PIK3CA and esophageal squamous cell carcinoma: In addition to the well-defined ESCC-related genes, including TP53, AJUBA, CDKN2A, KMT2D(MLL2), NOTCH1, NOTCH3, PIK3CA, RB1, CREBBP, NFE2L2, ZNF750, FAT1, KDM6A, FBXW7, and TGFBR2, we identified three novel oesophageal cancer-related genes: PTEN, DCDC1 and CUL3.