Genomic landscape of epithelium with low-grade atypia on gastric cancer after Helicobacter pylori eradiation therapy

Endoscopic risk factors to inform early detection of gastric cancer after Helicobacter pylori eradication: Meta-analysis and systematic review

Objectives

Helicobacter pylori eradication reduces but cannot eliminate the risk of gastric cancer (GC). The prevalence of post-eradication GC has been rising. Characterization of the endoscopic findings of post-eradication GC may facilitate its early detection. We performed a meta-analysis and systematic review to clarify endoscopic risk factors to accelerate the early diagnosis of post-eradication GC.

Methods

Medline and PubMed were searched for randomized controlled trials, cohort studies, and case-control studies published in the English-language medical literature between January 1997 and July 2023. The included articles assessed the correlation between post-eradication GC and pre- and post-eradication endoscopic findings, and associated post-eradication GC with gastric atrophy, intestinal metaplasia (IM), map-like redness, and xanthoma.

Results

A total of 963 articles were retrieved. In these articles, 66 papers were finally included, comprising randomized controlled trials, cohort studies, and case-control studies. The included articles addressed gastric atrophy (16 studies), IM (eight studies), map-like redness (six studies), and xanthoma (two studies). Risk ratio (RR) of incident post-eradication GC was 3.40 (95%confidence interval [95%CI]: 1.98-5.84; p < 0.001) in cases of severe atrophy, 5.38 (95%CI: 3.62-8.00) in cases of severe IM, 2.34 (95%CI: 1.16-4.68) in cases with post-eradication map-like redness, and 2.75 (95% CI: 1.78-4.26) in cases with xanthoma.

Conclusions

Endoscopic atrophy, IM, and xanthoma observed at pre- and post-eradication time points and post-eradication map-like redness were suggested as endoscopic risk factors for post-eradication GC. Further studies are needed to clarify the risk of post-eradication GC based on these risk factors.

Comparison of Genetic Mutations of Gastric Cancer Diagnosed before or after Helicobacter pylori Eradication and between Differentiated and Undifferentiated Types Using Next-Generation Sequencing

INTRODUCTION

Genetic abnormalities specific to post-Helicobacter pylori eradication gastric cancer (GC), especially those associated with undifferentiated post-eradication GC, are unknown. We conducted next-generation sequencing of GC diagnosed either before or after eradication to investigate the carcinogenesis of post-eradication GC.

METHODS

Five cases of post-eradication differentiated GC [HP(-)-D group], five cases of H. pylori-positive differentiated GC [HP(+)-D group], four cases of post-eradication undifferentiated GC [HP(-)-U group], and six cases of H. pylori-positive undifferentiated GC [HP(+)-U group] underwent analysis. DNA was extracted from tumor samples, and non-tumor samples of all subjects. Next-generation target sequencing was conducted using the Ion AmpliSeq Library Kit 2.0 with the Ion AmpliSeq Cancer Hotspot Panel v2. Next-generation targeted sequencing results of the cancer part were subtracted from the results of the non-cancer part.

RESULTS

The HP(-)-D group displayed significantly fewer SNPs in hotspot than the other groups (p < 0.01). Definitive DNA mutations were identified by sequencing of cancerous and non-cancerous tissues. 5 of 20 patients had specific somatic mutations, with different TP53 mutations in the HP(+)-D and HP(-)-U groups, CTNNB1 mutations in the HP(+)-U group, and ATM mutations in the HP(+)-U group, but no mutations in the HP(-)-D group.

CONCLUSION

Several definite genetic mutations involved in GC were observed. Mutations were less frequent in post-eradication differentiated GC. However, because of small number of cases analyzed to identify carcinogenic differences, further analysis with a large number of cases and with strictly grading GC samples is needed.

INTRODUCTION

Genetic abnormalities specific to post-Helicobacter pylori eradication gastric cancer (GC), especially those associated with undifferentiated post-eradication GC, are unknown. We conducted next-generation sequencing of GC diagnosed either before or after eradication to investigate the carcinogenesis of post-eradication GC.

