Circulating tumor cells and the correlation with metastasis and recurrence of tumor

Metastasis is the main cause of cancer related death.Most deaths of solid tumors are caused by haematogenous spread of cancer cells into distant organs and their subsequnent overt metastases.The cause of distant metastasis and recurrence of cancer is the presence of circulating tumor cells(circulating tumor cell,CTC) in peripheral blood.CTCs stimulate the immune response.Most of the circulating tumor cells are recognized by the immune system and therefore,difficult to survive.Only a small number of CTCs continue to stay in circulation,pass through the basement membrane,and form tumor colonies in other organs.CTCs are essential for tumor distant metastasis.In-depth study of CTCs contribute to the mechanism of tumor metastasis.In this paper,we review the technological methods for separation and identification of CTCs,and the mechanisms of tumor recurrence and metastasis.