Cancer surveillance as an alternative to prophylactic total gastrectomy in hereditary diffuse gastric cancer: a prospective cohort study

Adolescents and young adults with germline CDH1 variants and the risk of overtreatment

BACKGROUND

Adolescents and young adults (AYA) with germline CDH1 variants are at risk of overtreatment when precancer lesions are detected with endoscopic screening. We characterize diffuse-type gastric cancer prevalence and survival in AYA managed with prophylactic total gastrectomy (PTG) or endoscopic surveillance.

METHODS

Prospective cohort study of 188 individuals aged 39 and younger enrolled from January 27, 2017, to May 1, 2023. Clinicopathological data, prevalence of early gastric signet ring cell (SRC) lesions, advanced gastric cancer diagnoses, and cancer-specific survival were measured.

RESULTS

Among 188 AYA patients, 104 chose surveillance and 67 pursued PTG for management of elevated gastric cancer risk. AYA who enrolled early in the study period and had SRC lesions detected on preoperative endoscopy were more likely to elect for PTG compared with surveillance. SRC lesions were detected on preoperative endoscopy in 48% of patients who subsequently had PTG, and yet nearly all (93%, 62/67) had multifocal SRC (pT1aN0) on final pathology. Median age at enrollment (30 vs 31 years, P = .21), biological sex (P = .17), and median number of family members with gastric cancer (3 vs 4, P = .14) were not different between groups. No patients under surveillance developed advanced cancer or developed cancer recurrence after PTG with a median follow-up of 2.5 years (IQR = 1.6-4.0) from initial endoscopy.

CONCLUSIONS

Cancer-specific outcomes were not different in AYA who harbored SRC and were managed with surveillance or PTG. Lack of cancer-specific deaths and low prevalence of advanced gastric cancer underscore the risk of overtreatment of SRC lesions and suggest that active surveillance is warranted.

Tumour-intrinsic alterations and stromal matrix remodelling promote Wnt-niche independence during diffuse-type gastric cancer progression

BACKGROUND

Development of diffuse-type gastric cancer (DGC) starts with intramucosal lesions that are primarily composed of differentiated, non-proliferative signet ring cells (SRCs). These indolent lesions can advance into highly proliferative and metastatic tumours, which requires suppression of DGC cell differentiation.

OBJECTIVE

Our goal was to identify molecular changes contributing to the progression of indolent to aggressive DGC lesions.

DESIGN

We conducted spatial transcriptomic analysis of patient tumours at different stages of hereditary DGC, comparing transcriptional differences in tumour cell populations and tumour-associated cells. We performed functional analysis of identified changes in a human gastric (CDH1 KO) organoid model recapitulating DGC initiation.

RESULTS

Our analysis reveals that distinct DGC cell populations exhibit varying levels of Wnt-signalling activity, and high levels of Wnt signalling prevent differentiation into SRCs. We identify multiple adaptations during DGC progression that converge on Wnt signalling, allowing tumour cells to remain in an undifferentiated state as they disseminate away from the gastric stem cell niche. First, DGC cells establish a cell-autonomous source for Wnt-pathway activation through upregulated expression of Wnt-ligands and 'secreted frizzled-related protein 2' (SFRP2) that potentiates ligand-induced Wnt signalling. Second, early tumour development is marked by extracellular matrix remodelling, including increased deposition of collagen I whose interactions with DGC cells suppress their differentiation in the absence of exogenous Wnt ligands.

CONCLUSIONS

Our findings demonstrate that tumour cell-derived ligand expression and extracellular matrix remodelling sustain Wnt signalling during DGC progression. These complementary mechanisms promote niche independence enabling expansion of undifferentiated DGC cells needed for the development of advanced tumours.

Management Considerations in a Patient With a Germline CDH1 Pathogenic Variant and a History of Roux-en-Y Gastric Bypass Surgery

Individuals with a germline pathogenic variant in the CDH1 gene have a lifetime risk of advanced diffuse gastric cancer (DGC) of up to 10.3% and a 37%-52% risk of breast cancer, specifically the lobular subtype. Guidelines recommend prophylactic gastrectomy between ages 18-40 years for those with a family history of DGC. For patients declining surgery or lacking a family history of DGC, annual endoscopic surveillance according to recommended protocols is an alternative. This case reviews the management of a patient with a history of Roux-en-Y gastric bypass followed one year later by a diagnosis of lobular breast cancer due to a germline CDH1 pathogenic variant.

