Therapeutic Outcomes of Endoscopic Resection of Early Gastric Cancer with Undifferentiated-Type Histology: A Korean ESD Registry Database Analysis

An artificial intelligence system for comprehensive pathologic outcome prediction in early gastric cancer through endoscopic image analysis (with video)

BACKGROUND

Accurate prediction of pathologic results for early gastric cancer (EGC) based on endoscopic findings is essential in deciding between endoscopic and surgical resection. This study aimed to develop an artificial intelligence (AI) model to assess comprehensive pathologic characteristics of EGC using white-light endoscopic images and videos.

METHODS

To train the model, we retrospectively collected 4,336 images and prospectively included 153 videos from patients with EGC who underwent endoscopic or surgical resection. The performance of the model was tested and compared to that of 16 endoscopists (nine experts and seven novices) using a mutually exclusive set of 260 images and 10 videos. Finally, we conducted external validation using 436 images and 89 videos from another institution.

RESULTS

After training, the model achieved predictive accuracies of 89.7% for undifferentiated histology, 88.0% for submucosal invasion, 87.9% for lymphovascular invasion (LVI), and 92.7% for lymph node metastasis (LNM), using endoscopic videos. The area under the curve values of the model were 0.992 for undifferentiated histology, 0.902 for submucosal invasion, 0.706 for LVI, and 0.680 for LNM in the test. In addition, the model showed significantly higher accuracy than the experts in predicting undifferentiated histology (92.7% vs. 71.6%), submucosal invasion (87.3% vs. 72.6%), and LNM (87.7% vs. 72.3%). The external validation showed accuracies of 75.6% and 71.9% for undifferentiated histology and submucosal invasion, respectively.

CONCLUSIONS

AI may assist endoscopists with high predictive performance for differentiation status and invasion depth of EGC. Further research is needed to improve the detection of LVI and LNM.

A Rare Case of Primary Gastric Signet Ring Cell Carcinoma: a Review of Guidelines for the Management of Gastric Cancer

Gastric carcinoma is the fifth most common and the third leading cause of cancer deaths worldwide. The incidence of diffuse-type gastric cancer, of which signet ring cell carcinoma is a subtype, is rising in the world. Due to non-specific gastritis-like symptoms, difficulty in assessing true tumor characteristics owing to its horizontal spread, and non-distinguishable endoscopic appearance from other gastric pathologies, the diagnosis of this subtype is challenging. We present a case of a 67-year-old woman with progressively worsening abdominal pain who came for an endoscopic ultrasound evaluation of an incidentally noted pancreatic cyst on a previous MRI. During endoscopy, a 1-cm gastric ulcer was noted along the lesser curvature of the gastric body. Biopsy confirmed a diagnosis of gastric signet ring cell carcinoma (SRCC) with CDX-2 and keratin positivity. The patient underwent total gastrectomy with Roux-en-Y reconstruction. Gross specimen revealed a diffuse SRCC invading the muscularis propria, along with lymphovascular and perineural invasion. In the context of our case, we discuss the morphological features of SRCC and the effectiveness of treatment options based on existing literature. Early accurate diagnosis and staging play an important role in determining treatment options as well as the clinical course of gastric SRCC.

Clinical Features of Gastric Signet Ring Cell Cancer: Results from a Systematic Review and Meta-Analysis

BACKGROUND

Conflicting results about the prognostic relevance of signet ring cell histology in gastric cancer have been reported. We aimed to perform a meta-analysis focusing on the clinicopathological features and prognosis of this subgroup of cancer compared with other histologies.

METHODS

A systematic literature search in the PubMed database was conducted, including all publications up to 1 October 2021. A meta-analysis comparing the results of the studies was performed.

