Gastric cancer is highly prevalent in Lynch syndrome patients with atrophic gastritis

Diagnosis of patients with Lynch syndrome lacking the Amsterdam II or Bethesda criteria

BACKGROUND

Lynch Syndrome (LS) is an autosomal dominant inheritance disorder characterized by genetic predisposition to develop cancer, caused by pathogenic variants in the genes of the mismatch repair system. Cases are detected by implementing the Amsterdam II and the revised Bethesda criteria, which are based on family history.

MAIN BODY

Patients who meet the criteria undergo posterior tests, such as germline DNA sequencing, to confirm the diagnosis. However, these criteria have poor sensitivity, as more than one-quarter of patients with LS do not meet the criteria. It is very likely that the lack of sensitivity of the criteria is due to the incomplete penetrance of this syndrome. The penetrance and risk of developing a particular type of cancer are highly dependent on the affected gene and probably of the variant. Patients with variants in low-penetrance genes have a lower risk of developing a cancer associated with LS, leading to families with unaffected generations and showing fewer clear patterns. This study focuses on describing genetic aspects of LS cases that underlie the lack of sensitivity of the clinical criteria used for its diagnosis.

CONCLUSION

Universal screening could be an option to address the problem of underdiagnosis.

Penetrance of Gastric Adenocarcinoma Susceptibility Genes: A Systematic Review

BACKGROUND

Gastric adenocarcinoma (GAC) is the fifth most common cancer in the world, and the presence of germline pathogenic variants has been linked with approximately 5% of gastric cancer diagnoses. Multiple GAC susceptibility genes have been identified, but information regarding the risk associated with pathogenic variants in these genes remains obscure. We conducted a systematic review of existing studies reporting the penetrance of GAC susceptibility genes.

METHODS

A structured search query was devised to identify GAC-related papers indexed in MEDLINE/PubMed. A semi-automated natural language processing algorithm was applied to identify penetrance papers for inclusion. Original studies reporting the penetrance of GAC were included and the full-text articles were independently reviewed. Summary statistics, effect estimates, and precision parameters from these studies were compiled into a table using a predetermined format to ensure consistency.

RESULTS

Forty-five studies were identified reporting the penetrance of GAC among patients harboring mutations in 13 different genes: APC, ATM, BRCA1, BRCA2, CDH1, CHEK2, MLH1, MSH2, MSH6, PMS2, MUTYH-Monoallelic, NBN, and STK11.

CONCLUSION

Our systematic review highlights the importance of testing for germline pathogenic variants in patients before the development of GAC. Management of patients who harbor a pathogenic mutation is multifactorial, and clinicians should consider cancer risk for each applicable gene-cancer association throughout the screening and management process. The scarcity of studies we found investigating the risk of GAC among patients with pathogenic variants in GAC susceptibility genes highlights the need for more investigations that focus on producing robust risk estimates for gene-cancer associations.

Secondary Primary Cancer after Primary Gastric Cancer: Literature Review and Big Data Analysis Using the Health Insurance Review and Assessment Service (HIRA) Database of Republic of Korea

Advances in cancer screening and early detection, as well as improvements in surgical techniques and therapeutics, have contributed to decreasing gastric cancer mortality. The number of gastric cancer survivors continues to rise; however, long-term follow-up has revealed an increase in the risk of post-gastrectomy symptoms or other health problems, such as extra-gastric secondary primary cancer (SPC), in these survivors. Therefore, evidence-based screening for new primary cancer is needed in these populations; however, the incidence of SPC varies by country or continent and its characteristics have not been clearly reported. The characteristics of SPC are of increasing interest to both treatment providers and gastric cancer survivors; thus, this literature review explores not only the epidemiology and biology of SPC but also clinical and biological factors that influence its prognosis.

Endoscopic Surveillance in Patients with the Highest Risk of Gastric Cancer: Challenges and Solutions

Gastric cancer is one of the most significant causes of cancer-related morbidity and mortality worldwide. Recognized modifiable risk factors include Helicobacter pylori infection, geographic location, select dietary factors, tobacco use and alcohol consumption. In addition, multiple hereditary cancer predisposition syndromes are associated with significantly elevated gastric cancer risk. Endoscopic surveillance in hereditary gastric cancer predisposition syndromes has the potential to identify gastric cancer at earlier and more treatable stages, as well as to prevent development of gastric cancer through identification of precancerous lesions. However, much uncertainty remains regarding use of endoscopic surveillance in hereditary gastric cancer predisposition syndromes, including whether or not it should be routinely performed, the surveillance interval and age of initiation, cost-effectiveness, and whether surveillance ultimately improves survival from gastric cancer for these high-risk individuals. In this review, we outline the hereditary gastric cancer predisposition syndromes associated with the highest gastric cancer risks. Additionally, we cover current evidence and guidelines addressing hereditary gastric cancer risk and surveillance in these syndromes, along with current challenges and limitations that emphasize a need for continued research in this field.

