PIK3CA as an isoform member of the PI3K family is a common somatic mutant oncogene with a high mutation rate in various tumors, such as 32% in colon cancer, 4‐25% in stomach cancer, 8‐40% in breast cancer, 5‐27% in meningeal cancer, 4‐25% in ovarian cancer, 11% in head and neck tumor, and 4‐33.1% in lung cancer, which were obtained by deeply mining data from the Catalogue Of Somatic Mutations In Cancer database (https://cancer.sanger.ac.uk/cosmic). The gene discussed is PIK3CA; the disease is gastric cancer.