RESULTS

A total of 2062 studies referring to gastric cancer with signet ring cell histology were identified, of which 262 studies reported on its relationship with clinical information. Of these, 74 were suitable to be included in the meta-analysis. A slightly lower risk of developing nodal metastases in signet ring cell tumours compared to other histotypes was found (especially to undifferentiated/poorly differentiated/mucinous and mixed histotypes); the lower risk was more evident in early and slightly increased in advanced gastric cancer. Survival tended to be better in early stage signet ring cell cancer compared to other histotypes; no differences were shown in advanced stages, and survival was poorer in metastatic patients. In the subgroup analysis, survival in signet ring cell cancer was slightly worse compared to non-signet ring cell cancer and differentiated/well-to-moderately differentiated adenocarcinoma.

CONCLUSIONS

Most of the conflicting results in signet ring cell gastric cancer literature could be derived from the lack of standardisation in their classification and the comparison with the different subtypes of gastric cancer. There is a critical need to strive for a standardised classification system for gastric cancer, fostering clarity and coherence in the forthcoming research and clinical applications.

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.

Endoscopic Resection of Undifferentiated Early Gastric Cancer

Endoscopic resection (ER) is widely performed for early gastric cancer (EGC) with a negligible risk of lymph node metastasis (LNM) in Eastern Asian countries. In particular, endoscopic submucosal dissection (ESD) leads to a high en bloc resection rate, enabling accurate pathological evaluation. As undifferentiated EGC (UD-EGC) is known to result in a higher incidence of LNM and infiltrative growth than differentiated EGC (D-EGC), the indications for ER are limited compared with those for D-EGC. Previously, clinical staging as intramucosal UD-EGC ≤2 cm, without ulceration, was presented as 'weakly recommended' or 'expanded indications' for ER in the guidelines of the United States, Europe, Korea, and Japan. Based on promising long-term outcomes from a prospective multicenter study by the Japan Clinical Oncology Group (JCOG) 1009/1010, the status of this indication has expanded and is now considered 'absolute indications' in the latest Japanese guidelines published in 2021. In this study, which comprised 275 patients with UD-EGC (cT1a, ≤2 cm, without ulceration) treated with ESD, the 5-year overall survival (OS) was 99.3% (95% confidence interval, 97.1%-99.8%), which was higher than the threshold 5-year OS (89.9%). Currently, the levels of evidence grades and recommendations for ER of UD-EGC differ among Japan, Korea, and Western countries. Therefore, a further discussion is warranted to generalize the indications for ER of UD-EGC in countries besides Japan.

Endoscopic submucosal dissection for early signet ring cell gastric cancer: A systematic review and meta-analysis

BACKGROUND

The use of endoscopic submucosal dissection (ESD) for treating early signet ring cell carcinoma (SRC) is controversial due to the risk of lymph node metastasis.

AIM

To carry out a meta-analysis to evaluate ESD for therapeutic efficacy and safety in early signet ring cell gastric cancer.

METHODS

The PubMed, Web of Science, Cochrane Library, and EMBASE databases were used to search for relevant studies evaluating the therapeutic efficacy and safety of ESD in SRC. The rates of recurrence, complete resection, incomplete resection, curative resection, en bloc resection, and adverse events were extracted and analyzed. The methodological quality of the enrolled studies was assessed using the Newcastle-Ottawa Scale. Publication bias was evaluated by the Egger’s test. Institutional review board approval and written consent were not needed for this report.

RESULTS

This meta-analysis enrolled seven studies with 653 participants undergoing ESD treatment for early SRC. The overall recurrence rate was 0.010 [95% confidence interval (CI): 0.000-0.040, Z = 1.422, P = 0.155]. The total lymphovascular invasion rate was 0.038 (95%CI: 0.007-0.088, Z = 3.026, P = 0.002). The total en bloc resection rate was estimated at 0.984 (95%CI: 0.925-1.000, Z = 19.463, P = 0.000). The total complete and incomplete resection rates were estimated at 0.785 (95%CI: 0.596-0.928, Z = 9.789, P = 0.000) and 0.188 (95%CI: 0.016-0.468, Z = 2.531, P = 0.011), respectively. The total procedure-associated gastric hemorrhage and perforation rates were estimated at 0.026 (95%CI: 0.005-0.061, Z = 3.006 P = 0.003) and 0.004 (95%CI: 0.000-0.028, Z = 0.938, P = 0.348), respectively. The curative resection, vertical margin invasion, and lateral margin invasion rates were 72.1% (145/341), 2.3% (8/348), and 34.45% (41/119), respectively.