Diagnosis and clinical implication of collision gastric adenocarcinomas: a case report

BACKGROUND

Collision tumors are a subtype of simultaneous tumors wherein two unrelated tumors collide or infiltrate each other. Collision gastric adenocarcinomas (CGA) are rare and difficult to diagnose, and their clinical implications remain unclear. Herein, we aimed to reveal diagnostic methods for CGA and provide insight into its implications.

CASE PRESENTATION

Among 1041 cases of gastric cancers (GCs) resected between 2008 and 2018, we included cases of confirmed CGA. Patients' backgrounds, preoperative endoscopy findings, macroscopic imaging findings, and histopathology findings [including immunostaining for CK 7, MUC2, and mismatch repair (MMR) proteins] were investigated. The incidence of CGA was 0.5%: 5 of 81 cases having simultaneous multiple GCs. Tumors were mainly in the distal stomach. The CGA in two cases was between early cancers, in two cases was between early and advanced cancers, and in one case was between advanced cancers. There were three cases of collision between differentiated and undifferentiated types and two cases between differentiated types. Immunostaining with CK7 and MUC2 was useful for diagnosing collision tumor when the histology was similar to each other. Among ten GCs comprising CGA, nine tumors (90%) exhibited deficient MMR proteins, suggesting high microsatellite instability (MSI).

CONCLUSIONS

CGA is rare and usually found in the distal stomach. Close observation of shape, optimal dissection, and detailed pathological examination, including immunostaining, facilitated diagnosis. CGAs may have high MSI potential.

Risk factors for gastric cancer in patients with Lynch syndrome

INTRODUCTION

The cumulative lifetime risk of gastric cancer (GC) in patients with Lynch syndrome (LS) is reported to be 8%. There is limited evidence on specific risk factors for GC and no agreement among guidelines on gastric endoscopic surveillance schedule in LS patients.

AIMS AND METHODS

We conducted a retrospective cohort study to identify risk factors for gastric precancerous conditions (chronic atrophic gastritis and intestinal metaplasia) and GC in patients with LS and a case-control study to compare the prevalence of these conditions with a control group.

RESULTS

We included 385 LS patients (40.5% male, mean age 49.0 years). During a median follow-up period of 48 months (interquartile range, 24-84 months), precancerous conditions were identified in 110 patients (34%) and the prevalence of advanced stages of atrophic gastritis was 3% for OLGA III/IV and 0.6% OLGIM III/IV. Family history of GC was significantly associated with OLGA III/IV ( P = 0.020). Among LS patients, 10 patients (2.6%) were diagnosed with GC (incidence rate of 5/1000 persons-year). Older age and OLGA III/IV were identified as risk factors for GC ( P < 0.001). When compared with controls, patients with LS had significantly higher rates of Hp infection ( P = 0.035) and lower OLGA and OLGIM stages ( P < 0.001 and P = 0.026, respectively).

CONCLUSION

In our cohort, the incidence of GC and advanced stages of atrophic gastritis was low. Older age and OLGA III/IV were associated with a higher risk of GC. Identification of risk factors for GC in LS patients can help tailoring endoscopic surveillance.

Gastric metastasis from small bowel adenocarcinoma in a Lynch syndrome patient

Gastric cancer is a Lynch syndrome (LS)-associated tumor, with the cumulative lifetime risk in LS patients estimated to be 5.8-13%. Hence, surveillance for gastric cancer is important for LS patients, especially in those with a family history of gastric cancer or of Asian descent. We report a very rare case of a LS patient who showed gastric metastasis from jejunal adenocarcinoma curatively resected 8 years prior. A 79-year-old female was diagnosed with a synchronous gastric submucosal tumor (SMT) and right-sided colon cancer. She was referred to our hospital as she and her family had histories of LS-associated tumors. She underwent curative intent surgery for the tumors. Postoperative histopathological examination revealed the gastric SMT was an adenocarcinoma completely covered by non-neoplastic gastric mucosa. Immunohistochemical analyses showed the gastric SMT had the same expression pattern for CDX2, cytokeratins 7 and 20 as the jejunal adenocarcinoma. Thirty-four months after surgery the patient is alive without recurrence or any other LS-associated tumors. To the best of our knowledge, this is the first report of gastric metastasis from small bowel adenocarcinoma in a LS patient. Awareness of this case may be important for gastric cancer surveillance in LS patients.

Pathological Diversity of Gastric Cancer from the Viewpoint of Background Condition

BACKGROUND

The prevalence of Helicobacter pylori infection and chronic atrophic gastritis is decreasing in Japan, which has led to a decline in the incidence of gastric cancer. However, there are various subtypes of gastric cancer that arise from the background mucosa without H. pylori infection, and their histological characteristics are distinct from those of gastric cancer with chronic atrophic gastritis.

