CDKN2A and gastric cancer: These tumors appear mainly in the upper part of the stomach, specifically, in the gastric fundus. Histologically, EBV+ GC is moderate to poorly differentiated, usually with dense lymphocytic infiltration.20 Molecular characteristics of EBV+ GC include extreme hypermethylation, CDKN2A methylation, but without MLH1 methylation, and PIK3CA and ARID1A mutations.