CONCLUSION

ESD constitutes a promising therapeutic approach for early undifferentiated SRC gastric cancer. However, further improvements are required for increasing its treatment efficacy and reducing adverse outcomes.

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.

Establishing Machine Learning Models to Predict Curative Resection in Early Gastric Cancer with Undifferentiated Histology: Development and Usability Study

Background

Undifferentiated type of early gastric cancer (U-EGC) is included among the expanded indications of endoscopic submucosal dissection (ESD); however, the rate of curative resection remains unsatisfactory. Endoscopists predict the probability of curative resection by considering the size and shape of the lesion and whether ulcers are present or not. The location of the lesion, indicating the likely technical difficulty, is also considered.

Objective

The aim of this study was to establish machine learning (ML) models to better predict the possibility of curative resection in U-EGC prior to ESD.

Methods

A nationwide cohort of 2703 U-EGCs treated by ESD or surgery were adopted for the training and internal validation cohorts. Separately, an independent data set of the Korean ESD registry (n=275) and an Asan medical center data set (n=127) treated by ESD were chosen for external validation. Eighteen ML classifiers were selected to establish prediction models of curative resection with the following variables: age; sex; location, size, and shape of the lesion; and whether ulcers were present or not.

Results

Among the 18 models, the extreme gradient boosting classifier showed the best performance (internal validation accuracy 93.4%, 95% CI 90.4%-96.4%; precision 92.6%, 95% CI 89.5%-95.7%; recall 99.0%, 95% CI 97.8%-99.9%; and F1 score 95.7%, 95% CI 93.3%-98.1%). Attempts at external validation showed substantial accuracy (first external validation 81.5%, 95% CI 76.9%-86.1% and second external validation 89.8%, 95% CI 84.5%-95.1%). Lesion size was the most important feature in each explainable artificial intelligence analysis.

Conclusions

We established an ML model capable of accurately predicting the curative resection of U-EGC before ESD by considering the morphological and ecological characteristics of the lesions.

Long-term outcomes of endoscopic resection followed by additional surgery after non-curative resection in undifferentiated-type early gastric cancer: a nationwide multi-center study

BACKGROUND

Undifferentiated-type early gastric cancer (UD EGC) shows lower curative resection rates after endoscopic submucosal dissection (ESD). Additional surgery is recommended after non-curative resection. We evaluated the long-term outcomes of ESD followed by additional surgery after non-curative resection in UD EGC compared to those for surgery as initial treatment.

METHODS

We reviewed 1139 UD EGC patients who underwent ESD at 18 hospitals and 1956 patients who underwent surgery at two hospitals between February 2005 and May 2015. We enrolled 636 patients with non-curative ESD and 1429 surgery subjects beyond the curative ESD criteria. Among them, 133 patients with additional surgery after ESD (ESD + OP group) and 252 patients without additional surgery (ESD-only group) were matched 1:1 using propensity scores to patients with surgery as initial treatment (surgery group). Overall survival (OS) and recurrence-free survival (RFS) were compared.

RESULTS

Signet ring cell carcinoma and poorly differentiated adenocarcinoma (PDA) were observed in 939 and 1126 cases, respectively. OS was significantly longer in the surgery group than in the ESD + OP group, especially for PDA. However, RFS was shorter in the ESD-only group than those in the ESD + OP and surgery groups. RFS did not differ significantly between the ESD + OP and surgery groups. Compared to the surgery group, the ESD-only and ESD + OP groups had an overall hazard ratio for RFS of 3.58 (95% confidence interval 1.44-8.88) and 0.46 (0.10-2.20), respectively.

CONCLUSIONS

ESD followed by additional surgery after non-curative resection showed comparable cancer-specific outcomes to initial surgery in UD EGC.

Factors associated with overall survival in early gastric cancer patients who underwent additional surgery after endoscopic submucosal dissection

BACKGROUND

Controversy exists about the benefit of additional surgery after endoscopic submucosal dissection (ESD) for early gastric cancer (EGC).