Lessons learned from 150 total gastrectomies for prevention of cancer

BACKGROUND

Prophylactic total gastrectomy (PTG) is performed in carriers of CDH1 pathogenic and likely pathogenic (P/LP) variants and is becoming more frequent with broader use of germline genetic testing. There is an unmet need to standardize care and enhance outcomes among patients undergoing surgery for the prevention of gastric cancer.

METHODS

This was a retrospective analysis of 150 individuals with germline CDH1 P/LP variants who underwent PTG as part of a prospective natural history study from October 2017 to May 2023. All individuals received multidisciplinary, protocolized care before and after total gastrectomy.

RESULTS

A total of 150 asymptomatic patients with germline CDH1 P/LP variants underwent PTG with the aid of a multidisciplinary enhanced recovery after surgery (ERAS) pathway. This study demonstrated that acute major morbidity (Clavien-Dindo grade of ≥3) was low (17/150 [11.3%]) and that the most common complication was anastomotic leak (11/150 [7.3%]) in the setting of a comprehensive preoperative and postoperative care pathway. Nearly all gastrectomy specimens (132/150 [88.0%]) harbored occult signet ring cell lesions on final pathology. There were no gastric cancer recurrences or gastric cancer-related deaths during the study period, with a median overall follow-up of 36 months (IQR, 24-48) from gastrectomy.

CONCLUSION

PTG can be performed with low surgical morbidity in a high-volume center. The delivery of patient-centered care by a multidisciplinary team and the application of an ERAS pathway may improve short-term outcomes. However, interventions that can reduce chronic morbidity associated with total gastrectomy warrant further study.

Disappearing Signet Ring Cell Adenocarcinoma in Gastric Cancer Patients

BACKGROUND

The incidence of diffuse-type gastric cancer is increasing steadily in the United States, Europe, and Asia. This subtype is known for aggressive clinical characteristics and transmural invasion. However, T1a diffuse-type cancers have been observed to have a better 5-year, disease-specific mortality than stage-matched intestinal tumors, supporting a clinical difference in these early-stage cancers.

METHODS

Data on all living patients with T1a gastric adenocarcinoma with a finding of signet ring cell morphology on pathology and ≥1 year of follow-up from 2013 to 2023 at Memorial Sloan Kettering Cancer Center (MSK) was collected from a prospectively maintained database. Patients with known CDH1 or CTNNA1 mutations were excluded.

RESULTS

In 7 of 30 patients, sporadic pathologically confirmed T1a signet ring cell (diffuse) cancer identified on initial biopsy was no longer detectable upon subsequent biopsy or resection with mean follow-up of 50 months.

CONCLUSIONS

These cases allude to the distinct pathways of carcinogenesis in T1a signet ring cell cancers. Potential factors that may underlie the spontaneous regression of these T1a cancers include complete removal at initial biopsy, immune clearance, and lack of survival advantage conferred by signet ring cell genetic alterations in these cases. Given their more indolent behavior at an earlier stage, we suggest that these lesions can be closely followed by endoscopy in select circumstances with thorough disease assessment and an experienced care team.

Endoscopic screening for identification of signet ring cell gastric cancer foci in carriers of germline pathogenic variants in CDH1

