristics, feasibility, and effectiveness of ESD for anastomotic lesions of the upper gastrointestinal tract.

METHODS

We retrospectively investigated 43 patients with lesions involving the anastomoses of the upper GI tract who underwent ESD from April 2007 to February 2021. We collected clinicopathological characteristics, procedure‑related parameters and outcomes, and follow‑up data and analyzed the impact of anastomotic involvement.

RESULTS

The median duration from previous upper GI surgery was 60 months and the median procedure duration was 30 min. The rate of en bloc resection and en bloc with R0 resection was 90.7% and 81.4%, respectively. Two patients (4.7%) experienced major adverse events, including delayed bleeding and febrile episode. During a median follow-up of 80 months, 3 patients had local recurrence and 4 patients had metastases. The 5-year disease-free survival (DFS) and overall survival (OS) rates were 89.6% and 95.1%, respectively. Compared with the unilaterally involving group, the straddling anastomosis group had significantly longer procedure duration, larger specimen, lower rates of en bloc resection and en bloc with R0 resection, and shorter DFS and OS (all P < 0.05). However, rates of adverse events did not differ significantly between the two groups.

CONCLUSIONS

The short‑ and long-term outcomes of ESD for upper GI anastomotic lesions were favorable. Although with technically challenging, ESD could be performed safely and effectively for anastomotic lesions.

Gastric ulcer treated using an elastic traction ring combined with clip: A case report

BACKGROUND

There is a high annual incidence of acute, nonvariceal upper gastrointestinal bleeding in Chinese adults. Early endoscopic intervention can reduce rates of rebleeding, surgery, and mortality. The metal clip is the most common method for establishing homeostasis; however, it possesses several limitations. In patients with bleeding secondary to large gastric ulcers, the clip will often fail to stop the bleeding. This article highlights the use of an elastic traction ring as a novel hemostatic method for patients with upper gastrointestinal bleeding.

CASE SUMMARY

An elderly male presented to the emergency room with complaints of hematemesis and melena. Endoscopic examination revealed an ulcer (Forrest IIa) in the lesser curvature of the gastric antrum. Six tissue clips and one elastic traction ring were inserted into the stomach cavity to suture the ulcer. The patient recovered quickly without postoperative gastrointestinal bleeding. Two months later, the patient's ulcer was significantly healed.

CONCLUSION

To our best knowledge, this is the first report to demonstrate the safety and efficacy of elastic traction rings for upper gastrointestinal bleeding. Elastic traction rings should be considered a routine therapeutic modality for patients with upper gastrointestinal bleeds.

Feasibility, efficacy, and cautionary note of endoscopic resection for gastric tube cancer after esophagectomy

BACKGROUND

Gastric tube cancer (GTC), whose usual histology is adenocarcinoma, occurs frequently as a result of improved survival after esophagectomy. Whether endoscopic resection (ER) for GTC is safe and suitable and guidelines for treatment and follow-up remains unclear.

METHODS

Patients with GTC who underwent ER at Kanagawa Cancer Center Hospital between 1997 and 2020 were studied retrospectively to evaluate clinical characteristics and short- and long-term outcomes.

RESULTS

Twenty-two consecutive patients with 43 lesions were treated in 42 sessions of ER. Lesions were discovered at a median of 9.0 (0-21.8) years after esophageal surgery. Nine (40.9%) patients had multiple lesions at the time of the initial ER session. However, six (54.5%) of the 11 co-existing lesions were overlooked. The location of the middle third was an estimated risk factor for overlooking (p = 0.028). In endoscopic submucosal dissection (ESD) cases, the en bloc dissection rate was as high as 97.1%, and the rates of bleeding, perforation, and aspiration pneumonitis were 17.6%, 0%, and 2.9%, respectively. The bleeding rate was relatively higher than that in usual gastric ESD. Twelve patients (54.5%) experienced synchronous and/or metachronous multiple GTCs during their life span. Thirteen (61.9%) patients died during the median follow-up period of 5.9 (0.7-15.5) years. One patient (7.7%) died of GTC recurrence, 15.4 years after the initial non-curative ER date; 3 (23.1%) patients died of esophageal cancer recurrence, and 3 (23.1%) died of other organ malignancies. The 5-year overall survival rate was 85.0%, and the 5-year disease-specific survival rate was 100%.

CONCLUSIONS

ER is feasible for GTCs. However, the rate of bleeding was high in ESD cases. Life-long endoscopic screening of metachronous lesions is desirable. Care should be taken not to overlook lesions in the middle third of the gastric tube. Early detection of esophageal cancer recurrence and other organ malignancies may improve prognosis.

Effectiveness of a novel traction device in endoscopic submucosal dissection for colorectal lesions

BACKGROUND

Among all types of superficial gastrointestinal (GI) neoplasms, colorectal lesions are recognized as one of the most difficult locations to operate, due to the limited operation space, physiological bends, poor visualization of the submucosal dissection plane sheltered by colorectal crinkle wall, and the thin intestinal mucosa layer which is easy to perforation. The purpose of this prospective study is to evaluate the feasibility, efficacy, and safety of a novel endoscopic traction technique in assisting the endoscopic submucosal dissection (ESD) procedure in colorectal lesions.

METHOD

A total of 117 patients with colonic lesions who underwent endoscopic treatment were enrolled between August 2020 and January 2021 at the endoscopic center of Beijing Chao-yang Hospital of Capital Medical University. Based on whether traction device was used during the operation, 60 and 57 patients were assigned to the conventional ESD group and clips and rubber band triangle traction-assisted ESD group (CRT-ESD, in which three clips and a rubber band were used to form an elastic triangular traction device), respectively. The total procedure time (TPT), submucosal dissection time (SDT), submucosal dissection speed (SDS), and rate of adverse events of the two groups were analyzed.

