Clinical implication of endoscopic gross appearance in early gastric cancer: revisited. Surg Endosc. 2013;27:3690-3695. [PMID: 23588711 DOI: 10.1007/s00464-013-2947-y]

Advances in gastrointestinal endoscopy: A comprehensive review of innovations in cancer diagnosis and management

The field of gastroenterology has experienced revolutionary advances over the past years, as flexible endoscopes have become widely accessible. In addition to enabling faster, less invasive, and more affordable treatment, flexible endoscopes have greatly improved the detection and endoscopic screening of malignancies and prevented many cancer-related deaths. The development and clinical application of new diagnostic endoscopic technologies, such as magnification endoscopy, narrow-band imaging, endoscopic ultrasound with biopsy, and more recently, artificial intelligence enhanced technologies, have made the recognition and detection of various neoplasms and sub-epithelial tumors more possible. This review demonstrates the latest advancements in endoscopic procedures, techniques, and devices applied in the diagnosis and management of gastrointestinal cancer.

Endoscopic and clinicopathologic features of early gastric signet ring cell carcinoma ≤20 mm: a retrospective observational study

OBJECTIVES

Limited literature exists on the characteristics of early gastric signet ring cell carcinoma (GSRCC) within 20 mm. This study aimed to explore this type of cancer from several aspects, to provide guidance for early detection and intervention of GSRCC.

METHODS

We retrospectively collected data from 24 patients diagnosed with early GSRCC ≤20 mm in Beijing Friendship Hospital from 2016 to 2021. According to tumor size, those lesions were divided into three groups: diminutive group (1-5 mm, n = 4), small group (6-10 mm, n = 12) and intermediate group (11-20 mm, n = 8). The clinicopathologic and endoscopic characteristics of GSRCC were compared among the three groups.

RESULTS

Treatment strategies for lesions differed according to the size (p<.05). There were no significant differences among the three groups with regard to age, sex, Helicobacter pylori infection, tumor location and macroscopic type. Lesions were often flat type and more likely to present with discoloration, uneven color, ulceration and submucosal invasion with the increase of diameter. Almost all cases showed abnormal intervening part (IP) under magnifying endoscopy.

CONCLUSIONS

The location of early signet ring cell carcinoma is not specific, and the diminutive lesions are often flat. Abnormal IP may be the early endoscopic feature of early GSRCC.

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.

Comparison of endoscopic gastritis based on Kyoto classification between diffuse and intestinal gastric cancer

BACKGROUND

Gastric cancers can be categorized into diffuse- and intestinal-type cancers based on the Lauren histopathological classification. These two subtypes show distinct differences in metastasis frequency, treatment application, and prognosis. Therefore, accurately assessing the Lauren classification before treatment is crucial. However, studies on the gastritis endoscopy-based Kyoto classification have recently shown that endoscopic diagnosis has improved.

AIM

To investigate patient characteristics including endoscopic gastritis associated with diffuse- and intestinal-type gastric cancers in Helicobacter pylori (H. pylori)-infected patients.

METHODS

Patients who underwent esophagogastroduodenoscopy at the Toyoshima Endoscopy Clinic were enrolled. The Kyoto classification included atrophy, intestinal metaplasia, enlarged folds, nodularity, and diffuse redness. The effects of age, sex, and Kyoto classification score on gastric cancer according to the Lauren classification were analyzed. We developed the Lauren predictive background score based on the coefficients of a logistic regression model using variables independently associated with the Lauren classification. Area under the receiver operative characteristic curve and diagnostic accuracy of this score were examined.

RESULTS

A total of 499 H. pylori-infected patients (49.6% males; average age: 54.9 years) were enrolled; 132 patients with gastric cancer (39 diffuse- and 93 intestinal-type cancers) and 367 cancer-free controls were eligible. Gastric cancer was independently associated with age ≥ 65 years, high atrophy score, high intestinal metaplasia score, and low nodularity score when compared to the control. Factors independently associated with intestinal-type cancer were age ≥ 65 years (coefficient: 1.98), male sex (coefficient: 1.02), high intestinal metaplasia score (coefficient: 0.68), and low enlarged folds score (coefficient: -1.31) when compared to diffuse-type cancer. The Lauren predictive background score was defined as the sum of +2 (age ≥ 65 years), +1 (male sex), +1 (endoscopic intestinal metaplasia), and -1 (endoscopic enlarged folds) points. Area under the receiver operative characteristic curve of the Lauren predictive background score was 0.828 for predicting intestinal-type cancer. With a cut-off value of +2, the sensitivity, specificity, and accuracy of the Lauren predictive background score were 81.7%, 71.8%, and 78.8%, respectively.

