Perspectives on liquid biopsy for label-free detection of "circulating tumor cells" through intelligent lab-on-chips

Circulating tumor cells (CTCs) are rare tumor cells released from primary,metastatic, or recurrent tumors in the peripheral blood of cancer patients. CTCsisolation from peripheral blood and their molecular characterization representa new marker in cancer screening, a diagnostic tool called "liquid biopsy" (LB).Compared to traditional tissue biopsy that is invasive and does not reveal tumorheterogeneity, LB is noninvasive and reflects in "real-time" tumor dynamismand drug sensitivity. In the frame of LB, a new paradigm based on single-celland label-free analysis based on morphological analysis is emerging. Here, wereview the latest research developments in this emerging vision of LB. In par-ticular, we survey and discuss recent improvements in microfluidics, imaginglabel-free diagnosis and cell classification by artificial intelligence and how tocombine them to realize an intelligent platform based on lab-on-chip technol-ogy. This prospect appears to open up promising and intriguing new scenarios