To determine the preoperative detection of signet ring cancer cells (SRC) on upper endoscopy (EGD) in patients with CDH1 pathogenic variant (PV) undergoing gastrectomy. To evaluate the development of advanced diffuse gastric cancer (DGC) in patients choosing surveillance. Guidelines recommend prophylactic total gastrectomy (pTG) in CDH1 PV carriers with family history of DGC between 18 and 40 years. Annual EGD with biopsies according to established protocols is recommended in carriers with no SRC and no family history of DGC, with consideration of pTG. Retrospective analysis of asymptomatic patients with CDH1 PVs with ≥ 1 surveillance EGD. Outcomes included pre-operative EGD detection of SRC, surgical stage, and progression to advanced DGC in those electing surveillance with EGD. 48 patients with CDH1 PVs who had ≥ 1 EGD were included. 24/ 48 (50%) underwent gastrectomy, including pTG in 7 patients. SRCC were detected on gastrectomy specimen in 21/24 (87.5%). SRCs were identified by EGD in 17/21 patients who had SRCC on gastrectomy specimens (sensitivity 81%, 17/21). All cancers were stage pT1a. The remaining 17 patients (50% with a family history of gastric cancer) continue in annual EGD surveillance with a median follow-up of 34.6 months. No SRCC or advanced DGC have been diagnosed. No CDH1 PV carriers without SRCC on random biopsies followed in an endoscopic program developed advanced DGC over a median follow up of 3 years. In the short term, EGD surveillance might be a safe alternative to immediate pTG in experienced hands in referral centers.

Diffuse Gastric Cancer: A Comprehensive Review of Molecular Features and Emerging Therapeutics

Diffuse-type gastric cancer (DGC) accounts for approximately one-third of gastric cancer diagnoses but is a more clinically aggressive disease with peritoneal metastases and inferior survival compared with intestinal-type gastric cancer (IGC). The understanding of the pathogenesis of DGC has been relatively limited until recently. Multiomic studies, particularly by The Cancer Genome Atlas, have better characterized gastric adenocarcinoma into molecular subtypes. DGC has unique molecular features, including alterations in CDH1, RHOA, and CLDN18-ARHGAP26 fusions. Preclinical models of DGC characterized by these molecular alterations have generated insight into mechanisms of pathogenesis and signaling pathway abnormalities. The currently approved therapies for treatment of gastric cancer generally provide less clinical benefit in patients with DGC. Based on recent phase II/III clinical trials, there is excitement surrounding Claudin 18.2-based and FGFR2b-directed therapies, which capitalize on unique biomarkers that are enriched in the DGC populations. There are numerous therapies targeting Claudin 18.2 and FGFR2b in various stages of preclinical and clinical development. Additionally, there have been preclinical advancements in exploiting unique therapeutic vulnerabilities in several models of DGC through targeting of the focal adhesion kinase (FAK) and Hippo pathways. These preclinical and clinical advancements represent a promising future for the treatment of DGC.

Current advances and challenges in Managing Hereditary Diffuse Gastric Cancer (HDGC): a narrative review

More than 25 years ago, CDH1 pathogenic variants (PVs) were identified as the primary cause of hereditary diffuse gastric cancer (HDGC), an inherited cancer syndrome that increases the lifetime risk of developing diffuse gastric cancer (DGC) and lobular breast cancer (LBC). Since DGC is associated with a poor prognosis, a prophylactic total gastrectomy (PTG) is currently the gold standard for reducing the risk of DGC in CDH1 PV carriers. However, as germline genetic testing becomes more widespread, many CDH1 PV carriers have been identified, including in families with lower penetrance levels or without a history of gastric cancer (GC). When including these families, recent findings suggest that the cumulative lifetime risk of developing advanced DGC is much lower than previously thought and is now estimated to be 13-19%. This lower risk, combined with the fact that around one third of the CDH1 PV carriers decline PTG due to potential lifelong physical and psychological consequences, raises critical questions about the current uniformity in recommending PTG to all CDH1 PV carriers. As a result, there is a growing need to consider alternative strategies, such as endoscopic surveillance. However, despite the currently lower estimated risk of infiltrative (advanced) DGC, almost every PTG specimen shows the presence of small low-stage (pT1a) signet ring cell (SRC) lesions of which the behaviour is unpredictable but often are considered indolent or premalignant stages of DGC. Therefore, the primary goal of surveillance should be to identify atypical, deeper infiltrating lesions rather than every SRC lesion. Understanding the progression from indolent to more infiltrative lesions, and recognizing their endoscopic and histological features, is crucial in deciding the most suitable management option for each individual.