RESULTS

After excluding patients who did not undergo treatment (conventional ESD, 1; CRT-ESD, 4), 112 patients were included in the study (conventional ESD, 59; CRT-ESD, 53). The baseline characteristics of the patients were well balanced between the two groups. The TPT (58.71 ± 26.22 min vs 33.58 ± 9.88 min, p < 0.001) and SDT (49.24 ± 23.75 min vs 26.34 ± 8.75 min, p < 0.001) were significantly different between the conventional ESD group and CRT-ESD group. The CRT-ESD group had significantly higher SDS than that of the traditional ESD group (0.54 ± 0.42 cm2/min vs 0.89 ± 0.40 cm2/min, p < 0.001). There were 4 (6.8%) cases of perforation in the traditional ESD group, and no perforation occurred in traction-assisted ESD.

CONCLUSIONS

Compared with traditional ESD, CRT-ESD with clip and rubber band is both safer and more effective in the treatment of colorectal lesions.

Development and validation of a predictive model combining clinical, radiomics, and deep transfer learning features for lymph node metastasis in early gastric cancer

Background

This study aims to develop and validate a predictive model combining deep transfer learning, radiomics, and clinical features for lymph node metastasis (LNM) in early gastric cancer (EGC).

Materials and methods

This study retrospectively collected 555 patients with EGC, and randomly divided them into two cohorts with a ratio of 7:3 (training cohort, n = 388; internal validation cohort, n = 167). A total of 79 patients with EGC collected from the Second Affiliated Hospital of Soochow University were used as external validation cohort. Pre-trained deep learning networks were used to extract deep transfer learning (DTL) features, and radiomics features were extracted based on hand-crafted features. We employed the Spearman rank correlation test and least absolute shrinkage and selection operator regression for feature selection from the combined features of clinical, radiomics, and DTL features, and then, machine learning classification models including support vector machine, K-nearest neighbor, random decision forests (RF), and XGBoost were trained, and their performance by determining the area under the curve (AUC) were compared.

Results

We constructed eight pre-trained transfer learning networks and extracted DTL features, respectively. The results showed that 1,048 DTL features extracted based on the pre-trained Resnet152 network combined in the predictive model had the best performance in discriminating the LNM status of EGC, with an AUC of 0.901 (95% CI: 0.847–0.956) and 0.915 (95% CI: 0.850–0.981) in the internal validation and external validation cohorts, respectively.

Conclusion

We first utilized comprehensive multidimensional data based on deep transfer learning, radiomics, and clinical features with a good predictive ability for discriminating the LNM status in EGC, which could provide favorable information when choosing therapy options for individuals with EGC.

Advanced Endoscopic Resection Techniques in Cirrhosis-A Systematic Review and Meta-Analysis of Outcomes

BACKGROUND/AIMS

While safety and effectiveness of advanced endoscopic resection techniques such as endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) has been well established in general population, data regarding their utility in patients with cirrhosis is limited.

METHODS

We searched multiple databases from inception through July 2021 to identify studies that reported on outcomes of EMR and/or ESD in patients with cirrhosis. Meta-analysis was performed to determine pooled rates of immediate and delayed bleeding, perforation, death as well as rates of successful en bloc and R0 resection. Pooled relative risk (RR) was calculated for each outcome between patients with and without cirrhosis.

RESULTS

Ten studies with a total of 3244 patients were included in the final analysis. Pooled rates of immediate & delayed bleeding, perforation, and death during EMR and/or ESD in patients with cirrhosis were 9.5% (CI 4.0-21.1), 6.6% (CI 4.2-10.3), 2.1% (CI 1.1-3.9) and 0.6% (CI 0.2-1.7), respectively. Pooled rates of successful en bloc and R0 resection were 93% (CI 85.9-96.7) and 90.8% (CI 86.5-93.8), respectively. While incidence of immediate bleeding was higher in patients with cirrhosis, there was no statistically significant difference in any of the other outcomes between the patient groups.

CONCLUSIONS

Our study shows that performing EMR and ESD for gastrointestinal lesions in patients with cirrhosis is both safe and effective. The risks of procedural complications parallel those reported in general population.

Studies on endoscopic submucosal dissection in the past 15 years: A bibliometric analysis

Background and aims

Endoscopic submucosal dissection (ESD) is an advanced minimally invasive technique for en bloc resection of superficial gastrointestinal lesions, which is drawn an increasing attention from its emergence. This bibliometric analysis is to evaluate the origin, current hotspots, and research trends on ESD.

Methods

A total of 2,131 publications on ESD from 2006 to 2020 were obtained from the Web of Science Core Collection (WoSCC) database. Bibliometric visualization analyses of countries/regions, institutes, authors, journals, references and keywords were performed by CiteSpace V.5.8.R3.

Results

The quantity of publications on ESD increased significantly during the past 15 years. Japan occupied the leading position in terms of research power. Professor Yutaka Saito, together with the institute he belongs, the Endoscopy Division, National Cancer Center Hospital, Tokyo, Japan, were the most productive author and institute, respectively. Colorectal ESD led the main thematic concentrations in ESD research. The most prolific journal was Gastrointestinal Endoscopy. European ESD Guideline was the most frequently co-cited reference. Guideline, meta-analysis, endoscopic resection, poly-glycolic acid sheet, Barrett's esophagus, fibrin glue, risk and colorectal neoplasm will be the active research hotspots in the future.

