Risk-reducing total gastrectomy for germline mutations in E-cadherin (CDH1): Pathologic findings with clinical implications. Am J Surg Pathol. 2008;32:799-809. [PMID: 18391748 DOI: 10.1097/pas.0b013e31815e7f1a]

A Systematic Review of Surgical and Pathological Outcomes in Patients With a CDH1 Mutation Undergoing Total Gastrectomy

BACKGROUND

CDH1 (E-cadherin) genetic mutations are associated with a 30%-70% increased lifetime risk of hereditary diffuse gastric cancer (HDGC). Although prophylactic total gastrectomy (PTG) reduces long-term risk of gastric cancer, the associated morbidity and mortality remain unclear. This systematic review aims to characterise postoperative surgical outcomes in patients undergoing total gastrectomy.

METHODS

A systematic literature search was performed for studies reporting endoscopic surveillance, surgical and pathological outcomes for patients with CDH1 mutation undergoing a total gastrectomy.

RESULTS

Thirty-nine studies included 1849 patients, of which 96% had a CDH1 (n = 1777) or CTNNA1 (n = 3) mutation. Endoscopy outcomes were reported for 1640 patients. Cancer foci were identified in 32% (n = 523/1640) and 71% of these patients went on to have a total gastrectomy (n = 369/523). The remaining 78% of patients did not have cancer foci detected on endoscopy (n = 1117/1640). Of these patients, 62% underwent a total gastrectomy (n = 688/1117) and 81% were found to have cancer on surgical histology (n = 556/688). Pathological staging was reported for 790 patients undergoing surgery, of which 68% had pT1 disease (n = 537). Postoperative complications were reported for 430 patients across 23 studies, with the most common complications being anastomotic strictures (25%), anastomotic leaks (13%), wound infections (12%) and pulmonary complications (11%). Only one postoperative death was reported within 30 days.

CONCLUSION

Rates of early cancers are high in CDH1 patients undergoing PTG, highlighting the need for improvement in reliable endoscopic surveillance. Although postoperative mortality in this surgical cohort remains low, high rates of postoperative complications warrant careful patient counselling.

A Systematic Review on Clinical and Health-Related Quality of Life Outcomes following Total Gastrectomy in Patients with Hereditary Diffuse Gastric Cancer

Hereditary diffuse gastric cancer (HDGC) is an autosomal-dominant syndrome associated with early onset diffuse gastric cancer. Definitive treatment is prophylactic total gastrectomy (PTG) associated with significant morbidity. Studies published from January 2000 to December 2022 reporting clinical, histopathological or health-related quality of life outcomes in HDGC patients undergoing PTG were identified. The study quality was assessed by the "Newcastle-Ottawa scale". Of the 257 articles screened, 21 were selected. A total of 353 patients were examined in 15 studies that reported surgical outcomes. The median age was 42 years old. The median major complication and mortality rates were 19.2% and 0.3%, respectively. The most common complications were wound infection at 4.8% followed by anastomotic leak and pulmonary complications at 4.5% each. Following PTG, 88.6% of patients had early lesions amongst 414 patients. The mean/median number of signet ring cell carcinoma foci in the gastrectomy specimens was from 2 to 78. All cases were stage 1 with no lymph node involvement. There was a wide range of psychosocial effects following PTG closely related to the physical symptoms. It is imperative for patients to receive comprehensive preoperative counselling to make an informed decision and be followed up under the care of a multidisciplinary team.

The ECM and tissue architecture are major determinants of early invasion mediated by E-cadherin dysfunction

Germline mutations of E-cadherin cause Hereditary Diffuse Gastric Cancer (HDGC), a highly invasive cancer syndrome characterised by the occurrence of diffuse-type gastric carcinoma and lobular breast cancer. In this disease, E-cadherin-defective cells are detected invading the adjacent stroma since very early stages. Although E-cadherin loss is well established as a triggering event, other determinants of the invasive process persist largely unknown. Herein, we develop an experimental strategy that comprises in vitro extrusion assays using E-cadherin mutants associated to HDGC, as well as mathematical models epitomising epithelial dynamics and its interaction with the extracellular matrix (ECM). In vitro, we verify that E-cadherin dysfunctional cells detach from the epithelial monolayer and extrude basally into the ECM. Through phase-field modelling we demonstrate that, aside from loss of cell-cell adhesion, increased ECM attachment further raises basal extrusion efficiency. Importantly, by combining phase-field and vertex model simulations, we show that the cylindrical structure of gastric glands strongly promotes the cell's invasive ability. Moreover, we validate our findings using a dissipative particle dynamics simulation of epithelial extrusion. Overall, we provide the first evidence that cancer cell invasion is the outcome of defective cell-cell linkages, abnormal interplay with the ECM, and a favourable 3D tissue structure.

Germline CDH1 variants in hereditary diffuse gastric cancer syndrome with focus on younger women

PURPOSE

The objective of this study was to determine the male and female frequency of diffuse gastric cancer (DGC), the age at diagnosis, and the country of origin in a selected population with germline CDH1 variants from families with the hereditary diffuse gastric cancer (HDGC) syndrome.

METHODS

Relevant literature dating from 1998 to 2021 was systematically searched for data on CDH1 gene. The Wilcoxon rank sum test and the Chi-square test were used to estimate if the difference observed between patients with gastric cancer (GC) and unaffected individuals was significant.

RESULTS

We identified 80 families fulfilling the established clinical criteria for HDGC CDH1 genetic screening. There were more women than men with DGC and germline CDH1 variant (65.5%). Stratifying the age at diagnosis, we identified an association between DGC, positive CDH1 screening and young women (≤ 40 years) (p = 0.015). The mean age at diagnosis was 39.6 ys for women and 42.5 ys for men. There was an association between CDH1 carrier status and DGC (p = 0.021).

CONCLUSIONS

Young women carrying germline CDH1 variants with DGC are comparatively frequent in the HDGC syndrome, and potentially at higher risk to develop DGC particularly in low-incidence areas for GC.

Factors associated with detection of hereditary diffuse gastric cancer on endoscopy in individuals with germline CDH1 mutations

BACKGROUND AND AIMS

Individuals with germline pathogenic CDH1 variants have a high risk of hereditary diffuse gastric cancer. The sensitivity of EGD in detecting signet ring cell carcinoma (SRCC) in this population is low. We aimed to identify endoscopic findings and biopsy practices associated with detection of SRCC.

METHODS

This retrospective cohort included individuals with a germline pathogenic/likely pathogenic CDH1 variant undergoing at least 1 EGD at Memorial Sloan Kettering Cancer Center between January 1, 2006, and March 25, 2022. The primary outcome was detection of SRCC on EGD. Findings on gastrectomy were also assessed. The study included periods before and after implementation of the Cambridge protocol for endoscopic surveillance, allowing for assessment of a spectrum of biopsy practices.

RESULTS

Ninety-eight CDH1 patients underwent at least 1 EGD at our institution. SRCC was detected in 20 (20%) individuals on EGD overall and in 50 (86%) of the 58 patients undergoing gastrectomy. Most SRCC foci were detected in the gastric cardia/fundus (EGD, 50%; gastrectomy, 62%) and body/transition zone (EGD, 60%; gastrectomy, 62%). Biopsy results of gastric pale mucosal areas were associated with detection of SRCC (P < .01). The total number of biopsy samples taken on EGD was associated with increased detection of SRCC (P = .01), with 43% detected when ≥40 samples were taken.

CONCLUSIONS

Targeted biopsy sampling of gastric pale mucosal areas and increasing number of biopsy samples taken on EGD were associated with detection of SRCC. SRCC foci were mostly detected in the proximal stomach, supporting updated endoscopic surveillance guidelines. Further studies are needed to refine endoscopic protocols to improve SRCC detection in this high-risk population.

Pioneering use of genetic analysis for CDH1 to identify candidates for prophylactic total gastrectomy to prevent hereditary diffuse gastric cancer

Worldwide, gastric cancer results in significant morbidity and mortality. Ten per cent of patients with gastric cancer have a strong family history of the disease. CDH1 (E-cadherin) has been identified as a key gene whose mutation leads to hereditary diffuse gastric cancer. We overviewed 33 articles with prophylactic total gastrectomy and assessed the outcomes and benefits. Families with mutations in CDH1 may benefit from early prophylactic total gastrectomy. Dr Mark Duncan has applied his experience as a high-volume gastric cancer surgeon to treat not only individual patients, but several generations of patients within a family. This use of prophylactic total gastrectomy is well tolerated by patients and prevents the future development of gastric cancer.

