The majority of deaths associated with malignant tumor are due to the metastasis of the original tumor cells to tissues and organs distant from the initial tumor. Accordingly, early diagnosis of metastasis is a critical factor for the survival of a cancer patient, and early diagnosis of tumor and monitoring of tumor growth are considered as very important factors for successful treatment of a cancer patient. The diagnosis of cancer usually uses diagnosis techniques by histopathology. The histopathological diagnosis technique is a method of using a tissue sample from a living subject to diagnose a cancer. Such a histopathological approach allows a tumor cell to be directly observed. However, it may be incorrect whether there is a tumor from a tissue site selected in order to obtain a sample from a living subject, and only data about a particular site obtained from the living subject are provided and thus it is difficult to know whether tumor has metastasized to another site. For this reason, the applicability in diagnosing and monitoring tumors may be limited.
It is known that circulating tumor cells (CTCs) are found from a patient before the tumor is originally detected. Accordingly, CTCs may play an important role in early diagnosis and prognosis of cancers. In addition, because cancer usually metastasizes through blood, CTC may be a marker for determining whether cancer has metastasized. Even after cancer cells have been removed by surgery, CTCs may be still exist and cancer may reoccur. However, very small amounts of these CTCs are found in blood and the cells are themselves weak, and thus it is very difficult to detect them and grasp the number of the cells. Accordingly, there still remains a need for a diagnosis method that is highly sensitive to detect CTCs, cancer cells, or cancer stem cells in a patient's body.
CTC separation methods by using magnetic nanoparticles are described in the related art. However, the method according to the related art is disadvantageous because the processes are very complicated, for example, the method of separating serum from blood, and using the affinity of biotin and streptavidin even in a magnetic separation process have a risk of losing of CTCs in the separation steps.
Accordingly, there still remains a need for a method for efficiently separating tumor cells from a biological sample and an apparatus associated with that.