Fig. 2.

Molecular subtypes of gastric cancer classified via genomics. Gastric cancer is classified into four molecular subtypes: chromosomal instability (CIN), genome stability (GS), microsatellite instability (MSI), and Epstein-Barr virus (EBV) positivity. Most subtypes of CIN correspond to the intestinal type and are accompanied by TP53 mutations and tyrosine kinase receptor-RAS signal amplification. Most GS subtypes correspond to the diffuse type according to the histopathological classification of GC. In MSI- and EBV-positive subtypes, phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) and AT-rich interaction domain 1A (ARID1A) gene mutations are enriched. Furthermore, programmed cell death ligand 1/2 (PD-L1/2) is often overexpressed via gene amplification and structural variation in EBV-positive subgroups