Cancer stem cells with increased metastatic potential as a therapeutic target for esophageal cancer

Esophageal cancers (EC) are highly aggressive tumors, commonly presented in a locally advanced stage with a poor prognosis and survival. Up to 50% of the patients are eligible for treatment with curative intent and receive the standard treatment with neoadjuvant chemoradiotherapy (nCRT) and surgery. Currently, pathologic complete response to nCRT is 20-30%, with a partial or no response in about 50% and 20%, respectively. EC recurrences occur frequently even after successful anti-cancer treatment, suggesting high aggressiveness with increased metastatic potential. A tumor sub-population of so-called cancer stem cells (CSCs), is known to display a high metastatic potential and resistance to conventional anti-cancer therapy, hereby being responsible for the unbeneficial clinical features. In this review, a concise overview will be given of the current literature on esophageal CSCs and related metastases. Esophageal CSC markers will be discussed followed by the pathways that initiate and sustain these cells. In addition, the cellular processes, epithelial-mesenchymal transition (EMT), hypoxia and autophagy, known to contribute to cancer stemness and metastasis will be explained. Finally, potential options for treatment also related to cancer genome atlas (TCGA) data on EC will be discussed.