Circulating biomarkers for esophageal squamous cell carcinoma

Esophageal cancer is the eighth most common cancer worldwide and esophageal squamous cell carcinoma (ESCC) is the predominant type in Asia. Surgical resection of the tumor is the mainstay treatment for ESCC. Recent advances in neoadjuvant or adjuvant chemotherapy/chemoradiotherapy for treatment of ESCC have significantly improved prognosis. Despite these advancements, survival of some patients still remains poor in particular for those diagnosed at a late stage. In view of the asymptomatic nature of early ESCC and the limitations of currently used diagnostic methods, there is a pressing need to identify circulatory biomarkers to allow noninvasive and early detection of ESCC. In this chapter, we summarize circulating cancer biomarkers including circulatory proteins, microRNAs, and tumor cells that are found to have elevated level in serum and plasma of ESCC patients when compared to healthy subjects. These biomarkers could help improve the diagnostic efficiency of ESCC.