CEACAM5 and esophageal squamous cell carcinoma: Although the combined usage of some markers such as squamous cell carcinoma antigen (SCC), carcinoembryonic antigen (CEA) and cytokeratin-19-fragment (CYFRA21-1) is helpful for the diagnosis and prognosis prediction of ESCC patients [2], limited markers are used in the early diagnosis of ESCC.