Conclusions

These findings provide the trends and frontiers in the field of ESD, as well as valuable information for clinicians and scientists to discover the future perspectives with potential collaborators.

Development of new gastric endoscopic submucosal dissection training model: A reproducibility evaluation study

Background and study aims  Gastric endoscopic submucosal dissection (ESD) is a highly technical procedure mainly due to the distinctive shape of the stomach and diverse locations of lesions. We developed a new gastric ESD training model (G-Master) that could accurately recreate the location of the stomach and assessed the reproducibility of located lesions in the model. Methods  The model comprises a simulated mucous membrane sheet made of konjac flour and a setting frame, which can simulate 11 locations of the stomach. We assessed the reproducibility of each location in the model by assessing the procedure speed and using a questionnaire that was distributed among experts. In the questionnaire, each location was scored on a six-point scale for similarity of locations. Results  The mean score for all locations was high with > 4 points. Regarding locations, lower anterior and posterior walls had medium scores with 3 to 4 points. The procedure speed was slower in the greater curvature of the upper and middle gastric portions, where ESD is considered more difficult than the overall procedure speed. Conclusions  The new gastric ESD training model appears to be highly reproducible for each gastric location and its application for training in assuming actual gastric ESD locations.

Machine learning for lymph node metastasis prediction of in patients with gastric cancer: A systematic review and meta-analysis

Objective

To evaluate the diagnostic performance of machine learning (ML) in predicting lymph node metastasis (LNM) in patients with gastric cancer (GC) and to identify predictors applicable to the models.

Methods

PubMed, EMBASE, Web of Science, and Cochrane Library were searched from inception to March 16, 2022. The pooled c-index and accuracy were used to assess the diagnostic accuracy. Subgroup analysis was performed based on ML types. Meta-analyses were performed using random-effect models. Risk of bias assessment was conducted using PROBAST tool.

Results

A total of 41 studies (56182 patients) were included, and 33 of the studies divided the participants into a training set and a test set, while the rest of the studies only had a training set. The c-index of ML for LNM prediction in training set and test set was 0.837 [95%CI (0.814, 0.859)] and 0.811 [95%CI (0.785-0.838)], respectively. The pooled accuracy was 0.781 [(95%CI (0.756-0.805)] in training set and 0.753 [95%CI (0.721-0.783)] in test set. Subgroup analysis for different ML algorithms and staging of GC showed no significant difference. In contrast, in the subgroup analysis for predictors, in the training set, the model that included radiomics had better accuracy than the model with only clinical predictors (F = 3.546, p = 0.037). Additionally, cancer size, depth of cancer invasion and histological differentiation were the three most commonly used features in models built for prediction.

Conclusion

ML has shown to be of excellent diagnostic performance in predicting the LNM of GC. One of the models covering radiomics and its ML algorithms showed good accuracy for the risk of LNM in GC. However, the results revealed some methodological limitations in the development process. Future studies should focus on refining and improving existing models to improve the accuracy of LNM prediction.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022320752

Establishment and Validation for Predicting the Lymph Node Metastasis in Early Gastric Adenocarcinoma

Lymph node metastasis (LNM) is considered to be one of the important factors in determining the optimal treatment for early gastric cancer (EGC). This study aimed to develop and validate a nomogram to predict LNM in patients with EGC. A total of 842 cases from the Surveillance, Epidemiology, and End Results (SEER) database were divided into training and testing sets with a ratio of 6 : 4 for model development. Clinical data (494 patients) from the hospital were used for external validation. Univariate and multivariate logistic regression analyses were used to identify the predictors using the training set. Logistic regression, LASSO regression, ridge regression, and elastic-net regression methods were used to construct the model. The performance of the model was quantified by calculating the area under the receiver operating characteristic curve (AUC) with 95% confidence intervals (CIs). Results showed that T stage, tumor size, and tumor grade were independent predictors of LNM in EGC patients. The AUC of the logistic regression model was 0.766 (95% CI, 0.709-0.823), which was slightly higher than that of the other models. However, the AUC of the logistic regression model in external validation was 0.625 (95% CI, 0.537-0.678). A nomogram was drawn to predict LNM in EGC patients based on the logistic regression model. Further validation based on gender, age, and grade indicated that the logistic regression predictive model had good adaptability to the population with grade III tumors, with an AUC of 0.803 (95% CI, 0.606-0.999). Our nomogram showed a good predictive ability and may provide a tool for clinicians to predict LNM in EGC patients.

The Safety and Clinical Validity of Endoscopic Submucosal Dissection for Early Gastric Cancer in Patients Aged More Than 85 Years

Endoscopic submucosal dissection (ESD) is a safe and minimally invasive method for the treatment of early gastric cancer (EGC). However, whether ESD for EGC is also safe and feasible in patients aged ≥85 years is unclear. The patients enrolled in this study were divided into three groups: age ≥85 years (44 patients, 49 lesions), age 65−84 years (624 patients, 687 lesions), and age ≤64 years (162 patients, 174 lesions). We evaluated the incidence of adverse events (AEs) and overall survival (OS) and disease-specific survival (DSS). We analyzed the factors that had a significant impact on the prognosis of patients aged ≥85 years. No significant differences were found in the incidence of AEs among the three groups (p = 0.612). The OS was significantly lower in patients aged ≥85 years (p < 0.001). Conversely, DSS was not significantly worse in patients aged ≥85 years (p = 0.100). The poor Geriatric Nutritional Risk Index correlated with poor prognosis in patients aged ≥85 years (p < 0.001). ESD is a safe and valid treatment for EGC in patients aged ≥85 years. However, the indications should be carefully decided because it is difficult to estimate the survival contribution of ESD for EGC in patients aged ≥85 years, especially in those with poor nutritional status.