AIM

To examine risk factors for overall survival (OS) after additional surgery in patients with EGC who initially underwent ESD.

METHODS

This was a retrospective analysis of patients with EGC who underwent additional surgery after ESD at the Beijing Friendship Hospital affiliated to Capital Medical University between August 2012 and August 2019. OS was the primary outcome. Lymph node metastasis and residual tumor were secondary outcomes. Logistic regression models and Kaplan-Meier curves were used for further analysis.

RESULTS

Forty-two patients were evaluated, including 35 (83.3%) males and 7(16.7%) females. The mean age was 62 (range, 32-82) years. Male sex [hazard ratio (HR) = 21.906, 95% confidence interval (CI): 3.762-229.250; P = 0.039), T1b invasion (HR = 3.965, 95%CI: 1.109-17.432; P = 0.047), undifferentiated tumor (HR = 9.455, 95%CI: 0.946-29.482; P = 0.049), lymph node metastasis (HR = 2.126, 95%CI: 0.002-13.266; P = 0.031), and residual tumor (HR = 4.275, 95%CI: 1.049-27.420; P = 0.043) were independently associated with OS. The follow-up duration was 4-81 mo (median: 50.7 mo). OS was 77.0 ± 12.1 mo (95%CI: 53.3-100.7 mo). The 3-year and 5-year OS rates were 94.1% and 85%, respectively.

CONCLUSION

Male sex, T1b invasion, undifferentiated tumor, lymph node metastasis, and residual tumor are independently associated with OS in patients with EGC who underwent additional surgery after ESD.

Clinico-pathologic determinants of non-e-curative outcome following en-bloc endoscopic submucosal dissection in patients with early gastric neoplasia

Background

Endoscopic submucosal dissection (ESD) is gaining enormous popularity in the treatment of early gastric cancers (EGCs) in many institutions across the world. However, appropriate selection of candidates for endoscopic resection is crucial to sufficiently mitigate non-e-curative (NEC) resection. This study aims at identifying the various clinico-pathologic factors that independently predict the NEC outcome and depth of submucosal invasion following ESD procedure in patients with EGC.

Methods

Multiple logistic regression analysis was applied to investigate factors that independently predict both non-curability phenomenon and the level of submucosal invasion in patients with early gastric neoplasia. Statistical Packages for the Social Sciences version 23 was used for analysis.

Results

A total of 153 patients (162 EGC lesions) underwent en-bloc ESD after which the rate of complete resection and non-e-curative outcome were 95% and 22.2%, correspondingly. Multivariate analysis depicted that tumor location in the upper two third of stomach (odds ratio [OR], 5.46; 95% confidence interval [95% CI], 1.65–18.12; p = 0.006), tumor size > 2 cm (OR, 7.63; 95% CI, 2.29–25.42; p = 0.001), histologically undifferentiated tumor (OR, 15.54; 95% CI, 1.65–146.22; p = 0.001), and tumors with 0-IIa/0-IIc or their mixed variants with predominant 0-IIa/0-IIc (OR, 9.77; 95% CI, 1.23–77.65; p = 0.031) were all independent predictors of NEC resection for early gastric tumors. Additionally, location in the upper two third of the stomach (OR, 8.88; 95% CI, 2.90–27.17; p < 0.001), ulcerated lesions (OR, 3.70; 95% CI, 1.15–11.90; p = 0.028), lesions with > 2 cm (OR, 2.94; 95% CI, 1.08–8.02; p = 0.036) and those with poor differentiation (OR, 6.51; 95% CI, 2.23–18.98; p = 0.001) were found to have significant association with submucosal invasion.

Conclusions

Tumors located in the upper two third of the stomach having a larger size (> 2 cm), poor histo-differentiation and a gross type of 0-IIa/0-IIc or their mixed variants with predominant 0-IIa/0-IIc were significantly associated with a risk of NEC after ESD procedure. Thus, early gastric tumors displaying these features need to be handled carefully during endoscopic resection. Our findings may shed light on the pre-procedural detection of clinicopathologic factors that determine non-e-curability in patients with EGC.

