Clinical Factors Associated With Gastric Cancer in Individuals With Lynch Syndrome

Dual primary gastric and colorectal cancer: The known hereditary causes and underlying mechanisms

In this editorial, I commented on the paper by Lin et al, published in this issue of the World Journal of Gastrointestinal Oncology. The work aimed at analysing the clinicopathologic characteristics and prognosis of synchronous and metachronous cancers in patients with dual primary gastric and colorectal cancer (CRC). The authors concluded the necessity for regular surveillance for metachronous cancer during postoperative follow-up and reported the prognosis is influenced by the gastric cancer (GC) stage rather than the CRC stage. Although surveillance was recommended in the conclusion, the authors did not explore this area in their study and did not include tests used for such surveillance. This editorial focuses on the most characterized gastrointestinal cancer susceptibility syndromes concerning dual gastric and CRCs. These include hereditary diffuse GC, familial adenomatous polyposis, hereditary nonpolyposis colon cancer, Lynch syndrome, and three major hamartomatous polyposis syndromes associated with CRC and GC, namely Peutz-Jeghers syndrome, juvenile polyposis syndrome, and PTEN hamartoma syndrome. Careful assessment of these syndromes/conditions, including inheritance, risk of gastric and colorectal or other cancer development, genetic mutations and recommended genetic investigations, is crucial for optimum management of these patients.

Bleeding Mass in Remnant Stomach, Unveiling Lynch Syndrome 18 Years After Bariatric Roux-En-Y Gastric Bypass Surgery

There is sparse literature on the development of malignancy in remnant gastric stomach after bariatric Roux-en-Y gastric bypass surgery. We report a case of overt upper gastrointestinal bleeding from malignant adenocarcinoma in the remnant stomach presenting several years after bariatric Roux-En-Y gastric bypass surgery. The mass in the remnant stomach was surgically resected, and the patient was subsequently diagnosed with Lynch syndrome on genetic analysis.

Low prevalence of gastric intestinal metaplasia and Helicobacter pylori on surveillance upper endoscopy in Lynch syndrome

Lynch syndrome (LS) increases the risk of numerous different cancers including gastric cancer. While some current guidelines recommend empiric gastric biopsies be performed during upper gastrointestinal cancer surveillance in Lynch syndrome (LS), the yield of these biopsies and the prevalence of gastric intestinal metaplasia (GIM) and Helicobacter pylori (HP) in LS remains unknown. Herein we analyze 165 consecutive individuals with LS who underwent upper endoscopic surveillance with biopsies of the gastric antrum and body being performed universally in all individuals. Of the study cohort, 6.7% of universally biopsied individuals with LS had GIM and/or HP (5.5% GIM, 3.6% HP). Biopsies of the gastric body did not increase rates of GIM/HP identification compared to antral biopsies alone. GIM was detected on subsequent surveillance in 2.2% of individuals without prior GIM, which may represent either newly developed GIM or GIM that was missed on a prior upper endoscopy due to sampling error. These findings support inclusion of at least baseline gastric antrum biopsies as a routine component of all standard surveillance upper endoscopies performed in LS.

Gastric and duodenal cancer in individuals with Lynch syndrome: a nationwide cohort study

Background

Lynch syndrome increases the risk of gastric cancer (GC) and duodenal cancer (DC), particularly in individuals with MLH1 and MSH2 pathogenic variants (PVs). To provide further insight into whether, and from what age, esophagogastroduodenoscopy (EGD) surveillance may be beneficial, we evaluated the cumulative incidence and tumour characteristics of GC and DC in a large nationwide cohort of Dutch individuals with LS.

Methods

For this retrospective nationwide cohort study, clinical data of individuals with LS registered at the Dutch Hereditary Cancer Registry were matched with pathology reports filed by the Dutch Pathology registry. All individuals registered between Jan 1, 1989 and Dec 31, 2021 with proven or putative PVs in one of the mismatch repair genes were included. Cumulative incidences of GC and DC were estimated for high-risk (MLH1, MSH2 and EpCAM) and low-risk (MSH6 and PMS2) PVs using competing risk methodology (Fine and Gray method) with death due to other causes as competing risk.