Associated risk factor analysis and the prognostic impact of positive resection margins after endoscopic resection in early esophageal squamous cell carcinoma

Endoscopic resection for early esophageal cancer has a risk of residual margins. The risk these residual margins pose have not been fully evaluated. The present study aimed to investigate the associated risk factors and prognosis of residual margins following the endoscopic resection of early esophageal squamous cell carcinoma. In total, 369 patients (381 lesions) with early esophageal squamous cell carcinoma treated in the Fourth Hospital of Hebei Medical University (Shijiazhuang, China) with endoscopic resection were retrospectively analyzed. Sex, age, location, tumor diameter, depth of tumor invasion, endoscopic treatment, endoscopic ultrasonography (EUS) before resection, work experience of endoscopists and the degree of tumor differentiation were all evaluated as potential risk factors. In addition, the prognosis of patients with positive margins were analyzed. A total of 73 patients (73/381, 19.2%) had positive margins after endoscopic resection. Amongst the 65 patients who were successfully followed up, five patients succumbed to cardiovascular and cerebrovascular diseases, one patient received radiotherapy, two patients received radiotherapy and chemotherapy whilst one patient received chemotherapy. By contrast, 12 patients received surgery and 20 patients received additional endoscopic mucosal resection or endoscopic submucosal dissection. The other 29 patients were followed up regularly and no recurrence could be found. Univariate analysis revealed that tumor diameter, endoscopic treatment, depth of invasion, EUS before resection, degree of tumor differentiation and direction of invasion were all associated with the positive margin. Multivariate logistic regression analysis then found that EUS before resection, degree of tumor differentiation and depth of tumor invasion are independent risk factors for positive margins after endoscopic resection. These results suggest that poorly differentiated lesions and deeper invasion depth can increase the risk of positive margin after endoscopic resection. As a result, EUS evaluation before resection may reduce the risk of invasion depth. In addition, for poorly differentiated lesions, more aggressive treatment regimens may be recommended for preventing recurrence.

Efficacy of dexmedetomidine on postoperative pain in patients undergoing gastric and esophageal endoscopic submucosal dissection: a study protocol for a randomized controlled prospective trial

BACKGROUND

Endoscopic submucosal dissection (ESD) is widely used as an effective treatment of early gastric and esophageal tumors, as it is minimally invasive, safe, and convenient. Epigastric pain is a common complication of ESD. In the traditional cognition, the postoperative pain of ESD is not serious and does not attach too much attention. However, previous studies found that the incidence of moderate to severe pain after ESD can be as high as 44.9~62.8%. At present, there is no unified understanding of how to carry out good postoperative analgesia in patients undergoing ESD of stomach and esophagus. The purpose of present study is to investigate the efficacy of intraoperative dexmedetomidine (DEX) using on postoperative pain though observing the postoperative visual analog scale (VAS) score within 48 h after ESD surgery, so as to explore an effective analgesia and anesthetic method in patients undergoing gastric and esophagus ESD.

METHODS/DESIGN

This study is a prospective, single-center, two-arm, randomized control trail. In total, 120 patients undergoing endoscopic submucosal dissection were stratified by type of surgery (i.e., gastric or esophagus ESD) and randomized into two treatment groups, DEX group (group D, n = 60) and control group (group C, n = 60). Patients in the experimental group (DEX group) will be administrated a loading dose of DEX at 1 μg/kg for 15 min and a continuous infusion at 0.6 μg/kg/h until 30 min before the end of operation. In control group, the same volume of normal saline was infused. The primary outcome is VAS at 2 h after ESD surgery. The secondary outcome will be VAS at 1 h, 4 h, 6 h,18 h, 24 h, and 48 h, the status of perioperative hemodynamics, the use of remedial analgesics, sedation score, shivering, postoperative nausea and vomiting (PONV), and satisfaction scores of patient and complication of ESD (such as bleeding, perforation, aspiration pneumonia).

DISCUSSION

The results of this study will demonstrate that intraoperative application of DEX is beneficial for postoperative pain treatment in patients undergoing ESD. This study will not only confirm that postoperative pain treatment is necessary for patients undergoing ESD but also provides an effective anesthesia method for postoperative analgesia.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ID: ChiCTR2100043837 , registered on March 4, 2021, http://www.chictr.org.cn .

Regional lymph node recurrence without intragastric lesions after curative endoscopic resection of early gastric cancer meeting the absolute indications of endoscopic resection: A case report

RATIONALE

With the increase of gastric cancer surveillance and endoscopic resection techniques, the number of endoscopic resections being performed for the treatment of early gastric cancer in East Asian countries has been increasing. Previously, endoscopic resection has been limited to only differentiated type intramucosal cancers which had a diameter ≤2.0 cm, provided there was no evidence of ulceration and lymphovascular invasion, known as absolute indications. And recently, indications for endoscopic resection have been expanded to include even more cases.

PATIENT CONCERNS

A 57-year-old female, who had undergone curative endoscopic submucosal dissection for early gastric cancer under the absolute indications for endoscopic resection 5 years prior, was referred to the department of general surgery with metastatic perigastric lymph nodes without intragastric lesions.

