Clinical and genomic characteristics of mucosal signet-ring cell carcinoma in Helicobacter pylori-uninfected stomach

A mathematical simulation model to determine the optimal endoscopic screening strategy for detection of H. pylori-naïve gastric neoplasms

BACKGROUND

The effectiveness of esophagogastroduodenoscopy (EGD) screening in cohorts with low Helicobacter pylori prevalence is unknown. This study aimed to develop an optimally efficient EGD screening strategy for detecting H. pylori-naïve gastric neoplasms (HpNGNs).

METHODS

EGD data of 12 institutions from 2016 to 2022 were retrospectively analyzed. Age-related HpNGN prevalence, tumor growth rate, missing rate, and detection threshold size were calculated from the databases. Subsequently, using clinical data, a novel mathematical model that simultaneously simulated demographic changes and HpNGN detection was developed. Screening strategies using different starting ages (40/45/50 years) and intervals (2/5/10 years) were also compared. The detection rates of all tumors occurring within the virtual cohort and number-needed-to-test (NNT) were measured as outcomes.

RESULTS

Data of 519,368 EGDs and 97 HpNGNs (34 pure signet ring cell carcinomas, 26 gastric adenocarcinomas of the fundic gland type, 30 foveolar gastric adenoma-Raspberry type, and seven undifferentiated-type cancer cases) were analyzed. A virtual cohort with a 70-year time horizon was used to simulate the occurrence, growth, and detection of 346,5836 people. Among the strategies with detection rate > 50%, the screening strategy with a 5-year interval starting at 45 years of age had the lowest NNT. Adopting this strategy, most HpNGNs were detected at < 20 mm in size, and the deep submucosal invasion rate was less than 30%.

CONCLUSIONS

A mathematical simulation model revealed that screening every 5 years starting at 45 years of age could efficiently assist in identifying HpNGNs at an early stage.

Verrucous gastritis-like lesion in intramucosal Helicobacter pylori-uninfected signet ring cell carcinoma with poorly differentiated adenocarcinoma

In Japan, accessible Helicobacter pylori (Hp) eradication therapy is associated with an increase in the prevalence of gastric cancers (GCs) in Hp uninfected stomachs. Signet ring cell carcinoma (SRCC) is the most common of these GCs. Intramucosal SRCC with poorly differentiated adenocarcinoma (PDA) occurring in Hp uninfected gastric mucosa is rare; furthermore, many Hp uninfected pure SRCCs exhibit discoloration and flat or slightly depressed lesions, and morphological elevation is relatively rare. We report a case of intramucosal SRCC with PDA with an elevated, verrucous gastritis-like lesion in a 57-year-old male patient. In the present case, the PDA area showed dense tumor cell growth and coexisting desmoplastic and fibrotic reactions. Histopathology and immunohistochemical staining identified extensive fibromuscular obliteration with smooth muscle bundles extending from the muscularis mucosa into the lamina propria. The patient underwent curative endoscopic submucosal dissection. The reporting and analysis of such rare cases may lead to a better understanding of the characteristics of advanced Hp uninfected GCs.

Current advances in understanding the molecular profile of hereditary diffuse gastric cancer and its clinical implications

Hereditary diffuse gastric cancer (HDGC) is an autosomal dominant cancer syndrome attributed to germline CDH1 mutations that carries a high risk for early onset DGC. HDGC raises a significant health issue due to its high penetrance and mortality unless diagnosed early. The definitive treatment is to undergo prophylactic total gastrectomy which is associated with significant morbidity., highlighting the urgent need for alternative treatment methods. However, there is limited literature examining potential therapeutic strategies building on emerging insights into the molecular basis of progressive lesions in the context of HDGC. The aim of this review is to summarise the current understanding of HDGC in the context of CDH1 pathogenic variants followed by a review of the proposed mechanisms for progression. In addition, we discuss the development of novel therapeutic approaches and highlight pertinent areas for further research. A literature search was therefore performed for relevant studies examining CDH1 germline variants, second-hit mechanisms of CDH1, pathogenesis of HDGC and potential therapeutic strategies in databases, including PubMed, ScienceDirect and Scopus. Germline mutations are mostly truncating CDH1 variants affecting extracellular domains of E-cadherin, generally due to frameshift, single nucleotide variants or splice site mutations. A second somatic hit of CDH1 most commonly occurs via promoter methylation as shown in 3 studies, but studies are limited with a small sample size. The multi-focal development of indolent lesions in HDGC provide a unique opportunity to understand genetic events that drive the transition to the invasive phenotype. To date, a few signalling pathways have been shown to facilitate the progression of HDGC, including Notch and Wnt. In in-vitro studies, the ability to inhibit Notch signalling was lost in cells transfected with mutant forms of E-cadherin, and increased Notch-1 activity correlated with apoptosis resistance. Furthermore, in patient samples, overexpression of Wnt-2 was associated with cytoplasmic and nuclear β-catenin accumulation and increased metastatic potential. As loss-of-function mutations are challenging to target therapeutically, these findings pave the way towards a synthetic lethal approach in CDH1-deficient cells with some promising results in-vitro. In future, if we could better understand the molecular vulnerabilities in HDGC, there may be opportunities to offer alternative treatment pathways to avoid gastrectomy.

