Mastering gastric endoscopic submucosal dissection: A learning curve analysis of over 100 consecutive cases performed by Western endoscopist

Abstract

BACKGROUND

Gastric endoscopic submucosal dissection (ESD) is a minimally invasive therapeutic procedure indicated for en bloc resection of superficial gastric neoplasms, especially in cases of early-stage gastric adenocarcinoma. Its implementation has been widely consolidated in Asian countries and is growing steadily at Western endoscopy units.

AIM

To analyze the learning curve of gastric submucosal endoscopic dissection in one of the largest Western series reported to date.

METHODS

A retrospective study was conducted, including patients who underwent ESD for superficial gastric neoplasms between 2009 and 2025. Patients were divided into 4 consecutive chronological phases to assess temporal trends in outcomes: (1) Phase I: From case 1 to case 40; (2) Phase II: From case 41 to case 80; (3) Phase III: From case 81 to case 120; and (4) Phase IV: From case 121 to case 162. The following parameters were analyzed within each group and phase: Age, gender, average procedure time, tumor size, en bloc resection rate, complete resection rate (R0), curative resection rate, adverse event rate, histopathological report of the resected specimen, and location of the lesion.

RESULTS

A total of 164 ESD procedures were performed. The duration of the first phase, second phase, third phase, and fourth phase was 77 months, 40 months, 37 months, and 50 months, respectively. In the first phase of the study (phase I) the mean tumor size, mean procedure time, en bloc resection rate, complete resection rate and curative resection rate were: 21.5 mm, 99.4 minutes, 97.5% (39/40), 92.5% (37/40) and 87.5% (35/40) respectively, while in the last phase of the study (phase IV) those features were: 25.6 mm, 107.7 minutes, 90.4% (38/42), 83.3% (35/42) and 78.5% (33/42) respectively. Likewise, the overall rate of adverse events in phase I was 0% and in phase IV was 7.1% (3/42) (P = 0.35) (mortality associated with the procedure: 0%). The Cumulative Sum Curve showed a turning point in the curve in case number 112.

CONCLUSION

Proficiency in gastric ESD takes more than one hundred procedures to be achieved in Western settings, with high standards of safety and efficacy, provided that rigorous and systematic training is combined with a planned progression of case complexity.

Key Words: Stomach neoplasms; Learning curve; Endoscopic submucosal dissection; Gastric cancer; Western countries

Core Tip: Currently, scientific evidence on the learning curve in gastric endoscopic submucosal dissection (ESD) is limited, and most of the available data comes from Asian countries. This lack of scientific evidence represents a significant barrier, especially given the progressive increase in the early diagnosis of gastric cancer in Western regions and the growing interest in effective and minimally invasive endoscopic therapeutic strategies. The learning curve in gastric ESD is feasible, safe, and effective in Western countries, provided that intensive training and adequate progressive case selection are in place. According to our case series, after 112 ESD procedures, consolidated technical mastery is achieved.

INTRODUCTION

Gastric cancer is the fifth most common malignant neoplasm worldwide, with an estimated global prevalence of 5.7% of all diagnosed cancers, according to the most recent studies[1]. Its incidence is approximately 9.2 cases per 100000 inhabitants, and it is the third leading cause of cancer death globally, with a mortality rate ranging from 8% to 11% of all deaths from this disease[1]. Advances in endoscopic technology and the growing implementation of screening programs have facilitated the early diagnosis of gastric cancer, allowing for a more effective therapeutic approach using minimally invasive techniques. In this context, endoscopic submucosal dissection (ESD) has established itself as the first-line treatment for superficial gastric neoplasms. This technique has demonstrated efficacy and safety profiles comparable to those of gastrectomy in expert hands, with the additional advantage of preserving the affected organ, reducing post-surgical morbidity, and maintaining an optimal quality of life after the procedure. However, its correct performance involves a high level of technical complexity and requires a long and specialized learning curve[2-6].

Studies conducted in Asia have shown that technical skill in gastric ESD improves progressively with accumulated experience[6]. According to international consensus, mostly from Eastern countries, it is considered necessary to perform at least 30 procedures to achieve basic competence in ESD of the lower third of the stomach, evaluated in terms of en bloc resection, procedure time, and complication management. To achieve an advanced level of competence in the resection of more complex lesions located in the middle-upper third of the stomach, it is estimated that between 50 and 100 cases are required. Internationally, and especially in Eastern training programs, these ranges have been fundamental in structuring effective training programs, establishing objective criteria for technical competence, and reducing the gap in the adoption of this technique in regions where its implementation is still limited, such as in the West and Latin America[7-11].

