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Liquid biopsy was introduced to the oncology field with the promise of revolutionizing the management of cancer patients, minimizing the exposure to invasive procedures such as tissue biopsy, and providing reliable information regarding therapy response and detection of disease relapse. Despite the significant increase in the number of published studies on circulating tumor DNA (ctDNA) in the past years, the emphasis of most studies is on the development of new technologies or on the clinical utility of ctDNA. This leaves a clear gap of knowledge concerning the biology of ctDNA, such as the fundamental mechanisms through which DNA from tumor cells is released into the circulation. Moreover, considering that ctDNA analysis is now currently being applied in clinical practice, the need for rigorous quality control is arising, and with it the necessity to standardize procedures, from sample collection to data analysis. This review focuses on the main aspects of ctDNA, including approaches currently available to evaluate tumor genetics, as well as the points that still require improvement in order to make liquid biopsy a key player in precision medicine., (© 2019 S. Karger AG, Basel.)

Background: Despite the hype about circulating tumour cells (CTCs) in the early 2000s and their potential in the diagnosis of metastasis, in recent years, the hope for personalised cancer management relies more on circulating tumour (ct)DNA that has entered the clinic in a much more efficient way. So far, approved methods for CTCs in the clinic only provide the counting of CTCs, which enables monitoring of the progression of metastatic breast, prostate, and colorectal cancer patients with therapy. Approved methods for ctDNA facilitate the analysis of specific mutations in lung cancer, thereby providing indications for potentially successful treatments. This situation inclined the balance towards molecular analysis in liquid biopsy, leveraged by new technologies and companies providing broader mutation and gene expression analysis towards the early diagnosis of cancer., Study Design: We conducted a search for the studies published to date that provide details about the significance of CTCs in the clinic., Results: Many studies and clinical trials have demonstrated the potential of CTCs in patient screening, early diagnosis, therapy resistance, and patient prognosis., Conclusions: Large multi-centre studies are still needed to formally validate the clinical relevance of CTCs. Meticulous design of the clinical trials is a crucial point to achieve this long-sought objective., (© 2019 S. Karger AG, Basel.)

Liquid biopsy represents the analysis of tumor-derived material in the blood and other body fluids of cancer patients. This portrays a minimally invasive detection tool for molecular biomarkers. Liquid biopsy has emerged as a complementary or alternative method to surgical biopsy. This non-invasive detection tool overcomes the recurrent problems in the clinical assessment of tumors that stem from the lack of accessibility to the tumor tissue and its clonal heterogeneity. Moreover, body fluid-derived components have shown to reflect the genetic profile of both primary and metastatic lesions and provide a real-time monitoring of tumor dynamics, representing a great promise for personalized medicine. This review will highlight the latest breakthroughs and the current applications of several tumor-derived biomarkers that can be found in body fluids. The authors will focus on tumor-derived exosomes, tumor-educated platelets, and circulating tumor miRNAs and mRNAs, and how these can be used for tumor detection., (© 2019 S. Karger AG, Basel.)

Liquid biopsy provides the opportunity of detecting, analyzing and monitoring cancer in various body effluents such as blood or urine instead of a fragment of cancer tissue. It is composed of different biological matrices such as circulating tumor cells (CTCs), cell free nucleic acids, exosomes or tumors "educated platelets." In addition to representing a non- or minimally invasive procedure, it should represent a better view of tumor heterogeneity and allows for real-time monitoring of cancer evolution. Recent technological and molecular advances, greatly facilitated by the use of microfluidics in many cases, have permitted large progresses both in our ability to purify and analyze liquid biopsy components. In particular, the great developments of droplet-based digital PCR and the various optimizations of next generation sequencing technologies are central to the several validations of CTC-free DNA as a strong cancer biomarker. However, complete adoption of liquid biopsy in clinics will require pursuing recent efforts in the standardization of procedures both on the pre-analytical and analytical aspects., (© 2019 S. Karger AG, Basel.)