Variables affecting penetrance of gastric and duodenal phenotype in familial adenomatous polyposis patients

Endoscopic scoring indices for assessing disease severity in familial adenomatous polyposis: Systematic review

Background and study aims There is limited consensus on the optimal method for measuring disease severity in familial adenomatous polyposis (FAP). We aimed to systematically review the operating properties of existing endoscopic severity indices for FAP. Methods We searched MEDLINE, EMBASE, and the Cochrane Library from inception to February 2023 to identify randomized controlled trials (RCTs) that utilized endoscopic outcomes or studies that evaluated the operating properties of endoscopic disease severity indices in FAP. Results A total of 134 studies were included. We evaluated scoring indices and component items of scoring indices, such as polyp count, polyp size, and histology. Partial validation was observed for polyp count and size. The most commonly reported scoring index was the Spigelman classification system, which was used for assessing the severity of duodenal involvement. A single study reported almost perfect interobserver and intra-observer agreement for this system. The InSIGHT polyposis staging system, which was used for assessing colorectal polyp burden, has been partially validated. It showed substantial interobserver reliability; however, the intra-observer reliability was not assessed. Novel criteria for high-risk gastric polyps have been developed and assessed for interobserver reliability. However, these criteria showed a poor level of agreement. Other scoring indices assessing the anal transition zone, duodenal, and colorectal polyps have not undergone validation. Conclusions There are no fully validated endoscopic disease severity indices for FAP. Development and validation of a reliable and responsive endoscopic disease severity instrument will be informative for clinical care and RCTs of pharmacological therapies for FAP.

Updated European guidelines for clinical management of familial adenomatous polyposis (FAP), MUTYH-associated polyposis (MAP), gastric adenocarcinoma, proximal polyposis of the stomach (GAPPS) and other rare adenomatous polyposis syndromes: a joint EHTG-ESCP revision

BACKGROUND

Hereditary adenomatous polyposis syndromes, including familial adenomatous polyposis and other rare adenomatous polyposis syndromes, increase the lifetime risk of colorectal and other cancers.

METHODS

A team of 38 experts convened to update the 2008 European recommendations for the clinical management of patients with adenomatous polyposis syndromes. Additionally, other rare monogenic adenomatous polyposis syndromes were reviewed and added. Eighty-nine clinically relevant questions were answered after a systematic review of the existing literature with grading of the evidence according to Grading of Recommendations, Assessment, Development, and Evaluation methodology. Two levels of consensus were identified: consensus threshold (≥67% of voting guideline committee members voting either 'Strongly agree' or 'Agree' during the Delphi rounds) and high threshold (consensus ≥ 80%).

RESULTS

One hundred and forty statements reached a high level of consensus concerning the management of hereditary adenomatous polyposis syndromes.

CONCLUSION

These updated guidelines provide current, comprehensive, and evidence-based practical recommendations for the management of surveillance and treatment of familial adenomatous polyposis patients, encompassing additionally MUTYH-associated polyposis, gastric adenocarcinoma and proximal polyposis of the stomach and other recently identified polyposis syndromes based on pathogenic variants in other genes than APC or MUTYH. Due to the rarity of these diseases, patients should be managed at specialized centres.

Risk of gastric adenoma and adenocarcinoma in patients with familial adenomatous polyposis in Japan: a nationwide multicenter study

BACKGROUND

Patients with familial adenomatous polyposis (FAP) have an increased risk of developing gastric neoplasms. However, the clinical course of FAP with these gastric lesions has not yet been fully clarified. The present study aimed to clarify the changes in the incidence risk of developing gastric adenoma or gastric cancer during the lifespan of patients with FAP.

METHODS

Four hundred forty-three patients with data regarding gastric adenoma and gastric cancer retrospectively registered in a nationwide Japanese multicenter study were enrolled. The cumulative incidences and hazard rates (HRs) of gastric neoplasms were evaluated.

RESULTS

The cumulative incidence rates in 50-year-old patients with FAP were 22.8% for gastric adenoma and 7.6% for gastric cancer, respectively. No significant association was found between gastric neoplasms and the colonic phenotype. The peak age for the HR of gastric adenoma was 65 years, with the highest HR (0.043). Regarding the incidence of gastric cancer, the HR increased moderately up to the age of 40 years, but the increase accelerated from the age of 50 years (HR = 0.0067).

CONCLUSION

Careful surveillance of the upper gastrointestinal tract in elderly patients with FAP, such as shortening the interval of follow-up according to age, may be helpful for early diagnosis of gastric cancer.

