Abstract
In this review, we would like to focus on risk stratification and quality indicators of diagnostic upper gastrointestinal endoscopy in the detection and characterization of early gastric cancer. Preparation of the upper gastrointestinal tract with mucolytic agents or simethicone is often overlooked in the west, and this inexpensive step prior to endoscopy can greatly improve the quality of imaging of the upper digestive tract. Risk stratification based on epidemiological features including family history, Helicobacter pylori infection status, and tobacco smoking is often overlooked but may be useful to identify a subgroup of patients at higher risk of developing gastric cancer. Quality indicators of diagnostic upper gastrointestinal endoscopy are now well defined and include: minimal inspection time of 3 min, adequate photographic documentation of upper gastrointestinal landmarks, utilization of advanced endoscopic imaging technology including narrow band imaging and blue laser imaging to detect intestinal metaplasia and characterize early gastric cancer; and standardized biopsy protocols allow for histological evaluation of gastric mucosa and detection of atrophic gastritis and intestinal metaplasia. Finally, endoscopic and histologic classifications such as the Kimura–Takemoto Classification of atrophic gastritis and the OLGA–OLGIM classifications may help stratify patients at a higher risk of developing early gastric cancer.
Introduction
Early gastric cancer (EGC) is defined as cancer occurring in the gastric mucosa and confined to the mucosa or submucosa, irrespective of lymph node metastasis (). Patients with gastric mucosal atrophy and/or intestinal metaplasia affecting the gastric corpus alone and/or the antrum are at higher risk of gastric adenocarcinoma (–). Gastric cancer is the fifth most frequently diagnosed cancer and the third most common cause of death due to cancer, with the highest incidence being reported in Korea, Japan, and Mongolia (). Population-based gastric cancer screening endoscopy programs in Japan for adults aged >50 years and in Korea for adults aged >40 years have resulted in the early detection of gastric cancer with a resultant significant decrease in mortality (, ). Image enhanced endoscopic technology (IEE), also called advanced endoscopic imaging, which includes Narrow Band Imaging (NBI), Flexible Spectral Imaging Color Enhancement (FICE), blue laser imaging (BLI), probe based Confocal Laser Endomicroscopy (pCLE), improves detection of gastric intestinal metaplasia, dysplasia, and early gastric cancer (, , ).
Pre-endoscopic Stratification of Risk for Early Gastric Cancer
Although the optimal method for risk stratification of gastric cancer is still unclear, pre-endoscopic assessment of epidemiologic factors can help stratify patients at risk of gastric cancer (). Gastric cancer is a multifactorial disease and risk factors for gastric cancer identified include older age, male gender, Helicobacter pylori (H. pylori) infection, and smoking (–, –).
A family history of gastric cancer in a first-degree relative is significant as these patients have an approximately threefold greater risk of gastric cancer (, ). Concerning the location of gastric cancer, risk factors for cancer at the cardia include obesity and gastroesophageal reflux disease (, , ). For non-cardia gastric cancer, H. pylori infection and smoking have been identified as risk factors (, ). There is a predominance of non-cardia gastric cancer in poorly developed regions of the world, while cancer of the cardia is more frequent in highly developed countries, except China and Japan ().
Due to the higher risk of gastric atrophy and cancer in patients with low serum pepsinogen I levels, serum pepsinogen I/II ratio <3 and positive H. pylori antibody titers, screening endoscopy is recommended in these patients (, ). However, in patients with severe gastric mucosal atrophy and previous infection with H. pylori, false negative results may be observed (). Additionally, in countries with a high prevalence of H. pylori infection (>50%), the utility of serum pepsinogen levels has been questioned and considered irrelevant (). Machine learning models involving the age of the patient, presence of intestinal metaplasia, and gastric ulcer predict a higher risk of developing gastric cancer after H. pylori eradication ().
Preparation of the Upper Digestive Tract Before Endoscopy
A high-quality examination during an upper gastrointestinal endoscopy requires optimal mucosal visualization (, , ). The use of mucolytic and defoaming agents, such as simethicone and N-acetylcysteine, improves the visibility of gastric mucosa compared to water and is associated with an increased rate of detection of early gastric cancer (–). Recommended in Japanese guidelines on endoscopic diagnosis of EGC but often overlooked in the west, the preparation of the upper gastrointestinal tract with a mucolytic agent 10 to 30 min before endoscopy is an inexpensive method, with a low frequency of adverse reactions/minimal patient burden, that can help obtain the optimal gastric cleanliness (, , , ). The quality of mucosal visualization should be recorded in the endoscopic report (). Gastric peristalsis inhibitor drugs, namely, butilscopolamine and glucagon, should be considered where there is intense peristalsis to facilitate careful inspection of the gastric mucosa (). The use of sedation and analgesia is recommended in anxious patients while performing screening endoscopy to improve the quality of endoscopic evaluation ().
