Alterations in PIK3CA are also present in gastric (2–25%) [56,60,105,106,107,108,109,110,111], endometrial (16–51%) [112,113,114,115], head and neck (6–21%) [56,116,117,118,119,120], and esophageal cancers (5–21%) [121,122,123,124,125,126]. The gene discussed is PIK3CA; the disease is esophageal cancer.