RUNX3 and gastric cancer: Distinct from PGC-negative gastric cancer, gastric adenocarcinoma of the fundic gland type (GA-FG-CCP) is a rare variant of a well-differentiated and chief cell-predominant adenocarcinoma that is distributed to the fundus and cardia and characterized by frequent submucosal invasion, rare lymphatic and venous invasion, low-grade malignancy, low Ki-67 expression, high PGC and RUNX3 immunopositivity, nuclear β-catenin accumulation, and mutation or hypomethylation of the CTNNB1 or AXIN gene [27–32].