Immunosuppressive tumor microenvironment in gastric signet-ring cell carcinoma

Gastric signet-ring cell carcinoma (GSRCC) is a subtype of gastric cancer with distinct phenotype and high risk of peritoneal metastasis. Studies have shown that early GSRCC has a good prognosis, while advanced GSRCC is insensitive to radiotherapy, chemotherapy or immune checkpoint blockade therapy. With technological advancement of single-cell RNA sequencing analysis and cytometry by time of flight mass cytometry, more detailed atlas of tumor microenvironment (TME) in GSRCC and its association with prognosis could be investigated extensively. Recently, two single-cell RNA sequencing studies revealed that GSRCC harbored a unique TME, manifested as highly immunosuppressive, leading to high immune escape. The TME of advanced GSRCC was enriched for immunosuppressive factors, including the loss of CXCL13 +-cluster of differentiation 8+-Tex cells and declined clonal crosstalk among populations of T and B cells. In addition, GSRCC was mainly infiltrated by follicular B cells. The increased proportion of SRCC was accompanied by a decrease in mucosa-associated lymphoid tissue-derived B cells and a significant increase in follicular B cells, which may be one of the reasons for the poor prognosis of GSRCC. By understanding the relationship between immunosuppressive TME and poor prognosis in GSRCC and the underlying mechanism, more effective immunotherapy strategies and improved treatment outcomes of GSRCC can be anticipated.

Germline CDH1 Variants and Lifetime Cancer Risk

Importance

Approximately 1% to 3% of gastric cancers and 5% of lobular breast cancers are hereditary. Loss of function CDH1 gene variants are the most common gene variants associated with hereditary diffuse gastric cancer and lobular breast cancer. Previously, the lifetime risk of gastric cancer was estimated to be approximately 25% to 83% and for breast cancer it was estimated to be approximately 39% to 55% in individuals with loss of function CDH1 gene variants.

Objective

To describe gastric and breast cancer risk estimates for individuals with CDH1 variants.

Design, Setting, and Participants

Multicenter, retrospective cohort and modeling study of 213 families from North America with a CDH1 pathogenic or likely pathogenic (P/LP) variant in 1 or more family members conducted between January 2021 and August 2022.

Main Outcomes and Measures

Hazard ratios (HRs), defined as risk in variant carriers relative to noncarriers, were estimated for each cancer type and used to calculate cumulative risks and risks per decade of life up to age 80 years.

Results

A total of 7323 individuals from 213 families were studied, including 883 with a CDH1 P/LP variant (median proband age, 53 years [IQR, 42-62]; 4% Asian; 4% Hispanic; 85% non-Hispanic White; 50% female). In individuals with a CDH1 P/LP variant, the prevalence of gastric cancer was 13.9% (123/883) and the prevalence of breast cancer among female carriers was 26.3% (144/547). The estimated HR for advanced gastric cancer was 33.5 (95% CI, 9.8-112) at age 30 years and 3.5 (95% CI, 0.4-30.3) at age 70 years. The lifetime cumulative risk of advanced gastric cancer in male and female carriers was 10.3% (95% CI, 6%-23.6%) and 6.5% (95% CI, 3.8%-15.1%), respectively. Gastric cancer risk estimates based on family history indicated that a carrier with 3 affected first-degree relatives had a penetrance of approximately 38% (95% CI, 25%-64%). The HR for breast cancer among female carriers was 5.7 (95% CI, 2.5-13.2) at age 30 years and 3.9 (95% CI, 1.1-13.7) at age 70 years. The lifetime cumulative risk of breast cancer among female carriers was 36.8% (95% CI, 25.7%-62.9%).

Conclusions and Relevance

Among families from North America with germline CDH1 P/LP variants, the cumulative risk of gastric cancer was 7% to 10%, which was lower than previously described, and the cumulative risk of breast cancer among female carriers was 37%, which was similar to prior estimates. These findings inform current management of individuals with germline CDH1 variants.

A Decreased Appetite for Prophylactic Total Gastrectomy

Total gastrectomy should be performed less often in germline CDH1 variant carriers based on mounting clinical evidence.

Gastrointestinal Cancer Precursor Conditions and Their Detection

Gastrointestinal cancers are a leading cause of cancer morbidity and mortality. Many gastrointestinal cancers develop from cancer precursor lesions, which are commonly found in individuals with hereditary cancer syndromes. Hereditary cancer syndromes have advanced our understanding of cancer development and progression and have facilitated the evaluation of cancer prevention and interception efforts. Common gastrointestinal hereditary cancer syndromes, including their organ-specific cancer risk and surveillance recommendations, are reviewed in this article. The management of common gastroesophageal, pancreatic, and colonic precursor lesions is also discussed, regardless of their genetic background. Further research is needed to advance chemoprevention and immunoprevention strategies.