CDH1 mutations recurrence and global clustering in genetically tested families with hereditary diffuse gastric cancer syndrome: results from a systematic study

The global distribution of germline CDH1 mutations in hereditary diffuse gastric cancer families, is highly heterogenous. The aim of this study was to determine if there is any geographic clustering of CDH1 mutations in families with the hereditary diffuse gastric cancer syndrome. Data from 1998 to 2021 were collected systematically according to the PRISMA guidelines. 571 germline CDH1 mutations were recorded worldwide, with 387 (67.8%) of them reported in 108 families. The largest clusters of CDH1 mutations were identified in central Europe, north America, northern Europe, New Zealand (Māori), and south America. A high penetrance risk for GC development was observed for c.1008G > T in New Zealand (Māori), c.1565 + 2insT in northern Europe, c.1901C > T in Portugal, and c.1003C > T in the USA. Our observations are consistent with a specific local clustering of some recurrent CDH1 mutations within specific countries.

Hereditary Diffuse Gastric Cancer

Hereditary diffuse gastric cancer (HDGC) is a dominantly inherited cancer syndrome characterized by a high incidence of diffuse gastric cancer (DGC) and lobular breast cancer (LBC). HDGC is caused by germline mutations in 2 genes involved in the epithelial adherens junction complex, CDH1 and CTNNA1. We discuss the genetics of HDGC and the variability of its clinical phenotype, in particular the variable penetrance of advanced DGC and LBC, both within and between families. We review the pathology of the disease, the mechanism of tumor initiation, and its natural history. Finally, we describe current best practice for the clinical management of HDGC, including emerging genetic testing criteria for the identification of new families, methods for endoscopic surveillance, the complications associated with prophylactic surgery, postoperative quality of life, and the emerging field of HDGC chemoprevention.

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.

Potential therapeutic targets discovery by transcriptome analysis of an in vitro human gastric signet ring carcinoma model

BACKGROUND

Loss of E-cadherin expression is frequently observed in signet ring carcinoma (SRCC). People with germline mutations in CDH1, which encodes E-cadherin, develop diffuse gastric cancer at a higher rate. Loss of E-cadherin expression is thus assumed to trigger oncogenic development.

METHODS

To investigate novel therapeutic targets for gastric SRCC, we engineered an E-cadherin-deficient SRCC model in vitro using a human gastric organoid (hGO) with CDH1 knockout (KO).

RESULTS

CDH1 KO hGO cells demonstrated distinctive morphological changes similar to SRCC and high cell motility. RNA-sequencing revealed up-regulation of matrix metalloproteinase (MMP) genes in CDH1 KO hGO cells compared to wild type. MMP inhibitors suppressed cell motility of CDH1 KO hGO cells and SRCC cell lines in vitro. Immunofluorescent analysis with 95 clinical gastric cancer tissues revealed that MMP-3 was specifically abundant in E-cadherin-aberrant SRCC. In addition, CXCR4 molecules translocated onto the cell membrane after CDH1 KO. Addition of CXCL12, a ligand of CXCR4, to the culture medium prolonged cell survival of CDH1 KO hGO cells and was abolished by the inhibitor, AMD3100. In clinical SRCC samples, CXCL12-secreting fibroblasts showed marked infiltration into the cancer area.

CONCLUSIONS

E-cadherin deficient SRCCs might gain cell motility through upregulation of MMPs. CXCL12-positive cancer-associated fibroblasts could serve to maintain cancer-cell survival as a niche. MMPs and the CXCL12/CXCR4 axis represent promising candidates as novel therapeutic targets for E-cadherin-deficient SRCC.

Prédispositions génétiques au cancer gastrique et leur association au type histologique

About 5% of gastric cancers are associated with hereditary cancer syndromes. Histology is paramount in this context, as major susceptibility genes are associated with specific subtypes. Germline pathogenic variants in CDH1 and CTNNA1 cause Hereditary Diffuse Gastric Cancer (HDGC). Major advances have been made in the past ten years regarding HDGC. Penetrance estimates for diffuse cancer are now lower than previously thought, at 30-40%. Surveillance upper gastrointestinal endoscopy is now an acceptable alternative to prophylactic total gastrectomy. Indeed, its sensitivity in detecting advanced disease is satisfactory assuming it is performed by an expert and according to a specific protocol. The risk of intestinal-type gastric cancer is increased in patients with Lynch syndrome, although it is much lower than the risk of colorectal and endometrial cancer. Intestinal-type gastric cancers are also observed in excess in patients with hereditary polyposis, the main one being APC-associated familial adenomatous polyposis. The main and most clinically relevant manifestations in patients with polyposes remain colorectal and duodenal polyps and carcinomas, well ahead of gastric cancer. Finally, recent data point towards increased gastric cancer risk in hereditary breast and ovarian cancer.

Hereditary diffuse gastric cancer (HDGC). An overview

It is estimated that up to 10% of gastric carcinomas show familial aggregation. In contrast, around 1-3 % (approximately 33,000 yearly) are genuinely hereditary. Hereditary diffuse gastric cancer (HDGC) is a rare malignancy characterized by autosomal dominant inheritance of pathological variants of the CDH1 and CTNNA1 genes encoding the adhesion molecules E-cadherin and α-catenin, respectively. The multifocal nature of the disease and the difficulty of visualizing precursor lesions by endoscopy underscore the need to be aware of this malignancy as surgical prevention can be fully protective. Here, we provide an overview of the main epidemiological, clinical, genetic, and pathological features of HDGC, as well as updated guidelines for its diagnosis, genetic testing, counseling, surveillance, and management. We conclude that HDGC is a rare, highly penetrant disease that is difficult to diagnose and manage, so it is necessary to correctly identify it to offer patients and their families' adequate management following the recommendations of the IGCL. A critical point is identifying a mutation in HDGC families to determine whether unaffected relatives are at risk for cancer.

Diffuse gastric cancer: Emerging mechanisms of tumor initiation and progression

Gastric cancer is globally the fourth leading cause of cancer-related deaths. Patients with diffuse-type gastric cancer (DGC) particularly have a poor prognosis that only marginally improved over the last decades, as conventional chemotherapies are frequently ineffective and specific therapies are unavailable. Early-stage DGC is characterized by intramucosal lesions of discohesive cells, which can be present for many years before the emergence of advanced DGC consisting of highly proliferative and invasive cells. The mechanisms underlying the key steps of DGC development and transition to aggressive tumors are starting to emerge. Novel mouse- and organoid models for DGC, together with multi-omic analyses of DGC tumors, revealed contributions of both tumor cell-intrinsic alterations and gradual changes in the tumor microenvironment to DGC progression. In this review, we will discuss how these recent findings are leading towards an understanding of the cellular and molecular mechanisms responsible for DGC initiation and malignancy, which may provide opportunities for targeted therapies.

Surgery for Hereditary Diffuse Gastric Cancer: Long-Term Outcomes

Simple Summary

This study reports the long-term results of total gastrectomy for patients with a family history of gastric cancer and CDH1 gene mutations that predispose to hereditary diffuse gastric cancer (HDGC). Total gastrectomy was performed in 8 symptomatic patients and 22 asymptomatic patients of whom only 3 had HDGC diagnosed preoperatively. 7 of 8 symptomatic had metastatic lymph nodes with cancer. 21 of 22 asymptomatic patients had gastric cancer localized to the stomach and each was cured. 15 of those patients had 9-year follow-up. Each had significant weight loss (23% body weight) with a normal body mass index, 40% had bile reflux controlled with medication, and each returned to work and said they would do it again. Long-term quality of life following gastrectomy was acceptable.

