PIK3CA and esophageal adenocarcinoma: Progress in targeted therapy in esophageal adenocarcinoma has been slow primarily due to failure of conventional markers in other gastrointestinal adenocarcinoma (KRAS, EGFR, PTEN, PIK3CA, and c-MET) [28] to identify patients with esophageal adenocarcinoma who would respond to a targeted therapy.