CONCLUSION

Patient backgrounds, such as age, sex, endoscopic intestinal metaplasia, and endoscopic enlarged folds are useful for predicting the Lauren type of gastric cancer.

The Suggestion of Revised Criteria for Endoscopic Resection of Differentiated-Type Submucosal Gastric Cancer

BACKGROUND

Early gastric cancer that meets the expanded criteria for endoscopic resection (ER) is expected to be associated with a negligible risk for lymph node metastasis (LNM); however, recent studies have reported LNM in submucosal gastric cancer patients who met the existing criteria. In this study, we develop the revised criteria for ER of submucosal gastric cancer with the aim of minimizing LNM.

METHODS

We analyzed the clinicopathological data of 2461 patients diagnosed with differentiated, submucosal gastric cancer who underwent surgery at three tertiary hospitals between March 2001 and December 2012, and re-analyzed the pathological slides of all patients. The depth of submucosal invasion was measured histopathologically in two different ways (the classic and alternative methods) to obtain accurate data.

RESULTS

Of the enrolled subjects, 306 (17.0%) had LNM. The width of submucosal invasion correlated well with the LNM. We defined the depth and width of submucosal infiltration associated with the lowest incidence of LNM. None of the 254 subjects developed LNM when the following criteria were met: tumor diameter ≤ 3 cm, submucosal invasion depth < 1000 μm (as measured using the alternative method), submucosal invasion width < 4 mm, no lymphovascular invasion, and no perineural invasion; however, LNM was observed in 2.7% of subjects (6/218) who met the existing criteria.

CONCLUSIONS

We revised the criteria for ER by adopting the alternative method to measure the depth of submucosal invasion and adding the width of such invasion. Our criteria better predicted LNM than the current criteria used to select ER to treat submucosal gastric cancer.

Reliability of Paris Classification for superficial neoplastic gastric lesions improves with training and narrow band imaging

Background and study aims  Paris Classification is used to classify gastrointestinal superficial neoplastic lesions and to predict presence of submucosal invasion. We aimed to evaluate interobserver reliability and agreement for this classification among Western endoscopists. Methods  A total of 54 superficial gastric lesions were independently classified according to Paris classification by eight endoscopists (4 experts and 4 non-experts). Observers were asked to classify two sets of images - first, obtained with high-resolution white light (HR-WL) endoscopy and secondly, with the same HR-WL images paired with images obtained with high-resolution Narrow Band Imaging (HR-NBI) - HR-WL + NBI image group. Results  Overall interobserver reliability when asked to classify in I, II or III was good both using HR-WL images and HR-WL + NBI images (wK of 0.65 and 0.70, respectively). The proportion of agreement for type III lesions was 0.48 for HR-WL images increasing to 0.74 in the HR-WL + NBI group. Interobserver reliability for identification of a IIc component was only moderate (wK 0,47). NBI improves both sensitivity and interobserver reliability among trainees (from wK 0.19 to 0.47). Specificity was higher than sensitivity in predicting submucosal invasion. Conclusion  Overall, the reliability of Paris classification is moderate to good. Training on this classification or its revision and use of technology such as NBI may improve not only reliability and agreement but also accuracy.

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.

Clinical predictors of histologic type of gastric cancer

BACKGROUND AND AIMS

Gastric cancer is classified into differentiated and undifferentiated types according to the degree of glandular differentiation. Undifferentiated-type early gastric cancer (EGC) carries a higher risk of lymph-node metastasis than differentiated type, and therefore the indication criteria for endoscopic resection differ. This study aimed to clarify the ability of clinical predictors to distinguish between differentiated-type and undifferentiated-type EGCs.