METHODS

Five cases of post-eradication differentiated GC [HP(-)-D group], five cases of H. pylori-positive differentiated GC [HP(+)-D group], four cases of post-eradication undifferentiated GC [HP(-)-U group], and six cases of H. pylori-positive undifferentiated GC [HP(+)-U group] underwent analysis. DNA was extracted from tumor samples, and non-tumor samples of all subjects. Next-generation target sequencing was conducted using the Ion AmpliSeq Library Kit 2.0 with the Ion AmpliSeq Cancer Hotspot Panel v2. Next-generation targeted sequencing results of the cancer part were subtracted from the results of the non-cancer part.

RESULTS

The HP(-)-D group displayed significantly fewer SNPs in hotspot than the other groups (p < 0.01). Definitive DNA mutations were identified by sequencing of cancerous and non-cancerous tissues. 5 of 20 patients had specific somatic mutations, with different TP53 mutations in the HP(+)-D and HP(-)-U groups, CTNNB1 mutations in the HP(+)-U group, and ATM mutations in the HP(+)-U group, but no mutations in the HP(-)-D group.

CONCLUSION

Several definite genetic mutations involved in GC were observed. Mutations were less frequent in post-eradication differentiated GC. However, because of small number of cases analyzed to identify carcinogenic differences, further analysis with a large number of cases and with strictly grading GC samples is needed.

A case of colon cancer implanted on endoscopic resection ulcer certified by cancer genomic testing

A 90 year-old man underwent endoscopic mucosal resection for lesions in the descending and sigmoid colons as well as endoscopic submucosal dissection (ESD) for a lesion in the rectal peritoneal reflection (Ra) 1 month before undergoing laparoscopic resection and D3 dissection for advanced cancer in the descending colon. One year later, he underwent a surveillance colonoscopy, and advanced colorectal cancer was detected on the ESD scar. The history suggested that this newly detected recurrent colorectal neoplasm on the ESD scar may have originated from cancer cells derived from the descending colon cancer that were implanted in the ESD ulcer, thereby initiating a new colorectal neoplasm. Cancer genomic testing further indicated that three of the four pathogenic variants detected in the recurrent colorectal neoplasm were consistent with pathogenic variants of descending colon cancer. This finding strongly supports our contention that cancer cells derived from the descending colon cancer were implanted in the post-ESD ulcer of the rectal Ra and proliferated, forming the recurrent colorectal neoplasm. This case report highlights the potential for tumor cell implantation on endoscopic resection ulcers and the utility of cancer genomic testing in validating this phenomenon.

Variation in the rate of detection of minute and small early gastric cancers at diagnostic endoscopy may reflect the performance of individual endoscopists

OBJECTIVE

The documented variation in gastric cancer (GC) detection among endoscopists has often been dismissed as a coincidental artefact of the low incidence of gastric neoplasms; it is not considered associated with differences in physicians' performance of the esophagogastroduodenoscopy procedure. This study is to confirm whether significant variations among endoscopists in early GC detection suggest the individual performance of the upper endoscopy.

DESIGN

A retrospective observational study at a single centre in Japan assessed the results of 218 early GCs detected during 25 688 routine esophagogastroduodenoscopies by 12 endoscopists. The main outcome was the rate of early GC detection for each endoscopist under the same circumstances. Other measures included the major diameters and locations of the lesions, Helicobacter pylori infection status, and baseline patient characteristics that could affect the prevalence of GC.

RESULTS

The early GC detection rates exhibited wide variation among endoscopists (0.09%-2.87%) despite performing routine esophagogastroduodenoscopies in a population with a similar background. Endoscopists were assigned to a low-detection group (n=6; detection rate: 0.47% (range: 0.09%-0.55%)) and a high-detection group (n=5; detection rate: 0.83% (range: 0.63%-1.12%)), with the single highest detector analysed separately due to his distinct detection rate (2.87%). Endoscopists in the high-detection group had better detection rates for minute (major diameter ≤5 mm) and small (major diameter 6-10 mm) GCs than the low-detection group (0.19%/0.23% vs 0.085%/0.098%). These differences were significant (p<0.01), although there were no significant differences in detection of larger tumours (major diameter ≥11 mm; 0.40% vs 0.28%; p=0.13). The tumour location and H. pylori status were similar in the low-detection group, high-detection group and for the highest detector.

