Liquid biopsy (LB) is a minimally invasive method which aims to detect circulating tumor-derived components in body fluids. It provides an alternative to current cancer screening methods that use tissue biopsies for the confirmation of diagnosis. The revolutionary precision that molecular diagnostics can bring to healthcare and the dramatic improvements it can bring to oncology screening and treatment are now widely recognized. However, progress is hampered by several logistical and technical factors. 

The demand for LB tests is inevitably influenced by organizational issues relating to standardization, guidelines, and awareness among physicians and in the patient community, while supply of the tests is a function of the related infrastructure, arrangements for paying for procedures and materials, and how far underlying evidence generates calls for testing. Joint work at both the national and European level should concentrate on promoting cooperation among the widest range of stakeholders.

The development of LB assays is often based on the analysis of whole-genome sequencing (WGS) or whole-exome sequencing (WES) data from tumor tissue samples. It can be further processed into large and/or customized gene panels. The Integrated Mutation Profiling of Actionable Cancer Targets gene panel is FDA approved and was originally developed as a next-generation sequencing (NGS) hybrid assay for targeted deep sequencing. The FDA has already approved several single-gene tests and, more recently, multigene tests to detect genetic changes in plasma cell-free DNA (cfDNA). They would be used as companion diagnostics aligned with specific molecularly targeted therapies for cancer. These approvals are a major milestone for the widespread use of LB in the clinic, particularly in patients with advanced cancer.