Findings

Among 1002 individuals with high-risk and 765 individuals with low-risk PVs, 29 GCs (1.6%) and 39 DCs (2.2%) were diagnosed. Cumulative incidence of GC and DC under the age of 50 was very low (≤1%) for all individuals. At age 70 and 75, cumulative incidence of GC was 3% [95% CI 1%-5%] and 5% [3%-8%] for high-risk PVs and 1% [0%-2%] and 1% [0%-2%] for low-risk PVs (p = 0.006). For DC, cumulative incidence at age 70 and 75 was 5% [3%-7%] and 6% [3%-8%] in high-risk, 1% [0%-1%] and 2% [0%-4%] in low-risk PVs, respectively (p = 0.01). Primary tumour resection was performed in 62% (18/29) of GCs and 77% (30/39) of DC cases. Early-stage GC, defined as TNM stage I, was found in 32% (9/28) of GCs. Early-stage DC, defined as TNM stage I-IIa, was found in 39% (14/36) of DCs.

Interpretation

Individuals with MLH1, MSH2, and EpCAM PVs have an increased risk of developing GC and DC at the age of 70 years, but this risk is very low before the age of 50 years. The age of onset of surveillance, the yield of GC and DC during EGD surveillance, and its cost-effectiveness should be subject of future studies.

Funding

None.

Cancer surveillance for transgender and gender diverse patients with Lynch syndrome: a practice resource of the Collaborative Group of the Americas on Inherited Gastrointestinal Cancer

Transgender and gender diverse (TGD) populations with hereditary cancer syndromes face unique obstacles to identifying and obtaining appropriate cancer surveillance and risk-reducing procedures. There is a lack of care provider knowledge about TGD health management. Lynch syndrome (LS) is one of the most common hereditary cancer syndromes, affecting an estimated 1 in 279 individuals. There are no clinical guidelines specific for TGD individuals with LS, highlighting a need to improve the quality of care for this population. There is an urgent need for cancer surveillance recommendations for TGD patients. This commentary provides recommendations for cancer surveillance, risk-reducing strategies, and genetic counseling considerations for TGD patients with LS.

Gastric precancerous lesions:occurrence, development factors, and treatment

Patients with gastric precancerous lesions (GPL) have a higher risk of gastric cancer (GC). However, the transformation of GPL into GC is an ongoing process that takes several years. At present, several factors including H.Pylori (Hp), flora imbalance, inflammatory factors, genetic variations, Claudin-4, gastric stem cells, solute carrier family member 26 (SLC26A9), bile reflux, exosomes, and miR-30a plays a considerable role in the transformation of GPL into GC. Moreover, timely intervention in the event of GPL can reduce the risk of GC. In clinical practice, GPL is mainly treated with endoscopy, acid suppression therapy, Hp eradication, a cyclooxygenase-2 inhibitor, aspirin, and diet. Currently, the use of traditional Chinese medicine (TCM) or combination with western medication to remove Hp and the use of TCM to treat GPL are common in Asia, particularly China, and have also demonstrated excellent clinical efficacy. This review thoroughly discussed the combining of TCM and Western therapy for the treatment of precancerous lesions as conditions allow. Consequently, this review also focuses on the causes of the development and progression of GPL, as well as its current treatment. This may help us understand GPL and related treatment.

Cancer Progress and Priorities: Gastric Cancer

Gastric cancer, the fifth leading cause of cancer worldwide, is estimated to be responsible for approximately 1.4% of all new cancers and 1.8% of all cancer-related deaths in the United States. Despite declining incidence rates and improved survival rates, however, gastric cancer continues to disproportionately affect racial and ethnic minorities and individuals of lower socioeconomic status at higher rates than the general population. To improve outcomes globally and address disparities within the United States, continued improvements are needed in risk factor modification and biomarker development and to improve access to existing preventative measures such as genetic testing and H. pylori eradication testing, in addition to expanding upon current clinical guidelines for premalignant disease to address gaps in endoscopic surveillance and early detection.

