PIK3CA and esophageal squamous cell carcinoma: We compared the SMGs to known cancer genes annotated in the COSMIC as well as other published studies, most of the SMGs we identified (TP53, NOTCH1, FAT1, ZNF750, RB1, PTCH1, PIK3CA, FBXW7, NFE2L2 and CDKN2A) are consistent to the ones reported previously in ESCC [20, 23–25].