Deciphering the clinical spectrum of gastric disease in patients with juvenile polyposis syndrome.

Background And Aims: Juvenile polyposis syndrome (JPS) is a rare hereditary autosomal dominant cancer-predisposition syndrome caused by germline pathogenic variants (PVs) located in SMAD4 or BMPR1A genes. Accurate clinical and endoscopic data regarding the evolution of gastric lesions remain sparse.

Methods: Clinical, endoscopic, genetic, and pathologic data from patients with SMAD4 or BMPR1A PVs included between 2007 and 2020 in the French network on rare digestive polyposis (RENAPOL [French National Polyposis Register]) database were prospectively collected to address uncertainties regarding gastric involvement.

Results: Thirty-six patients were included: 25 (69.5%) had SMAD4 PVs, and 11 had BMPR1A PVs. For SMAD4 PV carriers, median age at inclusion was 43.0 years (range, 10-78 years). At baseline EGD, 22 (88%) of 25 patients exhibited at least 1 gastric juvenile polyp, and 5 (20%) of 25 had macroscopic signs of inflammatory gastritis. Early gastric disease was mostly located under the cardia, then progressed to the gastric antrum and body. During a mean follow-up period of 55.0 months, 12 of 25 patients had gastric disease progression (ie, new juvenile polyps [91.6%], diffuse gastric involvement [41.6%], inflammatory flat progression [25%]). Among 62 biopsies, low-grade dysplasia was observed in 5 (7.5%) samples from 2 patients. Nine carriers (36%) underwent gastrectomy (mean age, 47.2 years) due to diffuse gastric involvement or worsening clinical symptoms. Gastric adenocarcinoma (T1) was found in 1 gastrectomy specimen. Among the 11 patients with BMPR1A PVs, 2 had gastric hamartomatomas at baseline EGD, none with dysplasia or symptoms.

Conclusions: Gastric involvement in JPS seems to be progressive over a lifetime, initiates in the cardia area, and mostly involves SMAD4 PV carriers.