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.

Risk factors for gastric cancer in patients with Lynch syndrome

INTRODUCTION

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

AIMS AND METHODS

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

RESULTS

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

CONCLUSION

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

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.

Gastric metastasis from small bowel adenocarcinoma in a Lynch syndrome patient

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

Upper Gastrointestinal Cancer Surveillance in Lynch Syndrome

Simple Summary

Lynch syndrome is the most common cause of hereditary colorectal cancer, but is also associated with increased extracolonic cancer risk, including upper gastrointestinal cancers. While there is agreement regarding the benefit of frequent colonoscopic surveillance in Lynch syndrome, there remains a lack of consensus on the use of upper gastrointestinal cancer surveillance. Here, we review the upper gastrointestinal cancer risks in Lynch syndrome, the varying guideline recommendations in this area, and the published outcomes of upper gastrointestinal cancer surveillance in this high-risk population. Finally, we highlight ongoing controversies in upper gastrointestinal cancer surveillance and opine on how upper gastrointestinal cancer surveillance can be incorporated into a Lynch syndrome risk management program. Upper gastrointestinal cancer surveillance is an increasingly studied area of risk management in Lynch syndrome, and continued research will be vital in determining how to best incorporate this surveillance in these high-risk patients.

Abstract

Lynch syndrome is a common hereditary cancer predisposition syndrome associated with increased digestive cancer risk including colorectal, gastric, and duodenal cancers. While colorectal cancer surveillance is widely accepted to be an important part of a comprehensive Lynch syndrome risk management plan, the use of upper gastrointestinal cancer surveillance in Lynch syndrome remains more controversial. Currently, upper gastrointestinal cancer surveillance guidelines for Lynch syndrome vary widely, and there is no consensus on who should undergo upper gastrointestinal cancer surveillance, how surveillance should be performed, the age at which to initiate surveillance, or how often individuals with Lynch syndrome should undergo upper gastrointestinal cancer surveillance. Fortunately, research groups around the world have been focusing on upper gastrointestinal cancer surveillance in Lynch syndrome, and recent evidence in this field has demonstrated that upper gastrointestinal cancer surveillance can be performed with identification of precancerous lesions as well as early-stage upper gastrointestinal cancers. In this manuscript, we review the upper gastrointestinal cancer risks in Lynch syndrome, differing guideline recommendations for surveillance, outcomes of upper gastrointestinal cancer surveillance, and controversies in the field, and we provide a framework based on our collective experience with which to incorporate upper gastrointestinal cancer surveillance into a risk management program for individuals with Lynch syndrome.

Clinically actionable findings on surveillance EGD in asymptomatic patients with Lynch syndrome

BACKGROUND AND AIMS

Lynch syndrome (LS) predisposes patients to multiple cancers including of the gastric and small bowel. Data supporting EGD surveillance in LS are limited. Our aim is to describe upper GI (UGI) findings in asymptomatic LS patients undergoing EGD surveillance within a hereditary colorectal cancer registry.

METHODS

Asymptomatic patients with LS who underwent ≥1 surveillance EGD were included. Demographics, genotype, and EGD findings were reviewed. The frequency of clinically actionable findings including neoplasia (cancer, adenomas), Barrett's esophagus (BE), Helicobacter pylori, and hyperplastic polyps >5 mm were assessed.

RESULTS

Three hundred twenty-three patients underwent 717 EGDs starting at a median age of 49.5 years. On average, each patient had 2 EGDs with an interval of 2.3 years between examinations. Clinically actionable findings were identified in 57 patients (17.6%). On baseline EGD 27.7% of findings were identified, with the remainder on surveillance EGD over an average of 3.5 years. Five asymptomatic patients (1.5%) had an UGI cancer detected during surveillance, all at early stage, including 1 patient each with BE-related esophageal adenocarcinoma, gastric neuroendocrine tumor, and gastric adenocarcinoma and 2 patients with duodenal adenocarcinoma. Two cancers were found on baseline EGD and 3 on follow-up EGD.