DIAGNOSIS

Computed tomography scan revealed the presence of a few enlarged lymph nodes at the distal part of the lesser curvature of the stomach. And positron emission tomography scan further revealed the presence of two hypermetabolic lymph nodes near the common hepatic artery, suggestive of metastatic lymph nodes.

INTERVENTIONS

Laparoscopic distal gastrectomy and Roux-en-Y gastrojejunostomy with D2 lymph node dissection were performed.

OUTCOMES

Final pathology report revealed the absence of any residual carcinoma in the stomach. However lymphovascular invasion of omental fat, and 3 out of 29 perigastric lymph nodes harvested had metastatic adenocarcinoma.

LESSONS

The case demonstrates that regional lymph node recurrence without intragastric lesions after curative resection of early gastric cancer meeting the absolute indications for endoscopic resection is possible even 5 years after resection of the primary lesion.

Quality indicators in esophagogastroduodenoscopy

Esophagogastroduodenoscopy (EGD) has been used to diagnose a wide variety of upper gastrointestinal diseases. In particular, EGD is used to screen high-risk subjects of gastric cancer. Quality control of EGD is important because the diagnostic rate is examiner-dependent. However, there is still no representative quality indicator that can be uniformly applied in EGD. There has been growing awareness of the importance of quality control in improving EGD performance. Therefore, we aimed to review the available and emerging quality indicators for diagnostic EGD.

Photodynamic Diagnosis for the Identification of Intestinal-Type Gastric Cancers and High-Grade Adenomas

Gastric cancer is the second most common cancer in Japan. The incidence of gastric cancer remains high owing to the increase in the elderly population. Endoscopy outperforms radiography in identifying early gastric cancer (EGC). Furthermore, image-enhanced endoscopy (IEE) has been developed and implemented worldwide in clinical practice. Magnifying IEE images can help to visualize the microvascular pattern and microstructure architecture, which is used for the characterization of EGC. However, accurate endoscopic diagnosis requires the experience and skill of endoscopists, making an objective and simple diagnostic method desirable. In this retrospective study, we investigated the diagnostic yield of 5-aminolevulinic acid (5-ALA)-mediated photodynamic diagnosis (PDD) for identifying gastric cancers and high-grade adenomas. In total, 52 lesions from 43 patients were ultimately included in the study. We detected 5-ALA-mediated protoporphyrin IX fluorescence in 45 of the 52 lesions that were initially intended for PDD, resulting in a detection rate of 86.5%, whereas each signet ring cell carcinoma was negative using 5-ALA PDD. In eight of the patients with multiple lesions, 17 lesions were identified using 5-ALA PDD. Again, we took biopsies from six areas that we suspected as new lesions. While 4 lesions were gastric neoplasms resected by endoscopic submucosal dissection, two other lesions were normal. Preoperative 5-ALA-PDD could provide additional diagnostic yields to detect such multiple lesions simultaneously. No severe adverse events were observed. Prospective multicenter studies are warranted to confirm the usefulness of 5-ALA PDD for EGC identification.

Current and future imaging modalities in gastric cancer

Gastric adenocarcinoma treatment can include endoscopic mucosal resection, surgery, chemotherapy, radiation, and palliative measures depending on staging. Both invasive and noninvasive staging techniques have been used to dictate the best treatment pathway. Here, we review the current imaging modalities used in gastric cancer as well as novel techniques to accurately stage and screen these patients.

Relationship between histological mixed-type early gastric cancer and lymph node metastasis: A systematic review and meta-analysis

The clinicopathological features of early gastric cancer (EGC) with mixed-type histology (differentiated and undifferentiated) are incompletely understood, and the capacity of endoscopic submucosal dissection (ESD) to treat mixed-type cancer remains controversial. This systematic review analyzed the rate of lymph node metastasis (LNM) in mixed-type EGC. We gathered articles published up to February 21, 2021, that analyzed the relationship between LNM and mixed-type EGC from Embase, PubMed, and Web of Science. The primary outcome was the LNM rate associated with different histological types of EGC, and the secondary outcomes were the odds ratios (ORs) for LNM risk factors among EGC patients. From the 24 studies included in this meta-analysis, the overall rate of LNM in predominantly differentiated mixed-type (MD) EGC was 12%, whereas the LNM rate in predominantly undifferentiated mixed-type (MU) EGC was 22%. We further divided these studies into 2 groups according to the depth of invasion. In mixed-type mucosal EGC, the pooled LNM rate was 15%; in submucosal EGC, the rate was 33% for MU, which was higher than the rates for pure types (pure differentiated type, 13%; pure undifferentiated type, 21%; p<0.05). The LNM rate of MD was 20%, it was higher than those of the pure differentiated type and nearly the same as pure undifferentiated type. Other pooled statistics showed that submucosal invasion, pure undifferentiated EGC, and mixed-type EGC were independent risk factors for LNM. This meta-analysis showed that MD submucosal EGC has a high rate of LNM and is highly correlated with LNM; thus, the management of MD EGC as purely differentiated EGC according to the indications for ESD is inappropriate, and the mixed type should be added as a parameter in these indications.