Abstract

Introduction: Gastric cancer is inherited as an autosomal dominant condition in hereditary diffuse gastric cancer (HDGC). The gene associated with HDGC is an E-cadherin gene CDH1. At the time of initiation of this study, it was estimated that 70% of patients who inherited the CDH1 gene mutation would develop gastric cancer. We hypothesized that the rate of signet ring cell cancer in asymptomatic patients with CDH1 mutations may be higher than anticipated and that the surgery could be conducted with acceptable short-term and long-term complications suggesting that the quality of life with the surgery is acceptable. Methods: We prospectively studied the role of total gastrectomy in symptomatic and asymptomatic patients with CDH1 mutations. A total of 43 patients with mutations of the CDH1 gene were studied prospectively, including 8 with symptoms and 35 without symptoms. Total gastrectomy was recommended to each. Quality of life was assessed in patients who underwent prophylactic gastrectomy. Proportions are compared with Fisher’s exact test. Results: In total, 13 (30%) asymptomatic patients declined surgery. Total gastrectomy was performed in 8 symptomatic patients and 22 asymptomatic patients of whom only 3 asymptomatic patients (14%) had endoscopically proven signet ring cell cancer preoperatively, while 21 of 22 (95%) had it on final pathology (p = 0.05). Each asymptomatic patient was T1, N0, while seven out of eight symptomatic patients had T3-T4 tumors and six had positive lymph nodes. None had operative complications or operative death. The median follow-up was 7 years. Five (63%) symptomatic patients died, while only one (95%) prophylactic patient died of a non-gastric cancer- or surgery-related issue (p = 0.05). A total of 15 prophylactic patients had long-term follow-up. Each had significant weight loss (mean 23%) but all had a normal body mass index. In total, 40% had bile reflux gastritis controlled with sucralfate. Each returned to work and, if given the choice, said that they would undergo the surgery again. Conclusions: Total gastrectomy is indicated for patients who have an inherented CDH1 mutation. Endoscopic screening is not reliable for diagnosing signet ring cell stomach cancer. If patients wait for symptoms, they will have a more advanced disease and significantly reduced survival. Operative complications of prophylactic gastrectomy are minimal, and long-term quality of life is acceptable.

Surveillance and Surgical Considerations in Hereditary Diffuse Gastric Cancer

Inactivating germline variants in the CDH1 tumor suppressor gene cause the hereditary diffuse gastric cancer syndrome. Total gastrectomy is recommended for prevention, although it is associated with adverse outcomes and chronic health risks. Gastric cancer surveillance is an alternative to surgery; however, upper gastrointestinal endoscopy is limited by poor sensitivity. Cancer surveillance requires accurate detection of early carcinoma and patient-specific disease penetrance estimates. Current clinical care should incorporate up-to-date information on variable disease penetrance, which does not seem to correlate with CDH1 genotype. Affected patients and families warrant a balanced presentation of options for cancer surveillance and prophylaxis.

CDH1 germline mutations in a Chinese cohort with hereditary diffuse gastric cancer

PURPOSE

Germline mutations in CDH1 are associated with hereditary diffuse gastric cancer (HDGC) and have been identified in multiple ethnicities. However, CDH1 germline mutations have seldom been documented in Chinese patients with HDGC, and their frequency remains unclear. Here, we aimed to examine the frequency of CDH1 germline mutations in Chinese patients with HDGC. In total, 285 patients who met the International Gastric Cancer Linkage Consortium 2015 testing criteria of HDGC for CDH1 germline mutations were recruited.

METHODS

All 16 CDH1 exons, including neighboring intronic sequences, were amplified using polymerase chain reaction and screened using Sanger sequencing. Variants were analyzed using Mutation Surveyor V4.0, SIFT, and PolyPhen-2 software.

RESULTS

Three nonsense and nine missense CDH1 germline mutations were identified in 21 of 285 index cases (7.4%). Two CDH1 germline mutations, N405Y (Asn405Tyr) and W409X (Trp409Ter), were identified as new variants. In addition, up to 28.6% of CDH1 mutations in the 21 indicated patients were identified as c.1775G>C (E551Q). The frequency of CDH1 mutations was 6.5% (7/108) in HDGC and 7.9% (14/177) in early onset diffuse gastric cancer (EODGC). The mutation detection rates of CDH1 in males and females were 6.7% (4/60) and 8.5% (10/117) in EODGC and 4.6% (3/65) and 9.3% (4/43) in HDGC, respectively.

CONCLUSION

These data reveal, for the first time, the type and frequency of CDH1 germline mutations in Chinese HDGC and demonstrate that germline CDH1 mutations are a noteworthy contributor to the high frequency of HDGC in Chinese.

Random biopsies in patients harboring a CDH1 mutation: time to change the approach?

INTRODUCTION AND AIM

hereditary diffuse gastric cancer (HDGC) can be caused by a CDH1 mutation. It often presents as multiple foci of signet ring cell carcinoma (SRCC) that is rarely detected by gastroscopy. Prophylactic total gastrectomy is recommended at a young age. The aim of this study was to determine the adequacy of gastroscopy according to the Cambridge protocol in patients with a CDH1 mutation.

METHODS

patients with a CDH1 mutation admitted to our department between September 2016 and October 2018 were evaluated. All patients underwent a baseline gastroscopy according to the Cambridge protocol, followed by a recommended total gastrectomy. Endoscopic findings, the number of biopsies and histological evaluation of biopsy samples were registered. Postoperative histopathological assessment was compared with endoscopic findings in patients that underwent a total gastrectomy (n = 13).

RESULTS

twenty-five patients were included and 35 gastroscopies performed. On these, 996 gastric biopsies were performed, which included 952 random and 44 targeted. Only three patients had SRCC foci in random biopsies and one also had SRCC lesions in two targeted biopsies. In our cohort, 332 random and 22 targeted biopsies were needed to identify a single SRCC focus. Total gastrectomy was performed in 13 patients and SRCC foci were identified in 12 surgical specimens, the remaining specimen had a precursor lesion of HDGC.

DISCUSSION

gastroscopy has a poor sensitivity to detect SRCC. Even with Cambridge protocol, gastroscopy has a very limited role in the surveillance of patients with a CDH1 mutation and prophylactic total gastrectomy is the most advisable option. Nevertheless, endoscopic protocols should be optimized to favor targeted biopsies over a high number of random biopsies.

Laparoscopic Prophylactic Total Gastrectomy for Hereditary Diffuse Gastric Cancer in CDH1 Mutation Carriers

Background: Patients with hereditary diffuse gastric cancer (HDGC) and germline mutations in the E-cadherin gene, CDH1, have a very high cumulative lifetime risk of developing diffuse gastric cancer. In these patients, it is formally recommended to perform a prophylactic total gastrectomy (PTG). Materials and Methods: We analyzed the course of patients with HDGC who have undergone PTG in our institution. Pedigree analysis, preoperative screening results, operative course, postoperative data, and complete stomach pathologic examination were performed in all patients. Results: Seven patients with confirmed CDH1 mutation underwent PTG, five were women, and average age was 27 years (range 17-42). Signet ring cell carcinoma was found in 1 patient in the preoperative surveillance endoscopic biopsies. Laparoscopic PTG was performed in all patients. There were two complications, an intestinal obstruction that required reintervention and an asymptomatic esophagojejunal anastomosis leak that resolved with conservative treatment. In all gastrectomy specimens, intramucosal signet ring cell carcinoma foci limited to the lamina propria were found (range 1-31), 83.5% were in the body-fundus region. The mean follow-up was 28.5 months (range 8-72). The mean weight loss was 9% (range 2-18). Postoperative symptoms associated with Dumping syndrome were the most frequent. All the patients reported of being very satisfied with the procedure and of having a better quality of life than expected before the procedure. Conclusion: Laparoscopic PTG is an excellent resource to prevent the development of advanced diffuse gastric cancer (DGC) in patients with HDGC with CDH1 mutation. The procedure was well tolerated with a high satisfaction rate and very good functional results. It should be considered in these patients due to the high risk of developing advanced DGC and the lack of effective and reliable surveillance studies.

Evaluation of confocal laser endomicroscopy for detection of occult gastric carcinoma in CDH1 variant carriers

Background

Hereditary diffuse gastric cancer syndrome, attributed to inactivating germline CDH1 variants, is associated with an elevated lifetime risk of gastric cancer. We sought to evaluate cancer detection using probe-based confocal laser endomicroscopy (pCLE) during endoscopic surveillance.

Methods

A prospective, single-institution study was conducted in asymptomatic adults with pathogenic or likely pathogenic (P/LP) CDH1 variants. Subjects received endoscopic gastric surveillance using pCLE in conjunction with the Cambridge method (CM). Abnormalities visualized by pCLE were biopsied, followed by non-targeted mucosal biopsies according to the CM. Primary endpoint was to determine pCLE sensitivity for detection of occult SRC carcinoma compared to CM.