Regional Lymph Node Dissection as an Additional Treatment Option to Endoscopic Resection for Expanded Indications in Gastric Cancer: a Prospective Cohort Study

Purpose

Expanded indications for endoscopic submucosal dissection (ESD) in early gastric cancer (EGC) remain controversial due to the potential risk of undertreatment after adequate lymph node dissection (LND). Regional LND (RLND) is a novel technique used for limited lymphadenectomy to avoid gastrectomy. This study established the safety and effectiveness of RNLD as an additional treatment option after ESD for expanded indications.

Materials and Methods

A total of 69 patients who met the expanded indications for ESD were prospectively enrolled from 2014 to 2017. The tumors were localized using intraoperative esophagogastroduodenoscopy (EGD) before RLND. All patients underwent RLND first, followed by conventional radical gastrectomy with LND. The locations of the preoperative and intraoperative EGD were compared. Pathologic findings of the primary lesion and the RLND status were analyzed.

Results

The concordance rates of tumor location between the preoperative and intraoperative EGD were 79.7%, 76.8%, and 63.8% according to the longitudinal, circumferential, and regional locations, respectively. Of the 4 patients (5.7%) with metastatic LNs, 3 were pathologically classified as beyond the expanded indication for ESD and 1 had a single LN metastasis in the regional lymph node.

Conclusions

RLND is a safe additional option for the treatment of EGC in patients meeting expanded indications after ESD.

Protocol for expanded indications of endoscopic submucosal dissection for early gastric cancer in China: a multicenter, ambispective, observational, open-cohort study

BACKGROUND

The main treatment methods for early gastric cancer (EGC) include endoscopic submucosal dissection (ESD) and radical gastrectomy. However, appropriate treatment for patients who exceed the absolute indications for ESD remains unestablished. In China, evidence-based medicine for the expanding indications of ESD and accurate diagnostic staging for EGC patients are lacking. Thus, clinical studies involving Chinese patients with EGC are necessary to select appropriate treatment options and promote China's expanded indications for ESD and diagnostic staging scheme.

METHODS

This is a multicenter, ambispective, observational, open-cohort study that is expected to enroll 554 patients with EGC. The study was launched in May 2018 and is scheduled to end in March 2022. All enrolled patients should meet the inclusion criteria. Case report forms and electronic data capture systems are used to obtain clinical data, which includes demographic information, results of perioperative blood- and auxiliary examinations, surgical information, results of postoperative pathology, and the outcomes of postoperative recovery and follow-up. Patients are followed up every 6 months after surgery for a minimum of 5 years. The primary endpoint is the rate of lymph node metastasis (LNM), whereas the secondary endpoints include the following: consistency, sensitivity, and specificity of the results of preoperative examinations and postoperative pathology; cut-off values for LNM; logistic regression model of expanded indications for ESD; and incidence of postoperative complications within the 30-day and 5-year relapse-free survival rates.

DISCUSSION

This study will explore and evaluate expanded indications for ESD that match the characteristics of the Chinese population in patients with EGC and will introduce a related staging procedure and examination scheme that is appropriate for China. Ethical approval was obtained from all participating centers. The findings are expected to be disseminated through publications or presentations and will facilitate clinical decision-making in EGC.

TRIAL REGISTRATION

The name of the registry is ChiCTR. It was registered on May 9, 2018, with the registration number ( ChiCTR1800016084 ). The clinical trial was launched in May 2018 and will end in March 2022, with enrollment to be completed by December 2021. Trial status: Ongoing.

Usefulness of histologic differences and perivascular infiltration for preoperative T staging of advanced gastric cancer using computed tomography

PURPOSE

This study aimed to determine whether histologic differences and perivascular infiltration are useful for clinical T staging of advanced gastric cancer (AGC).

MATERIALS AND METHODS

This retrospective study included 160 patients with pathologically confirmed AGC who had available preoperative stomach computed tomography (CT). Using stomach CT, they were classified according to standard T stage, histologic T stage, and perivascular T stage. Accuracy of each T stage criteria was analyzed. Perivascular infiltrations for the evaluation of prognosis were correlated with time to tumor progression by log-rank test.