Recent approach for preventing complications in upper gastrointestinal endoscopic submucosal dissection

Although endoscopic submucosal dissection (ESD) is a minimally invasive treatment method for upper gastrointestinal (GI) tumors, patients undergoing upper GI ESD sometimes fall into a serious condition from complications. Thus, it is important to fully understand how to prevent complications when performing upper GI ESD. One of the major complications in esophageal and gastric ESD is intraoperative perforation. To prevent this complication, blind dissection should be avoided. Traction-assisted ESD is a useful technique for maintaining good endoscopic view. This method was proven to reduce the incidence of intraoperative perforation, which would become a standard technique in esophageal and gastric ESD. In gastric ESD, delayed bleeding is the most common complication. Recently, a novel prediction model (BEST-J score) consisting of 10 factors with four risk categories for delayed bleeding in gastric ESD was established, and a free mobile application is now available. For reducing delayed bleeding in gastric ESD, vonoprazan ≥20 mg/day is the sole reliable method in the current status. Duodenal ESD is still challenging with a much higher frequency of complications, such as perforation and delayed bleeding, than ESD in other organs. However, with the development of improved devices and techniques, the frequency of complications in duodenal ESD has been decreasing. To prevent intraoperative perforation, some ESD techniques, such as using the distal tips of the Clutch Cutter, were developed. An endoscopic mucosal defect closure technique would be mandatory for preventing delayed complications. However, several unresolved issues, including standardization of duodenal ESD, remain and further studies are demanded.

Traction method versus conventional endoscopic submucosal dissection for gastric epithelial neoplasms: A randomized controlled trial

INTRODUCTION

Endoscopic submucosal dissection (ESD) is an advanced therapeutic technique for en bloc resection of superficial gastrointestinal neoplasms. Although gastric ESD is minimally invasive and provides favorable outcomes, it is technically difficult and requires a long procedure time for dissection. The traction-assisted approach overcomes some of the difficulties of gastric ESD, but its ability to reduce the procedure time remains unclear. The traction-assisted approach using dental floss and a clip did not reduce procedure time in the total population, but it reduced procedure time for lesions limited to the greater curvature of the upper or middle of the stomach. Although the traction direction of the clip-with-line method may be limited to the oral side via the cardia, EndoTrac ESD may provide flexible traction at any time during the procedure. This prospective randomized control study has been designed to compare the efficacy and safety of EndoTrac and conventional gastric ESD.

METHODS/DESIGN

This multicenter, randomized control trial will enroll 150 patients at 2 hospitals in Japan undergoing EndoTrac or conventional ESD for gastric epithelial neoplasia. Patients with a single gastric epithelial neoplasm who meet the inclusion and exclusion criteria will be randomized to EndoTrac or conventional ESD. Patients will be randomized by a computer-generated random sequence with stratification by operator experience, tumor size, tumor location, and institution. The primary endpoint will be ESD procedure time, defined as the time from the start of the submucosal injection to the completion of resection. Other outcomes will include the rates of adverse events and pathological curability.

DISCUSSION

The ability of EndoTrac ESD to reduce the long procedure time and/or adverse events observed with conventional ESD can not only reduce physical stress on the patient, but can also reduce length of hospital stay and medical costs. Reduced technical difficulty will contribute to the widespread adoption of this ESD technique worldwide.

TRIAL REGISTRATION

University Hospital Medial Information Network Clinical Trials Registry (UMIN-CTR), ID: 000044450; Registered on June 6, 2021.https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000050485.

PROTOCOL VERSION NUMBER

1.1, March 1, 2022. Patient enrolment began on June 6, 2021 and is expected to be completed by July 19, 2025.

Implementation of artificial intelligence in upper gastrointestinal endoscopy

The application of artificial intelligence (AI) using deep learning has significantly expanded in the field of esophagogastric endoscopy. Recent studies have shown promising results in detecting and differentiating early gastric cancer using AI tools built using white light, magnified, or image‐enhanced endoscopic images. Some studies have reported the use of AI tools to predict the depth of early gastric cancer based on endoscopic images. Similarly, studies based on using AI for detecting early esophageal cancer have also been reported, with an accuracy comparable to that of endoscopy specialists. Moreover, an AI system, developed to diagnose pharyngeal cancer, has shown promising performance with high sensitivity. These reports suggest that, if introduced for regular use in clinical settings, AI systems can significantly reduce the burden on physicians. This review summarizes the current status of AI applications in the upper gastrointestinal tract and presents directions for clinical practice implementation and future research.

The safety and feasibility of endoscopic submucosal dissection using a flexible three-dimensional endoscope for early gastric cancer and superficial esophageal cancer: A prospective observational study

BACKGROUND AND AIM

Endoscopic submucosal dissection (ESD) is performed as one of standard treatments for patients with early gastric cancer (EGC) and superficial esophageal squamous cancer (SESCC). A prototype of a flexible endoscope with a 3-D system has been recently developed. This study aimed to investigate the safety and feasibility of ESD using a 3-D flexible endoscope (3-D ESD) for EGC and SESCC.

METHODS

This single-center, prospective, observational study enrolled patients who underwent planned 3-D ESD. The clinical outcomes, including the incidence of adverse events and treatment results, were analyzed. Visibility and manipulation during 3-D ESD were evaluated using a visual analog scale (VAS). We also evaluated the effect of the 3-D system on the endoscopist using VAS and the critical flicker fusion frequency (CFFF).

RESULTS

We analyzed 47 EGC and 20 SESCC cases. There are no bleeding cases that required transfusion and perforation during 3-D ESD in both EGC and SESCC patients. However, the incidence of delayed bleeding and delayed perforation was 1.5% (one case) each. The mean VAS scores for recognizing the submucosal layer during the submucosal dissection, visual perception of blood vessel, and depth perception were 72.7 ± 22.2, 74.7 ± 21.8, and 78.2 ± 19.9, respectively. In contrast, the mean VAS score for manipulation was 25.4 ± 19.7. Among endoscopists, there was no significant difference in the VAS of eyestrain and headache before and after ESD, and there was no significant difference in the CFFF.