Construction and validation of the prognostic nomogram model for patients with diffuse-type gastric cancer based on the SEER database

OBJECTIVE

The prognostic factors of diffuse GC patients were screened the prognostic nomogram was constructed, and the prediction accuracy was verified.

METHODS

From 2006 to 2018, there were 2877 individuals pathologically diagnosed with diffuse gastric cancer; the clinicopathological features of these patients were obtained from the SEER database & randomly divided into a training cohort (1439) & validation cohort (1438).To create prognostic nomograms & choose independent prognostic indicators to predict the overall survival (OS) of 1, 3, & 5 years, log-rank & multivariate COX analysis were utilized & discrimination ability of nomogram prediction using consistency index and calibration curve.

RESULTS

Age, T, N, M, TNM, surgical status, chemotherapy status, & all seven markers were independent predictors of OS (P < 0.05), & a nomogram of OS at 1, 3, & 5 years was created using these independent predictors. The nomogram's c-index was 0.750 (95% CI 0.734 ~ 0.766), greater than the TNM staging framework 0.658 (95%CI 0.639 ~ 0.677); the c-index was 0.753 (95% CI 0.737 ~ 0.769) as well as superior to the TNM staging mechanism 0.679 (95% CI 0.503-0.697). According to the calibration curve, the projected survival rate using the nomogram & the actual survival rate are in good agreement.

CONCLUSIONS

Prognostic nomograms are useful tools for physicians to assess every individual's individualised prognosis & create treatment strategies for those with diffuse gastric cancer. They can reliably predict the prognosis for individuals with diffuse gastrointestinal carcinoma.

Clinical approach for managing patients with unexpected CDH1 mutations: A case report

BACKGROUND

Hereditary diffuse gastric cancer (HDGC) (OMIM# 137215) is an autosomal dominant cancer syndrome associated with CDH1 (OMIM# 192090) mutations. Prophylactic total gastrectomy (PTG) is the most recommended preventive treatment when a pathogenic mutation is found. However, the increasing use of genetic testing has led to the identification of incidental CDH1 mutations in individuals without a family history of gastric cancer. It remains unclear whether these patients should undergo prophylactic total gastrectomy.

METHODS

Germline DNA, obtained from peripheral blood, was analysed by NGS.

RESULTS

A 47-year-old woman was diagnosed with high-grade serous ovarian carcinoma, FIGO stage IIIC, with a Homologous Recombination Deficiency (HRD) GIS status of 78 (positive, cut-off: 43). She received chemotherapy and niraparib treatment. A multigene panel test revealed no pathogenic mutations in BRCA1 (OMIM# 113705)/BRCA2 (OMIM# 600185) genes, but a de novo deletion of exon 16 in CDH1 was found incidentally. She had no previous family history of gastric or breast cancer. The patient was enrolled in a surveillance program involving periodic endoscopy and was diagnosed with diffuse gastric cancer through biopsies of a pale area in the antrum after 1 year of close endoscopic follow-up.

CONCLUSION

This case presents supportive evidence for the pathogenic classification of the loss of the last exon of CDH1.

Folic acid-mediated hollow Mn 3 O 4 nanocomposites for in vivo MRI/FLI monitoring the metastasis of gastric cancer

BACKGROUND

Metastasis is one of the main factors leading to the high mortality rate of gastric cancer. The current monitoring methods are not able to accurately monitor gastric cancer metastasis.

METHODS

In this paper, we constructed a new type of hollowMn 3 O 4 nanocomposites,Mn 3 O 4 @HMSN-Cy7.5-FA, which had a size distribution of approximately 100 nm and showed good stability in different liquid environments. The in vitro magnetic resonance imaging (MRI) results show that the nanocomposite has good response effects to the acidic microenvironment of tumors. The acidic environment can significantly enhance the contrast of T 1 -weighted MRI. The cellular uptake and endocytosis results show that the nanocomposite has good targeting capabilities and exhibits good biosafety, both in vivo and in vitro. In a gastric cancer nude mouse orthotopic metastatic tumor model, with bioluminescence imaging's tumor location information, we realized in vivo MRI/fluorescence imaging (FLI) guided precise monitoring of the gastric cancer orthotopic and metastatic tumors with this nanocomposite.