RESULTS

There was a significant difference between the accuracies of the standard and histologic T stages (p < 0.001), whereas there was no significant difference between the standard and perivascular T stages (p = 0.07). In 121 patients who were pathologically confirmed as having T3 or T4a tumor, there was a significant difference between the standard and perivascular T stage (p < 0.001). In patients having T3 or T4a tumor, time to tumor progression of the negative perivascular infiltration subgroup was significantly longer than the positive subgroup.

CONCLUSION

Consideration of histologic differences and perivascular infiltration may be useful for clinical T staging of AGC.

Characteristics of proximal early gastric cancer differentiating distal early gastric cancer

Previous studies reported substantial differences between proximal and distal gastric cancer, however, most of the cases included in these studies were advanced gastric cancers (AGCs). The aim of this study was to investigate the unique characteristics of proximal early gastric cancer (EGC) by comparing with distal EGC. From March 2007 to March 2016, proximal and distal EGC patients who underwent endoscopic or surgical resection at our institution were matched 1:3 according to age and sex. We retrospectively analyzed the clinical and histopathological information. A total of 368 patients were enrolled including 92 (25%) in the proximal and 276 (75%) in the distal group. The proportion of patients who underwent surgery (56.5 vs. 20.3%, p<0.001), undifferentiated type (38.0 vs. 19.6%, p<0.001), tumor size (29.5 ±19.4 vs. 20.3 ±16.8 mm, p<0.001) and submucosal (SM) invasion (60.9 vs. 25.7%, p<0.001) were significantly higher in the proximal group than in the distal group. In multivariate analysis, the proximal location of EGC was a significant risk factor for SM invasion in the total population (odds ratio [OR], 3.541; 95% confidence interval [CI], 2.053–6.110; p<0.001), and in subgroup with EGC < 30mm (n = 279) (OR, 5.940; 95% CI, 2.974–11.862; p<0.001). In conclusion, careful therapeutic decision of proximal EGC is essential due to the different histopathological characteristics such as large tumor size and higher potential for SM invasion.

Is Radical Surgery Necessary for All Patients Diagnosed as Having Non-Curative Endoscopic Submucosal Dissection?

If a lesion does not meet the expanded indication criteria for treatment with endoscopic therapy for early gastric cancer or has a positive resection margin, it is regarded as suitable for non-curative resection. Non-curative resection is closely related to the risk of local recurrence, lymph node metastasis, and poor prognosis. If the result is confirmed as non-curative resection, additional treatment should be considered depending on the risks of residual tumor, local recurrence, and lymph node metastasis. As lymphatic invasion is the most important risk factor of recurrence and poor prognosis, surgical treatment should be considered if lymphatic invasion is present. If patients are not suitable for additional surgery owing to old age or coexisting severe disease, close surveillance can be an alternative treatment option.

Risk Factors for Lymph Node Metastasis in Undifferentiated-Type Gastric Carcinoma

Undifferentiated-type carcinoma has a high incidence of lymph node metastasis. The independent risk factors for lymph node metastasis in undifferentiated-type carcinoma are invasion depth, tumor size, lymphovascular invasion, and presence of ulcer. In the cases that meet the curative resection criteria, no lymph node metastasis was observed in the Japanese studies, but some metastases were observed in Korean studies. After performing curative endoscopic submucosal dissection, the survival rate is similar to that of gastrectomy. The discrepancy between endoscopy and pathology is high in undifferentiated-type carcinoma. The tumor size in endoscopy is a significant risk factor for non-curative resection, and when the tumor size is small, the non-curative resection rate is significantly reduced. Lymphovascular invasion can be assessed in pathologic examination and D2-40 stain is helpful. The presence of ulcer should be determined by pathology, but ulcer's omission in pathology report makes the analysis difficult. Undifferentiatedtype carcinomas with differentiated-type components show higher lymph node metastasis rate than that of pure undifferentiatedtype carcinomas. The lymph node metastasis rate of signet ring cell type is lower than that of other undifferentiated-type carcinomas and is similar to differentiated-type carcinomas. The application of these additional histologic findings may improve the indication of endoscopic submucosal dissection.

