Compared with patients with early disease, patients with advanced GC exhibit greater frequencies of cumulative genetic events, such as increased rates of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) mutations, better detection of immunotherapy biomarkers, and mutations in the estrogen receptor 1 (ESR1) gene. This evidence concerns the gene ESR1 and gastric cancer.