RESULTS

This report demonstrates thatMn 3 O 4 @HMSN-Cy7.5-FA nanocomposites is a promising nano-diagnostic platform for the precision diagnosis and therapy of gastric cancer metastasis in the future.

CONCLUSIONS

In vivo MRI/FLI imaging results show that the nanocomposites can achieve accurate monitoring of gastric cancer tumors in situ and metastases. BLI's tumor location information further supports the good accuracy of MRI/FLI dual-modality imaging. The above results show that the MHCF NPs can serve as a good nano-diagnostic platform for precise in vivo monitoring of tumor metastasis. This nanocomposite provides more possibilities for the diagnosis and therapy of gastric cancer metastases.

Upper Gastrointestinal Cancers and the Role of Genetic Testing

Beyond the few established hereditary cancer syndromes with an upper gastrointestinal cancer component, there is increasing recognition of the contribution of novel pathogenic germline variants (gPVs) to upper gastrointestinal carcinogenesis. The detection of gPVs has potential implications for novel treatment approaches of the index cancer patient as well as long-term implications for surveillance and risk-reducing measures for cancer survivors and far-reaching implications for the patients' family. With widespread availability of multigene panel testing, new associations may be identified with germline-somatic integration being critical to determining true causality of novel gPVs. Comprehensive cancer care should incorporate both somatic and germline testing.

Points to consider regarding prophylactic total gastrectomy in germline CDH1 variant carriers

Pathogenic germline CDH1 mutation confers high risk for developing diffuse gastric and lobular breast cancers in asymptomatic carriers. In these individuals, the estimated gastric cancer risk at 80 years of age is up to 70% for males and 56% for females. Due to this high-risk predisposition, prophylactic total gastrectomy is considered a unique life-saving approach in germline CDH1 carriers, as endoscopy often fails to detect early stage diffuse gastric carcinoma. However, surgical indication is controversial in some clinical contexts, with possible contraindications. This review discusses points against and in favor of a more aggressive surgical approach for consideration during the decision-making process.

Costs of Cancer Prevention: Physical and Psychosocial Sequelae of Risk-Reducing Total Gastrectomy

PURPOSE

Risk-reducing surgery for cancer prevention in solid tumors is a pressing clinical topic because of the increasing availability of germline genetic testing. We examined the short- and long-term outcomes of risk-reducing total gastrectomy (RRTG) and its lesser-known impacts on health-related quality of life (QOL) in individuals with hereditary diffuse gastric cancer syndrome.

METHODS

Individuals who underwent RRTG as part of a single-institution natural history study of hereditary gastric cancers were examined. Clinicopathologic details, acute and chronic operative morbidity, and health-related QOL were assessed. Validated questionnaires were used to determine QOL scores and psycho-social-spiritual measures of healing.

RESULTS

One hundred twenty-six individuals underwent RRTG because of a pathogenic or likely pathogenic germline CDH1 variant between October 2017 and December 2021. Most patients (87.3%; 110/126) had pT1aN0 gastric carcinoma with signet ring cell features on final pathology. Acute (<30 days) postoperative major morbidity was low (5.6%; 7/126) and nearly all patients (98.4%) lost weight after total gastrectomy. At 2 years after gastrectomy, 94% (64/68) of patients exhibited at least one chronic complication (ie, bile reflux, dysphagia, and micronutrient deficiency). Occupation change (23.5%), divorce (3%), and alcohol dependence (1.5%) were life-altering consequences attributed to total gastrectomy by some patients. In patients with a median follow-up of 24 months, QOL scores decreased at 1 month after gastrectomy and returned to baseline by 6-12 months.

CONCLUSION

RRTG is associated with life-changing adverse events that should be discussed when counseling patients with CDH1 variants about gastric cancer prevention. The risks of cancer-prevention surgery should not only be judged in the context of likelihood of death due to disease if left untreated, but also based on the real consequences of organ removal.

