These genes included CNA gain genes - SQLE, ADCY8, TPCN2, NDUFB9, KCNQ3, NCEH1, and PIK3CA and CNA loss genes - PDE12, SLC25A20, and MTAP. These findings highlighted the possible roles of these genes in the tumorigenesis of ESCC. This evidence concerns the gene PIK3CA and esophageal squamous cell carcinoma.