CONCLUSION

Significant variation in the detection of hard-to-find, smaller GCs may reflect individual performance of the examination.

Differences in clinical features and morphology between differentiated and undifferentiated gastric cancer after Helicobacter pylori eradication

BACKGROUND/AIMS

Although undifferentiated gastric cancer (UGC) diagnosed after Helicobacter pylori eradication (HPE) carries a poor prognosis, characteristics of post-HPE UGC have not been evaluated in detail because of its low incidence. Therefore, we compared the clinicopathologic characteristics of UGC and differentiated gastric cancers (DGC) diagnosed after successful HPE.

METHODS

GC lesions from patients who had successfully completed HPE and who had undergone upper gastrointestinal endoscopy between January 2004 and March 2016 were analyzed. Tumors were divided into DGC and UGC groups. Clinicopathologic factors of background and tumor characteristics were compared using univariate and multiple logistic analyses.

RESULTS

A total of 129 tumors from 115 patients were evaluated; 113 tumors were in the DGC group and 16 in the UGC group. Depressed-type tumors (P = 0.024) and sub-submucosal invasion (P<0.001) were significantly higher in the UGC group. The UGC group had larger tumor diameters (25.9±7.3 mm) than the DGC group (13.2±10.2 mm) (P<0.001). Multivariate analysis showed that female sex (odds ratio [OR] 3.24, 95%CI:1.02-10.37; P = 0.047) and absent follow-up (OR 4.99, 95%CI:1.60-15.57; P = 0.006) were significant independent risk factors for UGC. The DGC group showed a gradually decreasing temporal trend by trend test (P = 0.015), while the UGC group showed a relatively constant incidence over time, although the number of cases was small.

CONCLUSION

UGC was diagnosed even after long time spans following HPE, although the number of cases was small. Female sex, and especially absent follow-up, were risks for post-HPE UGC, suggesting that diligent long-term follow-up after HPE is essential.

The Origin of Epithelium with Low-Grade Atypia in Early Gastric Cancer

INTRODUCTION

Helicobacter pylori (HP) infection causes chronic inflammation and atrophy of the gastric mucosa and thus a high risk of gastric cancer (GC). With the increasing success of HP infection treatment, a larger number of GCs that develop after eradication can be assessed. Several studies have shown that epithelium with low-grade atypia (ELA) is a frequent characteristic of these GCs, but the origin of this condition is unknown. In this study, we compared the mucin phenotype, cellular proliferation, and p53 staining in ELA and cancerous tissues obtained from patients with GC with and without HP eradication.

METHODS

The study population consisted of 23 patients with GC that developed after successful HP eradication therapy (eradicated group) and 24 patients with GC and HP infection (infected group). The prevalence of ELA was determined by hematoxylin and eosin staining. Tumor tissue and ELA samples were further analyzed by immunohistochemical staining for Muc5AC, Muc2, p53, and Ki-67.

RESULTS

The ELA coverage rate was significantly higher in the eradicated group than in the infected group. Gastric-type mucin was frequently expressed by the ELA, and the mucin phenotypes of ELA and cancerous areas differed in 75% of cases. The Ki-67 labeling index was consistently lower in ELA than in the cancerous mucosa. Fourteen of 21 (66.7%) cancerous lesions, but only 3 ELA samples, were p53-positive.

CONCLUSION

In most cases, ELA on the surfaces of GCs seems to have originated from normal gastric cells, not from cancer cells.