In the West, one of the main limitations to the effective eradication of superficial gastric neoplasms through ESD is the scarcity of centers specializing in highly complex endoscopic procedures that offer structured and accessible training programs for endoscopists interested in acquiring experience in this advanced technique[12-16]. Currently, scientific evidence on the learning curve in gastric ESD is limited, and most of the available data comes from Asian countries, where the prevalence of early gastric cancer is higher and ESD is more widely used[17-21]. This lack of scientific evidence represents a significant barrier, especially given the progressive increase in the early diagnosis of gastric cancer in Western regions and the growing interest in effective and minimally invasive endoscopic therapeutic strategies. In this context, it is a priority to understand and adequately characterize the learning curve in gastric ESD in order to validate and standardize training programs adapted to local realities. Our study aims to analyze the learning curve in gastric ESD in one of the largest Western cohorts, through a detailed analysis divided into four consecutive chronological phases.

MATERIALS AND METHODS

Patients

This is a retrospective study. Data were collected from a prospectively generated database of patients admitted in chronological order from 2009 to 2025 who underwent ESD for superficial gastric neoplasms performed by a single endoscopist (Arantes VN). The inclusion criteria were patients admitted for endoscopic resection for early gastric neoplasms. It is important to note that all participants enrolled in our study were thoroughly evaluated prior to ESD by an expert operator using high-definition white light endoscopy and image-enhanced endoscopy (digital chromoendoscopy and endoscopic magnification) to determine the degree of neoplastic invasion in deep layers. Only in doubtful cases were endoscopic ultrasonography and computed tomography used to optimize preoperative staging. Patients with advanced neoplasms that showed massive submucosal invasion or invasion into deeper layers during preoperative staging, as well as individuals with clinical conditions unacceptable for anesthesia or the endoscopic procedure, were excluded from the study.

Patients were divided into four chronological phases in order to obtain a similar number of participants in each group: The first period included patients from case 1 to case 40, the second period included patients from case 41 to case 80, the third period included patients from case 81 to case 120, and the fourth period included patients from case 121 to case 162. The following parameters were calculated for each study period: Age, gender, average procedure time, tumor size, en bloc resection rate, complete resection rate (R0), curative resection rate, adverse event rate, histopathological report of the resected specimen, and location of the lesion.

The rates of curative resection, en bloc resection, and complete resection with tumor-free margins were assessed based on the most recent Japanese clinical guidelines[2]. The parameters for defining curative treatment of gastric carcinoma were established as follows: (1) Endoscopic curability A: Predominantly differentiated type, tumors limited to the mucosa (pT1a), negative resection margins (complete R0 resection), absence of lympho-vascular invasion, absence of ulceration or ulcer scar, regardless of size. Long diameter ≤ 2 cm, predominantly undifferentiated type, pT1a, absence of ulceration or ulcer scar, negative resection margins, and absence of lympho-vascular invasion. Long diameter ≤ 3 cm, predominantly differentiated type, pT1a, finding of ulceration or ulcer scar, negative resection margins, and absence of lympho-vascular invasion; and (2) Endoscopic curability B: Resected en bloc, long diameter ≤ 3 cm, predominantly of the differentiated type, negative resection margins, absence of lympho-vascular invasion and tumors limited to the superficial submucosa [pT1b/SM1 (superficial submucosa)] < 500 μm from the muscularis mucosae. Histopathological assessment was performed according to the World Health Organization classification[8,9].

