Circulating Tumor Cells (CTCs) in Early Cancer Detection, Prognosis Evaluation and Monitoring Cancer Drug Efficacy

Tumour metastasis refers to the spread of cancer cells from the initial site of primary tumor to a distant secondary location. Cancerous tumor usually possesses a very large number of cells with genetic mutations which motivate them to grow, proliferate, and then, invade the local surrounding tissues. As the tumor grows larger, some of the cells are dislodged from the main tumor and carried away by the blood or lymphatic vessels. These "circulating tumor cells" or CTCs possess important information about the primary tumor from which they are detached. In fact, the presence and quantity of CTCs in the cancer patients' blood stream have been known to correlate directly to the stage of cancer as well as the effectiveness of cancer therapies. The ability to isolate and enrich a large number of intact CTCs for analysis and characterisation will be pivotal for deepening our understanding of the metastatic process. However, the extremely low abundance of CTCs in the blood makes enumeration and characterisation a huge technical challenge. their isolation is still a major challenge, very rare information is available regarding their nature and behaviour.