CONCLUSION

The safety and feasibility of 3-D ESD for EGC and SESCC are acceptable in both patients and endoscopists.

Comparable long-term outcomes after endoscopic therapy and gastrectomy of early adenocarcinoma of esophagogastric junction: a population-based study

BACKGROUND AND AIMS

Current guidelines recommend consideration of endoscopic therapy (ET) when treating selected early gastric cancers. However, clinical decision-making on ET versus gastrectomy for early adenocarcinoma of esophagogastric junction (AEGJ) remains challenging because of uncertain long-term outcomes.

METHODS

We performed a retrospective cohort study using the Surveillance, Epidemiology, and End Results database from 2004 to 2017 of early AEGJ patients underwent ET or gastrectomy. Multivariate models were used to compare cancer-specific survival (CSS).

RESULTS

Of 881 included early AEGJ patients, 227 (36.2%) patients underwent ET and 654 (63.8%) patients underwent gastrectomy. Early AEGJ patients who underwent ET experienced a similar hazard of cancer-specific death compared with those underwent gastrectomy in both multivariate Cox regression (HR [hazard ratio], 0.93; 95% CI [confidence interval], 0.55-1.56; P = 0.78) and the multivariate competing risk model (subdistribution HR [SHR], 0.86; 95% CI 0.50-1.45; P = 0.56). Propensity score matching was used, 210 patients underwent ET were matched with 210 patients underwent gastrectomy. Patients underwent ET experienced a similar hazard of cancer-specific death compared with those underwent gastrectomy in both multivariate Cox regression (HR, 0.97; 95% CI 0.53-1.77; P = 0.92) and the multivariate competing risk model (SHR, 0.96; 95% CI 0.52-1.77; P = 0.89).

CONCLUSION

Early AEGJ patients who received ET or gastrectomy had comparable long-term outcomes, which lend support to the role of ET in the treatment of these patients.

The Efficacy of a Novel Type of Integrated Knife for Endoscopic Submucosal Dissection in Early Gastric Cancer

Background/Aims: This study aimed to compare the efficacy of a recently developed clear-cut knife with that of widely used knives for endoscopic submucosal dissection (ESD) in early gastric cancer (EGC).Materials and Methods: Data were collected retrospectively from the National Health Insurance Service Ilsan Hospital between May 2017 and April 2019. The study included 105 patients (108 lesions) with EGC who underwent ESD. Fifty-six EGCs were dissected using an insulation-tipped diathermic knife in combination with a needle knife, while 52 EGCs were dissected using a clear-cut knife, a single device with an integrated needle and an insulated-tipped knife. Oncologic outcomes and technical success were compared between the two groups.Results: The distribution of the tumor locations, composition of the undifferentiated types of EGCs, and the size of EGCs (14.3±8.0 vs. 16.6±7.3 mm; P=0.130) were not significantly different between the groups. The complete (98.2% vs. 94.2%; P=0.273) and curative (87.5% vs. 88.5%; P=0.878) resection rates were not statistically different. Furthermore, no significant difference between the total procedure times (39±34.1 vs. 35.7±20.1 minutes; P=0.554), areas of the dissected specimen (858.6±406.5 vs. 980.3±393.8 mm2; P=0.119) and dissected areas per minute (32.4±17.9 vs. 35.5±16.2 mm²/min; P=0.345) were noted. Regarding complications, the overall perforation rates (3.6% vs. 4.0%) and bleeding rates (3.6% vs. 8.0%) were not statistically different.Conclusions: The newly developed clear-cut knife is as useful as the combination of classical knives for ESD in EGC.

Endoscopic submucosal dissection versus surgery in elderly patients with early gastric cancer of relative indication for endoscopic resection

OBJECTIVES

Surgery is recommended for early gastric cancer (EGC) beyond the endoscopic resection (ER)-indication for the risk of lymph node metastasis; however, ER may be chosen as a "relative ER-indication" considering age and comorbidities. This study aimed to compare outcomes of endoscopic submucosal dissection (ESD) only and surgery (primary surgery and additional surgery after non-curative ESD) among elderly patients with relative ER-indication EGC and to further assess prognostic factors.

METHODS

Outcomes of ESD and surgery (417 cases; 114 ESD, 303 surgery) in elderly patients (≥75 years) with relative ER-indication EGC were retrospectively analyzed. Prognostic factors were also examined.

RESULTS

During the observation period (median; ESD, 34 months; surgery, 61 months), 29% of ESD and 35% of surgery patients died, including 4% and 5% from gastric cancer (GC), respectively. ESD showed lower overall survival (OS) than surgery (P = 0.027) but comparable disease-free survival (P = 0.916). OS-associated factors were age and prognostic nutritional index (PNI) in males (age ≥79, hazard ratio [HR] 2.21, P = 0.001; PNI <45, HR 2.06, P = 0.031) and age in females (age ≥82, HR 4.06, P = 0.004). Treatment was not a prognostic factor in either subgroup. Pathological category ≥pT1b2 (submucosal invasion ≥500 µm) and lymphovascular invasion (LVI) were significantly associated with GC death (mortality: ≥pT1b2, 7.7%, P = 0.002; LVI, 10.1%, P < 0.001).

CONCLUSIONS

In elderly patients with relative ER-indication EGC, ESD may have comparable long-term efficacy to surgery, and treatment selection had a minor contribution to OS. For patients with poor preoperative prognostic factors, diagnostic ESD may be performed first, followed by additional surgery based on pathological results.