Results

Thirty-six patients with P/LP CDH1 variants underwent endoscopy using pCLE and CM. Majority were female (75%) with median age 47 years. Targeted biopsies of focal abnormalities on WLE were negative for carcinoma. Overall, 19.4% (7/36) patients had SRC detected on ≥1 biopsy. Non-targeted CM biopsies revealed SRC in 11.1% (4/36), whereas pCLE revealed SRC in 16.7% (6/36). Fifteen patients underwent total gastrectomy; all 15 explants contained occult carcinoma. In those 15 patients, the false-negative SRC detection rates for pCLE and CM were 67% and 87%, respectively.

Conclusions

Confocal endomicroscopy alone has low sensitivity for occult cancer detection in CDH1 variant carriers, although it appeared no worse than the current recommended method and required fewer biopsies per patient. A more reliable endoscopic surveillance is needed as a viable alternative to surgery in this high-risk population (ClinicalTrials.gov, Number: NCT03648879).

Hereditary Diffuse Gastric Cancer Syndrome and the Role of CDH1: A Review

Importance

Inherited variants in the tumor suppressor gene CDH1 are associated with an increased risk of gastric and breast cancers. This review aims to address the most current topics in management of the hereditary diffuse gastric cancer syndrome attributed to CDH1.

Observations

Consensus management guidelines have broadened genetic testing criteria for CDH1. Prophylactic total gastrectomy is recommended for any pathogenic or likely pathogenic CDH1 variant carrier starting at the age of 20 years. Annual surveillance endoscopy is recommended to those who defer prophylactic total gastrectomy. Women with a CDH1 variant should initiate magnetic resonance imaging breast surveillance starting at age 30 years. Further research is needed to understand the pathogenesis of early-stage gastric cancers (T1a), which are pathognomonic of hereditary diffuse gastric cancer syndrome, that lead to advanced gastric cancer to develop both treatment and prevention strategies for this patient population.

Conclusions and Relevance

The heritable CDH1 gene mutation is of importance to today's surgeons because it is associated with a substantial increased risk of developing both gastric and breast cancers. Management of this cancer syndrome currently uses prophylactic surgery and enhanced cancer surveillance strategies.

Geographical Distribution of E-cadherin Germline Mutations in the Context of Diffuse Gastric Cancer: A Systematic Review

Simple Summary

E-cadherin (CDH1 gene) germline mutations are associated with the development of the autosomal cancer syndrome known as hereditary diffuse gastric cancer. About 30% of families fulfilling the clinical criteria established by the International Gastric Cancer Linkage Consortium have constitutional alterations of the CDH1 gene. Different patterns of CDH1 germline mutations have described as truncating, deletion, insertion, splice site, non sense, silence, and at last, missense alterations. The frequency of the different E-cadherin germline mutations in countries with different incidence rates for gastric carcinoma has reported extremely variable. In this study we aimed to assess the worldwide frequency of CDH1 germline mutations in gastric cancers coming from different geographical areas, using a systematic approach.

Abstract

Hereditary diffuse gastric cancer (HDGC) is a complex and multifactorial inherited cancer predisposition syndrome caused by CDH1 germline mutations. Nevertheless, current CDH1 genetic screening recommendations disregard an unbalanced worldwide distribution of CDH1 variants, impacting testing efficacy and patient management. In this systematic review, we collected and analyzed all studies describing CDH1 variants in gastric cancer patients originating from both high- and low-prevalence countries. Selected studies were categorized as family study, series study, and unknown study, according to the implementation of HDGC clinical criteria for genetic testing. Our results indicate that CDH1 mutations are more frequently identified in gastric cancer low-incidence countries, and in the family study group that encompasses cases fulfilling criteria. Considering the type of CDH1 alterations, we verified that the relative frequency of mutation types varies within study groups and geographical areas. In the series study, the missense variant frequency is higher in high-incidence areas of gastric cancer, when compared with non-missense mutations. However, application of variant scoring for putative relevance led to a strong reduction of CDH1 variants conferring increased risk of gastric cancer. Herein, we demonstrate that criteria for CDH1 genetic screening are critical for identification of individuals carrying mutations with clinical significance. Further, we propose that future guidelines for testing should consider GC incidence across geographical regions for improved surveillance programs and early diagnosis of disease.

Indications for Total Gastrectomy in CDH1 Mutation Carriers and Outcomes of Risk-Reducing Minimally Invasive and Open Gastrectomies

Importance

CDH1 variants are increasingly identified on commercially available multigene panel tests, calling for data to inform counseling of individuals without a family history of gastric cancer.

Objectives

To assess association between CDH1 variant pathogenicity or family history of gastric or lobular breast cancer and identification of signet ring cell cancer and to describe outcomes of risk-reducing minimally invasive and open total gastrectomy.

Design, Setting, and Participants

This cohort study was performed from January 1, 2006, to January 1, 2020, in 181 patients with CDH1 germline variants from a single institution.

Interventions

Genetic counseling, esophagogastroduodenoscopy, and possible total gastrectomy.

Main Outcomes and Measures

CDH1 variant classification, family cancer history, findings of signet ring cell carcinoma at esophagogastroduodenoscopy and surgery, postoperative events and weight changes, and follow-up.

Results

Of 181 individuals with CDH1 germline variants (mean [SD] age at time of testing, 44 [15] years; 126 [70%] female), 165 harbored a pathogenic or likely pathogenic variant. Of these patients, 101 underwent open (n = 58) or minimally invasive (n = 43) total gastrectomy. Anastomotic leaks that required drainage were infrequent (n = 3), and median long-term weight loss was 20% (interquartile range [IQR], 10%-23%). In those undergoing minimally invasive operations, more lymph nodes were retrieved (median, 28 [IQR, 20-34] vs 15 [IQR, 9-19]; P < .001) and the hospital stay was 1 day shorter (median, 6 [IQR, 5-7] vs 7 [IQR, 6-7] days; P = .04). Signet ring cell cancer was identified in the surgical specimens of 85 of 95 patients (89%) with a family history of gastric cancer and 4 of 6 patients (67%) who lacked a family history. Among the latter 6 patients, 4 had a personal or family history of lobular breast cancer, including 2 with signet ring cell cancer. Of the 16 patients with pathogenic or likely pathogenic CDH1 variants who presented with locally advanced or metastatic gastric cancer, 3 (19%) had no family history of gastric cancer or personal or family history of lobular breast cancer.

Conclusions and Relevance

Total gastrectomy may be warranted for patients with pathogenic or likely pathogenic CDH1 variants and a family history of gastric or lobular breast cancer and may be appropriate for those without a family history. A minimally invasive approach is feasible and may be preferred for selected patients.

Recent advances in the pathology of heritable gastric cancer syndromes

Despite the relative rarity of hereditary gastric cancer syndromes, the prompt recognition of their specific clinical features and histopathological characteristics is pivotal in offering patients the most appropriate treatment. In this article, we address the three major inherited syndromes that primarily affect the stomach: hereditary diffuse gastric cancer (HDGC), caused by germline variants in CDH1 and CTNNA1; gastric adenocarcinoma and proximal polyposis of the stomach, caused by germline mutations in promoter 1B of APC; and familial intestinal gastric cancer, which has a poorly defined genetic cause. The main focus will be on HDGC, in light of the recent publication of updated clinical practice guidelines and emerging concepts regarding HDGC histopathology. In particular, we describe the broad morphological spectrum of HDGC lesions, stressing the importance of recognising indolent and aggressive phenotypes. Moreover, we discuss the increased risk of gastric (pre)malignancies developing in patients with other well-defined hereditary cancer syndromes, such as familial adenomatous polyposis, Lynch syndrome, Peutz-Jeghers syndrome, juvenile polyposis, Li-Fraumeni syndrome, and hereditary breast and ovarian cancer syndrome.