ESD procedures

All ESD procedures were performed under general anesthesia. The operator who conducted all gastric ESDs in our series received specialized training from experienced endoscopists at high-volume referral centers in Japan and has performed over 350 ESD procedures across various segments of the gastrointestinal tract to date. Following a thorough evaluation using high-definition white-light endoscopy and virtual chromoendoscopy, lesions eligible for ESD were classified according to the Paris classification system. All ESD procedures were carried out using standardized equipment, which included either a Flush Knife BT 2.0 or 2.5 (Fujifilm Co., Tokyo, Japan), connected to an electrosurgical unit (ERBE VIO 200S, 200D, or 300D, Tübingen, Germany), a 4-mm distal cap (Elastic Touch, Top Co., Tokyo, Japan) affixed to the endoscope tip and a 25-gauge injection needle (Boston Scientific Co., MA, United States) for delivering the submucosal solution. Each ESD was carried out following a structured sequence of steps: (1) Lesion marking (demarcation) was performed using diathermy in soft coagulation mode (effect 6, 30 watts); (2) Submucosal injection was done to elevate the lesion, utilizing 0.4% sodium hyaluronate in teardrops form (Adaptis Fresh^®, Legrand Laboratory, Brazil)[3]; (3) Mucosal incision was executed in endocut I mode (effect 2, cut duration 3, cut interval 2); (4) Dissection of the submucosal layer followed, using forced coagulation mode (effect 3, 50 watts); and (5) Pre-hemostasis of visible blood vessels was carried out using soft coagulation mode (effect 6, 100 watts). Depending on vessel size, hemostasis was achieved either with the dissection knife or with coagulation forceps (Coagrasper; Olympus Co., Tokyo, Japan). After the procedure, all patients were prescribed a proton pump inhibitor régimen for four weeks and sucralfate for two weeks.

Statistical analysis

All statistical analyses were performed using SPSS Statistics for Windows, version 24.0 (IBM Corp., Armonk, NY, United States) and Python version 3.11 for advanced graphical representation. The variables included in the analysis were compared between the four phases of the study (phase I: Case 1-40; phase II: Case 41-80; phase III: Case 81-120; phase IV: Case 121-162) to assess significant differences along the learning curve. For the comparison of the continuous variables among the four phases, a one-way analysis of variance (ANOVA) test was used due to the design with multiple independent groups. A value of P < 0.05 was considered statistically significant. For the analysis of categorical variables, the χ² test was used to compare proportions between phases. This test was selected whenever the expected frequencies in each cell were ≥ 5. For variables with extremely low frequencies, Fisher’s exact test was used in additional analyses by pairs of phases.

In addition to the comparative analysis of the clinical and demographic variables between the phases of the study, statistical analyses were performed to evaluate the evolution of the operator’s technical performance during the learning curve in gastric ESD. To evaluate the operator’s global learning curve, a Cumulative Sum Curve (CUSUM) was constructed. The main parameter used was technical success, defined as a en bloc resection, complete resection and absence of adverse events (perforation or clinically significant gastrointestinal bleeding), each case was classified as success (assigned value: 1) or failure (assigned value: 0). The calculation of the CUSUM curve was performed by accumulating, case by case, the deviations of the individual result from the predefined standard. This method makes it possible to detect graphically the point at which the failure rate begins to fall consistently, which indicates the consolidation of the technique. The curve was plotted with the sequential number of cases on the X-axis and the cumulative value on the Y-axis.

Ethical considerations

The authors declare that this study entailed a retrospective evaluation of the learning curve in gastric ESD and was conducted in accordance with the Declaration of Helsinki. The analysis was confined to the statistical assessment across four defined chronological periods. The research was conducted at two endoscopic referral centers in Brazil, with prior informed consent obtained from all patients and approval from the Institutional Review Board granted on May 6, 2020. The study adhered strictly to established ethical standards for scientific research, including the protection of patient confidentiality.

RESULTS

During the aforementioned study period, 162 gastric ESDs in 160 patients were performed; 89 patients were women (55.6%) and 71 were men (44.3%). The duration of the first phase, second phase, third phase, and fourth phase was 77 months, 40 months, 37 months, and 50 months, respectively. In the first phase of the study (phase I), it took a longer period of time to achieve 40 cases, as compared to the other 3 periods. In phase I the mean tumor size, the mean procedure time, the en bloc resection rate, the complete resection rate and curative resection rate were: 21.5 mm, 99.4 minutes, 97.5% (39/40), 92.5% (37/40) and 87.5% (35/40) respectively, while in the last phase of the study (phase IV) those features were: 25.6 mm, 107.7 minutes, 90.4% (38/42), 83.3% (35/42) and 78.5% (33/42) respectively. In phases II and III, the following was observed with respect to these parameters: A slight decrease in the en bloc resection rate from 95% (38/40) to 92.5% (37/40) (P = 0.58), a slight increase in the curative resection rate from 80% (32/40) to 82.5% (33/40), no change in the complete resection rate, a slight increase in procedure time and a slight decrease in the average lesion size, none of which were statistically significant. It is important to highlight that the statistically significant difference in the average size of the lesion was observed between phases I and II.