Characteristics and Early Diagnosis of Gastric Cancer Discovered after Helicobacter pylori Eradication

The prevalence of gastric cancer after eradication (GCAE) is increasing dramatically in Japan. GCAE has characteristic features, and we must understand these features in endoscopic examinations. Differentiated cancer types were frequently found after eradication and included characteristic endoscopic features such as reddish depression (RD). However, benign RD can be difficult to distinguish from gastric cancer because of histological alterations in the surface structures (nonneoplastic epithelium or epithelium with low-grade atypia [ELA]) as well as multiple appearances of RD. Recently, we clarified similar alterations in genetic mutations between ELA and gastric cancer, suggesting that ELA is derived from gastric cancer. Clinically, submucosal invasive cancer was frequently found in patients after eradication therapy even if they received annual endoscopic surveillance. We can improve the diagnostic ability using image-enhanced endoscopy with magnified observation.

Risk Factors for Gastric Cancer after the Eradication of Helicobacter pylori Evaluated Based on the Background Gastric Mucosa: A Propensity Score-matched Case-control Study

Objective The eradication of Helicobacter pylori (H. pylori) reduces the risk for gastric cancer (GC) development, but it cannot prevent GC completely. We investigated the risk factors of early GC development after the eradication of H. pylori, based on the histological characteristics of gastric mucosa. Methods Sixty-one patients who underwent endoscopic submucosal dissection for early GC after successful H. pylori eradication (Group A) and 122 patients without developing a gastric neoplasm over 3 years after successful H. pylori eradication (Group B) were analyzed. We compared the histological findings of the patients enrolled in Group A and Group B before and after the propensity score-matching. Results Comparing the characteristics of two the groups, Group A consisted predominantly of males, had significantly more elderly patients, and the years after successful eradication tended to be longer. We performed score matching for these three factors to reduce the influence of any confounding factors. After matching, the scores of inflammation for Group A (n=54) was significantly higher than those of Group B (n=54) at the greater curvature of the antrum, the lesser curvature of the corpus, and the greater curvature of the corpus. According to a multivariate analysis, inflammation of the greater curvature of the antrum and lesser curvature of the corpus were found to be independent risk factors. The risk ratio and 95% CI were 5.92 (2.11-16.6) (p<0.01), and 3.56 (1.05-13.2) (p=0.04), respectively. Conclusion A continuous high level of inflammation of the background gastric mucosa may be a risk factor for gastric cancer onset after H. pylori eradication.

Near-focus magnification and second-generation narrow-band imaging for early gastric cancer in a randomized trial

BACKGROUND

Magnifying endoscopy with narrow-band imaging (NBI) is effective for the diagnosis of early gastric cancer (EGC). However, magnifying endoscopy is not yet popular globally because of the required level of skill and lack of availability. To overcome these problems, dual-focus endoscopy (standard- and near-focus (NF) modes) has been developed. In this study, we evaluated the diagnostic performance of NF with second-generation (2G)-NBI (NF-NBI) for the diagnosis of EGC.

METHODS

This was a secondary analysis of a multicenter randomized controlled trial of 4523 high-risk patients who underwent gastroscopies at 13 institutions in Japan. Patients were randomly assigned to white-light imaging (WLI) followed by 2G-NBI or to 2G-NBI followed by WLI. Lesions suspicious for EGC, newly detected by non-magnifying WLI or 2G-NBI, were subsequently observed with NF-NBI. All detected lesions were biopsied or resected. The diagnostic performance of NF-NBI was compared with the final histology.

RESULTS

A total of 870 detected lesions (145 EGC, 725 non-EGC) were analyzed. Overall diagnostic performance for EGC using NF-NBI was accuracy 87.7%, sensitivity 60.7%, specificity 93.1%, positive predictive value 63.8%, and negative predictive value 92.2%. There were no significant differences in diagnostic performance between lesions detected by WLI or 2G-NBI. For lesions diagnosed with high (333 lesions) and low (537 lesions) confidences, accuracy was 92.2% and 84.9%, sensitivity was 64.7% and 58.5%, and specificity was 90.5% and 88.8%, respectively.

CONCLUSION

The diagnostic performance of NF-NBI is good and acceptable for diagnosis of EGC in combination with either WLI or 2G-NBI.