Histopathologic Analysis of Signet-ring Cell Carcinoma In Situ in Patients With Hereditary Diffuse Gastric Cancer

Hereditary diffuse gastric cancer (HDGC) is a rare autosomal dominant syndrome associated with an increased risk of developing Laurén's diffuse-type gastric carcinoma and lobular breast carcinoma. Although signet-ring cell carcinoma (SRCC) in situ (SRCC-pTis) has been reported as a characteristic lesion in HDGC cases with CDH1 germline mutations (CDH1 pathogenic variant), and a precursor of conventional intramucosal SRCC (SRCC-pT1a), its histopathologic features and specificity have not been sufficiently clarified. Here, we examined gastrectomy samples from 6 Japanese HDGC patients with CDH1 germline mutation, belonging to 4 families, and analyzed SRCC lesions histologically and immunohistochemically. Of the 274 foci found in the 6 samples, SRCC-pT1a accounted for 225 lesions (range: 8 to 107, mean 45.7 lesions per patient), while 46 foci were of SRCC-pTis (range: 1 to 15, mean 7.67 foci per patient). All SRCC-pTis foci were observed in the fundic gland area and on the superficial side of the mucosa. Histologically, tumor cells of SRCC-pTis were found between normal foveolar epithelial cells and the basement membrane, following a typical pagetoid spread pattern. Immunohistochemically, E-cadherin expression was lost in SRCC-pTis (27/28, 96.4%) more frequently than in SRCC-pT1a (95/197, 48.2%; P<0.001). To elucidate the specificity of SRCC-pTis for HDGC, 60 samples (range: 0.12 to 1.49 m, total 28.8 m of mucosal length) from gastric cancer cases were analyzed as controls, in which no SRCC-pTis were identified. Our results indicate that SRCC-pTis is a distinct histologic feature with high specificity for HDGC cases with CDH1 germline mutations.

Overview on new progress of hereditary diffuse gastric cancer with CDH1 variants

Hereditary diffuse gastric cancer (HDGC), comprising 1%-3% of gastric malignances, has been associated with CDH1 variants. Accumulating evidence has demonstrated more than 100 germline CDH1 variant types. E-cadherin encoded by the CDH1 gene serves as a tumor suppressor protein. CDH1 promoter hypermethylation and other molecular mechanisms resulting in E-cadherin dysfunction are involved in the tumorigenesis of HDGC. Histopathology exhibits characteristic signet ring cells, and immunohistochemical staining may show negativity for E-cadherin and other signaling proteins. Early HDGC is difficult to detect by endoscopy due to the development of lesions beneath the mucosa. Prophylactic gastrectomy is the most recommended treatment for pathogenic CDH1 variant carriers. Recent studies have promoted the progression of promising molecular-targeted therapies and management strategies. This review summarizes recent advances in CDH1 variant types, tumorigenesis mechanisms, diagnosis, and therapy, as well as clinical implications for future gene therapies.

Hereditary Gastric and Breast Cancer Syndromes Related to CDH1 Germline Mutation: A Multidisciplinary Clinical Review

E-cadherin (CDH1 gene) germline mutations are associated with the development of diffuse gastric cancer in the context of the so-called hereditary diffuse gastric syndrome, and with an inherited predisposition of lobular breast carcinoma. In 2019, the international gastric cancer linkage consortium revised the clinical criteria and established guidelines for the genetic screening of CDH1 germline syndromes. Nevertheless, the introduction of multigene panel testing in clinical practice has led to an increased identification of E-cadherin mutations in individuals without a positive family history of gastric or breast cancers. This observation motivated us to review and present a novel multidisciplinary clinical approach (nutritional, surgical, and image screening) for single subjects who present germline CDH1 mutations but do not fulfil the classic clinical criteria, namely those identified as-(1) incidental finding and (2) individuals with lobular breast cancer without family history of gastric cancer (GC).

[Hereditary gastric cancer: Challenges for the pathologist in 2020]

Gastric cancer is the third most common cancer worldwide. The majority of gastric cancers are sporadic but familial clustering is seen in more than 10% of cases. This manuscript is divided into two parts. The first part is dedicated to the non-syndromic hereditary gastric cancer, particularly the hereditary diffuse gastric cancer (HDGC) and other gastric polyposes including the recently described GAPPS (Gastric adenocarcinoma and proximal polyposis of the stomach). The second part concerns the syndromic gastric cancer, namely the HNPCC syndrome (Hereditary Non Polyposis Colorectal Cancer) occurring as part of a genetic predisposition syndrome to cancer. Recent advances in oncogenetics and next generation sequencing technology have enabled the identification of new entities. This enhancement in knowledge regarding inherited syndromes predisposing to gastric cancer has consequently improved the management of patients and their families. In this context, pathologists play a major role in identifying particular morphologic entities prompting genetic investigation. The aim of this manuscript is to provide an update on the current knowledge about hereditary gastric cancer.

Complete histopathologic examination of risk reduction gastrectomy specimens for CDH1 germline mutation: Is it warranted in routine clinical practice?

AIMS

CDH1 germline mutation is associated with high penetrance of hereditary diffuse gastric cancer (HDGC). Due to the lack of endoscopically identifiable lesions, routine surveillance is ineffective in the early detection of gastric cancer, and risk-reduction gastrectomy is often recommended. Many academic pathology departments elect to submit the entire gastrectomy specimen for histological examination, which is associated with significantly increased cost, technical and professional time, and turnaround time.

METHODS

We present our experience with 5 completely submitted and 2 representatively submitted prophylactic total gastrectomy cases in HDGC patients.

RESULTS

Multifocal intramucosal signet ring cell carcinoma was identified in all cases except one, in which only in situ carcinoma was identified. The tumoral foci (2 to 35 per case; average 14.4) were concentrated in proximal stomach. No submucosal invasion or nodal metastases was seen in any case. The final stage was either stage 0 (pTisN0cM0) or stage 1a (pT1aN0cM0).

CONCLUSIONS

Our findings are in line with that reported in the literature. Considering that deeply invasive carcinoma is very rare in this situation, and no further treatment is indicated for the vast majority of those patients, complete submission and pathologic examination of the entire stomach provides little additional value for routine clinical management. We propose a two-step approach with targeted submission of the proximal stomach, and subsequent entire submission of the remaining stomach if no intramucosal carcinoma is identified during the initial targeted examination.

Multigene Panel Testing Increases the Number of Loci Associated with Gastric Cancer Predisposition

The main gene involved in gastric cancer (GC) predisposition is CDH1, the pathogenic variants of which are associated with diffuse-type gastric cancer (DGC) and lobular breast cancer (LBC). CDH1 only explains a fraction (10–50%) of patients suspected of DGC/LBC genetic predisposition. To identify novel susceptibility genes, thus improving the management of families at risk, we performed a multigene panel testing on selected patients. We searched for germline pathogenic variants in 94 cancer-related genes in 96 GC or LBC Italian patients with early-onset and/or family history of GC. We found CDH1 pathogenic variants in 10.4% of patients. In 11.5% of cases, we identified loss-of-function variants in BRCA1, BRCA2, PALB2, and ATM breast/ovarian cancer susceptibility genes, as well as in MSH2, PMS2, BMPR1A, PRF1, and BLM genes. In 78.1% of patients, we did not find any variants with clear-cut clinical significance; however, 37.3% of these cases harbored rare missense variants predicted to be damaging by bioinformatics tools. Multigene panel testing decreased the number of patients that would have otherwise remained genetically unexplained. Besides CDH1, our results demonstrated that GC pathogenic variants are distributed across a number of susceptibility genes and reinforced the emerging link between gastric and breast cancer predisposition.

Clinical implications of CTNNA1 germline mutations in asymptomatic carriers

In 2017, we implemented CTNNA1 germline analysis in probands suspected of having hereditary diffuse gastric cancer. Here, we report the results from a retrospective series of 41 cases, including the identification of a new family with a CTNNA1 mutation and the first prophylactic total gastrectomy in an asymptomatic carrier after a normal upper endoscopy. Diffuse gastric cancer foci with loss of catenin alpha-1 expression were seen in the resected tissue, suggesting that CTNNA1 and CDH1 germline mutations behave in a similar manner. Life-changing prophylactic total gastrectomy should therefore also be considered in CTNNA1 mutation carriers.

