 Background Esophageal carcinoma is a common digestive system tumor, with number of deaths ranking No. 4 in malignant tumors. Surgery is the preferred method of treatment for esophageal cancer, but the local recurrence rate is as high as between 40 and 60, and 5-year overall survival is only about 30. Most of esophageal cancers are found in the middle and late stage, losing the chance of operation. Esophageal squamous cell carcinoma in stage II, III is the most common in China. The esophageal cancer during these stages is no longer localized lesions, and cancer will be transferred to other organs of the body through blood transmission, leading to tumor metastasis, which is the main cause of the patients death. The tumor cells invade the surrounding tissues of primary tumor cells and enter the blood and lymphatic system, thus the circulating tumor cells CTC is formed and transported to a distal tissue, then effusing, adapting to the new microenvironment and finally forming metastases through the process of seeding, proliferation and colonization. In recent years, as liquid pathology, CTCs are used for several studies of tumor, including the auxiliary diagnosis, recurrence and metastasis detection, prognosis, individualized treatment, medical screening, development of new targeted cancer therapy drugs, searching for a new target for cancer therapy, exploring the mechanism of drug resistance, etc. 