Quality Indicators of Diagnostic Upper Gastrointestinal Endoscopy
Quality indicators of diagnostic upper gastrointestinal endoscopy are now well defined and include minimal inspection time of the stomach of at least 3 min, adequate photographic documentation of upper gastrointestinal landmarks, usage of image enhanced endoscopic (IEE) technology including narrow band imaging and blue laser imaging to detect intestinal metaplasia and characterize EGC, and standardized biopsy protocols with separate biopsies from the gastric antrum and corpus allow for histological evaluation of gastric mucosa and detection of atrophic gastritis and intestinal metaplasia (, , , ).
Adequate inspection time of the stomach significantly improves gastric cancer detection (, ). In a study involving 30,506 upper GI endoscopies in asymptomatic patients screened for gastric cancer, an observation time of more than 3 min significantly increased neoplasm detection rates (). Identification of a gastric mucosa with a high risk of early gastric cancer is important (). The presence of gastric atrophy and intestinal metaplasia, thickened mucosal folds in the gastric corpus and xanthoma are associated with a higher risk of gastric cancer (, ).
Systematic evaluation of the stomach with photographic documentation is highly recommended by the Japanese and European Gastrointestinal Endoscopy Societies (, , ). A systematic screening protocol for the stomach allows for adequate mapping (, ).
High definition endoscopy with chromoendoscopy (CE) is better than high definition white-light endoscopy alone for the diagnosis of intestinal metaplasia and gastric dysplasia and EGC (). Virtual CE, with or without magnification, should be used for the diagnosis of gastric precancerous conditions, for guiding biopsies for staging atrophic and metaplastic changes, and helping target neoplastic lesions (, ). IEE technology, including NBI and Blue Laser imaging (BLI), has been shown to be as useful as conventional chromoendoscopy with indigo carmine in characterizing early gastric cancer (, , ).
Endoscopic and Histologic Classifications of Gastric Atrophy and Intestinal Metaplasia and Risk of Gastric Cancer
Endoscopic and histologic classifications such as the Kimura–Takemoto Classification of atrophic gastritis and the Operative Link on Gastritis Assessment (OLGA) and Operative Link on Gastric Intestinal Metaplasia assessment (OLGIM) classifications (Table 1) may help stratify patients at higher risk of developing early gastric cancer (, , –). The Kyoto classification, which includes 5 endoscopic findings: gastric atrophy, intestinal metaplasia, thickened gastric folds, mucosal nodularity, diffuse redness, and the presence or absence of regular arrangement of collecting venules, has been shown to be associated with H. pylori infection and gastric cancer risk ().
Table 1
| A. | |||||
|---|---|---|---|---|---|
| Atrophy score | Corpus | ||||
| No atrophy (Score 0) | Mild atrophy (Score 1) | Moderate atrophy (Score 2) | Severe atrophy (Score 3) | ||
| Antrum (Including incisura angularis) | No atrophy (Score 0) | Stage 0 | Stage I | Stage II | Stage II |
| Mild atrophy (Score 1) | Stage I | Stage I | Stage II | Stage III | |
| Moderate atrophy (Score 2) | Stage II | Stage II | Stage III | Stage IV | |
| Severe atrophy (Score 3) | Stage III | Stage III | Stage IV | Stage IV | |
| B. | |||||
| IM score | Corpus | ||||
| No IM (Score 0) | Mild IM (Score 1) | Moderate IM (Score 2) | Severe IM (Score 3) | ||
| Antrum (Including incisura angularis) | No IM (Score 0) | Stage 0 | Stage I | Stage II | Stage II |
| Mild IM (Score 1) | Stage I | Stage I | Stage II | Stage III | |
| Moderate IM (Score 2) | Stage II | Stage II | Stage III | Stage IV | |
| Severe IM (Score 3) | Stage III | Stage III | Stage IV | Stage IV | |
Operative link on gastric atrophy and gastric intestinal metaplasia assessment classification.
Operative link on gastritis assessment staging system (A) and operative link on gastric intestinal metaplasia assessment (B) staging system. IM, intestinal metaplasia; OLGA, Operative link on gastritis assessment system; OLGIM, Operative link on gastric intestinal metaplasia assessment.
Adapted from Weng CY et al. ()
Higher intensity of colour means higher risk of Early Gastric Cancer.
Endoscopic grading of gastric intestinal metaplasia (EGGIM) score has shown excellent correlation with the OLGIM classification and is determined by the presence of intestinal metaplasia detected by image enhanced endoscopy by narrow band imaging or blue laser imaging which detects light blue crest (LBC), white opaque substance or tubulovillous mucosal pattern in each of the five areas (lesser and greater curvatures of the gastric antrum and corpus and incisura) and is scored as 0 (none), 1 (focal, ≤30%), or 2 (extensive, >30%) (, , ).