Outcomes of Endoscopic Surveillance in Individuals With Genetic Predisposition to Hereditary Diffuse Gastric Cancer

BACKGROUND & AIMS

Pathogenic germline variants in CDH1 are associated with risk for diffuse gastric cancer (DGC) and lobular breast cancer. The reported high incidence of DGC and limited sensitivity of endoscopy in detection have prompted recommendation for total prophylactic gastrectomy for carriers of pathogenic or likely pathogenic (PLP) germline variants of CDH1. Multigene panel tests have identified increasing numbers of carriers of PLP variants in CDH1 who lack a family history of DGC. We evaluated outcomes of endoscopic surveillance for carriers of PLP variants of CDH1 with and without family history of DGC.

METHODS

Individuals from 13 families with germline PLP variants of CDH1 were evaluated at the Michigan Medicine Cancer Genetics Clinic from January 1998 through May 2018. Outcomes of esophagogastroduodenoscopy examinations, histopathology analyses, and surgery were compared between individuals with and without a family history of DGC.

RESULTS

We identified 20 carriers of germline CDH1 PLP variants; they underwent endoscopic examinations and/or gastrectomy. None had abnormal findings visible during endoscopy. Signet ring cell carcinoma (SRCC) was detected in 12 of 20 subjects. All but 1 of the carcinomas were tiny and confined to the lamina propria, and 1 was transmural. Seven of 12 subjects who had SRCC reported no diagnoses of DGC in first-degree relatives and did not meet established criteria for CDH1 analysis based on a 3-generation family pedigree.

CONCLUSIONS

More than half of individuals with germlines variants of CDH1 that are PLP had histopathologic evidence for DGC on endoscopy and/or gastrectomy. Family history of DGC and endoscopic findings therefore do not appear to be reliable determinants of risk of SRCC in individuals with genetic predisposition to DGC.

The role of endoscopy in the management of hereditary diffuse gastric cancer syndrome

Hereditary diffuse gastric cancer (HDGC) syndrome is an inherited cancer risk syndrome associated with pathogenic germline CDH1 variants. Given the high risk for developing diffuse gastric cancer, CDH1 carriers are recommended to undergo prophylactic total gastrectomy for cancer risk reduction. Current guidelines recommend upper endoscopy in CDH1 carriers prior to surgery and then annually for individuals deferring prophylactic total gastrectomy. Management of individuals from HDGC families without CDH1 pathogenic variants remains less clear, and management of families with CDH1 pathogenic variants in the absence of a family history of gastric cancer is particularly problematic at present. Despite adherence to surveillance protocols, endoscopic detection of cancer foci in HDGC is suboptimal and imperfect for facilitating decision-making. Alternative endoscopic modalities, such as chromoendoscopy, endoscopic ultrasound, and other non-white light methods have been utilized, but are of limited utility to further improve cancer detection and risk stratification in HDGC. Herein, we review what is known and what remains unclear about endoscopic surveillance for HDGC, among individuals with and without germline CDH1 pathogenic variants. Ultimately, the use of endoscopy in the management of HDGC remains a challenging arena, but one in which further research to improve surveillance is crucial.

Non-BRCA1/2 Variants Detected in a High-Risk Chilean Cohort With a History of Breast and/or Ovarian Cancer

METHODS

Data were retrospectively collected from the registry of the High-Risk Breast and Ovarian Cancer Program at Clínica Las Condes, Santiago, Chile. Data captured included index case diagnosis, ancestry, family history, and genetic test results.

RESULTS

Three hundred fifteen individuals underwent genetic testing during the study period. The frequency of germline pathogenic and likely pathogenic variants in a breast or ovarian cancer predisposition gene was 20.3%. Of those patients who underwent testing with a panel of both high- and moderate-penetrance genes, 10.5% were found to have pathogenic or likely pathogenic variants in non-BRCA1/2 genes.

CONCLUSION

Testing for non-BRCA1 and -2 mutations may be clinically relevant for individuals who are suspected to have a hereditary breast or ovarian cancer syndrome in Chile. Comprehensive genetic testing of individuals who are at high risk is necessary to further characterize the genetic susceptibility to cancer in Chile.

Outcomes after prophylactic gastrectomy for hereditary diffuse gastric cancer

BACKGROUND

Patients with hereditary diffuse gastric cancer and a CDH1 mutation have a 60-80 per cent lifetime risk of developing diffuse gastric cancer. Total prophylactic gastrectomy eliminates this risk, but is associated with considerable morbidity. The effectiveness (removal of all gastric mucosa) and outcomes of this procedure were evaluated retrospectively.

METHODS

All consecutive individuals undergoing a prophylactic gastrectomy for a CDH1 mutation or gastric signet ring cell foci at the authors' institute between 2005 and 2017 were included.

RESULTS

In 25 of 26 patients, intraoperative frozen-section examination (proximal resection margin) was used to verify complete removal of gastric mucosa. All definitive resection margins were free of gastric mucosa, but only after the proximal margin had been reresected in nine patients. In the first year after surgery, five of the 26 patients underwent a relaparotomy for adhesiolysis (2 patients) or jejunostomy-related complications (3 patients). Six patients were readmitted to the hospital within 1 year for nutritional and/or psychosocial support (4 patients) or surgical reintervention (2 patients). Mean weight loss after 1 year was 15 (95 per cent c.i. 12 to 18) per cent. For the 25 patients with a follow-up at 1 year or more, functional complaints were reported more frequently at 1 year than at 3 months after the operation: bile reflux (15 versus 11 patients respectively) and dumping (11 versus 7 patients). The majority of patients who worked or studied before surgery (15 of 19) had returned fully to these activities within 1 year.

CONCLUSION

The considerable morbidity and functional consequences of gastrectomy should be considered when counselling individuals with an inherited predisposition to diffuse gastric cancer. Intraoperative frozen-section examination is recommended to remove all risk-bearing gastric mucosa.

CDH1 Gene and Hereditary Diffuse Gastric Cancer Syndrome: Molecular and Histological Alterations and Implications for Diagnosis And Treatment

Gastric cancer, a group of common malignancies, results in the most cancer mortality worldwide after only lung and colorectal cancer. Although familial gastric cancers have long been recognized, it was not until recently that they were discovered to be associated with mutations of specific genes. Mutations of CDH1, the gene encoding E-cadherin, are the most common germline mutations detected in gastric cancer and underlie hereditary diffuse gastric cancer (HDGC) syndrome. All reported HDGCs are the pure diffuse type by Lauren classification and are associated with dismal prognosis once the tumor invades the submucosa. Because CDH1 germline mutations are inherited in an autosomal-dominant fashion and have high penetrance, the International Gastric Cancer Linkage Consortium (IGCLC) developed criteria to facilitate the screening of CDH1 mutation carriers; these criteria have been proven to have excellent sensitivity and specificity. Recent histologic studies suggest that HDGC progresses through several stages. Even when the tumor becomes "invasive" in lamina propria, it may stay indolent for a long time. However, the molecular mechanisms that induce the transitions between stages and determine the length of the indolent phase remain to be determined. Although the standard management for CDH1 mutation carriers is prophylactic total gastrectomy, many questions must be answered before the surgery can be done. These include the optimal surveillance strategy, the best strategy to choose surgical candidates, and the ideal time to perform surgery. In addition to increasing the risk of gastric cancer, CDH1 germline mutations also increase the risk of invasive lobular carcinoma of the breast, and possibly colorectal adenocarcinoma, and are associated with blepharocheilodontic syndrome (a congenital development disorder). However, the optimal management of these conditions is less established owing to insufficient data regarding the risk of cancer development. This review focuses on molecular and histological findings in HDGC, as opposed to sporadic diffuse gastric cancer, and their implications for the management of CDH1 mutation carriers and the diagnosis and treatment of HDGC. Other conditions associated with CDH1 germline mutations and future research directions are also discussed.

