177Alfred K. Lam (ed.), Esophageal Adenocarcinoma: Methods and Protocols, Methods in Molecular Biology, vol. 1756,
https://doi.org/10.1007/978-1-4939-7734-5_16, © Springer Science+Business Media, LLC 2018
Chapter 16
Circulatory Tumor Cells in Esophageal Adenocarcinoma
Vinod Gopalan and Alfred K. Lam
Abstract
While circulating tumor cells (CTCs) within peripheral blood of cancer patients are no new phenomenon
in many carcinomas, there is a lack of information on the biological and clinical implications of CTCs in
esophageal adenocarcinomas. Limited evidence suggests that the CTCs are frequently detected in esopha-
geal adenocarcinomas when compared to esophageal squamous cell carcinoma suggesting the potential
difference in the pathogenesis between these two carcinomas. In addition, the varied CTC levels between
adenocarcinoma and squamous cell carcinomas of the esophagus could be attributed to the varied expres-
sion pattern of epithelial markers such as epithelial cell adhesion molecule (EpCAM) and cytokeratin (CK).
In esophageal adenocarcinomas, CTC levels correlated with pathological T stages, lymph node metastasis,
and patient survival. Thus, detection of CTCs potentially acts as a noninvasive and real-time biomarker for
predicting patient prognosis in esophageal adenocarcinomas. Although the CTC detection is currently
performed using various methods, the only Food and Drug Administration (FDA) of USA approved CTC
detection method in clinics is the CELLSEARCH® system. This chapter will discuss various biological
characteristics of CTC and its potential implications in esophageal adenocarcinomas. In addition, a quick
overview of CTC detection methodology is outlined.
Key words Circulating tumor cell, Blood, CTC, Cytokeratin, Esophageal adenocarcinoma1 Introduction
Cell migration plays a key role in cancer cell metastasis from a pri-
mary tumor site to other areas of the body through the circulatory
or lymphatic system. Metastasis accounts for the majority of can-
cer-related deaths and many of these patients will present with
metastasis at the time of diagnosis. An early detection and preven-
tion of cancer metastasis can be achieved by studying the func-
tional and clinical characteristics of tumor cells, which are found in
the peripheral circulatory system of these patients. First identified
in 1869 by Thomas Ashworth, circulating tumor cells (CTCs) in
peripheral blood have long been hypothesized as a potential real-
time “liquid biopsy” for patients with cancer [ 1 ]. As postulated by
Ashworth, “... cells identical with those of cancer itself being seen
in the blood may tend to throw some light upon the mode of