The Importance of Circulating Tumor Cells and Tumor Models in Future of Cancer Therapy

Development of new technologies is taking cancer research on a new journey in which plenty of mysterious aspects of cancer biology are being unraveled. To defeat cancer, we first need to understand the biology of this smart complex system, which often hijacks several programs to proliferate, invade, escape the immune system and colonize distant organs. Therefore, studying cancer cells in every step of tumor development (including primary tumor formation, invasion, circulation and metastatic colonization) is absolutely essential. Analysis of human-derived cancer models in primary site, circulation or metastatic lesions outside their host is one of the most promising ways to understand these complexities. The most common currently used and more recently developed cancer cell lines consist of primary patient-derived tumor xenograft (PDTX), circulating tumor cells isolation and analyzes, and primary tumor organoids. In this chapter we provide a brief update of some of the most important advances in studying and treatment of cancer using new technologies.