Identifying factors associated with detection of sessile gastric polyps in patients with familial adenomatous polyposis

Background and study aims  Gastric cancer (GC) is increasingly reported and a leading cause of death in patients with familial adenomatous polyposis (FAP). Identifying features in patients with FAP who harbor sessile gastric polyps, likely precursors to GC, may lead to alterations in endoscopic surveillance in those patients and allow endoscopic intervention to decrease the risk of GC. The aim of this study was to identify demographic and clinical factors in patients with FAP who harbor sessile gastric polyps. Patients and methods  We retrospectively compared demographic, clinical, and endoscopic features in consecutive adult patients with FAP who presented for a surveillance endoscopy at a tertiary-care center with a FAP registry who harbor sessile gastric polyps to those without them. Sessile gastric polyps included pyloric gland adenomas, gastric adenomas, hyperplastic polyps, and fundic gland polyps with high-grade dysplasia. We also display the location of germline APC pathogenic variants in patients with and without sessile gastric polyps. Results  Eighty patients with FAP were included. Their average age was 48 years and 70 % were male . Nineteen (24 %) had sessile gastric polyps. They were older ( P  < 0.03), more likely to have a family history of GC ( P  < 0.05), white mucosal patches in the proximal stomach ( P  < 0.001), and antral polyps ( P  < 0.026) compared to patients without a gastric neoplasm. No difference in Spigelman stage, extra-intestinal manifestations, or surgical history was note. 89 % of patients with a gastric neoplasm had an APC pathogenic variant 5' to codon 1309. Conclusions  Specific demographic, endoscopic, and genotypic features are associated with patients with FAP who harbor sessile gastric polyps. We recommend heightened awareness of these factors when performing endoscopic surveillance of the stomach with resection of gastric neoplasia when identified.

Gastric Adenocarcinoma and Proximal Polyposis of the Stomach in a Hispanic Pediatric Patient With APC Gene Variant c.-191T>G

Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) is a rare gastric polyposis syndrome defined by numerous polyps (>100) in the fundus and body of the stomach with sparing of the lesser curvature and antrum. GAPPS is linked to a variant in the promoter 1B region of the APC gene. These variants carry a high risk of developing gastric adenocarcinoma, which can occur at an early age. We report a case of GAPPS discovered in a 16-year-old Hispanic girl after endoscopy detected extensive fundic gland polyposis. Genetic testing revealed a promoter 1B point mutation of the APC gene, variant c.-191T>G. Although similar variants have been reported (i.e., c.-191T>C, c.-195A>C, c.-192A>G) in association with GAPPS, variant c.-191T>G has not nor has GAPPS ever been described in a Hispanic individual before.

Gastric precancerous lesions present in ApcMin/+ mice

The Apc^Min/+ mouse is an animal model for familial adenomatous polyposis, and aged Apc^Min/+ mice also spontaneously develop multiple tumors in their stomachs. However, gastric premalignant lesions in Apc^Min/+ mice have not been well characterized. The stomachs of Apc^Min/+ mice were compared with those of their wild type littermates at 24 weeks with hematoxylin and eosin (H&E) staining and alcian blue staining. Ki67, CD68 and CA199 expression was analyzed by immunohistochemistry. The results revealed the presence of epithelial proliferation and inflammatory infiltration in the forestomachs, glandular atrophy and intestinal metaplasia in the gastric bodies, and dysplasia in the gastric antra. The effect of mutations in the Apc gene on chronic gastritis and gastric precancerous lesions was characterized in Apc^Min/+ mice. These results suggest that Apc^Min/+ mice represent a genetic model for mechanistic studies and drug discovery in gastric precancerous lesions.

Gastric adenocarcinoma and proximal polyposis of the stomach: diagnosis and clinical perspectives

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.

Dual gene deficient models of ApcMin/+ mouse in assessing molecular mechanisms of intestinal carcinogenesis

The Apc^Min/+ mouse, carrying an inactivated allele of the adenomatous polyposis coli (Apc) gene, is a widely used animal model of human colorectal tumorigenesis. While crossed with other gene knockout or knock-in mice, these mice possess advantages in investigation of human intestinal tumorigenesis. Intestinal tumor pathogenesis involves multiple gene alterations; thus, various double gene deficiency models could provide novel insights into molecular mechanisms of tumor biology, as well as gene-gene interactions involved in intestinal tumor development and assessment of novel strategies for preventing and treating intestinal cancer. This review discusses approximately 100 double gene deficient mice and their associated intestinal tumor development and progression phenotypes. The dual gene knockouts based on the Apc mutation background consist of inflammation and immune-related, cell cycle-related, Wnt/β-catenin signaling-related, tumor growth factor (TGF)-signaling-related, drug metabolism-related, and transcription factor genes, as well as some oncogenes and tumor suppressors. Future studies should focus on conditional or inducible dual or multiple mouse gene knockout models to investigate the molecular mechanisms underlying intestinal tumor development, as well as potential drug targets.