Liquid biopsies: tumor diagnosis and treatment monitoring

Abstract

Cancer is a disease with high evolutionary, i.e., malignant, characteristics that change under selective pressure from therapy. Characterization based on molecular or primary tumor properties or clinicopathological staging does not fully reflect the state of cancer, especially when cancer cells metastasize. This is the major reason for failure of cancer treatment. Currently, there is an urgent need for new approaches that allow more effective, but less invasive, monitoring of cancer status, thereby improving the efficacy of treatments. With recent technological advances, “liquid biopsies,” the isolation of intact cells or analysis of components that are secreted from cells, such as nucleic acids or exosomes, could be implemented easily. This approach would facilitate real-time monitoring and accurate measurement of critical biomarkers. In this review, we summarize the recent progress in the identification of circulating tumor cells using new high-resolution approaches and discuss new circulating tumor nucleic acid- and exosome-based approaches. The information obtained through liquid biopsies could be used to gain a better understanding of cancer cell invasiveness and metastatic competence, which would then benefit translational applications such as personalized medicine.