GC is a heterogeneous disease that is classified into intestinal, diffuse, mixed, and indeterminate histologic subtypes according to the Lauren classification and into 4 molecular subtypes: Epstein-Barr virus (EBV), microsatellite instability (MSI), chromosomal instability (CIN), and genomically stable (GS) by TCGA (The Cancer Genome Atlas).22 Therefore, understanding the prevalence of CLDN18.2 expression in gastric or GEJ adenocarcinoma patients, according to cancer staging, clinicopathologic features, and molecular subtypes, may guide CLDN18.2 testing. The gene discussed is CLDN18; the disease is cancer.