Pathological features of total gastrectomy specimens from asymptomatic hereditary diffuse gastric cancer patients and implications for clinical management

Hereditary diffuse gastric cancer (HDGC) is an autosomal dominant syndrome characterised by multigenerational diffuse gastric cancer, and is mainly caused by germline alterations in the CDH1 gene. Currently, endoscopy has limited diagnostic accuracy, and total gastrectomy (TG) is the treatment of choice for asymptomatic CDH1 carriers. In this study, we aimed to obtain a better understanding of HDGC syndrome by exploring the histopathological findings of TG specimens from asymptomatic HDGC patients. A comprehensive literature review was carried out, searching for TGs performed in asymptomatic HDGC patients. Fourteen unpublished cases, analysed in our institution, were also included. The series encompassed 174 CDH1 carriers. Preoperative endoscopic biopsies were positive in 28.3%. A macroscopic lesion was apparent in 11.7% of TGs. Histopathological analysis revealed intraepithelial lesions and/or intramucosal signet ring cell carcinoma in 87.9% of TGs. When we explored the type of protocol used for handling the specimens, we found that microscopic cancer foci were detected in 95.3% of TGs when a total-embedding protocol (assessment of the totality of gastric mucosa) was applied, and only in 62.5% when no specific protocol was used (P < 0.001). Helicobacter pylori infection was found in 23.4% cases. In conclusion, a thorough histopathological examination of gastric mucosa remains the gold standard for detection of cancer foci in HDGC gastrectomy specimens, requiring experienced pathologists for an accurate diagnosis. A better understanding of the natural history of HDGC will enable better clinical management of HDGC patients, particularly regarding the optimal timing for the performance of TG.

Emerging Concepts in Gastric Neoplasia: Heritable Gastric Cancers and Polyposis Disorders

Hereditary gastric cancer is a relatively rare disease with specific clinical and histopathologic characteristics. Hereditary gastric cancer of the diffuse type is predominantly caused by germline mutations in CDH1. The inherited cause of familial intestinal gastric cancer is unknown. Gastric adenocarcinoma and proximal polyposis of the stomach is a hereditary cancer syndrome caused by germline mutations in promoter 1B of APC. Other well-defined cancer syndromes, such as Lynch, Li-Fraumeni, and hereditary breast or ovarian cancer syndromes, are associated with increased risk of gastric cancer. This article reviews important histopathologic features and emerging concepts regarding gastric carcinogenesis in these syndromes.

Phenotypic heterogeneity of hereditary diffuse gastric cancer: report of a family with early-onset disease

BACKGROUND AND AIMS

The time course for the development of clinically significant hereditary diffuse gastric cancer (HDGC) is unpredictable. Little is known about the progression from preclinical, indolent lesions to widely invasive, aggressive phenotypes. Gastroendoscopy often fails to detect early lesions, and risk-reducing/prophylactic total gastrectomy (PTG) is the only curative approach. We present an HDGC family with early-onset disease in which clinical and histologic findings provided insight into the understanding of different HDGC phenotypes.

METHODS

The proband was diagnosed at age 18 years with widely invasive, metastatic DGC. CDH1 genetic testing identified a pathogenic, germline CDH1 variant (c.1901C>T, p.Ala634Val). Thirty family members were tested, and 15 CDH1 carriers were identified.

RESULTS

Six family members had PTG, with negative preoperative workup. The proband's 14-year-old sister is the youngest patient, reported to date, to have PTG after negative preoperative biopsy sampling. Intramucosal HDGC foci were detected in all PTG specimens (1-33). In contrast to the "indolent" phenotype of these foci, the aggressive DGC from the proband showed pleomorphic cells, absent E-cadherin expression, increased proliferation (Ki-67 index), and activation of oncogenic events (p53, pSrc and pStat3 overexpression). All family members had Helicobacter pylori gastritis. Cag-A-positive strains were detected in all specimens, except in the proband's sister.

CONCLUSIONS

HDGC is a heterogeneous disease regarding clinical behavior, endoscopic findings, histopathologic features, and immunophenotypic/molecular profile. The presence of bizarre, pleomorphic cells in endoscopic biopsy specimens is suggestive of advanced disease and should prompt clinical intervention. The involvement of a full multidisciplinary team is essential for the management of these patients.

Histologic and immunohistochemical differences between hereditary and sporadic diffuse gastric carcinoma

We aimed to identify histopathologic features unique in hereditary diffuse gastric cancer (HDGC) by comparing with its sporadic counterpart (SDGC). 11 patients with confirmed CDH1 mutation who were found to have HDGC in a prophylactic total gastrectomy were collected. Median age of HDGC patients was 39 years (range 24-57). All HDGC cases had intramucosal signet ring cell carcinoma. Twenty-three invasive tumor foci from 7 patients with HDGC were available for ancillary studies, and we evaluated each focus separately. Almost all foci (20/23) showed two distinct tumor cell populations, namely, large signet ring cells and small signet ring cells. The large cells were located just beneath the surface epithelium and were positive for mucicarmine and pCEA, while the small cells were found in the deeper lamina propria and were mostly negative for mucicarmine and pCEA. A subset of small cells (6 foci from two resected stomachs) showed poorly differentiated morphology with p16 positivity. All other tumor cells with well-differentiated signet ring cell morphology were negative for p16. In contrast, 18 of 20 SDGCs were positive for p16. In addition, all HDGCs were negative for CDX2, while 19 of 20 SDGCs were positive. We propose that there are three distinct tumor cell populations in HDGC: well-differentiated large cells, well-differentiated small cells, and poorly differentiated small cells, and that the latter group with aberrant p16 expression may represents a more aggressive phenotype. The absence of CDX2 in HDGC suggests that it may develop along a carcinogenetic pathway different from that of SDGC.

Total Gastrectomy for Hereditary Diffuse Gastric Cancer at a Single Center: Postsurgical Outcomes in 41 Patients

OBJECTIVE

The aim of this study was to describe postoperative outcomes of total gastrectomy at our institution for patients with hereditary diffuse gastric cancer (HDGC).

BACKGROUND

HDGC, which is mainly caused by germline mutations in the E-cadherin gene (CDH1), renders a lifetime risk of gastric cancer of up to 70%, prompting a recommendation for prophylactic total gastrectomy.

METHODS

A prospective gastric cancer database identified 41 patients with CDH1 mutation who underwent total gastrectomy during 2005 to 2015. Perioperative, histopathologic, and long-term data were collected.

RESULTS

Of the 41 patients undergoing total gastrectomy, median age was 47 years (range 20 to 71). There were 14 men and 27 women, with 25 open operations and 16 minimally invasive operations. Median length of stay was 7 days (range 4 to 50). In total, 11 patients (27%) experienced a complication requiring intervention, and there was 1 peri-operative mortality (2.5%). Thirty-five patients (85%) demonstrated 1 or more foci of intramucosal signet ring cell gastric cancer in the examined specimen. At 16 months median follow-up, the median weight loss was 4.7 kg (15% of preoperative weight). By 6 to 12 months postoperatively, weight patterns stabilized. Overall outcome was reported to be "as expected" by 40% of patients and "better than expected" by 45%. Patient-reported outcomes were similar to those of other patients undergoing total gastrectomy.

CONCLUSION

Total gastrectomy should be considered for all CDH1 mutation carriers because of the high risk of invasive diffuse-type gastric cancer and lack of reliable surveillance options. Although most patients have durable weight loss after total gastrectomy, weights stabilize at about 6 to 12 months postoperatively, and patients report outcomes as being good to better than their preoperative expectations. No patients have developed gastric cancer recurrence after resections.

Beyond gastric adenocarcinoma: Multimodality assessment of common and uncommon gastric neoplasms

Despite advances in molecular biology, imaging, and treatment, gastric neoplasms remain a significant cause of morbidity and mortality; gastric adenocarcinoma is the fifth most common malignancy and third most common cause of death worldwide (Brenner et al., Methods Mol Biol 472:467-477, 2009; Howson et al. Epidemiol Rev 8:1-27, 1986; Roder, Gastric Cancer 5(Suppl 1):5-11, 2002; Ferlay et al., GLOBOCAN 2012 v1.0, Cancer Incidence and Mortality Worldwide: IARC CancerBase No. 11 [Internet]. International Agency for Research on Cancer, 2013). Because of both the frequency at which malignant gastric tumors occur as well as the worldwide impact, gastric neoplasms remain important lesions to identify and characterize on all imaging modalities. Despite the varied histologies and behaviors of these neoplasms, many have similar imaging features. Nonetheless, the treatment, management, and prognosis of gastric neoplasms vary by pathology, so it is essential for the radiologist to make every effort to differentiate between these lesions and raise the less common entities as differential diagnostic considerations when appropriate.

