PIK3CA activation mutations are identified in multiple tumor types, such as breast cancer, uterine corpus endometrial carcinoma, carcinoma of the uterine cervix, colorectal carcinoma, esophageal carcinoma, gallbladder carcinoma, non-small cell lung cancer, ovarian carcinoma, and gastric cancer (Table 2). The gene discussed is PIK3CA; the disease is gastric cancer.