CONCLUSIONS

Clinically actionable findings were found in approximately 1 in 6 asymptomatic patients with LS undergoing EGD surveillance. Five patients (1.5%) were diagnosed with cancer, all detected at an early stage. These data suggest that both baseline and follow-up EGD surveillance are effective in detecting early-stage UGI cancers in asymptomatic patients with LS.

Lynch Syndrome-Associated Cancers Beyond Colorectal Cancer

Lynch syndrome (LS) is a common form of inherited cancer susceptibility, which predisposes to colorectal cancer (CRC) along with a wide array of other extracolonic malignancies, including other gastrointestinal cancers, cancers of the gynecologic and genitourinary tracts, and other organ sites. Recent data have provided novel insights into patient-specific factors that can help clinicians understand an individual LS carrier's risk of extracolonic cancers, including sex, specific LS gene, age, family history of cancer, and other factors. This summary seeks to provide an update on extracolonic cancer risks in LS and provide recommendations for surveillance and risk reduction.

Genetic Syndromes Associated with Gastric Cancer

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

Effectiveness of a surveillance program of upper endoscopy for upper gastrointestinal cancers in Lynch syndrome patients

BACKGROUND AND AIMS

Lynch syndrome (LS) is the most common cause of hereditary colorectal cancer and is associated with an increased lifetime risk of gastric and duodenal cancers of 8-16% and 7%, respectively; therefore, we aim to describe an esophagogastroduodenoscopy (EGD) surveillance program for upper gastrointestinal (GI) precursor lesions and cancer in LS patients.

METHODS

Patients who either had positive genetic testing or met clinical criteria for LS who had a surveillance EGD at our institution from 1996 to 2017 were identified. Patients were included if they had at least two EGDs or an upper GI cancer detected on the first surveillance EGD. EGD and pathology reports were extracted manually.

RESULTS

Our cohort included 247 patients with a mean age of 47.1 years (SD 12.6) at first EGD. Patients had a mean of 3.5 EGDs (range 1-16). Mean duration of follow-up was 5.7 years. Average interval between EGDs was 2.3 years. Surveillance EGD detected precursor lesions in 8 (3.2%) patients, two (0.8%) gastric cancers and two (0.8%) duodenal cancers. Two interval cancers were diagnosed: a duodenal adenocarcinoma was detected 2 years, 8 months after prior EGD and a jejunal adenocarcinoma was detected 1 year, 9 months after prior EGD.

CONCLUSIONS

Our data suggest that surveillance EGD is a useful tool to help detect precancerous and cancerous upper GI lesions in LS patients. To our knowledge, this is the first study to examine a program of surveillance EGDs in LS patients. More data are needed to determine the appropriate surveillance interval.

When to Consider Lynch Syndrome in Non-Colon and Non-Endometrial Malignancies

Lynch syndrome (LS) is a common genetic syndrome characterized by pathogenic mutations of DNA mismatch repair genes resulting in a hereditary predisposition to cancer. While typically associated with colonic and endometrial cancer, LS additionally influences the development of many other malignancies. The Amsterdam II and Revised Bethesda Guidelines are the established clinical criteria for diagnosing LS. These guidelines are based on the most general characteristics of LS and do not address specific characteristics of the less commonly LS-associated malignancies. For individuals that present initially with a non-colon and non-endometrial malignancy, recommendations and guidelines on when to consider screening for LS are limited. Therefore, it is essential that clinicians are familiar with distinct LS-associated patient- and tumor-specific characteristics, especially of the less common LS-associated cancers, so that LS's diagnosis is not missed. In this review article, we focus on extra-colonic and extra-endometrial LS-associated cancers, paying particular attention to any established or currently investigated cancer features that help raise suspicion for LS and potentially lead to its earlier diagnosis. This review will also discuss current guidelines specific to each LS-associated malignancy.

