Success in liquid biopsy - especially assay sensitivity and early detection of cancer markers - is highly dependent on the assay’s preanalytical steps, such as optimized sample collection and extraction of rare analytes, like ctDNA, ctRNA, and CTC's. Yet, preanalytical steps are often considered a low priority when establishing protocols for liquid biopsy assays. The objective of this presentation is to examine key preanalytical factors and data for the creation of highly sensitive and scalable liquid biopsy assays.