Is liquid biopsy ready for the litmus test and what has been achieved so far to deal with pre-analytical issues?
Currently, published data are scarce for many of the factors which potentially have an impact on the quantity and quality of cell-free nucleic acids. This short review summarizes the data on issues related to the pre-analytical handling of blood samples used for liquid biopsies. These include the use of a tourniquet for blood draw; the effect of the blood tube type; the impact of delayed blood processing, shipping temperature, and plasma preparation; the plasma/serum storage conditions; and the best method for the isolation of DNA from plasma. The fast pace in the development of techniques for the sensitive detection of genetic alterations in cell-free DNA obtained from different body liquids from tumor patients lead to the application of these methods in clinical studies. However, for routine clinical applications and in order to create standards for future guidelines, much more data on the biology of cell-free nucleic acids and their release mechanisms are needed.