Inherited Predisposition to Gastric Cancer

Approximately 10% of patients with gastric cancer show familial aggregation and up to 3% are related to an inherited cancer syndrome. There are multiple germline pathogenic variants and cancer syndromes associated with an increased risk of gastric cancer. Appropriate assessment of familial and genetic risk may allow a personalized approach to gastric cancer prevention through screening and risk-reducing surgeries. The ability to better identify carriers with pathogenic genetic variants associated with gastric cancer before a diagnosis of cancer requires effective genetic risk assessment and testing, followed by optimal screening and surveillance recommendations to further reduce the morbidity and mortality.

Familial Burden and Other Clinical Factors Associated With Various Types of Cancer in Individuals With Lynch Syndrome

BACKGROUND & AIMS

Lynch syndrome (LS) is associated with increased risks of various gastrointestinal, gynecologic, genitourinary, and other cancers. Many clinical practice guidelines recommend that LS carriers' screening strategies be devised based on their family history of various cancers, in addition to age-, sex-, and gene-specific considerations. The aim of this study was to examine the association between family history and other clinical factors with LS carriers' histories of various cancers.

METHODS

Two cohorts of LS carriers were analyzed: a laboratory-based cohort of consecutively ascertained individuals undergoing germline LS testing and a clinic-based cohort of LS carriers undergoing clinical care at an academic medical center. Multivariable logistic regression was performed to assess clinical factors associated with LS carriers' histories of various cancers/neoplasms. Familial burden was defined as LS carriers' aggregate number of first-/second-degree relatives with a history of a given malignancy.

RESULTS

Multivariable analysis of the laboratory-based cohort (3828 LS carriers) identified familial burden as being incrementally associated with LS carriers' personal history of endometrial (odds ratio [OR], 1.37 per affected first-/second-degree relative; 95% confidence interval [CI], 1.21-1.56), urinary tract (OR, 2.72; 95% CI, 2.02-3.67), small bowel (OR, 3.17; 95% CI, 1.65-6.12), gastric (OR, 1.93; 95% CI, 1.24-3.02), and pancreaticobiliary cancers (OR, 2.10; 95% CI, 1.21-3.65) and sebaceous neoplasms (OR, 7.39; 95% CI, 2.71-20.15). Multivariable analysis of the clinic-based cohort (607 LS carriers) confirmed a significant association of familial burden of endometrial and urinary tract cancers.

CONCLUSIONS

Familial burden - in addition to age, sex, and specific LS gene - should be used to assess LS carriers' risks of specific cancers and guide decision-making about organ-specific surveillance.

Clinical, Molecular and Genetic Characteristics of Early Onset Gastric Cancer: Analysis of a Large Multicenter Study

Gastric adenocarcinoma (GC) is a common tumor with high morbidity and mortality. Only 7% of patients with GC are diagnosed before age 50 (early onset gastric cancer (EOGC)), and their characteristics have been poorly described. We aimed to describe clinical, molecular, and genetic characteristics of EOGC. A total of 309 patients with EOGC were retrospectively studied in four Spanish centers. Personal information, family history, and tumor information were registered. Germinal genetic analysis was performed in patients who met current criteria of a hereditary syndrome at the time of diagnosis. The median age at diagnosis was 44 years. The majority (73.3%) of tumors were diffuse, and 78.3% were diagnosed in an advanced stage. Familial aggregation of GC was present in 18/117 (15.4%) cases, and 5/117 (4.3%) met criteria for familial GC. MMR-IHC was performed in 126/309 (40.7%) tumors: 4/126 (3.1%) had loss of expression in MLH1/PMS2, without an associated germline mutation. Sixteen germline genetic analyses were performed, detecting a pathogenic variant in four (25%) cases: one in BRCA2, one in TP53, and two in CDH1. Most EOGC are diffuse and diagnosed in an advanced stage. In these patients, DNA MMR system deficiency is uncommon. Although familial aggregation was observed in only 15% of cases, a germline mutation was found in 25% of patients tested with clinical criteria. This demonstrates that EOGC has a marked genetic heterogeneity, reinforcing the importance of an accurate genetic counseling and enhancing the emerging use of multigene panels.

A Case-Based Approach to Understanding Complex Genetic Information in an Evolving Landscape

The rapid integration of highly sensitive next-generation sequencing technologies into clinical oncology care has led to unparalleled progress, and yet these technological advances have also made genetic information considerably more complex. For instance, accurate interpretation of genetic testing for germline/inherited cancer predisposition syndromes and somatic/acquired pathogenic variants now requires a more nuanced understanding of the presence and incidence of clonal hematopoiesis and circulating tumor cells, with careful evaluation of pathogenic variants occurring at low variant allele frequency required. The interplay between somatic and germline pathogenic variants and awareness of distinct genotype-phenotype manifestations in various inherited cancer syndromes are now increasingly appreciated and can impact patient management. Through a case-based approach, we focus on three areas of particular relevance to the treating clinician oncologist: (1) understanding clonal hematopoiesis and somatic mosaicism, which can be detected on germline sequencing and lead to considerable confusion in clinical interpretation; (2) implications of the detection of a potentially germline pathogenic variant in a high-penetrance cancer susceptibility gene during routine tumor testing; and (3) a review of gene-specific risks and surveillance recommendations in Lynch syndrome. A discussion on the availability and difficulties often associated with direct-to-consumer genetic testing is also provided.

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

Simple Summary

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

Abstract

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

Genetic Gastric Cancer Risk Syndromes

Purpose of review

Gastric cancer is a leading cause of cancer death in the world. Between 1% and 3% of cases are associated with specific genetic cancer risk syndromes. The purpose of this article is to review the latest insights, as well as gaps in knowledge, regarding some of the most common hereditary gastric cancer syndromes: hereditary diffuse gastric cancer (HDGC), gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS), Lynch syndrome, the adenomatous polyposis syndromes, and the hamartomatous polyposis syndromes.

Recent findings

Patients carrying pathogenic variants in CDH1, but not meeting clinical criteria for HDGC, are increasingly being identified thanks to multigene panel testing; their absence from previous analyses overestimated gastric cancer penetrance. GAPPS is a recently described hereditary gastric cancer syndrome associated with specific point mutations in the promoter 1B region of the APC gene.

Summary

Risk of gastric cancer is highest among carriers of pathogenic variants in CDH1, with cumulative incidences approximately 40% and 30% for men and women, respectively. Mutations associated with Lynch syndrome and adenomatous polyposis syndromes confer greatest risk for gastric cancer in East Asian populations. Risk of gastric cancer in GAPPS and hamartomatous polyposis syndromes is difficult to estimate due to their rarity, but mutation status likely determines risk. Future research is needed to more precisely define risk of gastric cancer in these syndromes, so strategies for screening and prophylactic gastrectomy can be optimized.

Diagnosis of Lynch Syndrome and Strategies to Distinguish Lynch-Related Tumors from Sporadic MSI/dMMR Tumors

Simple Summary

Microsatellite instability (MSI) is a hallmark of Lynch syndrome (LS)-related tumors but is not specific, as most of MSI/mismatch repair-deficient (dMMR) tumors are sporadic. Therefore, the identification of MSI/dMMR requires additional diagnostic tools to identify LS. In this review, we address the hallmarks of LS and present recent advances in diagnostic and screening strategies to identify LS patients. We also discuss the pitfalls associated with current strategies, which should be taken into account in order to improve the diagnosis of LS.

Abstract

Microsatellite instability (MSI) is a hallmark of Lynch syndrome (LS)-related tumors but is not specific to it, as approximately 80% of MSI/mismatch repair-deficient (dMMR) tumors are sporadic. Methods leading to the diagnosis of LS have considerably evolved in recent years and so have tumoral tests for LS screening and for the discrimination of LS-related to MSI-sporadic tumors. In this review, we address the hallmarks of LS, including the clinical, histopathological, and molecular features. We present recent advances in diagnostic and screening strategies to identify LS patients. We also discuss the pitfalls associated with the current strategies, which should be taken into account to improve the diagnosis of LS and avoid inappropriate clinical management.

How Should We Test for Lynch Syndrome? A Review of Current Guidelines and Future Strategies

International guidelines for the diagnosis of Lynch syndrome (LS) recommend molecular screening of colorectal cancers (CRCs) to identify patients for germline mismatch repair (MMR) gene testing. As our understanding of the LS phenotype and diagnostic technologies have advanced, there is a need to review these guidelines and new screening opportunities. We discuss the barriers to implementation of current guidelines, as well as guideline limitations, and highlight new technologies and knowledge that may address these. We also discuss alternative screening strategies to increase the rate of LS diagnoses. In particular, the focus of current guidance on CRCs means that approximately half of Lynch-spectrum tumours occurring in unknown male LS carriers, and only one-third in female LS carriers, will trigger testing for LS. There is increasing pressure to expand guidelines to include molecular screening of endometrial cancers, the most frequent cancer in female LS carriers. Furthermore, we collate the evidence to support MMR deficiency testing of other Lynch-spectrum tumours to screen for LS. However, a reliance on tumour tissue limits preoperative testing and, therefore, diagnosis prior to malignancy. The recent successes of functional assays to detect microsatellite instability or MMR deficiency in non-neoplastic tissues suggest that future diagnostic pipelines could become independent of tumour tissue.

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.

Value of upper gastrointestinal endoscopy for gastric cancer surveillance in patients with Lynch syndrome

In our study, we evaluated the effectiveness of upper gastrointestinal (GI) endoscopy as an instrument for early gastric cancer (GC) detection in Lynch syndrome (LS) patients by analyzing data from the registry of the German Consortium for Familial Intestinal Cancer. In a prospective, multicenter cohort study, 1128 out of 2009 registered individuals with confirmed LS underwent 5176 upper GI endoscopies. Compliance was good since 77.6% of upper GI endoscopies were completed within the recommended interval of 1 to 3 years. Forty-nine GC events were observed in 47 patients. MLH1 (n = 21) and MSH2 (n = 24) mutations were the most prevalent. GCs in patients undergoing regular surveillance were diagnosed significantly more often in an early-stage disease (UICC I) than GCs detected through symptoms (83% vs 25%; P = .0231). Thirty-two (68%) patients had a negative family history of GC. The median age at diagnosis was 51 years (range 28-66). Of all GC patients, 13 were diagnosed at an age younger than 45. Our study supports the recommendation of regular upper GI endoscopy surveillance for LS patients beginning no later than at the age of 30.

Upper Endoscopic Surveillance in Lynch Syndrome Detects Gastric and Duodenal Adenocarcinomas

Lynch syndrome is a prevalent hereditary cancer predisposition syndrome. While colorectal cancer is the most common gastrointestinal (GI) cancer in Lynch syndrome, there is also increased risk of gastric and small intestinal cancers. Recommendations for upper GI cancer surveillance in Lynch syndrome vary widely with limited data supporting effectiveness. Herein, we collected data on individuals with a diagnosis of Lynch syndrome seen at our tertiary care referral center. We identified individuals who underwent upper endoscopy and those with upper GI cancers, and associated demographics, genetic testing results, and endoscopic information. Standard statistical analyses were performed. Among 295 individuals with Lynch syndrome seen at our center, 217 (73.6%) underwent 660 total upper endoscopies. Of these 217, precancerous upper endoscopy findings included Barrett's esophagus (7, 3.2%), gastric intestinal metaplasia (18, 8.3%), and duodenal adenomas (4, 1.8%), and Helicobacter pylori was identified in 6 (2.8%). Upper GI cancers were diagnosed in 11 individuals (3.7%), including esophageal in 1, gastric in 6, and duodenal in 4. Five (1.7%) of these upper GI cancers were identified on surveillance. Individuals with upper GI cancers identified on surveillance were older at first surveillance endoscopy, with median age 63.3 versus 44.9 years (P < 0.001). Of the upper GI cancers detected on surveillance, 80% (4/5) occurred within 2 years of last upper endoscopy and 80% were stage I. In conclusion, upper endoscopy surveillance in Lynch syndrome identifies upper GI cancers. For individuals with Lynch syndrome who undergo upper GI surveillance, a short surveillance interval may be warranted.