Chromoendoscopy in combination with random biopsies does not improve detection of gastric cancer foci in CDH1 mutation positive patients

Background and study aims: Hereditary diffuse gastric cancer (HGGC), an autosomal dominant tumor-syndrome, accounts for 1 % to 3 % of gastric cancers worldwide. Presumably 30 % to 40 % of all patients fulfilling the clinical guidelines for HDGC are carriers of a pathogenic mutation in the CDH1 gene. Patients often show multiple foci of signet ring cell carcinoma at early age and are advised to undergo prophylactic total gastrectomy (PTG). Our aim was to improve the endoscopic detection of HDGC by using an enhanced endoscopic protocol. Patient and methods: Patients with a proven CDH1 germline mutation identified in our institute were prospectively included. Patients were advised to undergo PTG and offered a baseline endoscopic examination prior surgery. Examination was performed by using high-resolution white-light endoscopy and pan-gastric chromoendoscopy with indigo carmine as dye combined with targeted and multiple random biopsies assessed by an expert histopathologist. Postoperative histopathology was compared with results from endoscopic biopsies. Results: Between September 2012 and November 2014 8 patients with a proven CDH1 germline mutation were included. We conducted 44 targeted (6.3/patient) and 225 random (32.1/patient) biopsies in 7 patients. We detected 1 gastric cancer by random biopsy (14 %). All other examinations showed no signs of cancer. Histopathology of gastrectomy specimen revealed multiple foci of gastric carcinoma in 6 patients (86 %) with a total number of 27 cancer foci. Conclusions: Examination with targeted and random biopsies combined with chromoendoscopy is not able to detect small foci of gastric cancer in CDH1 mutation carriers. Therefore PTG is advocated in these patients.

Prophylactic Total Gastrectomy: a Prospective Cohort Study of Long-Term Impact on Quality of Life

BACKGROUND

Hereditary diffuse gastric cancer (HDGC) syndrome is caused by germline mutations in the CDH1 gene and carries a lifetime gastric cancer risk of approximately 70 % in men and 56 % in women. Current consensus guidelines recommend that people of age ≥20 who harbor a CDH1 mutation undergo prophylactic total gastrectomy (PTG). However, the decision to proceed with a major visceral resection for prophylactic reasons may be difficult, especially since long-term outcomes are not well defined. We examined the decision-making process, physical symptoms, and psychosocial outcomes in adults who underwent PTG.

METHODS

Participants completed pre- and post-operative questionnaires that included standardized measures of health-related quality of life (HRQOL), body image, psychological distress, regret, and decisional conflict. Those who declined surgery completed a questionnaire that measured decisional conflict and explored reasons for their choice.

RESULTS

Forty of fifty (80 %) questionnaires distributed to 18 individuals were completed. In the 13 patients who underwent PTG, global HRQOL tended to decrease immediately post-operatively, climb to baseline by 6-12 months, then decrease again at 24 months. Body image and level of psychological distress remained relatively stable, and most patients expressed little decisional conflict or regret. All five individuals who declined surgery did so for practical reasons and would consider surgery in the future.

CONCLUSIONS

While most patients do not experience negative psychosocial consequences following PTG, mild physical symptoms persist and may affect long-term HRQOL. The present study emphasizes the need for long-term follow-up of this unique population of survivors.

Genetic predisposition to gastric cancer

Gastric cancer ranks as the third leading cause of cancer mortality worldwide and confers a 5-year survival of 20%. While most gastric cancers are sporadic, ~1%-3% can be attributed to inherited cancer predisposition syndromes. Germline E-cadherin/CDH1 mutations have been identified in families with an autosomal dominant inherited predisposition to diffuse gastric cancer. The cumulative risk of gastric cancer for CDH1 mutation carriers by age 80 years is reportedly 70% for men and 56% for women. Female mutation carriers also have an estimated 42% risk for developing lobular breast cancer by age 80 years. However, most individuals meeting clinical criteria for hereditary diffuse gastric cancer syndrome (HDGC) do not have a germline CDH1 mutation, and germline CDH1 mutation carriers do not all exhibit similar clinical outcomes in terms of age of diagnosis or cancer types. E-cadherin (CDH1) as the one known causative gene for HDGC accounts for only 40% of cases, leaving 60% with an unknown genetic diagnosis. In addition to HDGC, we will review other genetic syndromes with elevated gastric cancer risk, as well as newly implicated alterations in other genes (CTNNA1, DOT1L, FBXO24, PRSS1, MAP3K6, MSR1, and INSR) that may affect gastric cancer susceptibility and age-specific penetrance.

Histopathological, Molecular, and Genetic Profile of Hereditary Diffuse Gastric Cancer: Current Knowledge and Challenges for the Future

Familial clustering is seen in 10 % of gastric cancer cases and approximately 1-3 % of gastric cancer arises in the setting of hereditary diffuse gastric cancer (HDGC). In families with HDGC, gastric cancer presents at young age. HDGC is predominantly caused by germline mutations in CDH1 and in a minority by mutations in other genes, including CTNNA1. Early stage HDGC is characterized by a few, up to dozens of intramucosal foci of signet ring cell carcinoma and its precursor lesions. These include in situ signet ring cell carcinoma and pagetoid spread of signet ring cells. Advanced HDGC presents as poorly cohesive/diffuse type carcinoma, normally with very few typical signet ring cells, and has a poor prognosis. Currently, it is unknown which factors drive the progression towards aggressive disease, but it is clear that most intramucosal lesions will not have such progression.Immunohistochemical profile of early and advanced HDGC is often characterized by abnormal E-cadherin immunoexpression, including absent or reduced membranous expression, as well as "dotted" or cytoplasmic expression. However, membranous expression of E-cadherin does not exclude HDGC. Intramucosal HDGC (pT1a) presents with an "indolent" phenotype, characterized by typical signet ring cells without immunoexpression of Ki-67 and p53, while advanced carcinomas (pT > 1) display an "aggressive" phenotype with pleomorphic cells, that are immunoreactive for Ki-67 and p53. These features show that the IHC profile is different between intramucosal and more advanced HDGC, providing evidence of phenotypic heterogeneity, and may help to define predictive biomarkers of progression from indolent to aggressive, widely invasive carcinomas.

Accuracy of Hereditary Diffuse Gastric Cancer Testing Criteria and Outcomes in Patients With a Germline Mutation in CDH1

BACKGROUND & AIMS

Germline mutations in the cadherin 1, type 1, E-cadherin gene (CDH1) cause a predisposition to gastric cancer. We evaluated the ability of the internationally accepted hereditary diffuse gastric cancer (HDGC) criteria to identify individuals with pathogenic mutations in CDH1, and assessed their outcomes. The criteria were as follows: families with 2 or more cases of gastric cancer, with at least 1 patient diagnosed with diffuse gastric cancer (DGC) before age 50; families with 3 or more cases of DGC; families with 1 DGC before the age of 40; and families with a history of DGC and lobular breast cancer, with 1 diagnosis before the age of 50.

METHODS

We collected results of a CDH1 mutation analysis of 578 individuals from 499 families tested in The Netherlands between 1999 and 2014 (118 families met the HDGC criteria for testing and 236 did not; there were 145 families with incomplete data and/or availability of only first-degree relatives). Data were linked with family histories and findings from clinical and pathology analyses. The Kaplan-Meier method and Cox regression analysis were used to evaluate the overall survival of patients with and without CDH1 mutations.

RESULTS

In a cohort study in The Netherlands, the HDGC criteria identified individuals with a germline CDH1 mutation with a positive predictive value of 14% and 89% sensitivity. There were 18 pathogenic CDH1 mutations in 499 families (4%); 16 of these mutations were detected in the 118 families who met the HDGC criteria for testing. One pathogenic CDH1 mutation was detected in the 236 families who did not meet HDGC criteria and 1 in the 145 families with incomplete data and/or availability of only first-degree relatives. No CDH1 mutations were found in the 67 families whose members developed intestinal-type gastric cancer, or in the 22 families whose families developed lobular breast cancer. Among patients who fulfilled the HDGC criteria and had pathogenic CDH1 mutations, 36% survived for 1 year and 4% survived for 5 years; among patients who fulfilled the HDGC criteria but did not carry pathogenic CDH1 mutations, 48% survived for 1 year and 13% survived for 5 years (P = .014 for comparative survival analysis between patients with and without a CDH1 mutation).

CONCLUSIONS

All individuals with a CDH1 mutation had a personal or family history of diffuse gastric cancer. Patients with gastric cancer and germline CDH1 mutations had shorter survival times than patients who met the HDGC criteria but did not have CDH1 mutations.