Likewise, the overall rate of adverse events in phase I was 0% and in phase IV was 7.1% (3/42) (P = 0.35). In phases II and III, there was a decrease in the overall rate of adverse events from 5% (2/40) to 2.5% (1/40), without showing statistically significant results. All adverse events were successfully managed endoscopically by thermal coagulation and clips closure (mortality associated with the procedure: 0%). Table 1 shows a detailed analysis of all these parameters in each of the study phases in sequential order. The CUSUM showed a turning point in case number 112 (maximum CUSUM peak: 3.90 and overall technical success rate: 85.8%). From this case onwards, there was a sustained decline in the curve, indicating the achievement of technical proficiency of gastric ESD in this series. Figure 1 shows a graphical representation of the CUSUM.

Figure 1 Cumulative Sum Curve for analysis of the learning curve in gastric endoscopic submucosal dissection. CUSUM: Cumulative Sum Curve; ESD: Endoscopic submucosal dissection.

Table 1 Outcomes of the learning curve in gastric endoscopic submucosal dissection in four chronological phases.

	Phase I (case 1-40) (n = 40)	Phase II (case 41-80) (n = 40)	Phase III (case 81-120) (n = 40)	Phase IV (case 121-162) (n = 42)	P value
Age	65.2 years (23-86)	65.8 years (30-85)	65.6 years (19-89)	69.5 years (24-88)	0.71
Male/female	18/22	16/24	23/16	14/27	0.14
En bloc resection	97.5 (39/40)	95 (38/40)	92.5 (37/40)	90.4 (38/42)	0.58
Complete resection (R0)	92.5 (37/40)	87.5 (35/40)	87.5 (35/40)	83.3 (35/42)	0.66
Curative resection	87.5 (35/40)	80 (32/40)	82.5 (33/40)	78.5 (33/42)	0.73
Size	21.5 mm (10-40)	32.1 mm (15-60)	26.2 mm (10-60)	25.6 mm (10-80)	< 0.01
Procedure time (minute) (mean ± SD)	99.4 ± 40.9	105.8 ± 60.2	110 ± 52.4	107.7 ± 57.5	0.87
Adverse events
Overall adverse event rate	0	5 (2/40)	2.5 (1/40)	7.1 (3/42)	0.35
Digestive bleeding	0	5 (2/40)	0	7.1 (3/42)	0.14
Perforation	0	0	2.5 (1/40)	0	0.38
Histological type of lesions
Benign neoplasms	32.5 (13/40)	20 (8/40)	15 (6/40)	7.1 (3/42)	0.02
Low grade dysplasia	12.5 (5/40)	10 (4/40)	27.5 (11/40)	26.1 (11/42)	0.09
High grade dysplasia	17.5 (7/40)	20 (8/40)	30 (12/40)	35.7 (15/42)	0.19
Adenocarcinoma	37.5 (15/40)	50 (20/40)	27.5 (11/40)	30.9 (13/42)	0.16
Intramucosal	27.5 (11/40)	40 (16/40)	22.5 (9/40)	23.8 (10/42)	0.28
SM1 invasion	2.5 (1/40)	0	2.5 (1/40)	2.3 (1/42)	0.80
SM2 invasion	7.5 (3/40)	10 (4/40)	2.5 (1/40)	4.7 (2/42)	0.53
Undifferentiated type (signet ring)	2.5 (1/40)	0	2.5 (1/40)	9.5 (4/42)	0.11
Location of the lesion
Lower third of the stomach	57.5 (23/40)	72.5 (29/40)	70 (28/40)	66.6 (28/42)	0.50
Upper-middle third of the stomach	42.5 (17/40)	27.5 (11/40)	30 (12/40)	33.3 (14/42)	0.50

SM1: Superficial submucosa; SM2: Deep submucosa.

Factors that increase the technical difficulty of gastric ESD include the location of the lesion and the histopathology of the resected lesion. It was observed that in phase I, lesions located in the distal and proximal thirds of the stomach were: 57.5% (23/40) and 42.5% (17/40), respectively, while in phase IV, lesions located in the distal and proximal thirds of the stomach were 66.6% (28/42) and 33.3% (14/42), respectively, showing no statistically significant differences. In phases II and III, there was an increase in the number of lesions located in the upper-middle third of the stomach and a decrease in the number of lesions located in the lower third of the stomach, both without showing statistically significant differences.

