title: Real-time liquid biopsy in cancer patients: fact or fiction?
abstract: Distant metastases harbor unique genomic characteristics not detectable in the corresponding primary tumor of the same patient and metastases located at different sites show a considerable intrapatient heterogeneity. Thus, the mere analysis of the resected primary tumor alone (current standard practice in oncology) or, if possible, even reevaluation of tumor characteristics based on the biopsy of the most accessible metastasis may not reveal sufficient information for treatment decisions. Here, we propose that this dilemma can be solved by a new diagnostic concept: liquid biopsy, that is, analysis of therapeutic targets and drug resistance-conferring gene mutations on circulating tumor cells (CTC) and cell-free circulating tumor DNA (ctDNA) released into the peripheral blood from metastatic deposits. We discuss the current challenges and future perspectives of CTCs and ctDNA as biomarkers in clinical oncology. Both CTCs and ctDNA are interesting complementary technologies that can be used in parallel in future trials assessing new drugs or drug combinations. We postulate that the liquid biopsy concept will contribute to a better understanding and clinical management of drug resistance in patients with cancer.
authors.affiliation: Authors' Affiliations: Department of Tumor Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; University Medical Centre, Saint-Eloi Hospital, Institute of Research in Biotherapy, Laboratory of Rare Human Circulating Cells, Cell and Tissue Biopathology of Tumors Department; and University Institute of Clinical Research UM1-EA2415-Epidemiology, Biostatistics & Public Health, Montpellier, France.
authors.forename: Klaus
authors.initials: K
authors.lastname: Pantel
authors.forename: Catherine
authors.initials: C
authors.lastname: Alix-Panabières
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D004273:DNA, Neoplasm / Q000032:analysis*; D006801:Humans; D009369:Neoplasms / Q000175:diagnosis*; D009360:Neoplastic Cells, Circulating / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm