Phenotypic Spectrum of Gastric Adenocarcinoma and Proximal Polyposis of the Stomach (GAPPS) in Denmark: A Case Series Characterizing the First Danish Families With the APC Promotor 1B Variant c.‐191T > C

Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) is a rare hereditary gastric cancer syndrome linked to APC promoter IB variants and characterized by gastric polyposis. Its natural history and management are poorly defined. We sought to characterize the clinicopathological features of GAPPS and infer management guidelines. We retrospectively analyzed individuals with GAPPS enrolled in a natural history study from January 2017 to September 2023. Demographics, pathogenic gene variants, endoscopic findings, and histopathology results were studied. Of 21 patients with GAPPS, 11 (52%) were male, and most were non-Hispanic white (71%). Median age at germline genetic testing was 44 years (range 12-75 years), and all individuals had a pathogenic variant in the APC promoter IB. Esophagogastroduodenoscopy (EGD) was performed in almost all patients (91%), with a median age of 37 years (range 12-75 years) at initial EGD. Gastric polyps carpeting the fundus and body with antral sparing were noted in all individuals. Gastric adenocarcinoma (n = 3), high-grade dysplasia (n = 7), low-grade dysplasia (n = 3), and benign fundic gland polyposis (n = 6) were demonstrated on endoscopic biopsies. Then, 43% (9/21) of patients underwent total gastrectomy (TG) at a median age of 44 years (range 15-63 years). Histopathology of final gastrectomy specimens demonstrated more advanced pathology compared with endoscopic biopsies in five of nine patients. Given the challenge of effective endoscopic surveillance owing to extensive polyposis, and the risk of malignant transformation, prophylactic TG should be considered for patients with GAPPS. Longitudinal studies are needed to delineate lifetime cancer risk and clinical management guidelines.

Pathogenic variants in the APC gene are classically associated with autosomal dominant familial adenomatous polyposis (FAP), characterized by tens-to-thousands of colonic adenomatous polyps and a high-penetrance predisposition to colorectal cancer. More recently, specific PVs in the YY1 binding motif of APC promoter 1B have been associated with autosomal dominant gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS), characterized by tens-to-thousands of fundic gland polyps and a predisposition to gastric cancer but which are only rarely associated with features consistent with FAP. Although management guidelines currently treat FAP and GAPPS as mutually exclusive conditions, the extent of phenotypic overlap is not well-characterized. Here, we present a multi-clinic and -laboratory collaboration reporting a previously undescribed APC promoter 1B insertion/deletion likely pathogenic variant in a family with mixed GAPPS and FAP phenotype. The family proband is a female of unspecified white ancestry. She was diagnosed with GAPPS at age 30 and, after developing gastric cancer at age 39, underwent curative gastrectomy. She is now 61 with a cumulative history of between 50 and 100 colon adenomas and recently completed subtotal colectomy. Her multi-gene panel testing in 2022 demonstrated a likely pathogenic insertion/deletion (indel) within the APC promoter 1B YY1 binding motif (APC c.-192_-191delATinsTAGCAAGGG). Review of a four-generation pedigree revealed the ages of gastric cancer presentation in the family ranged from 39–60’s, with advanced gastric polyposis and prophylactic gastrectomy as early as ages 11 and 13 in the proband’s daughter and nephew, respectively. Six of 10 (60%) family members known or presumed to carry the APC likely pathogenic variant underwent colectomy or hemicolectomy due to colon polyposis. The youngest known carrier in the family is a 12-year-old female, and the oldest living carrier is the proband’s brother, age 66. A novel APC indel causes concomitant GAPPS and FAP presentations in this previously unreported large kindred. Mixed gastric and colon phenotypes have been rarely described in GAPPS families and the ages of presentation of gastric polyposis are strikingly young in the current family with prophylactic gastrectomies completed as early as age 11 and 13. These ages are significantly younger than the 15 years of age at which national guidelines currently recommend initiation of EGD for screening in GAPPS. Although the mechanism for this combined GAPPS-FAP phenotype is unclear, patients in this family and those with similar APC promoter 1B variants should be offered both gastric and colon cancer risk management.

BackgroundGastric adenocarcinoma and proximal polyposis of the stomach (GAPPS), a hereditary gastric polyposis syndrome that presents with fundic gastric polyposis, is associated with an increased risk of gastric adenocarcinoma. The four patterns of point mutation in the adenomatous polyposis coli (APC) promoter 1B region have been identified as the cause of GAPPS. GAPPS was first reported in 2012, and only 33 families with GAPPS have been reported worldwide to date. Therefore, the clinical management for GAPPS are still controversial. We herein report two unrelated GAPPS families with the same point mutation site.Case DescriptionTotal seven patients of two families had >100 carpeting polyps in the gastric body and fundus, and one of them (69-year-old female) had gastric adenocarcinoma. As a result of germline analysis, both families harbored a point mutation (c.-192A>G) in APC promoter 1B region, previously reported in only one family. Three of seven patients underwent total gastrectomy, and others were followed-up with regular esophagogastroduodenoscopy (EGD) and biopsy every 6 months. To summarize the reported cases, total 42 patients of 35 families have developed gastric adenocarcinoma.ConclusionsThis report may contribute to determining the appropriate guidelines for the clinical practice of GAPPS. When EGD reveals gastric polyposis localized to the gastric body and fundus, it is important to obtain a detailed family history and perform germline mutational analysis. And more, point mutation type of our family cases was a rare pattern, suggested that c.-192A>G pattern might be a pathogenic variant.

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. 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. This cohort study was performed from January 1, 2006, to January 1, 2020, in 181 patients with CDH1 germline variants from a single institution. Genetic counseling, esophagogastroduodenoscopy, and possible total gastrectomy. CDH1 variant classification, family cancer history, findings of signet ring cell carcinoma at esophagogastroduodenoscopy and surgery, postoperative events and weight changes, and follow-up. 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. 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.

Family History As a Positive Prognostic Factor in Gastric Cancer

Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) is an autosomal dominant syndrome characterized by polyposis localized in the gastric body and fundus with a strong tendency for adenocarcinoma. The genetic mutations that accumulate during the progression from normal mucosa through polyp to carcinoma in GAPPS remain unclear. We investigated the evolutionary process from normal mucosa to polyp and carcinoma in GAPPS. Through comprehensive mutational and transcriptome analyses, we aimed to provide insights into the biology of this disease. Whole-exome sequencing and RNA sequencing were performed on carcinoma, polyp, and normal mucosa samples from multiple sites from seven patients with GAPPS (n = 54 samples). We comprehensively investigated genomic alterations (including copy number alterations and somatic mutations), clonal architecture, and transcriptome dynamics during carcinogenesis. Genomic evolutionary analysis showed that in GAPPS, somatic mutations of APC occur in carcinoma and polyp while mutations of KRAS additionally occur in carcinoma. We also found the co-occurrence of APC and KRAS mutations in carcinoma recurrently both across cases and within subclones of the same case. The co-occurrence of APC/KRAS mutations may contribute to the carcinogenesis of GAPPS. Our study provides detailed information on the genomic and transcriptomic landscape in GAPPS carcinogenesis, conferring valuable insights into its underlying mechanisms.

Table 1 Personal and family GC history in index cases assessed for germline variants in the APC promoter 1B Personal cancer history No of index cases Family history of GC,...

Background: The E-cadherin (CDH1) gene is involved in cell adhesion and maintenance of tissue architecture. Loss of expression of CDH1 has been found in both invasive lobular carcinoma (ILCA) of the breast as well as hereditary diffuse gastric cancer (HDGC). While mutations in CDH1 have been found in patients with hereditary diffuse gastric cancer, less is known about the role of CDH1 mutations in patients with breast cancer, thus mutation status was determined in a breast cancer cohort with and without family histories of gastric cancer. Methods: The Clinical Breast Care Project database was queried to identify all patients with ILCA with or without a family history of gastric or stomach cancer as well as those with non-lobular invasive cancer with a family history of gastric or stomach cancer. Genomic DNA was isolated from peripheral blood samples. DNA variants were detected for each exon using high-resolution melting technology and the underlying change identified by direct sequencing. Results: Of the 72 patients with ILCA, five had a first degree relative with stomach cancer; 14 patients with non-lobular invasive cancer (12 IDCA, one mixed lobular and ductal, and one tubular) had first degree relatives with stomach or gastric cancer. Three mutations previously associated with gastric cancer were identified: A617T and V832M were identified in a patient with ILCA with no history of gastric cancer and in a patient with IDCA with a family history of gastric cancer, respectively, while one patient with ILCA and no family history harbored the splice site mutation 1137G-T. Three novel variants were also identified: G879S, in a patient with ILCA and no family history, P825Q in a patient with mixed lobular and ductal features with a family history of stomach cancer and L230F in a patient with IDCA and a family history of stomach cancer. Conclusions: The frequency of CDH1 mutations in this patient population was low (∼7%) and were split between patients with ILCA and no family history of gastric cancer and those with non-lobular cancers and at least one family member with gastric or stomach cancer. Identification of known mutations in patients with non-lobular carcinomas suggests that while these specific CDH1 mutations are associated with increased risk of hereditary diffuse gastric cancer, they do not confer increased risk for lobular cancer. In those patients with ILCA, the low frequency of germline mutations in CDH1 suggests alternate methods, such as epigenetic modification or miRNA silencing, may be driving the suppression of expression of E-cadherin and the development of ILCA. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2202. doi:10.1158/1538-7445.AM2011-2202

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. 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. 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.

Background/Objectives: Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) is a recently discovered autosomal dominant transmission disease. Patients with this condition have a higher risk of developing gastric cancer. There are numerous questions regarding the natural history of this condition, as well as concerning the diagnostic and therapeutic management of these patients. In this systematic review, we aimed to examine the current literature to determine the role of prophylactic gastrectomy in patients diagnosed with gastric adenocarcinoma and proximal polyposis of the stomach. Additional outcomes are Helicobacter pylori (HP) infection, treatment with proton pump inhibitors (PPI), and colonoscopic examination and abdominal imaging examination, as they are important factors in the therapeutic decision. Methods: We performed a systematic review of the articles published in PubMed and Google Scholar, according to the PRISMA 2020 criteria. Results: We obtained 24 studies that included 83 patients diagnosed with GAPPS, of which 42 underwent prophylactic gastrectomy, 24 benefited from endoscopic follow-up, and 17 were diagnosed with gastric cancer at the first gastroscopic examination. In the prophylactic gastrectomy specimens, malignant gastric disease was confirmed in 10% of cases. GAPPS has been diagnosed more frequently in women. Conclusions: So far, the specialized literature includes a limited number of patients diagnosed with GAPPS. There are also no guidelines yet for the diagnosis and treatment of these patients. Prophylactic gastrectomy or endoscopic surveillance are the only options for patients diagnosed with GAPPS without gastric cancer at the initial examination. For prophylactic gastrectomy, the robotic and laparoscopic approach was preferred. For establishing appropriate lymphadenectomy in prophylactic gastrectomy, future research on gastrectomy specimens is necessary. Most of the included studies were deficient in terms of postoperative follow-up of patients. Thus, we consider it useful to include these patients in a single database. For a comprehensive examination of these and making an appropriate therapeutic decision, we consider it necessary to perform a colonoscopic evaluation, take abdominal imaging, and determine the Helicobacter pylori infection status.

Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) was first proposed by Wothley et al. in 2012 as a rare familial gastric cancer syndrome associated with an autosomal dominant form of inheritance. GAPPS is characterized by gastric basal gland polyposis from the hilum to the body of the stomach. Li et al. in 2016 showed that the cause of the disease is a point mutation in the promotor 1B region of the APC gene, and genetic testing was used to confirm the diagnosis. If the patient has already developed gastric cancer, treatment should be based on the usual treatment for gastric cancer. If no distant metastases exist, a good prognosis can be expected by performing a total gastrectomy. On the other hand, patients with distant metastasis have a poor prognosis. In the case of dysplasia, prophylactic total gastrectomy is recommended, but because it is highly invasive and postoperative postgastrectomy syndrome must be considered, the decision should be made with careful consideration of the patient's background. Therefore, there are no guidelines for screening for GAPPS, the timing of prophylactic total gastrectomy, or methods of endoscopic surveillance. Because GAPPS is a rare disease, its natural history is still unclear. Further case series are needed to elucidate the molecular biology and clinicopathological features of GAPPS and to establish clinical management, including diagnosis, treatment, and surveillance. In this review, we provide an overview of GAPPS, its clinical management, and its problems, which will be useful for the treatment of GAPPS.

We evaluated the associations between gastric cancer (GC) family history (FH) and colorectal cancer (CRC) risk and between CRC FH and GC/gastric adenoma risk. We used data of participants who underwent national cancer screening between 2013 and 2014. Participants with GC or CRC FH in first-degree relatives (n=1 172 750) and those without cancer FH (n=3 518 250) were matched 1:3 by age and gender. Of the 1 172 750 participants with a FH, 871 104, 264 040, and 37 606 had FHs of only GC, only CRC, and both GC and CRC, respectively. The median follow-up time was 4.8years. GC and CRC FHs were associated with increased GC and CRC risks, respectively. GC FH was associated with CRC risk (adjusted hazard ratio 1.05; 95% confidence interval [CI] 1.01-1.10), whereas CRC FH was not associated with the risk of GC or gastric adenoma. However, gastric adenoma risk increased 1.62-fold (95% CI 1.40-1.87) in participants with FHs of both GC and CRC, demonstrating a significant difference with the 1.39-fold (95% CI 1.34-1.44) increase in participants with only GC FH. Furthermore, GC risk increased by 5.32 times (95% CI 1.74-16.24) in participants with FHs of both GC and CRC in both parents and siblings. GC FH was significantly associated with a 5% increase in CRC risk. Although CRC FH did not increase GC risk, FH of both GC and CRC further increased the risk of gastric adenoma. FHs of GC and CRC may affect each other's neoplastic lesion risk.

Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) is a recently described, rare gastric polyposis syndrome. It is characterized by extensive involvement of the fundus and body of the stomach with fundic gland polyps sparing the antrum and lesser curvature, an autosomal dominant inheritance pattern with incomplete penetrance, and a significant predisposition for the development of gastric adenocarcinoma. Due to the recent discovery of APC promotor IB mutations (c.-191T>C, c.-192A>G, and c.-195A>C), which reduce binding of the transcription factor Yin Yang 1 (YY1) and transcriptional activity of the promotor, as its underlying genetic perturbation, GAPPS has been added to the growing molecular class of APC-associated disorders. Recent reports on family members afflicted by gastric polyposis due to GAPPS have described the development of metastatic cancer or the presence of invasive gastric adenocarcinoma in total gastrectomy specimens after variable periods of endoscopic surveillance emphasizing the need for an improved understanding of the to-date poorly characterized natural history of the syndrome. There are, however, currently no guidelines on screening, timing of prophylactic gastrectomy, or endoscopic surveillance for GAPPS available. In this review, we summarize the clinical, pathological, and genetic aspects of GAPPS as well as management approaches to this rare cancer predisposition syndrome, highlighting the need for early recognition, a multidisciplinary approach, and the creation of prospective family registries and consensus guidelines in the near future.

A 48-year-old Japanese female with left hypochondralgia presented at our hospital. Esophagogastroduodenoscopy (EGD) revealed gastric cancers and carpeting fundic gland polyposis (FGPs) without Helicobacter pylori infection. Computed tomography showed multiple liver metastases. Total colonoscopy revealed a colonic tubular adenoma but not polyposis. She was diagnosed as having advanced gastric cancer with liver metastasis and received chemotherapy. Her mother had died from gastric cancer, and her elderly brother and niece had FGPs as revealed by EGD. Thus, the pedigree was diagnosed as gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS). Germline mutation analysis exhibited a point mutation in exon1B of the APC gene (c.-191T > C). Adenocarcinoma showed a gastric mucinous phenotype and was positive for a somatic mutation of p53, suggesting that p53 mutation may play a role in FGPs carcinogenesis. This is the first family with GAPPS in Asia in whom germline mutation of APC exon 1B has been detected.

Gastric Adenocarcinoma and Proximal Polyposis of the Stomach (GAPPS) is a very rare gastric polyposis syndrome characterized by numerous polyps of the gastric fundus and body. We present the unusual case of a 10-year-old Polish-American male with history of eosinophilic esophagitis, who was found to have multiple fundic gland polyps (FGP) with low grade dysplasia on esophagogastroduodenoscopy. Subsequent evaluation including genetic testing confirmed the diagnosis of GAPPS, and after exhaustive multidisciplinary consultation the decision was made to proceed with prophylactic total gastrectomy given the markedly increased risk of gastric adenocarcinoma in GAPPS patients. To our knowledge, this represents the youngest patient diagnosed with GAPPS and the youngest patient who has undergone prophylactic gastrectomy for this disease at age 8 and 10years, respectively. The pathophysiology, presentation, and treatment of GAPPS in a pediatric patient are discussed.