PIK3CA and esophageal squamous cell carcinoma: A comparative genomic study revealed many focal DNA amplifications or losses such as SOX2, PIK3CA, CCND1, FGFR1, MYC, GATA4, and GATA6 in ESCC and EAC.[13] Of note, FGFR1 was amplified in 21% of ESCC samples compare with 8% in EAC.