Strategy for Curative Endoscopic Resection of Undifferentiated-Type Early Gastric Cancer

Endoscopic resection (ER) of undifferentiated-type early gastric cancer (UD-EGC) has a lower curative resection (CR) rate than differentiated-type EGC. However, if UD-EGC is curatively resected using ER, long-term outcomes can be favorable. Thus, the strategy for CR by ER is important in UD-EGC. To achieve CR in UD-EGC, biological behaviors including tumor growth patterns must be considered. This review aims to describe what is important for curative ER of UD-EGC.

Pitfalls in the Interpretation of Publications about Endoscopic Submucosal Dissection of Early Gastric Cancer with Undifferentiated-Type Histology

Endoscopic submucosal dissection (ESD) is a standard treatment for patients with gastrointestinal neoplasms with a negligible risk of lymph node metastasis. ESD enables en bloc resection of gastrointestinal neoplasms and organ preservation, thereby, avoiding surgical treatment. Although small (<2 cm) intramucosal early gastric cancer with undifferentiated-type histology (EGC-UH) without ulceration is included in the expanded criteria for ESD, controversies remain due to different biology and characteristics compared to EGC with differentiated-type histology. The authors previously presented studies about the technical feasibility of ESD for these lesions using a meta-analysis and retrospective multicenter analysis. However, many pitfalls were identified in the interpretation of studies analyzing histologic discrepancy, mixed-type histology, criteria-based analysis of therapeutic outcomes, interpretation of curative resection, and long-term clinical outcomes. In this review, the authors discuss pitfalls in the interpretation of publications on ESD for EGC-UH.

Effect of age on the clinical outcomes of patients with early gastric cancer with undifferentiated-type histology

BACKGROUND

Undifferentiated-type early gastric cancers account for a large proportion of gastric cancers in younger patients. Therefore, the clinical outcomes of endoscopic resection in younger patients are a major concern. We aimed to investigate the influence of age on lymph node metastasis and long-term survival after surgery for undifferentiated-type early gastric cancers.

METHODS

We identified 4,236 patients who underwent surgery for undifferentiated-type early gastric cancers. For each T stage, the correlation between age and lymph node metastasis was analyzed using a multivariate logistic regression. Lymph node metastasis rates were compared between younger (<40 years) and older patients (≥40 years) who fulfilled the expanded criteria for endoscopic resection. The Kaplan-Meier method was used to compare long-term survival between younger and older patients.

RESULTS

Younger age groups (20-29 and 30-39 years) had the highest lymph node metastasis rate within each T stage (5.7% and 5.7% for T1a, 26.3% and 24.1% for T1b, respectively). After adjusting for possible covariates, however, age did not have a significant effect on lymph node metastasis in either T stage (P = .127 for T1a, P = .114 for T1b). Among patients fulfilling the expanded indication for endoscopic resection, younger patients had a slightly higher lymph node metastasis rate compared with older patients (2.7% versus 2.0%), although this difference was not statistically significant. Although younger patients had a significantly better overall survival (P < .001), no significant age-related differences were observed in recurrence-free and disease-specific survival (P = .051 and P = .069) CONCLUSION: Endoscopic resection may be feasible in young patients with undifferentiated-type early gastric cancers because these patients share a similar lymph node metastasis rate and long-term survival outcomes with older patients.

Self-expandable metal stents in patients with postoperative delayed gastric emptying after distal gastrectomy

AIM

To investigate the efficacy and safety of endoscopic stent insertion in patients with delayed gastric emptying after gastrectomy.

METHODS

In this study, we prospectively collected data from patients who underwent stent placement for delayed gastric emptying (DGE) after distal gastrectomy between June 2010 and April 2017, at a tertiary referral academic center. Clinical improvement, complications, and consequences after stent insertion were analyzed.

