在传统观点下，癌症转移灶的形成被认为是肿瘤发生、发展的终末事件，而近年

In the traditional view, the formation of cancer metastases is considered the final event of tumor occurrence and development. Recent studies have shown that even in the early stages of cancer, tumor cells can enter the blood circulatory system directly or indirectly via the lymphatic pathway, and then Distant tissues or organs colonize and eventually proliferate to form metastases. This part of the tumor cells that fall off the primary tumor or metastases into the blood circulation is called Circulating Tumor Cell (CTC). The appearance of CTC is the occurrence The premise and basis of distant transfer [5,6].

In the traditional view, the formation of cancer metastatic lesions is considered to be the final event of tumor occurrence and development, and recent studies have shown that even in the early stages of cancer, tumor cells can enter the blood circulation system directly or indirectly through lymphatic pathways, which in turn can be planted in distant tissues or organs and eventually proliferated to form metastatic lesions, which fall off from the tumor primary or metastasis to enter the blood circulation of tumor cells called circulatory tumor fine (Circulating Cell, CTC), The emergence of CTC is the premise and basis for distant transfer.

In the traditional view, the formation of cancer metastasis is considered to be the terminal event of tumor occurrence and development. However, recent studies have shown that even in the early stage of cancer, tumor cells can directly or indirectly enter the blood circulation system through the lymphatic pathway, and then colonize in distant tissues or organs and finally proliferate to form metastasis, which falls off from the primary tumor or metastasis and enters the blood circulation Circulating tumor cell is called circulating tumor cell (CTC). The appearance of CTC is the premise and basis of distant metastasis [5,6].<br>