As shown in Figure 1, the Kimura–Takemoto Classification divides gastritis into open (O) and closed (C) types with three subdivisions in each of these main subtypes (O1–3, C1–3). In the closed type, atrophic mucosa is limited to: the antrum in C-1; the incisura angularis or the lower corpus and antrum in C2; the upper corpus extending to the cardia and involving the antrum in C3. In the open type, atrophic mucosa extends to the fundus over the cardia and the atrophic border of the body lies between the lesser curvature and the anterior wall with maintained folds of the greater curvature in O1; O2 is an intermediate type between O1 and O3, extending to the anterior and posterior walls of the corpus but not involving the greater curvature with the atrophic border on the anterior wall of the stomach; and in O3, atrophy is present in the entire stomach, with a lack of folds in the greater curvature as a whole ().
Figure 1
In a study involving 27,777 patients, the prevalence of gastric cancer was 0% (0/4,506) for C1, 0.25% (9/3,660) for C2, 0.71% (21/2,960) for C3, 1.32% (75/5,684) for O1, 3.70% (140/3,780) for OII, and 5.33% (160/3,004) for O3 (
The replacement of atrophic gastritis by intestinal metaplasia in the staging of gastritis considerably increased interobserver agreement, with the correlation with the severity of gastritis remaining at least as strong (
High OLGA and OLGIM stages have been found to be independent risk factors for gastric cancer, and may be useful for risk assessment in high-risk regions, especially for intestinal-type gastric cancer (
Patients with advanced stages of atrophic gastritis (severe atrophic changes or intestinal metaplasia in both antrum and corpus, OLGA/OLGIM III/IV, EGGIM scores 5–10) have increased the risk of gastric cancer and should be followed up with a high quality endoscopy every 3 years (
The Kyoto classification score in patients without a history of H. pylori eradication of 0, 1, and ≥2 was found to be associated with H. pylori infection rates of 1.5, 45, and 82%, respectively (
Detection and Characterization of Early Gastric Cancer
An adequate endoscopic evaluation with a histological diagnosis of EGC is crucial in order to plan an endoscopic therapeutic strategy (
In cases of doubt regarding the depth of submucosal invasion, echoendoscopic evaluation can be useful in characterization of the depth of submucosal invasion as well as ruling out loco regional lymph node metastases (
The Japanese Gastroenterological Endoscopy Society has proposed a magnified endoscopy simple diagnostic algorithm (MESDA) for gastric cancer (Figure 2) (
Figure 2

Diagnostic algorithm for gastric cancer with magnifying endoscopy. Reproduced with permission from Yao K et al. (
Figure 3

Demarcation line (yellow arrows) and irregular microvascular pattern (blue arrows) suggesting early gastric cancer. Reproduced with permission from Muto M et al. (
Patients with dysplasia detected in the gastric mucosa should be referred to a reference center, with all dysplastic lesions resected and in the absence of an endoscopically visible lesion, repeat endoscopy performed within 6 months if high-grade dysplasia and within 6 to 12 months if low-grade dysplasia (
Finally, a gastric cancer detected within 3 years of upper gastrointestinal endoscopy is considered a failure to detect cancer and should be auditable (
In conclusion, adequate preparation of the upper digestive tract, risk stratification, and careful inspection of the gastric mucosa with high definition endoscopes with image enhanced endoscopic technology is crucial for the detection of early gastric cancer.
Publisher’s Note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
Statements
Author contributions
CNF prepared the manuscript and revised it for intellectual content. JS provided intellectual input for the manuscript and prepared part of the manuscript and revised it for intellectual content. RM revised the manuscript for intellectual content. All authors listed have made a substantial, direct, and intellectual contribution to the work and approved it for publication.
Acknowledgments
We would like to thank Dr. João Pereira da Silva, Consultant Gastroenterologist, Hospital dos Lusíadas, Lisbon for his valuable comments and suggestions.
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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Summary
Keywords
early gastric cancer, risk stratification, quality indicators, upper gastrointestinal endoscopy, advanced endoscopic imaging
Citation
Ferreira CN, Serrazina J and Marinho RT (2022) Detection and Characterization of Early Gastric Cancer. Front. Oncol. 12:855216. doi: 10.3389/fonc.2022.855216
Received
14 January 2022
Accepted
10 June 2022
Published
22 July 2022
Volume
12 - 2022
Edited by
Yuming Jiang, Stanford University, United States
Reviewed by
Zhendong Jin, Second Military Medical University, China; Ryota Niikura, Tokyo Medical University, Japan; Valli De Re, Aviano Oncology Reference Center (IRCCS), Italy
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Copyright
© 2022 Ferreira, Serrazina and Marinho.
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*Correspondence: Carlos Noronha Ferreira, carlosnferreira@hotmail.com
This article was submitted to Gastrointestinal Cancers: Gastric and Esophageal Cancers, a section of the journal Frontiers in Oncology
Disclaimer
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.