Secondary Prevention in Hereditary Breast and/or Ovarian Cancer Syndromes Other Than BRCA

BRCA1- and BRCA2-associated hereditary breast and ovarian cancer syndromes are among the best-known and most extensively studied hereditary cancer syndromes. Nevertheless, many patients who proved negative at BRCA genetic testing bring pathogenic mutations in other suppressor genes and oncogenes associated with hereditary breast and/or ovarian cancers. These genes include TP53 in Li-Fraumeni syndrome, PTEN in Cowden syndrome, mismatch repair (MMR) genes in Lynch syndrome, CDH1 in diffuse gastric cancer syndrome, STK11 in Peutz-Jeghers syndrome, and NF1 in neurofibromatosis type 1 syndrome. To these, several other genes can be added that act jointly with BRCA1 and BRCA2 in the double-strand break repair system, such as PALB2, ATM, CHEK2, NBN, BRIP1, RAD51C, and RAD51D. Management of primary and secondary cancer prevention in these hereditary cancer syndromes is crucial. In particular, secondary prevention by screening aims to discover precancerous lesions or cancers at their initial stages because early detection could allow for effective treatment and a full recovery. The present review aims to summarize the available literature and suggest proper screening strategies for hereditary breast and/or ovarian cancer syndromes other than BRCA.

Clinical Factors Associated with Urinary Tract Cancer in Individuals with Lynch Syndrome

BACKGROUND

Lynch syndrome confers markedly increased risks of various malignancies, including urinary tract cancers (UTC; renal pelvis, ureter, bladder, and possibly kidney cancers). It is unknown how to determine which Lynch syndrome carriers are at highest UTC risk. Our aim was to identify clinical factors associated with UTC among Lynch syndrome carriers.

METHODS

The study population was a cohort of 52,758 consecutively ascertained individuals undergoing Lynch syndrome testing at a commercial laboratory. Clinical data were obtained from test request forms completed by the ordering provider. Univariate analysis and multivariate logistic regression were performed to identify factors associated with UTC among Lynch syndrome carriers.

RESULTS

Compared with noncarriers, Lynch syndrome carriers were significantly more likely to have had UTC (4.1% vs. 1.2%; P < 0.0001). Lynch syndrome-associated UTC was independently associated with male sex [OR 1.95; 95% confidence interval (CI), 1.38-2.76], increased age (OR 2.44 per 10 years; 95% CI, 2.11-2.82), familial burden of UTC (OR 2.69 per first-/second-degree relative with UTC; 95% CI, 1.99-3.63), and pathogenic EPCAM/MSH2 variants (OR 4.01; 95% CI, 2.39-6.72) but not MLH1 variants (OR 1.17; 95% CI, 0.63-2.17), race, or history of other Lynch syndrome-associated malignancy. A total of 143 of 158 (90.5%) Lynch syndrome carriers with UTC had ≥1 of the following characteristics: male sex, EPCAM/MSH2 variants, or family history of UTC; 1,236 of 1,251 (98.8%) Lynch syndrome carriers lacking all of these characteristics had no history of UTC.

CONCLUSIONS

Specific clinical factors can reliably identify Lynch syndrome carriers most likely to be at risk for UTC.

IMPACT

A predictable subset of Lynch syndrome carriers may be most likely to benefit from UTC surveillance/prevention.