TogoVar: A comprehensive Japanese genetic variation database

TogoVar ( https://togovar.org ) is a database that integrates allele frequencies derived from Japanese populations and provides annotations for variant interpretation. First, a scheme to reanalyze individual-level genome sequence data deposited in the Japanese Genotype-phenotype Archive (JGA), a controlled-access database, was established to make allele frequencies publicly available. As more Japanese individual-level genome sequence data are deposited in JGA, the sample size employed in TogoVar is expected to increase, contributing to genetic study as reference data for Japanese populations. Second, public datasets of Japanese and non-Japanese populations were integrated into TogoVar to easily compare allele frequencies in Japanese and other populations. Each variant detected in Japanese populations was assigned a TogoVar ID as a permanent identifier. Third, these variants were annotated with molecular consequence, pathogenicity, and literature information for interpreting and prioritizing variants. Here, we introduce the newly developed TogoVar database that compares allele frequencies among Japanese and non-Japanese populations and describes the integrated annotations.

A Rare Case of Metastatic Gastric Signet Ring Cell Adenocarcinoma in a 23-Year-Old Female Presenting as Malignant Pleural Effusion

Signet ring cell carcinoma (SRCC) is a poorly differentiated mucin-producing adenocarcinoma with greater than 50% signet ring cells. It commonly arises from the gastrointestinal (GI) tract and rarely from extraintestinal organs. This is a rare case of a young African American female who presented with metastatic spread of signet ring cell gastric cancer (pleural and lymph nodal involvement) as the initial presentation of SRCC. Knowledge of the various clinical manifestations of SRCC can help with its early diagnosis, and there is a high need for detailed physical examination, early referral, and prompt treatment in patients with SRCC.

Genomic features of Helicobacter pylori-naïve diffuse-type gastric cancer

Helicobacter pylori (HP) is a major etiologic driver of diffuse-type gastric cancer (DGC). However, improvements in hygiene have led to an increase in the prevalence of HP-naïve DGC; that is, DGC that occurs independent of HP. Although multiple genomic cohort studies for gastric cancer have been conducted, including studies for DGC, distinctive genomic differences between HP-exposed and HP-naïve DGC remain largely unknown. Here, we employed exome and RNA sequencing with immunohistochemical analyses to perform binary comparisons between 36 HP-exposed and 27 HP-naïve DGCs from sporadic, early-stage, and intramucosal or submucosal tumor samples. Among the samples, 33 HP-exposed and 17 HP-naïve samples had been preserved as fresh-frozen samples. HP infection status was determined using stringent criteria. HP-exposed DGCs exhibited an increased single nucleotide variant burden (HP-exposed DGCs; 1.97 [0.48-7.19] and HP-naïve DGCs; 1.09 [0.38-3.68] per megabase; p = 0.0003) and a higher prevalence of chromosome arm-level aneuploidies (p < 0.0001). CDH1 was mutated at similar frequencies in both groups, whereas the RHOA-ARHGAP pathway misregulation was exclusive to HP-exposed DGCs (p = 0.0167). HP-exposed DGCs showed gains in chromosome arms 8p/8q (p < 0.0001), 7p (p = 0.0035), and 7q (p = 0.0354), and losses in 16q (p = 0.0167). Immunohistochemical analyses revealed a higher expression of intestinal markers such as CD10 (p < 0.0001) and CDX2 (p = 0.0002) and a lower expression of the gastric marker, MUC5AC (p = 0.0305) among HP-exposed DGCs. HP-naïve DGCs, on the other hand, had a purely gastric marker phenotype. This work reveals that HP-naïve and HP-exposed DGCs develop along different molecular pathways, which provide a basis for early detection strategies in high incidence settings. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

The Incidence-Based Mortality and Survival Trends in Patients with Gastric Signet Ring Cell Carcinoma