RESULTS

Technical success was achieved in all patients (100%). Early symptom improvement was observed in 15 of 20 patients (75%) and clinical success was achieved in all patients. Mean follow-up period was 1178.3 ± 844.1 d and median stent maintenance period was 51 d (range 6-2114 d). During the follow-up period, inserted stents were passed spontaneously per rectum without any complications in 14 of 20 patients (70%). Symptom improvement was maintained after stent placement without the requirement of any additional intervention in 19 of 20 patients (95%).

CONCLUSION

Endoscopic stent placement provides prompt relief of obstructive symptoms. Thus, it can be considered an effective and safe salvage technique for post-operative DGE.

Effect of ilaprazole on the healing of endoscopic submucosal dissection-induced gastric ulcer: randomized-controlled, multicenter study

BACKGROUND

The optimal treatment regimen or the duration of treatment for an endoscopic submucosal dissection (ESD)-induced gastric ulcer has not been established. The aim of this study was to assess the efficacy of novel proton-pump inhibitor, ilaprazole, for the treatment of ESD-induced gastric ulcer.

METHODS

This was a prospective, open-label, randomized multicenter study. Between June 2015 and March 2018, a total of 176 patients (178 lesions) who underwent ESD for a gastric neoplasm were randomly allocated to receive the oral proton-pump inhibitor ilaprazole 20 mg or rabeprazole 20 mg daily for 8 weeks. The primary outcome was the ulcer healing rate at 4 and 8 weeks.

RESULTS

A total of 155 (157 lesions) and 154 patients (156 lesions) were included in the modified intention-to-treat (mITT) and per-protocol analyses, respectively. There was no significant difference in the ulcer healing rate (ilaprazole vs. rabeprazole, 97.4% vs. 97.0 p = 0.78 at 4 weeks, 100% vs. 100%, p = 0.95 at 8 weeks in the mITT analysis) or stage of ulcer (scar stage, 25.6% vs. 17.7%, p = 0.25 at 4 weeks, 92.3% vs. 88.6%, p = 0.59 at 8 weeks in the mITT analysis) between the treatment groups. The quality of ulcer healing was not significantly different between the two groups. No independent predictive factor for higher-quality ulcer healing was found in the multivariate analysis.

CONCLUSIONS

According to this trial, ilaprazole and rabeprazole showed no significant difference in the healing of artificial gastric ulcers. Most of the ulcers achieved complete healing within 4-8 weeks.

TRIAL REGISTRATION

ClinicalTrial.gov NCT02638584.

Mixed poorly differentiated adenocarcinoma in undifferentiated-type early gastric cancer predicts endoscopic noncurative resection

BACKGROUND

Comparisons between surgical cases of mixed poorly differentiated adenocarcinoma and pure signet ring cell carcinoma have revealed higher frequencies of lymph node metastasis and submucosal invasion in the former. However, this comparison has not been reported for endoscopically treated cases. Therefore, we compared cases of curative and noncurative resection in patients who underwent endoscopic submucosal dissection to determine what factors could influence the curative resection rate.

METHODS

We analyzed 268 undifferentiated-type early gastric cancers in 264 patients treated with endoscopic submucosal dissection in our hospital between March 2005 and March 2017, involving 229 and 39 cases of curative and noncurative resection, respectively. Treatment results were compared between 129 lesions of pure signet ring cell carcinoma and 139 lesions of mixed poorly differentiated adenocarcinoma.

RESULTS

The overall curative resection rate was 85.4% (229/268). On comparing noncurative and curative resection cases, after excluding factors that determine curative resection (e.g., tumor diameter), we found that the former was associated with older age and significantly more mixed poorly differentiated adenocarcinomas, with odds ratios of 1.052 [95% confidence interval (CI), 1.017-1.089] and 2.746 (95% CI, 1.162-6.485), respectively, on multivariate analysis. The curative resection rate was significantly higher in pure signet ring cell carcinoma than in mixed poorly differentiated adenocarcinoma (93.8% vs. 77.7%, respectively).

CONCLUSION

Advanced age and mixed poorly differentiated adenocarcinoma predicted endoscopic noncurative resection.