Regarding histopathological analysis of the resected specimen, the following distribution was observed in the first phase of the study: Benign neoplasms - 32.5% (13/40) and adenocarcinoma - 37.5% (15/40); intramucosal - 27.5% (11/40). With deep submucosal invasion (SM2) - 7.5% (3/40) and undifferentiated type (signet ring) - 2.5% (1/40). In the last phase of the study, the following distribution was observed: Benign neoplasms - 7.1% (3/42) and adenocarcinoma - 30.9% (13/42); intramucosal - 23.8% (10/42). With deep submucosal invasion (SM2) - 4.7% (2/42) and undifferentiated type (signet ring) - 9.5% (4/42). In phases II and III, there was a decrease in the number of benign neoplasms and an increase in the number of lesions with high- and low-grade dysplasia. Likewise, a decrease in the number of adenocarcinoma cases was observed, in this group of lesions also showing a reduction in the number of intramucosal adenocarcinomas and an increase in cases of adenocarcinomas with superficial and deep submucosal invasion. There was also an increase in cases of undifferentiated adenocarcinomas; however, none of these showed statistically significant results. It is important to highlight that a statistically significant difference in the number of benign neoplasms was observed between phases I and IV.

DISCUSSION

Systematic analysis of the learning curve in gastric ESD is essential to accurately define the point at which technical competence in this procedure is consolidated. Although the eradication of superficial gastric neoplasms using ESD is routinely performed in Asia, its implementation in Western countries has been slower due to the reduced incidence of early gastric cancer, the high technical complexity of the procedure, and the limited availability of structured endoscopic training programs. This study analyzed 162 consecutive cases of gastric ESD performed by a single Western operator, constituting one of the largest series reported in the West. The cases were grouped into four successive phases of 40 to 42 procedures each to evaluate the technical evolution and possible turning points associated with the progressive mastery of gastric ESD.

In terms of technical success, our results show consistently high rates of en bloc, complete, and curative resection from phase I to phase IV with no statistically significant differences, showing a slight downward trend in the later phases. This phenomenon could be explained by a progressive increase in the complexity of the selected cases, as evidenced by the increase in the average size of lesions in phase II (32.1 mm) compared to phase I (21.5 mm) (P < 0.01). This demonstrates that a structured learning curve can lead to highly effective implementation of gastric ESD in Western contexts. These findings are consistent with the proposal of the European Society of Gastrointestinal Endoscopy (ESGE), which emphasizes the need for tiered training programs with initial supervision and progressive assessment of competencies[7,10-14].

Regarding the duration of the procedure, no significant decrease was observed between stages (P = 0.87), which can be explained by the progressive increase in the technical difficulty of the selected cases, as demonstrated by the increase in tumor size and the higher proportion of advanced neoplasms (high-grade dysplasia/adenocarcinoma) in later stages. This trend is consistent with the findings of Yano et al[20], who described that as endoscopists gain experience, they tend to take on more technically challenging cases, which may mask improvements in operational efficiency when procedure time is evaluated as the single indicator.

In analyzing the learning curve for gastric ESD, adverse events are a critical indicator for evaluating the safety of the procedure in the hands of endoscopists in training. In our cohort, the overall rate of adverse events associated with the procedure was low, with a predominant concentration in the initial phases (P = 0.35). This pattern is consistent with that described by Hong et al[21], who found that after the first 60 gastric ESD procedures, the frequency of adverse events decreased considerably, especially in the third and fourth phases of learning (P < 0.05). Our study reaffirms these results, highlighting the need for supervised training protocols and gradual evaluation to reduce clinical risks during the progressive acquisition of technical competence, and showing that gastric ESD can be safely implemented in Western centers.

Regarding the CUSUM curve analysis, our results identified a turning point in case number 112 (total = 162 cases), from which a sustained decrease in the technical failure rate was observed, defined as the inability to achieve complete resection, en bloc, and without associated complications. Yoshida et al[22] analyzed the learning curve in 334 gastric ESDs performed by seven endoscopists in training (42-50 consecutive cases per endoscopist in training), demonstrating through a CUSUM curve a higher level of technical competence after 30 cases. This reinforces the validity of our results and supports the use of this methodological approach to determine the moment of technical consolidation in gastric ESD, but in a Western context and with a greater number of consecutive cases per endoscopist in training.

