Emerging single-cells technologies open-up the possibility to profile individual circulating cancer cells overcoming the well known cancer heterogeneity. Indeed tumour cells are heterogeneous cells with different phenotypes and genotypes that are responsible for drug resistance and metastasis.

Cancer metastasis of solid tumors happens when the tumor cells enter the blood circulation and disseminate in distant sites. These circulating tumor cells can have a mutational landscape which is different from the primary tumor. Thus therapeutic interventions against the primary tumor could be different from the ones selected to fight metastatic cancer.