Familial Adenomatous Polyposis with Multiple <i>Helicobacter</i>-negative Early Gastric Cancers Treated by Endoscopic Submucosal Dissection

Abstract

Stomach cancer rarely develops in patients with familial adenomatous polyposis (FAP), and Helicobacter pylori infection may increase the risk of FAP-related gastric cancer. We describe the case of a 64-year-old woman who developed multiple synchronous early gastric cancers without H. pylori infection. Nine cancer lesions were successfully treated by endoscopic submucosal dissection. An immunohistochemical analysis revealed that the tumors were positive for mucin (MUC)2, MUC6, and CDX2, but negative for MUC5AC, suggesting that the tumors were gastrointestinal mixed type. Periodical endoscopic surveillance is important for the detection of cancers at an early stage.

Genetic alteration of colorectal adenoma‐carcinoma sequence among gastric adenocarcinoma and dysplastic lesions in a patient with attenuated familial adenomatous polyposis

“…A case report on gastric cancers in a Japanese FAP patient showed that the tumors were of the gastrointestinal type (Yaguchi et al, 2017). Another case report showed that an FAP patient had a gastric-type adenocarcinoma whereas his pedigree had an intestinal-type adenocarcinoma (Mitsui et al, 2019).…”

“…MUC2, CDX2, and CD10 are also useful immunohistochemical markers that can be used to subclassify gastric cancers into the gastric, intestinal, and mixed gastrointestinal types (Mitsui et al., 2019). A case report on gastric cancers in a Japanese FAP patient showed that the tumors were of the gastrointestinal type (Yaguchi et al., 2017). Another case report showed that an FAP patient had a gastric‐type adenocarcinoma whereas his pedigree had an intestinal‐type adenocarcinoma (Mitsui et al., 2019).…”

Japanese Society for Cancer of the Colon and Rectum (JSCCR) guidelines 2020 for the Clinical Practice of Hereditary Colorectal Cancer

“…Studies in Japan have indicated that the prevalence rate of gastric cancer in patients with FAP was 3.1–4.2% [ 49 , 60 ], but studies in Western countries indicated that the prevalence rate was low at 0.6% [ 46 ]. Studies in Japan on gastric cancer in patients with FAP are more diverse than the general population, including gastric cancer caused by fundic gland polyposis, gastric cancer caused by gastric mucosal atrophy due to H. Pylori infection, and coexistence high-grade adenoma/ dysplasia [ 44 , 133 , 134 ], and there are many cases of early detection with periodic endoscopic surveillance [ 130 , 133 , 134 ]. Meanwhile, gastric cancers that develop in GAPPS, which is a polyposis limited to the stomach due to pathogenic germline variants in the promoter 1B of the APC gene, require differentiation at the time of initial diagnosis due to its high malignancy [ 135 ].…”