METHODS

This was a post hoc study of a multicenter prospective trial carried out in 5 Japanese hospitals, including 343 patients with cT1 EGC of ≥10 mm. According to the protocol, age, sex, and endoscopic findings of cancer (diameter, location, macroscopic type, and invasion depth) were evaluated, and the final diagnosis was confirmed from resected specimens. We evaluated the associations between these clinical factors and the histologic type of cancer and calculated the ability of the factors to diagnose differentiated-type EGC. The diagnostic ability of forceps biopsy was also calculated as a reference.

RESULTS

Multivariate analysis identified older age (≥72 years), male sex, larger tumor size (>30 mm), elevated type, and shallower invasion depth (cT1a) as independent significant predictors for differentiated-type EGC, with elevated type showing the highest positive likelihood ratio. The sensitivity, specificity, accuracy, and positive and negative likelihood ratios of elevated type for differentiated-type EGC were 24%, 99%, 38%, 15.7, and 0.77, respectively, compared with 96%, 86%, 95%, 7.0, and 0.04 for forceps biopsy.

CONCLUSIONS

Endoscopic elevated type is a significant predictor for differentiated-type EGC and may exclude undifferentiated-type EGC without the need for forceps biopsy.

The longest diameter of tumor as a parameter of endoscopic resection in early gastric cancer: In comparison with tumor area

Background and aim

Tumor burden is important to predict clinical behaviors of cancer such as lymph node metastasis (LNM). Tumor size has been used as a parameter of tumor burden such as indication of endoscopic resection in early gastric cancer (EGC) to predict LNM. Thus, we aimed to investigate whether tumor area can be more helpful to predict clinical behaviors than longest diameter of tumor in EGC.

Patients and methods

3,059 patients who underwent gastrectomy for EGC were reviewed retrospectively. Tumor area was calculated by multiplying long and short diameter of the tumor in surgical specimen. Longest diameter means maximal longitudinal diameter of tumor in specimen. Clinicopathologic features were compared between longest diameter and area using area under receiver operating characteristic (AUROC) curves.

Results

Longest diameter and area of tumor showed a strong correlation (correlation coefficient 0.859, p<0.01). The cutoff value for prediction of LNM was 20 mm of longest diameter of tumor and 270 mm² of tumor area. There was no significant difference between longest diameter and area for prediction of LNM (AUC 0.850 vs. 0.848, respectively). In differentiated-type EGC and undifferentiated-type EGC, there was no significant difference between longest diameter and area for prediction of LNM. Among mucosal or submucosal cancer prediction value of LNM between longest diameter and area was not significantly different.

Conclusion

Tumor area may not be more helpful to predict LNM than longest diameter in EGC. Therefore, the longest diameter of tumor may be sufficient as an indicator of tumor burden in EGC.

Risk factors for early metachronous tumor development after endoscopic resection for early gastric cancer

BACKGROUND

Metachronous gastric tumor (MGT) is one of major concerns after endoscopic submucosal dissection (ESD) for early gastric cancer (EGC). Optimal follow-up strategy has not been yet well-established. The aim of this study was to identify the different clinical features of the patients according to the time interval to development of MGT.

METHODS

Among 1,780 consecutive patients with EGC who underwent ESD between 2005 and 2014, 115 patients with MGT were retrospectively reviewed. MGT was defined as secondary gastric cancer or dysplasia detected > 1 year after initial ESD. Clinicopathological factors associated with early development of MGT were evaluated.

RESULTS

The median interval to development of MGT was 37 months. In univariate analysis, the median interval to MGT was shorter if EGC lesion was non-elevated type (39.4 vs 57.0 months, p = 0.011), or synchronous primary lesion was absent (39.8 vs 51.4 months, p = 0.050). In multivariate Cox's proportional hazards analysis, the hazard ratios for early occurrence of MGT were 1.966 (95% CI: 1.141-3.386, p = 0.015) and 1.911 (95% CI: 1.163-3.141, p = 0.011), respectively. There was no significant difference in overall survival after diagnosis of MGT between the early occurrence group and the late occurrence group.

CONCLUSIONS

Non-elevated gross type and absence of synchronous gastric tumor were independent risk factors for early development of MGT. Meticulous endoscopic inspection is especially important for the detection of MGT during the early follow-up period in patients with these initial tumor characteristics.