Combining clinical and molecular characterization of CDH1: a multidisciplinary approach to reclassification of a splicing variant

Pathogenic germline variants (PGVs) in the CDH1 gene are associated with diffuse gastric and lobular breast cancer syndrome (DGLBC) and can increase the lifetime risk for both diffuse gastric cancer and lobular breast cancer. Given the risk for diffuse gastric cancer among individuals with CDH1 PGVs is up to 30-40%, prophylactic total gastrectomy is often recommended to affected individuals. Therefore, accurate interpretation of CDH1 variants is of the utmost importance for proper clinical decision-making. Herein we present a 45-year-old female, with lobular breast cancer and a father with gastric cancer of unknown pathology at age 48, who was identified to have an intronic variant of uncertain significance in the CDH1 gene, specifically c.833-9 C > G. Although the proband did not meet the International Gastric Cancer Linkage Consortium (IGCLC) criteria for gastric surveillance, she elected to pursue an upper endoscopy where non-targeted gastric biopsies identified a focus of signet ring cell carcinoma (SRCC). The proband then underwent a total gastrectomy, revealing numerous SRCC foci, but no invasive diffuse gastric cancer. Simultaneously, a genetic testing laboratory performed RNA sequencing to further analyze the CDH1 intronic variant, identifying an abnormal transcript from a novel acceptor splice site. The RNA analysis in conjunction with the patient's gastric foci of SRCC and family history was sufficient evidence for reclassification of the variant from uncertain significance to likely pathogenic. In conclusion, we report the first case of the CDH1 c.833-9 C > G intronic variant being associated with DGLBC and illustrate how collaboration among clinicians, laboratory personnel, and patients is crucial for variant resolution.

The bidirectional interplay between ncRNAs and methylation modifications in gastrointestinal tumors

The aberrant expression of methylation and ncRNAs, two crucial regulators of epigenetic modifications, has been widely demonstrated in cancer. The complex interplay between them is essential in promoting malignant phenotype, poor prognosis, and drug resistance in GI tumors (including esophageal, gastric, colorectal, liver, and pancreatic cancers). Therefore, we summarize the interrelation process between ncRNAs and methylation modifications in GI tumors, including the detailed mechanism of methylation enzyme regulation of ncRNAs, the molecular mechanism of ncRNAs regulation of methylation modifications, and the correlation between the interactions between ncRNAs and methylation modifications and clinical features of tumors. Finally, we discuss the potential value of ncRNAs and methylation modifications in clinical diagnosis and therapy.

Case Series of 11 CDH1 Families (47 Carriers) Including Incidental Findings, Signet Ring Cell Colon Cancer and Review of the Literature

Germline pathogenic variants in E-cadherin (CDH1) confer high risk of developing lobular breast cancer and diffuse gastric cancer (DGC). The cumulative risk of DGC in CDH1 carriers has been recently reassessed (from 40-83% by age 80 to 25-42%) and varies according to the presence and number of gastric cancers in the family. As there is no accurate estimate of the risk of gastric cancer in families without DGC, the International Gastric Cancer Linkage Consortium recommendation is not straightforward: prophylactic gastrectomy or endoscopic surveillance should be proposed for these families. The inclusion of CDH1 in constitutional gene panels for hereditary breast and ovarian cancer and for gastrointestinal cancers, recommended by the French Genetic and Cancer Consortium in 2018 and 2020, leads to the identification of families with lobular cancer without DGC but also to incidental findings of pathogenic variants. Management of CDH1 carriers in case of incidental findings is complex and causes dilemmas for both patients and providers. We report eleven families (47 CDH1 carriers) from our oncogenetic department specialized in breast and ovarian cancer, including four incidental findings. We confirmed that six families did not have diffuse gastric cancer in their medical records. We discuss the management of the risk of diffuse gastric cancer in Hereditary Lobular Breast Cancer (HLBC) through a family of 11 CDH1 carriers where foci were identified in endoscopic surveillance. We also report a new colon signet ring cancer case in a CDH1 carrier, a rare aggressive cancer included in CDH1-related malignancies.