As in a previous study (9), a nine-gene mutation panel was used to perform genetic analysis with the MassARRAY method; in addition, Helicobacter pylori (HP) infection, Epstein–Barr virus (EBV) infection, and PIK3CA amplification were compared between cardia and noncardia GC patients. The gene discussed is PIK3CA; the disease is Epstein-Barr virus infection.