Introduction

Adenomatous polyposis syndromes comprise familial adenomatous polyposis (FAP), linked to a mutation in the APC gene, and MUTYH-associated polyposis (MAP), when there is a biallelic mutation in the MUTYH gene. These conditions result in a high risk of colorectal and duodenal cancers, with well-established recommendations for screening and preventive treatment for these locations. Recent studies also suggest an increased incidence of gastric cancer in these patients, associated with different types of dysplastic lesions in contact or at distance from the classic fundic gland polyps (FGP).

Aims & Methods

The aim of this study was to determine the prevalence, treatment, and follow-up of gastric dysplastic lesions in patients with an adenomatous polyposis syndrome.
We retrospectively analysed clinical and endoscopic data from all patients with adenomatous polyposis syndrome (FAP or MAP) who underwent follow-up esophagogastroduodenoscopy (EGD) in our center, between January 2015 and May 2022. Data was collected from a national prospective database of patients with digestive polyposis diseases created in 2011. We distinguished two types of dysplastic lesions: on the one hand, well-defined umbilicated sessile nodules of the antrum, and on the other hand, whitish flat lesions showing a "blue crest" sign in NBI, often fundic and within FGPs.

Results

A total of 227 patients were included. Thirteen (5.7%) presented a MUTYH mutation. Twenty-seven patients (11.9%) had gastric dysplasia (with 17 (63%) women and a mean age of 52 [23-68] years), located proximally in 70.4% of cases and mostly corresponding to low-grade dysplasia (18 cases, 66.7%), followed by high-grade dysplasia (8 cases, 29.6%) and 1 case of cancer (3.7%). One patient died of metastatic gastric cancer not detected by endoscopy, within a very dense fundic polyposis. None of these patients had an Helicobacter pylori (HP) infection (vs 13 (6.5%) in the control group). Whitish flat areas of the proximal stomach were observed in 27 (11.9%) patients, with confirmed (low-grade) dysplasia in 17 cases (63%). Sessile antral lesions were reported in 21 cases (9.2%), with confirmed dysplasia in 6 (29%). One of the flat fundic lesions was already invasive adenocarcinoma (pT2). Three other cases of dysplasia were revealed by systematic biopsies. The presence of fundic whitish flat lesions was strongly correlated with the presence of dysplasia (relative risk of 31 (95% CI [12.7-74.9], p <0.001)). The mean age and smoking were significantly higher in the dysplasia group (p <0.001). In multivariate analysis, smokers or patients with high-density FGPs (>50) had a significantly higher risk of gastric dysplasia (absolute risk of 13.08, 95% CI [2.67-64.10] and 22.06, 95% CI [4.28-113.58], respectively). Among the cases of dysplasia, 21 (77.8%) were treated by endoscopic resection, mostly ESD (10 cases (47.6%), for lesions with a median diameter of 62.5 [35-160] mm). One of these patients had a deeply invasive pT2 adenocarcinoma and therefore received systemic treatment. A patient with multiple and extensive adenomatous lesions was referred for gastrectomy, which he refused. The remaining patients are still under endoscopic surveillance. The median follow-up duration after treatment was 21 [0-72] months, with 2 proximal recurrences (7%, low grade dysplasia) treated endoscopically.

Conclusion

We present one of the largest gastric follow-up cohorts of patients with familial polyposis, with a non-negligible frequency of gastric dysplasia and risk of cancer. The latter is possibly preventable by endoscopic resection if the dysplasia is recognized early. This accentuates the importance of educating gastroenterologists on recognizing these sometimes very difficult to see lesions (dyschromic flat lesions).