During the longitudinal analysis of our case series, a progressive variation was observed in the histopathological profile of lesions treated by gastric ESD throughout the learning curve. In the initial phase, neoplasms with benign histology predominated (phase I: 32.5%; phase IV: 7.1%; P = 0.02), while in the final phases there was an increase in the proportion of lesions with histology showing greater oncological progression (low-grade dysplasia, high-grade dysplasia, intramucosal adenocarcinoma, adenocarcinoma with superficial/deep submucosal invasion, undifferentiated adenocarcinoma). This progressive pattern suggests a stepwise selection of histological complexity, in accordance with the pedagogical principle of therapeutic endoscopy, in which the safety of the operator in training is prioritized by initially addressing less aggressive lesions. The most representative studies do not systematically report an evolution of the histopathological profile throughout training, focusing mainly on technical aspects (efficacy-safety). Therefore, our findings would provide a novel perspective to the field of gastric ESD training, highlighting the importance of considering the histopathological progression of treated cases as an indirect indicator of the endoscopist’s technical maturity and confidence.

One of the most decisive factors in the technical evolution of gastric ESD is the anatomical topography of the lesion. Not all regions of the stomach present the same technical challenge or require the same degree of surgical skill, and this aspect is highly relevant in the context of the learning curve[23-26]. Recently, Aliaga Ramos et al[27] demonstrated that proximal gastric lesions require longer procedure times and have significantly lower rates of en bloc, complete, and curative resection compared to distal gastric lesions. The authors also observed that proximal gastric lesions showed a higher incidence of submucosal invasion, demonstrating that these lesions pose a technical-oncological challenge. These findings reinforce the notion that technical progression in gastric ESD should consider a strategic anatomical sequence, in which initial learning focuses on the management of more accessible distal lesions before advancing to more challenging regions such as the upper-middle third of the stomach. Recognizing this topographical variability not only allows for safe and efficient planning of endoscopist training but also helps to minimize the risk of adverse events and optimize oncological outcomes from the early stages of learning.

The topographical distribution of gastric cancer shows significant geographical differences between the East and the West. In Western countries, a relative increase in neoplasms located in the proximal third of the stomach (cardia and gastroesophageal junction) has been observed in recent decades[28]. This pattern is mainly attributed to the increasing prevalence of risk factors characteristic of these populations, such as visceral obesity, gastroesophageal reflux disease, autoimmune gastritis (type A), and Epstein-Barr virus infection[28-30]. In addition, the greater efficacy in eradicating Helicobacter pylori in Western countries has contributed to the progressive decline in distal gastric cancers, modifying the topographic distribution toward a relative predominance of tumors located in the proximal segments of the stomach. In contrast, in Eastern countries, the trend continues to show a predominance of neoplasms located in the distal third of the stomach (antrum and body), where Helicobacter pylori infection and atrophic gastritis remain epidemiological determinants. These differences reflect the fact that geographical distribution has a decisive influence on the topography of gastric cancer and emphasize the need for prevention and early detection strategies tailored to each region[31,32]. Our casuistry shows that most cases of gastric cancer are located in the distal third of the stomach, confirming that this region continues to be the most affected in our population. However, recently, a considerable percentage of tumors has been progressively detected in the proximal third of the stomach, reflecting a growing trend toward the presentation of gastric neoplasms in this location in our community.

Our study has certain limitations that must be acknowledged when interpreting its results. First, our sample size could be considered small compared to similar Asian studies previously published; however, to our knowledge, our gastric ESD cohort is one of the largest in the West. Another limitation is that the analysis was based on the experience of a single operator with background training in Japan, which, while ensuring consistency in technique and clinical judgment, limits the generalizability of our results to endoscopy centers with different levels of training or endoscopic infrastructure. Finally, the retrospective design of the study imposes inherent restrictions on variable control and standardized follow-up; thus, future studies with a prospective design should be conducted to validate these results.

CONCLUSION

In conclusion, our results confirm that the learning curve in gastric ESD is feasible, safe, and effective in Western countries, provided that intensive training and adequate progressive case selection are in place. According to our case series, starting with case 112, consolidated technical mastery is achieved, with optimal therapeutic success rates and no clinical failures, even in complex lesions. This finding confirms that excellence in gastric ESD is an achievable goal outside Asia, provided that technical discipline, strategic anatomical progression, and a commitment to continuous improvement are integrated.

ACKNOWLEDGEMENTS

Endoscopy Unit, Alfa Institute of Gastroenterology; School of Medicine, Federal University of Minas Gerais; Hospital Mater Dei Contorno, Belo Horizonte, Minas Gerais, Brazil