Enrichment and Analysis of ctDNA.

ctDNA provided by liquid biopsy offers a promising alternative to tumor biopsy as it gives a non-invasive and «real-time» access to the cancer genome and reflects tumor intra and extra heterogeneity. ctDNA has shown growing clinical interest for cancer diagnosis, prognosis, theragnostics, therapeutic monitoring, and clonal evolution tracking. A major technical limit for ctDNA analysis from body fluids is the extremely low proportion of ctDNA compared to non-malignant cell-free DNA, underscoring the need for highly sensitive and specific detection techniques. The control of pre-analytical procedures appears essential for optimal ctDNA analysis and need to be standardized for clinical research applications. This chapter provides insights into major current technologies for ctDNA detection. Overall, PCR-based techniques are able to detect limited molecular alterations and have a high sensitivity suitable for monitoring purposes while NGS-based approaches are broad range molecular screening assays more specifically indicated for treatment selection. We briefly reviewed new technical innovations that are now available for ctDNA detection.