Predictive factors for lymph node metastasis in early gastric cancer with signet ring cell histology: a meta-analysis

BACKGROUND

Less invasive surgery is widely used in the treatment of early gastric cancer; however, no definite guidelines exist regarding indications for less invasive surgery to treat early gastric cancer with signet ring cell histology. The aim of this study was to identify risk factors for lymph node metastasis (LNM) in early signet ring cell carcinoma (SRC). An extensive search of PubMed, Embase and the Cochrane library was performed for pertinent articles involving early SRC and LNM.

METHODS

Eligible data (gender, depth of invasion, lymphovascular invasion, size, ulceration, macroscopic type and location) were extracted from the included studies and systematically reviewed via a meta-analysis. Review Manager version 5.3 was used to perform the data processing. The Newcastle-Ottawa Scale was utilized to evaluate the quality of the included articles.

RESULTS

Fourteen studies were included in the final analysis. After meta-analysis, female gender, submucosal invasion, lymphovascular invasion and size >20 mm were associated with LNM in early SRC.

CONCLUSION

Four variables were identified as risk factors for LNM in early SRC. The significance of the results of the present study should be further confirmed in more early SRC patients for future clinical use.

Clinical implication of endoscopic gross appearance in superficial esophageal squamous carcinoma: revisited

BACKGROUND

Standard endoscopic appearance is essential for the diagnosis and treatment of superficial esophageal squamous carcinoma (SESC). The aim of this study was to investigate the association between the endoscopic gross appearance and the clinicopathologic characteristics of SESC.

METHODS

We retrospectively analyzed the clinicopathologic characteristics of SESC according to gross endoscopic appearance in 275 patients with SESC that underwent esophagectomy or endoscopic resection (ER).

RESULTS

The proportion of type I or type III gross appearance, and that of types IIa, IIb, or IIc, were 26.2 and 73.8%, respectively. Type I or type III gross appearance was significantly associated with the female sex, submucosal invasion, lymphovascular invasion (LVI), and lymph node metastasis (LNM). In addition, younger age, larger tumor size, higher proportion of circumferential extension, type I or type III endoscopic gross appearance, submucosal invasion, moderate or poorly differentiated carcinoma, and LVI were significantly associated with LNM. Multivariate logistic regression analysis determined that independent predictors of LNM in patients with SESC included endoscopic gross appearance, submucosal invasion, and presence of LVI. Additionally, type I or type III endoscopic gross appearance lesions were more likely to have submucosal invasion than types IIa, IIb, or IIc. Risk factors for submucosal invasion included a gross appearance of type I or type III, moderately or poorly differentiated tumors, and presence of LVI.

CONCLUSIONS

We found that SESC clinical features are correlated with the endoscopic appearance. Therefore, we suggest that the endoscopic gross appearance may be a candidate for additive criteria in the indications for ER.

The Implications of Endoscopic Ulcer in Early Gastric Cancer: Can We Predict Clinical Behaviors from Endoscopy?

Background

The presence of ulcer in early gastric cancer (EGC) is important for the feasibility of endoscopic resection, only a few studies have examined the clinicopathological implications of endoscopic ulcer in EGC.

Objectives

To determine the role of endoscopic ulcer as a predictor of clinical behaviors in EGC.

Methods

Data of 3,270 patients with EGC who underwent surgery between January 2005 and December 2012 were reviewed. Clinicopathological characteristics were analyzed in relation to the presence and stage of ulcer in EGC. Based on endoscopic findings, the stage of ulcer was categorized as active, healing, or scar. Logistic regression analysis was performed to analyze factors associated with lymph node metastasis (LNM).

Results

2,343 (71.7%) patients had endoscopic findings of ulceration in EGC. Submucosal (SM) invasion, LNM, lymphovascular invasion (LVI), perineural invasion, and undifferentiated-type histology were significantly higher in ulcerative than non-ulcerative EGC. Comparison across different stages of ulcer revealed that SM invasion, LNM, and LVI were significantly associated with the active stage, and that these features exhibited significant stage-based differences, being most common at the active stage, and least common at the scar stage. The presence of endoscopic ulcer and active status of the ulcer were identified as independent risk factors for LNM.