Background and Aim. Gastric signet ring cell carcinoma (SRC) is a distinct subtype of gastric cancer. This study aims to analyze the incidence-based mortality and survival trends in patients with gastric SRC over the past decades. Materials and Methods. The patients from the Surveillance, Epidemiology, and End Results (SEER) database were recruited to explore the incidence-based mortality and survival trends from 2000 to 2017. We further analyzed the differences in mortality and survival trends in these patients by sex and stage. We also used joinpoint software to evaluate the trends in annual percentage change (APC) for statistical significance. Results. 14916 patients were collected, including 7801 (52.3%) male and 7115 (47.7%) female. We identified a single joinpoint at 2002. The overall incidence-based mortality of gastric SRC declined in America after 2002 (APC = −1.21, $P<0.05$ ). In stratified analysis by sex and stage, the incidence-based mortality rate was higher in males than females. After 2002, the mortality rate decreased significantly in male (APC = −1.68, $P<0.05$ ) and M0-stage patients (APC = −1.75, $P<0.05$ ). In survival trend analysis, the 2-year relative survival improved in M0-stage gastric SRC, especially for males (APC = 1.14, $P<0.05$ ). As for M1-stage patients, the 2-year relative survival significantly elevated in both male (APC = 3.87, $P<0.05$ ) and female (APC = 5.63, $P<0.05$ ) patients. Conclusions. The incidence-based mortality of gastric SRC has declined, and survival has improved in America over time. These optimistic trends may be attributed to cancer screening implementation and advances in novel treatments in the past decades.

Comparative Study of Modified Silver Nitrate Staining for the Detection of Helicobacter pylori

BACKGROUND/AIMS

Helicobacter pylori (Hp) infection is associated with a variety of diseases, such as benign lesions, precancerous lesions, and malignant lesions, especially diseases in the digestive system. Most people with Hp infection have mild early symptoms that are not easily noticed. Therefore, the diagnosis and treatment of Hp infection is particularly important. At present, there are many methods to detection Hp infection, but there is a lack of effective detection method with high sensitivity and specificity. On the basis of the existing detection methods, the modified silver nitrate staining method in this study improved the sensitivity and specificity of Hp detection.

MATERIALS AND METHODS

We selected gastric antrum and gastric angle mucosal biopsy tissues from 60 inpatients that were archived in the Pathology Department of Zhongnan Hospital of Wuhan University from July to December 2020. An Hp immunohistochemical assay, histochemical assay kit (methylene blue), and modified silver nitrate staining were used to measure the Hp infection positivity rate.

RESULTS

Comparison of Hp sensitivity and specificity among the 3 methods showed that the modified silver nitrate staining method was the most excellent. The sensitivity of modified silver nitrate staining method was 98.3%, which is statistically significantly higher compared with the other 2 methods.

CONCLUSION

The modified silver nitrate staining method for Hp detection is convenient and effective, and could be widely used for clinical Hp detection.

Indolent feature of Helicobacter pylori-uninfected intramucosal signet ring cell carcinomas with CDH1 mutations

BACKGROUND

In Helicobacter pylori (Hp)-uninfected individuals, diffuse-type gastric cancer (DGC) was reported as the most common type of cancer. However, the carcinogenic mechanism of Hp-uninfected sporadic DGC is largely unknown.

METHODS

We performed whole-exome sequencing of Hp-uninfected DGCs and Hp-uninfected normal gastric mucosa. For advanced DGCs, external datasets were also analyzed.

RESULTS

Eighteen patients (aged 29-78 years) with DGCs and nine normal subjects (28-77 years) were examined. The mutation burden in intramucosal DGCs (10-66 mutations per exome) from individuals aged 29-73 years was not very different from that in the normal gastric glands, which showed a constant mutation accumulation rate (0.33 mutations/exome/year). Unbiased dN/dS analysis showed that CDH1 somatic mutation was a driver mutation for intramucosal DGC. CDH1 mutation was more frequent in intramucosal DGCs (67%) than in advanced DGCs (27%). In contrast, TP53 mutation was more frequent in advanced DGCs (52%) than in intramucosal DGCs (0%). This discrepancy in mutations suggests that CDH1-mutated intramucosal DGCs make a relatively small contribution to advanced DGC formation. Among the 16 intramucosal DGCs (median size, 6.5 mm), 15 DGCs were pure signet ring cell carcinoma (SRCC) with reduced E-cadherin expression and a low proliferative capacity (median Ki-67 index, 2.4%). Five SRCCs reviewed endoscopically over 2-5 years showed no progression.

CONCLUSIONS

Impaired E-cadherin function due to CDH1 mutation was considered as an early carcinogenic event of Hp-uninfected intramucosal SRCC. Genetic and clinical analyses suggest that Hp-uninfected intramucosal SRCCs may be less likely to develop into advanced DGCs.