Long-term outcomes of endoscopic submucosal dissection and surgery for undifferentiated intramucosal gastric cancer regardless of size

BACKGROUND

The clinical outcomes of endoscopic submucosal dissection (ESD) for undifferentiated (UD) intramucosal early gastric cancer (EGC) compared with those of surgery, regardless of lesion size, are not well known. Furthermore, there is a concern regarding the treatment plan before and after ESD in cases of UD intramucosal EGC within expanded indications.

AIM

To evaluate clinical outcomes of ESD compared with those of surgery in UD intramucosal EGC patients regardless of tumor size.

METHODS

We enrolled patients with UD intramucosal EGC after ESD with complete resection or surgery from January 2005 to August 2020 who met the within or beyond expanded indications with lesion size > 2 cm (the only non-curative factor). Overall, 123 and 562 patients underwent ESD and surgery, respectively. After propensity-score matching, clinical and long-term outcomes, i.e., recurrence-free survival (RFS) and overall survival (OS), were analyzed. The multivariable Cox proportional hazard model with treatment modality and ESD indication was used to evaluate the recurrence risk.

RESULTS

After matching, 119 patients each were finally enrolled in the ESD and surgery groups. The median length of hospital stay was shorter in the ESD group than surgery group (4.0 vs 9.0 days, P < 0.001). Four cases of recurrence after ESD were local recurrences, all of which occurred within 1 year. Total recurrence was seven (5.9%) and two (1.7%) in the ESD and surgery groups, respectively. No difference was observed between the two groups with respect to OS (P = 0.948). However, the ESD group had inferior RFS compared with the surgery group (P = 0.031). ESD was associated with the risk of recurrence after initial treatment in all enrolled patients (hazard ratio, 5.2; 95% confidence interval: 1.0-25.8, P = 0.045).

CONCLUSION

Although OS was similar between the two groups, surveillance endoscopy was important for the ESD than for the surgery group because RFS was inferior and local recurrence was an issue.

Prognosis after curative resection for stage IA gastric cancer in elderly patients: endoscopic submucosal dissection versus surgery

PURPOSE

To establish whether gastrectomy for early gastric cancer (EGC) in elderly patients is related to poor survival.

METHODS

The subjects of this retrospective study were patients aged ≥ 75 years with primary stage IA EGC, who underwent curative resection with endoscopic submucosal dissection (ESD) or surgery.

RESULTS

We analyzed data on 365 patients who underwent ESD and 170 patients who underwent surgery. Overall survival (OS) was not significantly different for the ESD group vs. the surgery group (5-year cumulative rates, 81.5% vs. 79.7%; log-rank test, P = 0.506). Multivariate analysis revealed that treatments; namely, ESD or surgery, were not associated with OS (hazard ratio 1.09, 95% confidence interval 0.77-1.51). Similar results were observed even in the subgroups with worse conditions, such as age > 80 years, Eastern Cooperative Oncology Group performance status 2-3, Charlson comorbidity index ≥ 2, and prognostic nutritional index ≤ 46.7. Using propensity score matching, we selected 88 pairs of patients who underwent ESD or surgery with baseline characteristics matched and found that OS was not different between the two groups (log-rank test, P = 0.829).

CONCLUSION

OS was comparable for elderly patients who underwent ESD and those who underwent surgery for EGC. Surgical invasiveness did not worsen the prognosis, even for elderly patients.

Multi-loop traction device facilitates gastric endoscopic submucosal dissection: ex vivo pilot study and an inaugural clinical experience

BACKGROUND

Endoscopic submucosal dissection (ESD) is technically difficult and requires considerable training. The authors have developed a multi-loop traction device (MLTD), a new traction device that offers easy attachment and detachment. We aimed to evaluate the utility of MLTD in ESD.

METHODS

This ex vivo pilot study was a prospective, block-randomized, comparative study of a porcine stomach model. Twenty-four lesions were assigned to a group that undertook ESD using the MLTD (M-ESD group) and a group that undertook conventional ESD (C-ESD group) to compare the speed of submucosal dissection. In addition, the data of consecutive 10 patients with eleven gastric lesions was collected using electronic medical records to clarify the inaugural clinical outcomes of gastric ESD using MLTD.

RESULTS

The median (interquartile range) speed of submucosal dissection in the M-ESD and C-ESD groups were 141.5 (60.9-177.6) mm2/min and 35.5 (20.8-52.3) mm2/min, respectively; submucosal dissection was significantly faster in the M-ESD group (p < 0.05). The rate of en bloc resection and R0 resection was 100% in both groups, and there were no perforation in either group. The MLTD attachment time was 2.5 ± 0.9 min and the MLTD extraction time was 1.0 ± 1.1 min. Clinical outcomes of MLTD in gastric ESD were almost the same as those of ex vivo pilot study.

CONCLUSIONS

MLTD increased the speed of submucosal dissection in ESD and was similarly effective when used by expert and trainee endoscopists without perforation. MLTD can potentially ensure a safer and faster ESD.

One stomach, two subtypes of carcinoma—the differences between distal and proximal gastric cancer

Gastric cancer (GC) is one of the most common malignant tumors of the digestive tract, posing a significant risk to human health. Over the past 10 years, the pathological characteristics and the prognosis of GC have been determined based on the locations of the tumors that were then classified into two types—proximal and distal GC. This review focuses on the differences in epidemiology, etiology, cell source, pathological characteristics, gene expression, molecular markers, manifestations, treatment, prognosis, and prevention between proximal and distal GC to provide guidance and a basis for clinical diagnosis and treatment.