Conclusions

Ulcerative EGC detected by endoscopy exhibited more aggressive behaviors than non-ulcerative EGC. Additionally, the endoscopic stage of ulcer may predict the clinicopathological behaviors of EGC. Therefore, the appearance of ulcers should be carefully evaluated to determine an adequate treatment strategy for EGC.

Additive treatment improves survival in elderly patients after non-curative endoscopic resection for early gastric cancer

BACKGROUND AND STUDY AIMS

Endoscopic resection (ER) is accepted as a curative treatment option for selected cases of early gastric cancer (EGC). Although additional surgery is often recommended for patients who have undergone non-curative ER, clinicians are cautious when managing elderly patients with GC because of comorbid conditions. The aim of the study was to investigate clinical outcomes in elderly patients following non-curative ER with and without additive treatment.

PATIENTS AND METHODS

Subjects included 365 patients (>75 years old) who were diagnosed with EGC and underwent ER between 2007 and 2015. Clinical outcomes of three patient groups [curative ER (n = 246), non-curative ER with additive treatment (n = 37), non-curative ER without additive treatment (n = 82)] were compared.

RESULTS

Among the patients who underwent non-curative ER with additive treatment, 28 received surgery, three received a repeat ER, and six experienced argon plasma coagulation. Patients who underwent non-curative ER alone were significantly older than those who underwent additive treatment. Overall 5-year survival rates in the curative ER, non-curative ER with treatment, and non-curative ER without treatment groups were 84, 86, and 69 %, respectively. No significant difference in overall survival was found between patients in the curative ER and non-curative ER with additive treatment groups. The non-curative ER groups were categorized by lymph node metastasis risk factors to create a high-risk group that exhibited positive lymphovascular invasion or deep submucosal invasion greater than SM2 and a low-risk group without risk factors. Overall 5-year survival rate was lowest (60 %) in the high-risk group with non-curative ER and no additive treatment.

CONCLUSIONS

Elderly patients who underwent non-curative ER with additive treatment showed better survival outcome than those without treatment. Therefore, especially with LVI or deep submucosal invasion, additive treatment is recommended in patients undergoing non-curative ER, even if they are older than 75 years.

Clinicopathologic features of gastric carcinoma with lymphoid stroma in early gastric cancer

BACKGROUND AND OBJECTIVES

Gastric carcinoma with lymphoid stroma (GCLS) is a rare variant of gastric cancer. The aims of this study were to investigate the clinicopathologic features of GCLS in early gastric cancer (EGC).

METHODS

Analysis included 3,385 patients who were diagnosed with EGC after surgery between 2005 and 2012. This study compared GCLS with non-GCLS patients in terms of clinicopathological features including lymph node metastasis (LNM).

RESULTS

Forty-one (1.2%) patients were diagnosed as GCLS among those with EGC. When GCLS and non-GCLS patients were compared, the GCLS group showed a greater predominance among males, greater tendency towards proximal location, a more elevated gross appearance, and deeper submucosal invasion. In particular, more than 90% of GCLS cases showed deep submucosal invasion. The LNM rate was significantly lower in GCLS than non-GCLS cases after adjustment for depth of invasion. Among the GCLS group, there was no LNM in the cases with lesions confined to the mucosa or submucosal invasive lesions with tumor size ≤10 mm.

CONCLUSIONS

In EGC, GCLS showed deeper submucosal invasion and a lower LNM rate compared with non-GCLS. Thus, clinical considerations of GCLS may be helpful to decide on a specific cancer treatment. J. Surg. Oncol. 2016;114:769-772. © 2016 Wiley Periodicals, Inc.

Improving the Endoscopic Detection Rate in Patients with Early Gastric Cancer

Endoscopists should ideally possess both sufficient knowledge of the endoscopic gastrointestinal disease findings and an appropriate attitude. Before performing endoscopy, the endoscopist must identify several risk factors of gastric cancer, including the patient's age, comorbidities, and drug history, a family history of gastric cancer, previous endoscopic findings of atrophic gastritis or intestinal metaplasia, and a history of previous endoscopic treatments. During endoscopic examination, the macroscopic appearance is very important for the diagnosis of early gastric cancer; therefore, the endoscopist should have a consistent and organized endoscope processing technique and the ability to comprehensively investigate the entire stomach, even blind spots.