SUMMARY

In this review, after a brief overview of conventional gastric carcinoma with H. pylori infection, including its molecular classification, histological characteristics of gastric cancer after eradicating H. pylori are described. The clinicopathological characteristics of gastric cancer independent of H. pylori infection are then explained. Autoimmune gastritis (type A gastritis) increases the risk of gastric adenocarcinoma and neuroendocrine tumors. Gastric carcinoma without H. pylori infection has various histological subtypes, including fundic gland-type adenocarcinoma (oxyntic gland adenoma), foveolar-type adenocarcinoma/adenoma, signet ring cell carcinoma, and adenocarcinoma of the esophagogastric junction. In addition, some familial gastric cancer syndromes, including hereditary diffuse gastric cancer, familial adenomatous polyposis, and gastric adenocarcinoma and proximal polyposis of the stomach, are also discussed. Key Messages: Although the incidence of gastric cancer will decrease in the near future, the diversity of gastric cancer pathology will be enhanced because H. pylori-negative gastric cancer will have a significant impact on the clinical practice guidelines for gastric cancer. Gastroenterologists and pathologists should be aware of the morphological diversity of H. pylori-negative gastric cancer, and attention should be paid to the status of the background gastric mucosa while examining gastric cancer.

Genetic Syndromes Associated with Gastric Cancer

Although environmental factors such as Helicobacter pylori, tobacco, and diet are major contributors to the development of gastric cancer (GC) worldwide, it is estimated that up to 5% to 10% of GC cases are due to an underlying hereditary susceptibility caused by germline pathogenic variants. Hereditary diffuse gastric cancer (HDGC) caused by germline pathogenic variants in the CDH1 gene is the principal familial GC syndrome. However, other well-established hereditary gastrointestinal syndromes have been associated with an increased risk of GC. In this review, we will discuss the latest insights and advances in our understanding of GC associated with Lynch syndrome (LS), familial adenomatous polyposis (FAP), gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS), Li-Fraumeni syndrome (LFS), Peutz-Jeghers syndrome (PJS), and juvenile polyposis syndrome (JPS). We will also discuss the emergence of new associations of the homologous recombination pathway genes (BRCA1, BRCA2) with GC.

Upper Gastrointestinal Lesions during Endoscopy Surveillance in Patients with Lynch Syndrome: A Multicentre Cohort Study

Simple Summary

Patients with Lynch syndrome are at increased risk of upper gastrointestinal cancer. Recommendations for upper gastrointestinal endoscopy screening vary widely with limited data supporting effectiveness. The aim of our study was to investigate yields of upper gastrointestinal endoscopy screening in a large multicentre cohort of 172 Lynch syndrome mutation carriers. In our study, upper gastrointestinal endoscopy surveillance detects frequent neoplastic lesions particularly after the age of 40 years. Ours results suggest that Lynch patients should be considered for upper gastrointestinal endoscopic and Helicobacter pylori screening.

Abstract

Background: Patients with Lynch syndrome are at increased risk of gastric and duodenal cancer. Upper gastrointestinal endoscopy surveillance is generally proposed, even though little data are available on upper gastrointestinal endoscopy in these patients. The aim of this retrospective study was to evaluate the prevalence and incidence of gastrointestinal lesions following upper gastrointestinal endoscopy examination in Lynch patients. Methods: A large, multicentre cohort of 172 patients with a proven germline mutation in one of the mismatch repair genes and at least one documented upper gastrointestinal endoscopy screening was assessed. Detailed information was collected on upper gastrointestinal endoscopy findings and the outcome of endoscopic follow-up. Results: Seventy neoplastic gastrointestinal lesions were diagnosed in 45 patients (26%) out of the 172 patients included. The median age at diagnosis of upper gastrointestinal lesions was 54 years. The prevalence of cancer at initial upper gastrointestinal endoscopy was 5% and the prevalence of precancerous lesions was 12%. Upper gastrointestinal lesions were more frequent after 40 years of age (p < 0.001). Helicobacter pylori infection was associated with an increased prevalence of gastric, but not duodenal, lesions (p < 0.001). Conclusions: Neoplastic upper gastrointestinal lesions are frequent in patients with Lynch syndrome, especially in those over 40 years of age. The results of our study suggest that Lynch patients should be considered for upper gastrointestinal endoscopic and Helicobacter pylori screening.

Helicobacter pylori induced gastric carcinogenesis - The best molecular model we have?

Gastric carcinogenesis can be described as a consequence of multilevel molecular alterations that is triggered by a cascade of events. Historically, diet and environmental factors have been identified to substantially contribute to carcinogenesis before the discovery of Helicobacter pylori (H. pylori). But H. pylori infection has revolutionized the understanding of gastric carcinogenesis. Although the model of H. pylori-driven carcinogenesis remains valid, there is a continuous effort to precisely delineate the molecular pathways involved and to understand the interplay with additional risk factors including recent relevant knowledge on the stomach microbiota. In this review, we provide an updated view on the models of gastric carcinogenesis. This includes historically appreciated H. pylori-induced models and expands these taking recent molecular data into consideration. Based on the data provided, we conclude that indeed H. pylori-carcinogenesis remains one of the best-established models at least for a subset of gastric cancers. Implementation of the recently identified molecular subtypes in novel genetic animal models is required to expand our knowledge on H. pylori-independent carcinogenesis.