Endoscopic submucosal dissection for undifferentiated-type early gastric cancer: do we have enough data to support this?

Although endoscopic submucosal dissection (ESD) is now accepted for treatment of early gastric cancers (EGC) with negligible risk of lymph node (LN) metastasis, ESD for intramucosal undifferentiated type EGC without ulceration and with diameter ≤ 2 cm is regarded as an investigational treatment according to the Japanese gastric cancer treatment guidelines. This consideration was largely based on the analysis of surgically resected EGCs that contained undifferentiated type EGCs; however, results from several institutes showed some discrepancies in sample size and incidence of LN metastasis. Recently, some reports about the safety and efficacy of ESD for undifferentiated type EGC meeting the expanded criteria have been published. Nonetheless, only limited data are available regarding long-term outcomes of ESD for EGC with undifferentiated histology so far. At the same time, endoscopists cannot ignore the patients' desire to guarantee quality of life after the relatively non-invasive endoscopic treatment when compared to conventional surgery. To satisfy the needs of patients and provide solid evidence to support ESD for undifferentiated EGC, we need more delicate tools to predict undetected LN metastasis and more data that can reveal predictive factors for LN metastasis.

Endoscopic predictors for undifferentiated histology in differentiated gastric neoplasms prior to endoscopic resection

BACKGROUND

There is often a discrepancy between results from endoscopic forceps biopsy and resected specimen. We aimed to identify endoscopic predictors for undifferentiated histology in differentiated gastric neoplasms prior to endoscopic resection.

METHODS

Medical records of the patients who underwent endoscopic submucosal dissection (ESD) for biopsy-proven differentiated gastric neoplasms at Seoul National University Hospital between July 2005 and July 2014 were retrospectively reviewed. The lesions were divided into two groups based on the final histologic result of ESD: differentiated adenocarcinoma (DA group) and undifferentiated histology (UDH group). The discordant rate, clinicopathologic characteristics, and endoscopic factors were analyzed.

RESULTS

A total of 1641 early gastric cancers from 1615 patients were included. Of these, 1556 (94.8%) were diagnosed as DA and 85 (5.2%) as UDH. The mean age was significantly lower, and number of women was higher in the UDH group than in the DA group. On multivariate analysis, age <65 years [odds ratio (OR) 1.75, 95 % confidence interval (CI) 1.10-2.80], female sex (OR 3.19, 95% CI 2.00-5.08), endoscopic size >10 mm (OR 1.81, 95% CI 1.12-2.92), depressed type (OR 2.85, 95% CI 1.56-5.21), nodularity (OR 2.83, 95% CI 1.59-5.05), and whitish discoloration (OR 19.64, 95% CI 6.98-55.25) were independent predictors.

CONCLUSIONS

Female sex, age <65 years, large endoscopic size, depressed morphology, surface nodularity, and whitish discoloration were predictors for UDH. Meticulous attention should be paid to the lesions with these endoscopic predictors for determining the risk of UDH prior to endoscopic resection.

Endoscopic submucosal dissection for undifferentiated-type early gastric cancer: do we have enough data to support this?

Although endoscopic submucosal dissection (ESD) is now accepted for treatment of early gastric cancers (EGC) with negligible risk of lymph node (LN) metastasis, ESD for intramucosal undifferentiated type EGC without ulceration and with diameter ≤ 2 cm is regarded as an investigational treatment according to the Japanese gastric cancer treatment guidelines. This consideration was largely based on the analysis of surgically resected EGCs that contained undifferentiated type EGCs; however, results from several institutes showed some discrepancies in sample size and incidence of LN metastasis. Recently, some reports about the safety and efficacy of ESD for undifferentiated type EGC meeting the expanded criteria have been published. Nonetheless, only limited data are available regarding long-term outcomes of ESD for EGC with undifferentiated histology so far. At the same time, endoscopists cannot ignore the patients' desire to guarantee quality of life after the relatively non-invasive endoscopic treatment when compared to conventional surgery. To satisfy the needs of patients and provide solid evidence to support ESD for undifferentiated EGC, we need more delicate tools to predict undetected LN metastasis and more data that can reveal predictive factors for LN metastasis.